CHAPTER V OF ANTHRANILIC ACID AND ANTHRANILATES WITH DICHLORAMINE-T The successful application of dibromamine-T in acetic acid as an oxidimetric titrant for the determi- nation of anthranilic acid and metal prompted us to examine the feasibility of employing di- chloramine-T (the chlorine analogue of dibromamine-T) in this context. has been introduced as an 'd' .. .,. ., . Ii 42-46 1 oy ear er workers in our a- boratories. The full list of substances determined by dichloramine-T titrations is given in Table 1. The present studies showed that dichloramine-T may be employed instead of dibromamine-T for the determination of acid and metal in presence of bromide ions. Neither of these oxidants has advantage over the other in this context. In fact the course of titrations was found to be almost identical. This is not surprising since, in both cases, the oxidant de facto is the bromine
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CHAPTER V
D~ERMINATION OF ANTHRANILIC ACID AND ~AL
ANTHRANILATES WITH DICHLORAMINE-T
The successful application of dibromamine-T in
acetic acid as an oxidimetric titrant for the determi-
nation of anthranilic acid and metal antr~anilates
prompted us to examine the feasibility of employing di
chloramine-T (the chlorine analogue of dibromamine-T) in
this context. Dicr~oramine-T has been introduced as an
'd' .. .,. ., . Ii 42-46 1ox~ ~me~r~c ~~~ran~ oy ear er workers in our a-
boratories. The full list of substances determined by
dichloramine-T titrations is given in Table 1.
The present studies showed that dichloramine-T may
be employed instead of dibromamine-T for the determination
of antr~anilic acid and metal antr~anilates in presence of
bromide ions. Neither of these oxidants has advantage over
the other in this context. In fact the course of titrations
was found to be almost identical. This is not surprising
since, in both cases, the oxidant de facto is the bromine
142
produced in situ by the reaction of dibromamine-T or di-
chloramine-T with the bromide ions present. The results of
our studies on dichloramine-T are presented in this chapter.
1EXPERlMENTAL
Using chloramine-T as a starting material dichloramine-T
was prepared by the method of Jacob and Nair46b (vide page 39,
Chapter II). The details of preparation and standardisation
of stock solutions of dichloramine-T in anhydrous acetic acid
have already been given in Chapter II.
Procedure for Eotentiometric titrations
The procedure was identical with that of the dibro-
mamine-T titrations.
Procedure for visual indicator titrations
The procedure was similar to that in the case of the
dibromamine-T titrations.
RESULTS AND DISCUSSION
Some attempts were made to carry out these titrations
in pure acetic acid medium. In such cases, the antt~anilic
acid or metal antt~anilates were dissolved in anhydrous acetic
acid and were titrated with dichloramine-T solutions in acetic
acid. It was shown that visual indicator response in such a
purely nonaqueous medium was very feeble and the titrations
143
could not be carried out. Potentiometric titrations were
also sluggish in such a medium. These difficulties vanished
when water (~5 ml) was added. The best results were obtained
when the titrate was taken in a mixed aqueous acetic acid
medium containing also hydrochloric acid and the titrant was
taken in anhydrous acetic acid medium. The presence of water
in the titrate system increases the dielectric constant and
favours quicker electrode equilibration. On the other hand
the presence of acetic acid in appreciable concentrations
(~20%) prevents the precipitation of tribromo anthranilic
acid. It was observed that if no acetic acid is taken along
with the titrate, some tribromoantr~anilic acid would get
precipitated; this would adhere to the electrode and cause
complications.
Typical results including statistical data are pre
sented in Tables 67 to 82. Typical titration curves are
given in figures 15 to 21.
The dichloramine-T titrations have the same advantages
as the dibromamine-T titrations (cf page 37) over the con
-------------------------------------------------------------------------------------------*Assuming that 6 equivalents of oxidant are consumed per mole
of anthranilic acid. ~
~
"""
TABLE 68
DETERMINATION OF MANGANESE ANTHRANILATE WITH DICHLORAMINE-T
---------------------------------------------------------------------------------------*Assuming that 12 equivalentsof oxidant are consumed per mole of
cobalt antrJanilate.-'~0'\
TABLE 70
DETERMINATION OF COPPER .ANTHR.ANILATE WITH DICHLORAMINE-T
(POTENTIOMETRIC TITRATION)
Expt.No.
Copper antr.lXanilate taken~
Dichloramine-Tconsumedmeg
Equivalents ofdichloramine-Tconsumed permole of copperantru-anilate
Copper antrJIanilate found*mmol
Erroro;~
1• 0.07702 0.9275 12003 0.0772'9 + 0.35
2. .0.08156 0.9787 12.00 0.08156 0.00
3. 0.1063 1.285 12.09 0.1071 + 0.75
4. 0.1158 1.384 11.96 0.1154 - 0.35
5. 0.1322 1.586 11-.99 0.1321 - 0.08
6. 0.1437 1.725 12.0~ 0.1439 + 0.14
---------------------------------------------------------------------------------------------*Assuming that 12 equivalents of oxidant are consumed per mole of
copper anthranilate.
-'~
--J
TABLE 71
DETERMINATION OF NICKEL ANTHRANILATE WITH DICHