Research Article Perborate Oxidation of Substituted 5-Oxoacids in Aqueous Acetic Acid Medium: A Kinetic and Mechanistic Study S. Shree Devi, 1,2 B. Muthukumaran, 3 and P. Krishnamoorthy 4 1 Research and Development Centre, Bharathiar University, Coimbatore 641 046, India 2 Department of Chemistry, Arignar Anna Government Arts College, Cheyyar 604 407, India 3 Department of Chemistry, Presidency College, Chennai 600005, India 4 Department of Chemistry, Dr. Ambedkar Government Arts College, Chennai 600 039, India Correspondence should be addressed to P. Krishnamoorthy; [email protected] Received 22 November 2013; Accepted 5 January 2014; Published 4 February 2014 Academic Editors: M. Sikorski, D. Strout, and D. A. Wild Copyright © 2014 S. Shree Devi et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Kinetics and mechanism of oxidation of substituted 5-oxoacids by sodium perborate in aqueous acetic acid medium have been studied. e reaction exhibits first order both in [perborate] and [5-oxoacid] and second order in [H + ]. Variation in ionic strength has no effect on the reaction rate, while the reaction rates are enhanced on lowering the dielectric constant of the reaction medium. Electron releasing substituents in the aromatic ring accelerate the reaction rate and electron withdrawing substituents retard the reaction. e order of reactivity among the studied 5-oxoacids is p-methoxy ≫ p-methyl > p-phenyl > –H > p-chloro > p-bromo > m-nitro. e oxidation is faster than H 2 O 2 oxidation. e formation of H 2 BO 3 + is the reactive species of perborate in the acid medium. Activation parameters have been evaluated using Arrhenius and Eyring’s plots. A mechanism consistent with the observed kinetic data has been proposed and discussed. Based on the mechanism a suitable rate law is derived. 1. Introduction Sodium perborate (NaBO 3 ⋅4H 2 O) is a nontoxic cheap large scale industrial chemical primarily used as a source of “active oxygen” in detergents and as a mild antiseptic. is active oxygen has the oxidising properties of hydrogen peroxide. PMR spectral analysis [1] and X-ray diffraction studies [2] conclude that perborate is a true peroxy salt with water of crystallisation. Perborate is a heterocycle and is in a dimeric tetrahedral configuration with dihedral angle of 64 ∘ and anionic formula: B 2 (O 2 ) 2 (OH) 4 2− [3]. Oxidative study suggests perborate as not peroxoborate but borate peroxyhy- drate. Hydrogen peroxide acquires stronger electrophilicity by the coordination with borate [4]. It is an effective reagent in organic synthesis and acetic acid is the solvent of choice [5– 7]. Perborate in aqueous solution yields hydrogen peroxide and the kinetic studies in aqueous and partly aqueous acidic media confirm that perborate oxidation is hydrogen peroxide oxidation [8–10]. is stable and easily handled crystalline substance oxidizes organic sulphides [11–13], anilines [14], and indole [15]. 5-Oxoacid is an attractive substrate in terms of its enolization. In strong acid medium the substrate undergoes enolization. e reactive species of the substrate has been reported in the literature to be the enol form [16, 17]. In recent years, studies of the oxidation of various organic compounds by perborate have attracted considerable attention. A thorough literature survey reveals that relatively little work on the oxidation of oxoacid has been reported so far [18–21]. Although the perborate oxidation of organic compounds has been studied, there seems to be no report on a systematic kinetic study of the oxidation of 5-oxoacids by perborate and we report here for the first time the kinetics and mechanism of perborate oxidation of substituted and unsubstituted 5-oxoacids. e various unsubstituted and substituted 5-oxoacids (S1–S7) employed in the present study are listed in Figure 1. Hindawi Publishing Corporation ISRN Physical Chemistry Volume 2014, Article ID 924827, 7 pages http://dx.doi.org/10.1155/2014/924827
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Research ArticlePerborate Oxidation of Substituted 5-Oxoacids in AqueousAcetic Acid Medium A Kinetic and Mechanistic Study
S Shree Devi12 B Muthukumaran3 and P Krishnamoorthy4
1 Research and Development Centre Bharathiar University Coimbatore 641 046 India2Department of Chemistry Arignar Anna Government Arts College Cheyyar 604 407 India3 Department of Chemistry Presidency College Chennai 600005 India4Department of Chemistry Dr Ambedkar Government Arts College Chennai 600 039 India
Correspondence should be addressed to P Krishnamoorthy krishthihotmailcouk
Received 22 November 2013 Accepted 5 January 2014 Published 4 February 2014
Academic Editors M Sikorski D Strout and D A Wild
Copyright copy 2014 S Shree Devi et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Kinetics and mechanism of oxidation of substituted 5-oxoacids by sodium perborate in aqueous acetic acid medium have beenstudied The reaction exhibits first order both in [perborate] and [5-oxoacid] and second order in [H+] Variation in ionic strengthhas no effect on the reaction rate while the reaction rates are enhanced on lowering the dielectric constant of the reaction mediumElectron releasing substituents in the aromatic ring accelerate the reaction rate and electron withdrawing substituents retard thereaction The order of reactivity among the studied 5-oxoacids is p-methoxy≫ p-methyl gt p-phenyl gt ndashH gt p-chloro gt p-bromogt m-nitro The oxidation is faster than H
2O2oxidation The formation of H
2BO3
+ is the reactive species of perborate in the acidmedium Activation parameters have been evaluated usingArrhenius and Eyringrsquos plots Amechanism consistent with the observedkinetic data has been proposed and discussed Based on the mechanism a suitable rate law is derived
1 Introduction
Sodium perborate (NaBO3sdot4H2O) is a nontoxic cheap large
scale industrial chemical primarily used as a source of ldquoactiveoxygenrdquo in detergents and as a mild antiseptic This activeoxygen has the oxidising properties of hydrogen peroxidePMR spectral analysis [1] and X-ray diffraction studies [2]conclude that perborate is a true peroxy salt with waterof crystallisation Perborate is a heterocycle and is in adimeric tetrahedral configuration with dihedral angle of 64∘
and anionic formula B2(O2)2(OH)4
2minus [3] Oxidative studysuggests perborate as not peroxoborate but borate peroxyhy-drate Hydrogen peroxide acquires stronger electrophilicityby the coordination with borate [4] It is an effective reagentin organic synthesis and acetic acid is the solvent of choice [5ndash7] Perborate in aqueous solution yields hydrogen peroxideand the kinetic studies in aqueous and partly aqueous acidicmedia confirm that perborate oxidation is hydrogen peroxideoxidation [8ndash10] This stable and easily handled crystalline
substance oxidizes organic sulphides [11ndash13] anilines [14]and indole [15]
5-Oxoacid is an attractive substrate in terms of itsenolization In strong acid medium the substrate undergoesenolization The reactive species of the substrate has beenreported in the literature to be the enol form [16 17]
In recent years studies of the oxidation of variousorganic compounds by perborate have attracted considerableattention A thorough literature survey reveals that relativelylittle work on the oxidation of oxoacid has been reportedso far [18ndash21] Although the perborate oxidation of organiccompounds has been studied there seems to be no reporton a systematic kinetic study of the oxidation of 5-oxoacidsby perborate and we report here for the first time thekinetics andmechanism of perborate oxidation of substitutedand unsubstituted 5-oxoacidsThe various unsubstituted andsubstituted 5-oxoacids (S1ndashS7) employed in the present studyare listed in Figure 1
Hindawi Publishing CorporationISRN Physical ChemistryVolume 2014 Article ID 924827 7 pageshttpdxdoiorg1011552014924827
2 ISRN Physical Chemistry
0
02
04
06
08
10
log[
perb
orat
e]
0 200 400 600 800 1000
Time (min)p-OCH3
p-CH3
p-C6H5
ndashH
p-Clp-Brm-NO2
Figure 1 S1 unsubstituted S2 41015840-methoxy S3 41015840-methyl S4 41015840-phenyl S5 41015840-chloro S6 41015840-bromo and S7 31015840-nitro
2 Experimental
21 Materials Sodium perborate NaBO3sdot4H2O (Riedel)
was used as received Acetic acid (BDH) was refluxed for6 h over chromium (VI) oxide and distilled through acolumn Aqueous solutions of perborate were preparedas and when required and standardized iodometricallySodium metaborate and perchloric acid were prepared indouble distilled water Double distilled water (conductivitylt 10 120583Ssdotcmminus1) has been employed in all kinetic runs Allthe chemicals used were 998 pure The parent 5-oxoacidnamely 5-oxo-5-phenylpentanoic acid (S1) and the phenyl
substituted 5-oxoacids (S2ndashS7) were prepared by Friedel-Crafts acylation of the substituted benzene with glutaricanhydride [22ndash26] All the 5-oxoacids were crystallized twicefrom water and their purity was checked by their meltingpoints and UV IR and NMR spectra All other chemicalswere of analytical grade
All absorption measurements were made with ShimadzuUV-visible spectrophotometer (MPS-5000) equipped with atemperature controller Regression analysis of experimentaldata yielded the regression coefficient (r) and standarddeviation (s)
22 Kinetic Measurements The reaction mixture contain-ing 5-oxoacid and sulphuric acid solutions was thermallyequilibrated and the reaction was initiated by the additionof temperature-equilibrated perborate solution of requisiteconcentration The oxidation kinetics was followed in aque-ous acetic acid at constant temperature by measuring theconcentration of benzoic acid formed iodometrically underpseudo-first order conditions by keeping the substrate inexcess over the oxidant The pseudo-first-order rate constant(1198961015840) was calculated from the slope of the linear plot ofln [perborate] versus time by the method of least squaresThe error quoted in 1198961015840 is the 95 confidence limit of theStudentrsquos t-test The progress of the oxidation was followedby iodometric determination of the oxidant Freshly preparedsolutions of oxoacids in purified acetic acidwere used to avoidany possible side reactions
23 Reaction Stoichiometry and Product Analysis The stoi-chiometry of the reaction was determined by equilibratingreaction mixture of various [perborate][5-oxoacid] ratios at313 K for 12 h keeping all other reagents constant Estimationof unconsumed perborate (iodometrically) revealed that onemole of 5-oxoacid consumed one mole of perborate
R
O
OH
O
R COH
O HOOC
COOH
(HO)2BO++
+
H2O
+ +H3BO3 4H+
(1)
The products were extracted with ether dried and analyzedBenzoic acid was identified by its melting point (121∘C)Then it has been estimated quantitatively using UV-Visspectrophotometry with a standard curve at 120582max = 235 nmSuccinic acid was identified by its melting point (185∘C) andalso tested with its characteristic spot test [27] Identificationof the products namely benzoic and succinic acids was alsomade by comparing the 119877
119891values of the authentic samples
Boric acid was identified by adding an alkaline solutionof benzoin resulting in the formation of a yellow-greenfluorescent complex
3 Results and Discussion
At fixed concentrations of acid and substrate the decrease inthe concentration of perborate is followed first order kineticsThe first order rate constants (119896
1) were calculated from the
linear plots (r ge 098 s le 003) of log [perborate] against timeSuch plots are linear for more than three half-lives of thereaction (Figure 2) The 119896
1value was independent of initial
[perborate] for all the studied substratesThe reactions of all the studied 5-oxoacids are first order
in the [substrate] (Table 1) and in [H+]2 in the range of
ISRN Physical Chemistry 3
Table 1 Effect of varying [substrate] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Perborate] = 0001mol dmminus3 [H2SO4] =20molmolminus3 HOAc-H2O = 1 1 (vv)
[5-oxo acid] (mol dmminus3) 105
times 119896obs (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
0005 9591 1344 943 636 214 177 077001 1919 2685 2167 1278 425 215 1520015 2879 4033 2998 1920 640 443 234002 3837 5371 3671 2559 851 574 305003 5758 8059 6076 3814 1278 892 456004 7677 1075 12491 5113 1715 1253 605006 1152 1613 14224 7675 2559 1753 910aMean of duplicate experiments
27 28 29 3 31 32 33 34 35 36
1T times 103 (Kminus1)
0
1
2
3
4
5
7+logk
3572K
p-OCH3
p-CH3
p-C6H5
ndashH
p-Clp-Brm-NO2
Figure 2 Typical first order plots in the perborate oxidation of 5-oxoacids
05ndash40mol dmminus3 sulphuric acid (Table 2) From the Zucker-Hammett plots of log 119896 versus ndashHo the slopes obtained werein the range of 10ndash12 indicating the noninvolvement ofwater molecule in the rate determining step The Ho valueswere taken from Long and Paul [28] assuming that the Hovalues do not change much in a media containing acetic acidup to 50
The effect of dielectric constant (119863) on the rate of reactionwas studied by varying acetic acid-water content in thereactionmixture Acetic acid does not react with the oxidants[29] yet the rate of the reaction is enhanced by increasingacetic acid content of the medium (Table 3) Also log 119896against 1119863 is found linear suggesting a positive ion-dipoletype of interaction [30] in the rate determining step
There was no induced polymerization of acrylonitrilemonomer ruling out the possibility of free radical formationduring the course of the reaction
In the temperature range of 298ndash323K in 20mol dmminus3sulphuric acid and acetic acid-water medium (50 vv)
(Figure 3) the activation energy (119864119886) and related thermody-
namic parameters (Δ119867 Δ119866 and Δ119878) were evaluated Theplot between Δ119867 and Δ119878 is linear (Figure 4 r ge 098 s le0028) and the isokinetic temperature (120573) obtained is 357KThe isokinetic relationship in the present study implies thatall the 5-oxoacids undergo oxidation by the samemechanism[31]
The effect of substituents on the rate of oxidationwas studied using different phenyl substituted 5-oxoacids(ArCOCH
2CH2CH2COOH where Ar = 41015840-methoxy 41015840-
methyl 41015840-phenyl 41015840-chloro 41015840-bromo 31015840-nitro substitutedphenyl) at different temperatures In all these cases thereaction orders are the same namely first order with respectto [oxidant] and [substrate] and second order with respectto [acid] Electron releasing substituents in the phenyl ringenhance the rate of oxidation and electron withdrawingsubstituents decrease it (Table 4) The order of reactivityamong the studied 5-oxoacids is p-methoxy ≫p-methyl gtp-phenyl gt ndashH gt p-chloro gt p-bromo gt m-nitrophenylsubstituted 5-oxoacids The Hammett plots of log 119896 versus120590 (substituent constant) are smooth curves and concavedownward at all the studied temperatures However theHammett plots are linear with good correlation coefficient atfour different temperatureswhen exalted substituent constant(Brownrsquos 120590+) values are used (Figure 5)The reaction constant(120588+) is negative and decreases (in magnitude) from minus165 tominus132 with increasing temperature from 303K to 323K TheHammett lines intersect at a point correspondent to a 120590+isovalue ofminus142 and a 119896iso value of 1318times 10
minus3 sminus1 (Figure 5) Anoxoacid with a substituent having this 120590+ value (minus142) willbe oxidized by perborate at the same rate at all temperaturesSuch insensitivity of the reaction rate to temperature is apointer to the existence of an isokinetic phenomenon
A reaction series which exhibits a common point of inter-section in the Hammett plot (Figure 5) is expected to have acommon point of intersection in the Arrhenius plot as well[32] From the plots of Δ119867 against Δ119878 and 120588 against 1119879the119879iso value is found to be 359K which is in good agreementwith the value obtained from the slope of Exnerrsquos plot
31 Mechanism In aqueous acetic acid the possible oxidizingspecies of perborate are perborate anion perboric acidperacetic acid and H
2O2 Even though isolation of free
4 ISRN Physical Chemistry
Table 2 Effect of varying [H2SO4] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate] =0001mol dmminus3 HOAc-H2O = 1 1 (vv)
[H2SO4] (mol dmminus3) minusHo105
times 119896 (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
051 minus013 1189 231 187 158 mdash mdash mdash075 007 2993 438 328 288 mdash mdash mdash101 026 4798 768 519 452 127 121 118149 056 9596 1598 1267 884 232 198 126201 084 1919 2687 1928 1278 426 309 152249 112 2879 4798 3869 2559 719 516 257300 138 4798 1343 7981 3485 1279 728 397401 185 1151 2878 14063 5758 2558 1689 769119878b 201 201 20 200 201 20 200119899c 13 10 10 10 11 11 10
aMean of duplicate experiments bslopes of log k versus log [H2SO4]cslopes of the Zucker-Hammett plots
Table 3 Effect of varying solvent composition on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3[perborate] = 0001mol dmminus3 [H2SO4] = 20molmolminus3
ACOH-H2O (vv ) 105
times 119896 (sminus1)b
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
30 70 (5318) 638 950 867 760 238 197 11840 60 (4648) 1152 1310 1186 960 310 212 12950 50 (3978) 1918 2687 1873 1280 427 362 15060 40 (3308) 586 4470 3101 1590 720 489 17570 30 (2638) 1751 1629 7123 3830 1280 761 269aValues of dielectric constant of the media are given in parentheses bmean of duplicate experiments
20
40
60
80
100
120
140
160
(KJ m
ol)
minus50 0 50 100 150 200 250
(m-NO2)
(p-Br)
(p-Cl)
(ndashH)
(p-C6H5)
(p-CH3)
(p-OCH3)
(JKminus1 molminus1)
minus1
minusΔS
ΔH
Figure 3 Arrhenius plots of log 119896 against 1119879 showing the isokinetictemperature
perboric acid has been proved exceedingly difficult it hasdemonstrable existence in solution [33] Perborate is reportedto exist in a dimeric tetrahedral configuration with theanionic formula B
2(O2)2(OH)4
2minus The oxidation has beencarried out in aqueous acetic acid and from the ionizationconstant of perboric acid reported as (06ndash16) times 10minus8 it
Table 4 Effect of substituent on the rate of oxidation of 5-oxoacidsby perborate at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate]= 0001mol dmminus3 [H2SO4] = 20molmolminus3 HOAC-H2O = 1 1vv
Substituent 120590 120590+
105
times 119896 (sminus1) 5 + log kp-OCH3 minus027 minus078 1918 22829p-CH3 minus017 minus031 269 14293p-C6H5 minus011 minus022 188 12623minusH 000 000 128 11070p-Cl 023 011 43 06299p-Br 043 038 27 03470m-NO2 071 067 15 01802
may be concluded that perborate exists mainly as perboricacid in aqueous acetic acid at very low pH maintained withsulphuric acid and hence is unlikely to be the oxidant Therate of perborate oxidation in aqueous acetic acid compareswith that in aqueous ethanol and hence the oxidation is notthrough peracetic acid H
2O2is less likely to be the oxidant
as the rate of H2O2oxidation is about one-fifth of that of
perborate oxidation The enhancement of reaction rate withan increase in the amount of acetic acid and linear plots oflog 119896 versus 1119863 with positive slopes indicate an interactionbetween a positive ion and a dipole molecule in the slowstep This supports the postulation of H
2BO3
+ as the reactive
ISRN Physical Chemistry 5
0
1
2
3
4
5
7+logk
kiso = 1318 times 10minus3 (sminus1)
minus16 minus12 minus08 minus04 00 04 08 12
120590+
323K 308K303K318K
313K
120590+iso = minus142
Figure 4 Plot of Δ119867 against minusΔ119878 showing the isokinetic relationship
O
OH
O
12
3
45
1998400
2998400
39984004998400
5998400
6998400
5-oxoacid (S1)
Figure 5 Hammett plots of log 119896 against 120590+at different tempera-
tures
species of perborate in the acidmediumThe rate accelerationwith an increase in [acid] and second order dependence ofrate on [acid] in the range studied also confirm that H
2BO3
+
is the reactive species of perborate taking part in the oxidationof 5-oxoacids
The oxoacid is a weak acid (119901119870119886= 577 at 40∘C in
aqueous solution) [34] and the undissociated form of thesubstrate can be taken as the only form in acidic media Inacid solutions 5-oxoacid undergoes keto enol tautomerism(2)
O
OH
O OH
OH
O
(keto form) (enol form)H+
Ke(2)
In oxidation reactions the keto group of the substrate canreact either directly or through the enol form Oxidationrates faster than the rates of enolization have been observedwith ceric ion [35] manganic ion [36] cobaltic vanadateions [37] mercuric perchlorate [38] and alkaline diperiodateargenate(III) [39] as oxidants indicating that the keto groupof the substrate reacts directly All of these oxidants undergoone-electron reduction and the reactions proceeded via a freeradical mechanism [35ndash39]
The rates of oxidation and enolization were found to beequal in the oxidation reactions by manganic pyrophosphate[40] thallium triacetate [41] and by diperiodatonickelate(IV) [42] These reactions were zero order in [oxidant]indicating the enol formation as the rate determining step
In the present study the rate of enolization (measuredby the bromination method [43]) is greater than the rate ofoxidation by a factor ofsim13ndash15 and the enolization step can bevisualized as proceeding via the enol form of the keto groupof 5-oxoacid Hence the step involving enol formation can beassumed to be a fast step and thus is not the rate determiningstep of the reactionThe most plausible mechanism thereforeseems to be shown in Scheme 1 The proposed mechanism isalso in accordance with the observed stoichiometry The rateequation in consonance with the mechanism proposed is asgiven in the following equation
minus119889 [perborate]119889119905
= 119870119901119870119890119896[H+]2 [5-oxoacid] [perborate]
(3)
6 ISRN Physical Chemistry
O
OH
O
(keto form)
OH
OH
O
(enol form)(I) (II)
OH
OH
O
(enol form)(II)
+k
(III)
Slow
Fast
Fast
(V)
+
(IV)
B+
OH
HO O
C+
OHC OH
OH
OB
OHH
C OH
OH
COH
OB
OH
O
C
OOH
HOOC
COOH++
(HO)2BOOH + H+ (HO)2BO+ + H2O
H+
Ke
Kp
minusH+
H3BO34H+
Scheme 1 Formations of benzoic acid and succinic acid were the final products of oxidation
The obtained rate law could explain the second order in [H+]and first order both in [perborate] and [5-oxoacid]
4 Conclusions
The above study shows that the H2BO3
+ reacts with the enolform of 5-oxoacid in the rate determining step giving thecyclic boronate ester Decomposition of the boronate esterresults in the cleavage of the carbon-carbon bond yieldingcarboxylic acids This experimental protocol suggests thatthis reaction could find utility as a regioselective route for thesynthesis of carboxylic acids specially succinic and benzoicacids
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] T M Connor and R E Richards ldquoNuclear resonance spectra ofsome peroxy-saltsrdquo Journal of the Chemical Society pp 289ndash2931958
[2] J O Edwards and V F Ross ldquoThe Structural chemistry of theboratesrdquo in The Chemistry of Boron and Its Compounds E LMuetterties Ed p 192 JohnWileyamp Sons NewYorkNYUSA1967
[3] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988
[4] Y Ogata and H Shimizu ldquoOxidation of organic compoundswith perborates or H
2O2ndashboric acidsrdquo Bulletin of the Chemical
Society of Japan vol 52 no 2 pp 635ndash636 1979[5] A McKillop and W R Sanderson ldquoSodium perborate and
sodium percarbonate cheap safe and versatile oxidising agentsfor organic synthesisrdquo Tetrahedron vol 51 no 22 pp 6145ndash6166 1995
[6] A McKillop and W R Sanderson ldquoSodium perborate andsodiumpercarbonate further applications in organic synthesisrdquoJournal of the Chemical Society Perkin Transactions vol 1 no 4pp 471ndash476 2000
[7] J Muzart ldquoSodium perborate and sodium percarbonate inorganic synthesisrdquo Synthesis no 11 pp 1325ndash1347 1995
[8] C Karunakaran and P N Palanisamy ldquoKinetic evidence for(NN-dimethylaniline)-oxodiperoxomolybdenum(VI) or tung-sten(VI) as oxidizing species in molybdenum(VI) or tung-sten(VI) catalyzed hydrogen peroxide (Perborate) oxidation ofNN-dimethylanilinerdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 28 pp 1115ndash1125 1998
[9] C Karunakaran and B Muthukumaran ldquoZirconium(IV) catal-ysis in perborate oxidation of iodiderdquo Reaction Kinetics andCatalysis Letters vol 60 pp 387ndash394 1997
[10] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
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Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
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Chromatography Research International
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Applied ChemistryJournal of
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Theoretical ChemistryJournal of
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Journal of
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Analytical ChemistryInternational Journal of
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Quantum Chemistry
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Organic Chemistry International
ElectrochemistryInternational Journal of
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
2 ISRN Physical Chemistry
0
02
04
06
08
10
log[
perb
orat
e]
0 200 400 600 800 1000
Time (min)p-OCH3
p-CH3
p-C6H5
ndashH
p-Clp-Brm-NO2
Figure 1 S1 unsubstituted S2 41015840-methoxy S3 41015840-methyl S4 41015840-phenyl S5 41015840-chloro S6 41015840-bromo and S7 31015840-nitro
2 Experimental
21 Materials Sodium perborate NaBO3sdot4H2O (Riedel)
was used as received Acetic acid (BDH) was refluxed for6 h over chromium (VI) oxide and distilled through acolumn Aqueous solutions of perborate were preparedas and when required and standardized iodometricallySodium metaborate and perchloric acid were prepared indouble distilled water Double distilled water (conductivitylt 10 120583Ssdotcmminus1) has been employed in all kinetic runs Allthe chemicals used were 998 pure The parent 5-oxoacidnamely 5-oxo-5-phenylpentanoic acid (S1) and the phenyl
substituted 5-oxoacids (S2ndashS7) were prepared by Friedel-Crafts acylation of the substituted benzene with glutaricanhydride [22ndash26] All the 5-oxoacids were crystallized twicefrom water and their purity was checked by their meltingpoints and UV IR and NMR spectra All other chemicalswere of analytical grade
All absorption measurements were made with ShimadzuUV-visible spectrophotometer (MPS-5000) equipped with atemperature controller Regression analysis of experimentaldata yielded the regression coefficient (r) and standarddeviation (s)
22 Kinetic Measurements The reaction mixture contain-ing 5-oxoacid and sulphuric acid solutions was thermallyequilibrated and the reaction was initiated by the additionof temperature-equilibrated perborate solution of requisiteconcentration The oxidation kinetics was followed in aque-ous acetic acid at constant temperature by measuring theconcentration of benzoic acid formed iodometrically underpseudo-first order conditions by keeping the substrate inexcess over the oxidant The pseudo-first-order rate constant(1198961015840) was calculated from the slope of the linear plot ofln [perborate] versus time by the method of least squaresThe error quoted in 1198961015840 is the 95 confidence limit of theStudentrsquos t-test The progress of the oxidation was followedby iodometric determination of the oxidant Freshly preparedsolutions of oxoacids in purified acetic acidwere used to avoidany possible side reactions
23 Reaction Stoichiometry and Product Analysis The stoi-chiometry of the reaction was determined by equilibratingreaction mixture of various [perborate][5-oxoacid] ratios at313 K for 12 h keeping all other reagents constant Estimationof unconsumed perborate (iodometrically) revealed that onemole of 5-oxoacid consumed one mole of perborate
R
O
OH
O
R COH
O HOOC
COOH
(HO)2BO++
+
H2O
+ +H3BO3 4H+
(1)
The products were extracted with ether dried and analyzedBenzoic acid was identified by its melting point (121∘C)Then it has been estimated quantitatively using UV-Visspectrophotometry with a standard curve at 120582max = 235 nmSuccinic acid was identified by its melting point (185∘C) andalso tested with its characteristic spot test [27] Identificationof the products namely benzoic and succinic acids was alsomade by comparing the 119877
119891values of the authentic samples
Boric acid was identified by adding an alkaline solutionof benzoin resulting in the formation of a yellow-greenfluorescent complex
3 Results and Discussion
At fixed concentrations of acid and substrate the decrease inthe concentration of perborate is followed first order kineticsThe first order rate constants (119896
1) were calculated from the
linear plots (r ge 098 s le 003) of log [perborate] against timeSuch plots are linear for more than three half-lives of thereaction (Figure 2) The 119896
1value was independent of initial
[perborate] for all the studied substratesThe reactions of all the studied 5-oxoacids are first order
in the [substrate] (Table 1) and in [H+]2 in the range of
ISRN Physical Chemistry 3
Table 1 Effect of varying [substrate] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Perborate] = 0001mol dmminus3 [H2SO4] =20molmolminus3 HOAc-H2O = 1 1 (vv)
[5-oxo acid] (mol dmminus3) 105
times 119896obs (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
0005 9591 1344 943 636 214 177 077001 1919 2685 2167 1278 425 215 1520015 2879 4033 2998 1920 640 443 234002 3837 5371 3671 2559 851 574 305003 5758 8059 6076 3814 1278 892 456004 7677 1075 12491 5113 1715 1253 605006 1152 1613 14224 7675 2559 1753 910aMean of duplicate experiments
27 28 29 3 31 32 33 34 35 36
1T times 103 (Kminus1)
0
1
2
3
4
5
7+logk
3572K
p-OCH3
p-CH3
p-C6H5
ndashH
p-Clp-Brm-NO2
Figure 2 Typical first order plots in the perborate oxidation of 5-oxoacids
05ndash40mol dmminus3 sulphuric acid (Table 2) From the Zucker-Hammett plots of log 119896 versus ndashHo the slopes obtained werein the range of 10ndash12 indicating the noninvolvement ofwater molecule in the rate determining step The Ho valueswere taken from Long and Paul [28] assuming that the Hovalues do not change much in a media containing acetic acidup to 50
The effect of dielectric constant (119863) on the rate of reactionwas studied by varying acetic acid-water content in thereactionmixture Acetic acid does not react with the oxidants[29] yet the rate of the reaction is enhanced by increasingacetic acid content of the medium (Table 3) Also log 119896against 1119863 is found linear suggesting a positive ion-dipoletype of interaction [30] in the rate determining step
There was no induced polymerization of acrylonitrilemonomer ruling out the possibility of free radical formationduring the course of the reaction
In the temperature range of 298ndash323K in 20mol dmminus3sulphuric acid and acetic acid-water medium (50 vv)
(Figure 3) the activation energy (119864119886) and related thermody-
namic parameters (Δ119867 Δ119866 and Δ119878) were evaluated Theplot between Δ119867 and Δ119878 is linear (Figure 4 r ge 098 s le0028) and the isokinetic temperature (120573) obtained is 357KThe isokinetic relationship in the present study implies thatall the 5-oxoacids undergo oxidation by the samemechanism[31]
The effect of substituents on the rate of oxidationwas studied using different phenyl substituted 5-oxoacids(ArCOCH
2CH2CH2COOH where Ar = 41015840-methoxy 41015840-
methyl 41015840-phenyl 41015840-chloro 41015840-bromo 31015840-nitro substitutedphenyl) at different temperatures In all these cases thereaction orders are the same namely first order with respectto [oxidant] and [substrate] and second order with respectto [acid] Electron releasing substituents in the phenyl ringenhance the rate of oxidation and electron withdrawingsubstituents decrease it (Table 4) The order of reactivityamong the studied 5-oxoacids is p-methoxy ≫p-methyl gtp-phenyl gt ndashH gt p-chloro gt p-bromo gt m-nitrophenylsubstituted 5-oxoacids The Hammett plots of log 119896 versus120590 (substituent constant) are smooth curves and concavedownward at all the studied temperatures However theHammett plots are linear with good correlation coefficient atfour different temperatureswhen exalted substituent constant(Brownrsquos 120590+) values are used (Figure 5)The reaction constant(120588+) is negative and decreases (in magnitude) from minus165 tominus132 with increasing temperature from 303K to 323K TheHammett lines intersect at a point correspondent to a 120590+isovalue ofminus142 and a 119896iso value of 1318times 10
minus3 sminus1 (Figure 5) Anoxoacid with a substituent having this 120590+ value (minus142) willbe oxidized by perborate at the same rate at all temperaturesSuch insensitivity of the reaction rate to temperature is apointer to the existence of an isokinetic phenomenon
A reaction series which exhibits a common point of inter-section in the Hammett plot (Figure 5) is expected to have acommon point of intersection in the Arrhenius plot as well[32] From the plots of Δ119867 against Δ119878 and 120588 against 1119879the119879iso value is found to be 359K which is in good agreementwith the value obtained from the slope of Exnerrsquos plot
31 Mechanism In aqueous acetic acid the possible oxidizingspecies of perborate are perborate anion perboric acidperacetic acid and H
2O2 Even though isolation of free
4 ISRN Physical Chemistry
Table 2 Effect of varying [H2SO4] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate] =0001mol dmminus3 HOAc-H2O = 1 1 (vv)
[H2SO4] (mol dmminus3) minusHo105
times 119896 (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
051 minus013 1189 231 187 158 mdash mdash mdash075 007 2993 438 328 288 mdash mdash mdash101 026 4798 768 519 452 127 121 118149 056 9596 1598 1267 884 232 198 126201 084 1919 2687 1928 1278 426 309 152249 112 2879 4798 3869 2559 719 516 257300 138 4798 1343 7981 3485 1279 728 397401 185 1151 2878 14063 5758 2558 1689 769119878b 201 201 20 200 201 20 200119899c 13 10 10 10 11 11 10
aMean of duplicate experiments bslopes of log k versus log [H2SO4]cslopes of the Zucker-Hammett plots
Table 3 Effect of varying solvent composition on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3[perborate] = 0001mol dmminus3 [H2SO4] = 20molmolminus3
ACOH-H2O (vv ) 105
times 119896 (sminus1)b
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
30 70 (5318) 638 950 867 760 238 197 11840 60 (4648) 1152 1310 1186 960 310 212 12950 50 (3978) 1918 2687 1873 1280 427 362 15060 40 (3308) 586 4470 3101 1590 720 489 17570 30 (2638) 1751 1629 7123 3830 1280 761 269aValues of dielectric constant of the media are given in parentheses bmean of duplicate experiments
20
40
60
80
100
120
140
160
(KJ m
ol)
minus50 0 50 100 150 200 250
(m-NO2)
(p-Br)
(p-Cl)
(ndashH)
(p-C6H5)
(p-CH3)
(p-OCH3)
(JKminus1 molminus1)
minus1
minusΔS
ΔH
Figure 3 Arrhenius plots of log 119896 against 1119879 showing the isokinetictemperature
perboric acid has been proved exceedingly difficult it hasdemonstrable existence in solution [33] Perborate is reportedto exist in a dimeric tetrahedral configuration with theanionic formula B
2(O2)2(OH)4
2minus The oxidation has beencarried out in aqueous acetic acid and from the ionizationconstant of perboric acid reported as (06ndash16) times 10minus8 it
Table 4 Effect of substituent on the rate of oxidation of 5-oxoacidsby perborate at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate]= 0001mol dmminus3 [H2SO4] = 20molmolminus3 HOAC-H2O = 1 1vv
Substituent 120590 120590+
105
times 119896 (sminus1) 5 + log kp-OCH3 minus027 minus078 1918 22829p-CH3 minus017 minus031 269 14293p-C6H5 minus011 minus022 188 12623minusH 000 000 128 11070p-Cl 023 011 43 06299p-Br 043 038 27 03470m-NO2 071 067 15 01802
may be concluded that perborate exists mainly as perboricacid in aqueous acetic acid at very low pH maintained withsulphuric acid and hence is unlikely to be the oxidant Therate of perborate oxidation in aqueous acetic acid compareswith that in aqueous ethanol and hence the oxidation is notthrough peracetic acid H
2O2is less likely to be the oxidant
as the rate of H2O2oxidation is about one-fifth of that of
perborate oxidation The enhancement of reaction rate withan increase in the amount of acetic acid and linear plots oflog 119896 versus 1119863 with positive slopes indicate an interactionbetween a positive ion and a dipole molecule in the slowstep This supports the postulation of H
2BO3
+ as the reactive
ISRN Physical Chemistry 5
0
1
2
3
4
5
7+logk
kiso = 1318 times 10minus3 (sminus1)
minus16 minus12 minus08 minus04 00 04 08 12
120590+
323K 308K303K318K
313K
120590+iso = minus142
Figure 4 Plot of Δ119867 against minusΔ119878 showing the isokinetic relationship
O
OH
O
12
3
45
1998400
2998400
39984004998400
5998400
6998400
5-oxoacid (S1)
Figure 5 Hammett plots of log 119896 against 120590+at different tempera-
tures
species of perborate in the acidmediumThe rate accelerationwith an increase in [acid] and second order dependence ofrate on [acid] in the range studied also confirm that H
2BO3
+
is the reactive species of perborate taking part in the oxidationof 5-oxoacids
The oxoacid is a weak acid (119901119870119886= 577 at 40∘C in
aqueous solution) [34] and the undissociated form of thesubstrate can be taken as the only form in acidic media Inacid solutions 5-oxoacid undergoes keto enol tautomerism(2)
O
OH
O OH
OH
O
(keto form) (enol form)H+
Ke(2)
In oxidation reactions the keto group of the substrate canreact either directly or through the enol form Oxidationrates faster than the rates of enolization have been observedwith ceric ion [35] manganic ion [36] cobaltic vanadateions [37] mercuric perchlorate [38] and alkaline diperiodateargenate(III) [39] as oxidants indicating that the keto groupof the substrate reacts directly All of these oxidants undergoone-electron reduction and the reactions proceeded via a freeradical mechanism [35ndash39]
The rates of oxidation and enolization were found to beequal in the oxidation reactions by manganic pyrophosphate[40] thallium triacetate [41] and by diperiodatonickelate(IV) [42] These reactions were zero order in [oxidant]indicating the enol formation as the rate determining step
In the present study the rate of enolization (measuredby the bromination method [43]) is greater than the rate ofoxidation by a factor ofsim13ndash15 and the enolization step can bevisualized as proceeding via the enol form of the keto groupof 5-oxoacid Hence the step involving enol formation can beassumed to be a fast step and thus is not the rate determiningstep of the reactionThe most plausible mechanism thereforeseems to be shown in Scheme 1 The proposed mechanism isalso in accordance with the observed stoichiometry The rateequation in consonance with the mechanism proposed is asgiven in the following equation
minus119889 [perborate]119889119905
= 119870119901119870119890119896[H+]2 [5-oxoacid] [perborate]
(3)
6 ISRN Physical Chemistry
O
OH
O
(keto form)
OH
OH
O
(enol form)(I) (II)
OH
OH
O
(enol form)(II)
+k
(III)
Slow
Fast
Fast
(V)
+
(IV)
B+
OH
HO O
C+
OHC OH
OH
OB
OHH
C OH
OH
COH
OB
OH
O
C
OOH
HOOC
COOH++
(HO)2BOOH + H+ (HO)2BO+ + H2O
H+
Ke
Kp
minusH+
H3BO34H+
Scheme 1 Formations of benzoic acid and succinic acid were the final products of oxidation
The obtained rate law could explain the second order in [H+]and first order both in [perborate] and [5-oxoacid]
4 Conclusions
The above study shows that the H2BO3
+ reacts with the enolform of 5-oxoacid in the rate determining step giving thecyclic boronate ester Decomposition of the boronate esterresults in the cleavage of the carbon-carbon bond yieldingcarboxylic acids This experimental protocol suggests thatthis reaction could find utility as a regioselective route for thesynthesis of carboxylic acids specially succinic and benzoicacids
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] T M Connor and R E Richards ldquoNuclear resonance spectra ofsome peroxy-saltsrdquo Journal of the Chemical Society pp 289ndash2931958
[2] J O Edwards and V F Ross ldquoThe Structural chemistry of theboratesrdquo in The Chemistry of Boron and Its Compounds E LMuetterties Ed p 192 JohnWileyamp Sons NewYorkNYUSA1967
[3] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988
[4] Y Ogata and H Shimizu ldquoOxidation of organic compoundswith perborates or H
2O2ndashboric acidsrdquo Bulletin of the Chemical
Society of Japan vol 52 no 2 pp 635ndash636 1979[5] A McKillop and W R Sanderson ldquoSodium perborate and
sodium percarbonate cheap safe and versatile oxidising agentsfor organic synthesisrdquo Tetrahedron vol 51 no 22 pp 6145ndash6166 1995
[6] A McKillop and W R Sanderson ldquoSodium perborate andsodiumpercarbonate further applications in organic synthesisrdquoJournal of the Chemical Society Perkin Transactions vol 1 no 4pp 471ndash476 2000
[7] J Muzart ldquoSodium perborate and sodium percarbonate inorganic synthesisrdquo Synthesis no 11 pp 1325ndash1347 1995
[8] C Karunakaran and P N Palanisamy ldquoKinetic evidence for(NN-dimethylaniline)-oxodiperoxomolybdenum(VI) or tung-sten(VI) as oxidizing species in molybdenum(VI) or tung-sten(VI) catalyzed hydrogen peroxide (Perborate) oxidation ofNN-dimethylanilinerdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 28 pp 1115ndash1125 1998
[9] C Karunakaran and B Muthukumaran ldquoZirconium(IV) catal-ysis in perborate oxidation of iodiderdquo Reaction Kinetics andCatalysis Letters vol 60 pp 387ndash394 1997
[10] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ISRN Physical Chemistry 3
Table 1 Effect of varying [substrate] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Perborate] = 0001mol dmminus3 [H2SO4] =20molmolminus3 HOAc-H2O = 1 1 (vv)
[5-oxo acid] (mol dmminus3) 105
times 119896obs (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
0005 9591 1344 943 636 214 177 077001 1919 2685 2167 1278 425 215 1520015 2879 4033 2998 1920 640 443 234002 3837 5371 3671 2559 851 574 305003 5758 8059 6076 3814 1278 892 456004 7677 1075 12491 5113 1715 1253 605006 1152 1613 14224 7675 2559 1753 910aMean of duplicate experiments
27 28 29 3 31 32 33 34 35 36
1T times 103 (Kminus1)
0
1
2
3
4
5
7+logk
3572K
p-OCH3
p-CH3
p-C6H5
ndashH
p-Clp-Brm-NO2
Figure 2 Typical first order plots in the perborate oxidation of 5-oxoacids
05ndash40mol dmminus3 sulphuric acid (Table 2) From the Zucker-Hammett plots of log 119896 versus ndashHo the slopes obtained werein the range of 10ndash12 indicating the noninvolvement ofwater molecule in the rate determining step The Ho valueswere taken from Long and Paul [28] assuming that the Hovalues do not change much in a media containing acetic acidup to 50
The effect of dielectric constant (119863) on the rate of reactionwas studied by varying acetic acid-water content in thereactionmixture Acetic acid does not react with the oxidants[29] yet the rate of the reaction is enhanced by increasingacetic acid content of the medium (Table 3) Also log 119896against 1119863 is found linear suggesting a positive ion-dipoletype of interaction [30] in the rate determining step
There was no induced polymerization of acrylonitrilemonomer ruling out the possibility of free radical formationduring the course of the reaction
In the temperature range of 298ndash323K in 20mol dmminus3sulphuric acid and acetic acid-water medium (50 vv)
(Figure 3) the activation energy (119864119886) and related thermody-
namic parameters (Δ119867 Δ119866 and Δ119878) were evaluated Theplot between Δ119867 and Δ119878 is linear (Figure 4 r ge 098 s le0028) and the isokinetic temperature (120573) obtained is 357KThe isokinetic relationship in the present study implies thatall the 5-oxoacids undergo oxidation by the samemechanism[31]
The effect of substituents on the rate of oxidationwas studied using different phenyl substituted 5-oxoacids(ArCOCH
2CH2CH2COOH where Ar = 41015840-methoxy 41015840-
methyl 41015840-phenyl 41015840-chloro 41015840-bromo 31015840-nitro substitutedphenyl) at different temperatures In all these cases thereaction orders are the same namely first order with respectto [oxidant] and [substrate] and second order with respectto [acid] Electron releasing substituents in the phenyl ringenhance the rate of oxidation and electron withdrawingsubstituents decrease it (Table 4) The order of reactivityamong the studied 5-oxoacids is p-methoxy ≫p-methyl gtp-phenyl gt ndashH gt p-chloro gt p-bromo gt m-nitrophenylsubstituted 5-oxoacids The Hammett plots of log 119896 versus120590 (substituent constant) are smooth curves and concavedownward at all the studied temperatures However theHammett plots are linear with good correlation coefficient atfour different temperatureswhen exalted substituent constant(Brownrsquos 120590+) values are used (Figure 5)The reaction constant(120588+) is negative and decreases (in magnitude) from minus165 tominus132 with increasing temperature from 303K to 323K TheHammett lines intersect at a point correspondent to a 120590+isovalue ofminus142 and a 119896iso value of 1318times 10
minus3 sminus1 (Figure 5) Anoxoacid with a substituent having this 120590+ value (minus142) willbe oxidized by perborate at the same rate at all temperaturesSuch insensitivity of the reaction rate to temperature is apointer to the existence of an isokinetic phenomenon
A reaction series which exhibits a common point of inter-section in the Hammett plot (Figure 5) is expected to have acommon point of intersection in the Arrhenius plot as well[32] From the plots of Δ119867 against Δ119878 and 120588 against 1119879the119879iso value is found to be 359K which is in good agreementwith the value obtained from the slope of Exnerrsquos plot
31 Mechanism In aqueous acetic acid the possible oxidizingspecies of perborate are perborate anion perboric acidperacetic acid and H
2O2 Even though isolation of free
4 ISRN Physical Chemistry
Table 2 Effect of varying [H2SO4] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate] =0001mol dmminus3 HOAc-H2O = 1 1 (vv)
[H2SO4] (mol dmminus3) minusHo105
times 119896 (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
051 minus013 1189 231 187 158 mdash mdash mdash075 007 2993 438 328 288 mdash mdash mdash101 026 4798 768 519 452 127 121 118149 056 9596 1598 1267 884 232 198 126201 084 1919 2687 1928 1278 426 309 152249 112 2879 4798 3869 2559 719 516 257300 138 4798 1343 7981 3485 1279 728 397401 185 1151 2878 14063 5758 2558 1689 769119878b 201 201 20 200 201 20 200119899c 13 10 10 10 11 11 10
aMean of duplicate experiments bslopes of log k versus log [H2SO4]cslopes of the Zucker-Hammett plots
Table 3 Effect of varying solvent composition on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3[perborate] = 0001mol dmminus3 [H2SO4] = 20molmolminus3
ACOH-H2O (vv ) 105
times 119896 (sminus1)b
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
30 70 (5318) 638 950 867 760 238 197 11840 60 (4648) 1152 1310 1186 960 310 212 12950 50 (3978) 1918 2687 1873 1280 427 362 15060 40 (3308) 586 4470 3101 1590 720 489 17570 30 (2638) 1751 1629 7123 3830 1280 761 269aValues of dielectric constant of the media are given in parentheses bmean of duplicate experiments
20
40
60
80
100
120
140
160
(KJ m
ol)
minus50 0 50 100 150 200 250
(m-NO2)
(p-Br)
(p-Cl)
(ndashH)
(p-C6H5)
(p-CH3)
(p-OCH3)
(JKminus1 molminus1)
minus1
minusΔS
ΔH
Figure 3 Arrhenius plots of log 119896 against 1119879 showing the isokinetictemperature
perboric acid has been proved exceedingly difficult it hasdemonstrable existence in solution [33] Perborate is reportedto exist in a dimeric tetrahedral configuration with theanionic formula B
2(O2)2(OH)4
2minus The oxidation has beencarried out in aqueous acetic acid and from the ionizationconstant of perboric acid reported as (06ndash16) times 10minus8 it
Table 4 Effect of substituent on the rate of oxidation of 5-oxoacidsby perborate at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate]= 0001mol dmminus3 [H2SO4] = 20molmolminus3 HOAC-H2O = 1 1vv
Substituent 120590 120590+
105
times 119896 (sminus1) 5 + log kp-OCH3 minus027 minus078 1918 22829p-CH3 minus017 minus031 269 14293p-C6H5 minus011 minus022 188 12623minusH 000 000 128 11070p-Cl 023 011 43 06299p-Br 043 038 27 03470m-NO2 071 067 15 01802
may be concluded that perborate exists mainly as perboricacid in aqueous acetic acid at very low pH maintained withsulphuric acid and hence is unlikely to be the oxidant Therate of perborate oxidation in aqueous acetic acid compareswith that in aqueous ethanol and hence the oxidation is notthrough peracetic acid H
2O2is less likely to be the oxidant
as the rate of H2O2oxidation is about one-fifth of that of
perborate oxidation The enhancement of reaction rate withan increase in the amount of acetic acid and linear plots oflog 119896 versus 1119863 with positive slopes indicate an interactionbetween a positive ion and a dipole molecule in the slowstep This supports the postulation of H
2BO3
+ as the reactive
ISRN Physical Chemistry 5
0
1
2
3
4
5
7+logk
kiso = 1318 times 10minus3 (sminus1)
minus16 minus12 minus08 minus04 00 04 08 12
120590+
323K 308K303K318K
313K
120590+iso = minus142
Figure 4 Plot of Δ119867 against minusΔ119878 showing the isokinetic relationship
O
OH
O
12
3
45
1998400
2998400
39984004998400
5998400
6998400
5-oxoacid (S1)
Figure 5 Hammett plots of log 119896 against 120590+at different tempera-
tures
species of perborate in the acidmediumThe rate accelerationwith an increase in [acid] and second order dependence ofrate on [acid] in the range studied also confirm that H
2BO3
+
is the reactive species of perborate taking part in the oxidationof 5-oxoacids
The oxoacid is a weak acid (119901119870119886= 577 at 40∘C in
aqueous solution) [34] and the undissociated form of thesubstrate can be taken as the only form in acidic media Inacid solutions 5-oxoacid undergoes keto enol tautomerism(2)
O
OH
O OH
OH
O
(keto form) (enol form)H+
Ke(2)
In oxidation reactions the keto group of the substrate canreact either directly or through the enol form Oxidationrates faster than the rates of enolization have been observedwith ceric ion [35] manganic ion [36] cobaltic vanadateions [37] mercuric perchlorate [38] and alkaline diperiodateargenate(III) [39] as oxidants indicating that the keto groupof the substrate reacts directly All of these oxidants undergoone-electron reduction and the reactions proceeded via a freeradical mechanism [35ndash39]
The rates of oxidation and enolization were found to beequal in the oxidation reactions by manganic pyrophosphate[40] thallium triacetate [41] and by diperiodatonickelate(IV) [42] These reactions were zero order in [oxidant]indicating the enol formation as the rate determining step
In the present study the rate of enolization (measuredby the bromination method [43]) is greater than the rate ofoxidation by a factor ofsim13ndash15 and the enolization step can bevisualized as proceeding via the enol form of the keto groupof 5-oxoacid Hence the step involving enol formation can beassumed to be a fast step and thus is not the rate determiningstep of the reactionThe most plausible mechanism thereforeseems to be shown in Scheme 1 The proposed mechanism isalso in accordance with the observed stoichiometry The rateequation in consonance with the mechanism proposed is asgiven in the following equation
minus119889 [perborate]119889119905
= 119870119901119870119890119896[H+]2 [5-oxoacid] [perborate]
(3)
6 ISRN Physical Chemistry
O
OH
O
(keto form)
OH
OH
O
(enol form)(I) (II)
OH
OH
O
(enol form)(II)
+k
(III)
Slow
Fast
Fast
(V)
+
(IV)
B+
OH
HO O
C+
OHC OH
OH
OB
OHH
C OH
OH
COH
OB
OH
O
C
OOH
HOOC
COOH++
(HO)2BOOH + H+ (HO)2BO+ + H2O
H+
Ke
Kp
minusH+
H3BO34H+
Scheme 1 Formations of benzoic acid and succinic acid were the final products of oxidation
The obtained rate law could explain the second order in [H+]and first order both in [perborate] and [5-oxoacid]
4 Conclusions
The above study shows that the H2BO3
+ reacts with the enolform of 5-oxoacid in the rate determining step giving thecyclic boronate ester Decomposition of the boronate esterresults in the cleavage of the carbon-carbon bond yieldingcarboxylic acids This experimental protocol suggests thatthis reaction could find utility as a regioselective route for thesynthesis of carboxylic acids specially succinic and benzoicacids
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] T M Connor and R E Richards ldquoNuclear resonance spectra ofsome peroxy-saltsrdquo Journal of the Chemical Society pp 289ndash2931958
[2] J O Edwards and V F Ross ldquoThe Structural chemistry of theboratesrdquo in The Chemistry of Boron and Its Compounds E LMuetterties Ed p 192 JohnWileyamp Sons NewYorkNYUSA1967
[3] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988
[4] Y Ogata and H Shimizu ldquoOxidation of organic compoundswith perborates or H
2O2ndashboric acidsrdquo Bulletin of the Chemical
Society of Japan vol 52 no 2 pp 635ndash636 1979[5] A McKillop and W R Sanderson ldquoSodium perborate and
sodium percarbonate cheap safe and versatile oxidising agentsfor organic synthesisrdquo Tetrahedron vol 51 no 22 pp 6145ndash6166 1995
[6] A McKillop and W R Sanderson ldquoSodium perborate andsodiumpercarbonate further applications in organic synthesisrdquoJournal of the Chemical Society Perkin Transactions vol 1 no 4pp 471ndash476 2000
[7] J Muzart ldquoSodium perborate and sodium percarbonate inorganic synthesisrdquo Synthesis no 11 pp 1325ndash1347 1995
[8] C Karunakaran and P N Palanisamy ldquoKinetic evidence for(NN-dimethylaniline)-oxodiperoxomolybdenum(VI) or tung-sten(VI) as oxidizing species in molybdenum(VI) or tung-sten(VI) catalyzed hydrogen peroxide (Perborate) oxidation ofNN-dimethylanilinerdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 28 pp 1115ndash1125 1998
[9] C Karunakaran and B Muthukumaran ldquoZirconium(IV) catal-ysis in perborate oxidation of iodiderdquo Reaction Kinetics andCatalysis Letters vol 60 pp 387ndash394 1997
[10] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
4 ISRN Physical Chemistry
Table 2 Effect of varying [H2SO4] on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate] =0001mol dmminus3 HOAc-H2O = 1 1 (vv)
[H2SO4] (mol dmminus3) minusHo105
times 119896 (sminus1)a
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
051 minus013 1189 231 187 158 mdash mdash mdash075 007 2993 438 328 288 mdash mdash mdash101 026 4798 768 519 452 127 121 118149 056 9596 1598 1267 884 232 198 126201 084 1919 2687 1928 1278 426 309 152249 112 2879 4798 3869 2559 719 516 257300 138 4798 1343 7981 3485 1279 728 397401 185 1151 2878 14063 5758 2558 1689 769119878b 201 201 20 200 201 20 200119899c 13 10 10 10 11 11 10
aMean of duplicate experiments bslopes of log k versus log [H2SO4]cslopes of the Zucker-Hammett plots
Table 3 Effect of varying solvent composition on the rate of perborate oxidation of 5-oxoacids at 313 plusmn 01 K [Substrate] = 001mol dmminus3[perborate] = 0001mol dmminus3 [H2SO4] = 20molmolminus3
ACOH-H2O (vv ) 105
times 119896 (sminus1)b
p-OCH3 p-CH3 p-C6H5 minusH p-Cl p-Br m-NO2
30 70 (5318) 638 950 867 760 238 197 11840 60 (4648) 1152 1310 1186 960 310 212 12950 50 (3978) 1918 2687 1873 1280 427 362 15060 40 (3308) 586 4470 3101 1590 720 489 17570 30 (2638) 1751 1629 7123 3830 1280 761 269aValues of dielectric constant of the media are given in parentheses bmean of duplicate experiments
20
40
60
80
100
120
140
160
(KJ m
ol)
minus50 0 50 100 150 200 250
(m-NO2)
(p-Br)
(p-Cl)
(ndashH)
(p-C6H5)
(p-CH3)
(p-OCH3)
(JKminus1 molminus1)
minus1
minusΔS
ΔH
Figure 3 Arrhenius plots of log 119896 against 1119879 showing the isokinetictemperature
perboric acid has been proved exceedingly difficult it hasdemonstrable existence in solution [33] Perborate is reportedto exist in a dimeric tetrahedral configuration with theanionic formula B
2(O2)2(OH)4
2minus The oxidation has beencarried out in aqueous acetic acid and from the ionizationconstant of perboric acid reported as (06ndash16) times 10minus8 it
Table 4 Effect of substituent on the rate of oxidation of 5-oxoacidsby perborate at 313 plusmn 01 K [Substrate] = 001mol dmminus3 [perborate]= 0001mol dmminus3 [H2SO4] = 20molmolminus3 HOAC-H2O = 1 1vv
Substituent 120590 120590+
105
times 119896 (sminus1) 5 + log kp-OCH3 minus027 minus078 1918 22829p-CH3 minus017 minus031 269 14293p-C6H5 minus011 minus022 188 12623minusH 000 000 128 11070p-Cl 023 011 43 06299p-Br 043 038 27 03470m-NO2 071 067 15 01802
may be concluded that perborate exists mainly as perboricacid in aqueous acetic acid at very low pH maintained withsulphuric acid and hence is unlikely to be the oxidant Therate of perborate oxidation in aqueous acetic acid compareswith that in aqueous ethanol and hence the oxidation is notthrough peracetic acid H
2O2is less likely to be the oxidant
as the rate of H2O2oxidation is about one-fifth of that of
perborate oxidation The enhancement of reaction rate withan increase in the amount of acetic acid and linear plots oflog 119896 versus 1119863 with positive slopes indicate an interactionbetween a positive ion and a dipole molecule in the slowstep This supports the postulation of H
2BO3
+ as the reactive
ISRN Physical Chemistry 5
0
1
2
3
4
5
7+logk
kiso = 1318 times 10minus3 (sminus1)
minus16 minus12 minus08 minus04 00 04 08 12
120590+
323K 308K303K318K
313K
120590+iso = minus142
Figure 4 Plot of Δ119867 against minusΔ119878 showing the isokinetic relationship
O
OH
O
12
3
45
1998400
2998400
39984004998400
5998400
6998400
5-oxoacid (S1)
Figure 5 Hammett plots of log 119896 against 120590+at different tempera-
tures
species of perborate in the acidmediumThe rate accelerationwith an increase in [acid] and second order dependence ofrate on [acid] in the range studied also confirm that H
2BO3
+
is the reactive species of perborate taking part in the oxidationof 5-oxoacids
The oxoacid is a weak acid (119901119870119886= 577 at 40∘C in
aqueous solution) [34] and the undissociated form of thesubstrate can be taken as the only form in acidic media Inacid solutions 5-oxoacid undergoes keto enol tautomerism(2)
O
OH
O OH
OH
O
(keto form) (enol form)H+
Ke(2)
In oxidation reactions the keto group of the substrate canreact either directly or through the enol form Oxidationrates faster than the rates of enolization have been observedwith ceric ion [35] manganic ion [36] cobaltic vanadateions [37] mercuric perchlorate [38] and alkaline diperiodateargenate(III) [39] as oxidants indicating that the keto groupof the substrate reacts directly All of these oxidants undergoone-electron reduction and the reactions proceeded via a freeradical mechanism [35ndash39]
The rates of oxidation and enolization were found to beequal in the oxidation reactions by manganic pyrophosphate[40] thallium triacetate [41] and by diperiodatonickelate(IV) [42] These reactions were zero order in [oxidant]indicating the enol formation as the rate determining step
In the present study the rate of enolization (measuredby the bromination method [43]) is greater than the rate ofoxidation by a factor ofsim13ndash15 and the enolization step can bevisualized as proceeding via the enol form of the keto groupof 5-oxoacid Hence the step involving enol formation can beassumed to be a fast step and thus is not the rate determiningstep of the reactionThe most plausible mechanism thereforeseems to be shown in Scheme 1 The proposed mechanism isalso in accordance with the observed stoichiometry The rateequation in consonance with the mechanism proposed is asgiven in the following equation
minus119889 [perborate]119889119905
= 119870119901119870119890119896[H+]2 [5-oxoacid] [perborate]
(3)
6 ISRN Physical Chemistry
O
OH
O
(keto form)
OH
OH
O
(enol form)(I) (II)
OH
OH
O
(enol form)(II)
+k
(III)
Slow
Fast
Fast
(V)
+
(IV)
B+
OH
HO O
C+
OHC OH
OH
OB
OHH
C OH
OH
COH
OB
OH
O
C
OOH
HOOC
COOH++
(HO)2BOOH + H+ (HO)2BO+ + H2O
H+
Ke
Kp
minusH+
H3BO34H+
Scheme 1 Formations of benzoic acid and succinic acid were the final products of oxidation
The obtained rate law could explain the second order in [H+]and first order both in [perborate] and [5-oxoacid]
4 Conclusions
The above study shows that the H2BO3
+ reacts with the enolform of 5-oxoacid in the rate determining step giving thecyclic boronate ester Decomposition of the boronate esterresults in the cleavage of the carbon-carbon bond yieldingcarboxylic acids This experimental protocol suggests thatthis reaction could find utility as a regioselective route for thesynthesis of carboxylic acids specially succinic and benzoicacids
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] T M Connor and R E Richards ldquoNuclear resonance spectra ofsome peroxy-saltsrdquo Journal of the Chemical Society pp 289ndash2931958
[2] J O Edwards and V F Ross ldquoThe Structural chemistry of theboratesrdquo in The Chemistry of Boron and Its Compounds E LMuetterties Ed p 192 JohnWileyamp Sons NewYorkNYUSA1967
[3] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988
[4] Y Ogata and H Shimizu ldquoOxidation of organic compoundswith perborates or H
2O2ndashboric acidsrdquo Bulletin of the Chemical
Society of Japan vol 52 no 2 pp 635ndash636 1979[5] A McKillop and W R Sanderson ldquoSodium perborate and
sodium percarbonate cheap safe and versatile oxidising agentsfor organic synthesisrdquo Tetrahedron vol 51 no 22 pp 6145ndash6166 1995
[6] A McKillop and W R Sanderson ldquoSodium perborate andsodiumpercarbonate further applications in organic synthesisrdquoJournal of the Chemical Society Perkin Transactions vol 1 no 4pp 471ndash476 2000
[7] J Muzart ldquoSodium perborate and sodium percarbonate inorganic synthesisrdquo Synthesis no 11 pp 1325ndash1347 1995
[8] C Karunakaran and P N Palanisamy ldquoKinetic evidence for(NN-dimethylaniline)-oxodiperoxomolybdenum(VI) or tung-sten(VI) as oxidizing species in molybdenum(VI) or tung-sten(VI) catalyzed hydrogen peroxide (Perborate) oxidation ofNN-dimethylanilinerdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 28 pp 1115ndash1125 1998
[9] C Karunakaran and B Muthukumaran ldquoZirconium(IV) catal-ysis in perborate oxidation of iodiderdquo Reaction Kinetics andCatalysis Letters vol 60 pp 387ndash394 1997
[10] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ISRN Physical Chemistry 5
0
1
2
3
4
5
7+logk
kiso = 1318 times 10minus3 (sminus1)
minus16 minus12 minus08 minus04 00 04 08 12
120590+
323K 308K303K318K
313K
120590+iso = minus142
Figure 4 Plot of Δ119867 against minusΔ119878 showing the isokinetic relationship
O
OH
O
12
3
45
1998400
2998400
39984004998400
5998400
6998400
5-oxoacid (S1)
Figure 5 Hammett plots of log 119896 against 120590+at different tempera-
tures
species of perborate in the acidmediumThe rate accelerationwith an increase in [acid] and second order dependence ofrate on [acid] in the range studied also confirm that H
2BO3
+
is the reactive species of perborate taking part in the oxidationof 5-oxoacids
The oxoacid is a weak acid (119901119870119886= 577 at 40∘C in
aqueous solution) [34] and the undissociated form of thesubstrate can be taken as the only form in acidic media Inacid solutions 5-oxoacid undergoes keto enol tautomerism(2)
O
OH
O OH
OH
O
(keto form) (enol form)H+
Ke(2)
In oxidation reactions the keto group of the substrate canreact either directly or through the enol form Oxidationrates faster than the rates of enolization have been observedwith ceric ion [35] manganic ion [36] cobaltic vanadateions [37] mercuric perchlorate [38] and alkaline diperiodateargenate(III) [39] as oxidants indicating that the keto groupof the substrate reacts directly All of these oxidants undergoone-electron reduction and the reactions proceeded via a freeradical mechanism [35ndash39]
The rates of oxidation and enolization were found to beequal in the oxidation reactions by manganic pyrophosphate[40] thallium triacetate [41] and by diperiodatonickelate(IV) [42] These reactions were zero order in [oxidant]indicating the enol formation as the rate determining step
In the present study the rate of enolization (measuredby the bromination method [43]) is greater than the rate ofoxidation by a factor ofsim13ndash15 and the enolization step can bevisualized as proceeding via the enol form of the keto groupof 5-oxoacid Hence the step involving enol formation can beassumed to be a fast step and thus is not the rate determiningstep of the reactionThe most plausible mechanism thereforeseems to be shown in Scheme 1 The proposed mechanism isalso in accordance with the observed stoichiometry The rateequation in consonance with the mechanism proposed is asgiven in the following equation
minus119889 [perborate]119889119905
= 119870119901119870119890119896[H+]2 [5-oxoacid] [perborate]
(3)
6 ISRN Physical Chemistry
O
OH
O
(keto form)
OH
OH
O
(enol form)(I) (II)
OH
OH
O
(enol form)(II)
+k
(III)
Slow
Fast
Fast
(V)
+
(IV)
B+
OH
HO O
C+
OHC OH
OH
OB
OHH
C OH
OH
COH
OB
OH
O
C
OOH
HOOC
COOH++
(HO)2BOOH + H+ (HO)2BO+ + H2O
H+
Ke
Kp
minusH+
H3BO34H+
Scheme 1 Formations of benzoic acid and succinic acid were the final products of oxidation
The obtained rate law could explain the second order in [H+]and first order both in [perborate] and [5-oxoacid]
4 Conclusions
The above study shows that the H2BO3
+ reacts with the enolform of 5-oxoacid in the rate determining step giving thecyclic boronate ester Decomposition of the boronate esterresults in the cleavage of the carbon-carbon bond yieldingcarboxylic acids This experimental protocol suggests thatthis reaction could find utility as a regioselective route for thesynthesis of carboxylic acids specially succinic and benzoicacids
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] T M Connor and R E Richards ldquoNuclear resonance spectra ofsome peroxy-saltsrdquo Journal of the Chemical Society pp 289ndash2931958
[2] J O Edwards and V F Ross ldquoThe Structural chemistry of theboratesrdquo in The Chemistry of Boron and Its Compounds E LMuetterties Ed p 192 JohnWileyamp Sons NewYorkNYUSA1967
[3] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988
[4] Y Ogata and H Shimizu ldquoOxidation of organic compoundswith perborates or H
2O2ndashboric acidsrdquo Bulletin of the Chemical
Society of Japan vol 52 no 2 pp 635ndash636 1979[5] A McKillop and W R Sanderson ldquoSodium perborate and
sodium percarbonate cheap safe and versatile oxidising agentsfor organic synthesisrdquo Tetrahedron vol 51 no 22 pp 6145ndash6166 1995
[6] A McKillop and W R Sanderson ldquoSodium perborate andsodiumpercarbonate further applications in organic synthesisrdquoJournal of the Chemical Society Perkin Transactions vol 1 no 4pp 471ndash476 2000
[7] J Muzart ldquoSodium perborate and sodium percarbonate inorganic synthesisrdquo Synthesis no 11 pp 1325ndash1347 1995
[8] C Karunakaran and P N Palanisamy ldquoKinetic evidence for(NN-dimethylaniline)-oxodiperoxomolybdenum(VI) or tung-sten(VI) as oxidizing species in molybdenum(VI) or tung-sten(VI) catalyzed hydrogen peroxide (Perborate) oxidation ofNN-dimethylanilinerdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 28 pp 1115ndash1125 1998
[9] C Karunakaran and B Muthukumaran ldquoZirconium(IV) catal-ysis in perborate oxidation of iodiderdquo Reaction Kinetics andCatalysis Letters vol 60 pp 387ndash394 1997
[10] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
6 ISRN Physical Chemistry
O
OH
O
(keto form)
OH
OH
O
(enol form)(I) (II)
OH
OH
O
(enol form)(II)
+k
(III)
Slow
Fast
Fast
(V)
+
(IV)
B+
OH
HO O
C+
OHC OH
OH
OB
OHH
C OH
OH
COH
OB
OH
O
C
OOH
HOOC
COOH++
(HO)2BOOH + H+ (HO)2BO+ + H2O
H+
Ke
Kp
minusH+
H3BO34H+
Scheme 1 Formations of benzoic acid and succinic acid were the final products of oxidation
The obtained rate law could explain the second order in [H+]and first order both in [perborate] and [5-oxoacid]
4 Conclusions
The above study shows that the H2BO3
+ reacts with the enolform of 5-oxoacid in the rate determining step giving thecyclic boronate ester Decomposition of the boronate esterresults in the cleavage of the carbon-carbon bond yieldingcarboxylic acids This experimental protocol suggests thatthis reaction could find utility as a regioselective route for thesynthesis of carboxylic acids specially succinic and benzoicacids
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] T M Connor and R E Richards ldquoNuclear resonance spectra ofsome peroxy-saltsrdquo Journal of the Chemical Society pp 289ndash2931958
[2] J O Edwards and V F Ross ldquoThe Structural chemistry of theboratesrdquo in The Chemistry of Boron and Its Compounds E LMuetterties Ed p 192 JohnWileyamp Sons NewYorkNYUSA1967
[3] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988
[4] Y Ogata and H Shimizu ldquoOxidation of organic compoundswith perborates or H
2O2ndashboric acidsrdquo Bulletin of the Chemical
Society of Japan vol 52 no 2 pp 635ndash636 1979[5] A McKillop and W R Sanderson ldquoSodium perborate and
sodium percarbonate cheap safe and versatile oxidising agentsfor organic synthesisrdquo Tetrahedron vol 51 no 22 pp 6145ndash6166 1995
[6] A McKillop and W R Sanderson ldquoSodium perborate andsodiumpercarbonate further applications in organic synthesisrdquoJournal of the Chemical Society Perkin Transactions vol 1 no 4pp 471ndash476 2000
[7] J Muzart ldquoSodium perborate and sodium percarbonate inorganic synthesisrdquo Synthesis no 11 pp 1325ndash1347 1995
[8] C Karunakaran and P N Palanisamy ldquoKinetic evidence for(NN-dimethylaniline)-oxodiperoxomolybdenum(VI) or tung-sten(VI) as oxidizing species in molybdenum(VI) or tung-sten(VI) catalyzed hydrogen peroxide (Perborate) oxidation ofNN-dimethylanilinerdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 28 pp 1115ndash1125 1998
[9] C Karunakaran and B Muthukumaran ldquoZirconium(IV) catal-ysis in perborate oxidation of iodiderdquo Reaction Kinetics andCatalysis Letters vol 60 pp 387ndash394 1997
[10] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ISRN Physical Chemistry 7
[11] C Karunakaran and P Manimekalai ldquoKinetics and mechanismof perborate oxidation of organic sulphidesrdquo Tetrahedron vol47 no 41 pp 8733ndash8738 1991
[12] C Karunakaran and R Kamalam ldquoOn the mechanism of theperborate oxidation of organic sulfides in glacial acetic acidrdquoEuropean Journal of Organic Chemistry no 19 pp 3261ndash32632000
[13] C Karunakaran V Ramachandran and P N PalanisamyldquoLinear free energy relationship in complex reaction tung-sten(VI) catalyzed perborate oxidation of S-Phenylmercaptoa-cetic acidsrdquo International Journal of Chemical Kinetics vol 31pp 675ndash681 1999
[14] C Karunakaran and R Kamalam ldquoMechanism and reactivityin perborate oxidation of anilines in acetic acidrdquo Journal of theChemical Society Perkin Transactions vol 2 no 12 pp 2011ndash2018 2002
[15] D Kungumathilagam and K Karunakaran ldquoKinetics andmechanism of meso-tetraphenylporphyriniron(III) chloride(TPP) catalysed oxidation of indole by sodium perboraterdquoPolish Journal of Chemical Technology vol 15 no 2 pp 107ndash1112013
[16] N PMarigangaiah andK K Banerji ldquoKinetics ampmechanismofoxidation of acetone butanone pentan-2-one 3-methylbutan-2-one hexan-2-one amp 4-methylpentan-2-one by acid perman-ganaterdquo Indian Journal of Chemistry A vol 14 pp 660ndash6621976
[17] A Meenakshi and M Santhappa ldquoOxidation studies involvingTl(III)rdquo Indian Journal of Chemistry vol 11 pp 393ndash394 1973
[18] N A M Farook ldquoKinetics of oxidation of 4-oxoacids by N-chlorosaccharin in aqueous acetic acid mediumrdquo Journal ofSolution Chemistry vol 36 no 3 pp 345ndash356 2007
[19] N A Mohamed Farook and G A Seyed Dameem ldquoKinetics ofoxidation of 3-benzoylpropionic acid by N-chlorobenzamide inaqueous acetic acid mediumrdquo E-Journal of Chemistry vol 8 no2 pp 561ndash564 2011
[20] D F Gnana Rani F J M Pushparaj I Alphonse and K SRangappa ldquoKinetics andmechanism of oxidation of 4-oxoacidsby hexacyanoferrate(III) catalysed by Os(VIII)rdquo Indian Journalof Chemistry B vol 41 no 10 pp 2153ndash2159 2002
[21] G Sikkandar ldquoKinetics of oxidative decarboxylation of 120573-Ben-zoylpropionic acid byManganese (III) acetaterdquoAsian Journal ofChemistry vol 12 no 4 pp 1037ndash1040 2000
[22] B Kenneth K Wiberg and R Stewart ldquoSolvents havinghigh dielectric constants II Solutions of alkali halides in N-methylacetamide from 30 to 60∘rdquo Journal of the AmericanChemical Society vol 77 pp 1986ndash1989 1955
[23] A I Vogel Text Book of Quantitative Chemical Analysis ELBSLongmans New York NY USA 5th edition 1958
[24] F C Tompkins ldquoKinetics of the oxidation of organic com-pounds by potassium permanganate Part VI BenzaldehyderdquoTransactions of the Faraday Society vol 39 pp 280ndash287 1943
[25] F R Duke ldquoThe disproportionation of manganate ion Man-aganese dioxide as heterogeneous catalystrdquo The Journal ofPhysical Chemistry vol 56 pp 882ndash884 1952
[26] M G Alder and J E Leffler ldquoThe role of the solvent in radicaldecomposition reactions phenylazotriphenylmethanerdquo Journalof the American Chemical Society vol 76 no 5 pp 1425ndash14271954
[27] F Feigl andVAnger Spot Tests inOrganicAnalysis AmsterdamThe Netherlands Elsevier 1975
[28] F A Long and M A Paul ldquoApplication of the HO acidityfunction to kinetics andmechanisms of acid catalysisrdquoChemicalReviews vol 57 pp 955ndash1010 1957
[29] C S Reddy and T Vijaya Kumar ldquoAquachlororuthenium(III)complex catalysis in the oxidation of malonic and methyl-malonic acids by bromate in perchloric acid medium Study ofinduction period and evaluation of individual kinetic parame-tersrdquo Transition Metal Chemistry vol 32 pp 246ndash256 2007
[30] E S Amis Solvent Effects on Reaction Rates and MechanismsAcademic Press New York NY USA 1967
[31] J E Leffler and E Grunwald Rates and Equilibrium of OrganicReactions John Wiley amp Sons New York NY USA 1963
[32] R Schmid and V N Sapunov Non-Formal Kinetics VerlagChemie Weinheim Germany 1982
[33] Adams and R M Boron Metallo-Boron Compounds andBoranes Interscience New York NY USA 1964
[34] G Sikkandar K A B Ahamed and S Kannan ldquoKinetics ofoxidation of 4-oxoacids by permanganate in buffer mediardquoIndian Journal of Chemistry A vol 38 no 2 pp 183ndash186 1999
[35] S Venkatakrishnan and M Santappa ldquoOxidation of acetoneand methyl ethyl ketone by ceric ions in aqueous solutionrdquoZeitschrift fur Physikalische Chemie vol 16 pp 73ndash84 1958
[36] J S Littler ldquoThe mechanisms of oxidation of cyclohexanoneunder acid conditions Part II One-electron oxidantsrdquo Journalof the Chemical Society pp 832ndash837 1962
[37] D G Hoare and W A Waters ldquoOxidations of organic com-pounds by cobaltic salts Part II The oxidation of diethylketonerdquo Journal of the Chemical Society pp 971ndash975 1962
[38] A J Green T J Kemp S S Littler and W A Waters ldquoThemechanism of oxidation of cyclohexanone under acid condi-tions Part III Corrected enolization rates and kinetic isotopeeffectsrdquo Journal of the Chemical Society pp 2722ndash2726 1974
[39] G Sarala P J P Rao B Sethuram and T N Rao ldquoKinetics andmechanism of uncatalyzed and Os(VIII)-catalyzed oxidation ofacetophenones by diperiodatoargentate(III)rdquo Indian Journal ofChemistry A vol 26 pp 475ndash479 1987
[40] A Y Drumond and W A Waters ldquoStages in oxidations oforganic compounds by potassium permanganate Part VI Oxi-dations of ketones and of pyruvic acidrdquo Journal of the ChemicalSociety pp 497ndash504 1955
[41] P S R Murthy and S N Pati ldquoOxidation of aliphatic ary-laliphatic and cyclic-ketones by thallium triacetaterdquo IndianJournal of Chemistry A vol 17 pp 97ndash101 1979
[42] MAA Siddiqui C S KumarUChandraiah and SKandlikarldquoKinetics of oxidation of acetophenones by diperiodatonick-elate(IV) in the presence and absence of Os(VIII)rdquo IndianJournal of Chemistry A vol 30 pp 849ndash854 1991
[43] W S Nathan and H B Waston ldquoConstitutional factors con-trolling prototropic changes in carbonyl compounds Part IIIThe prototropy of nuclear-substitutedrdquo Journal of the ChemicalSociety pp 217ndash220 1933
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
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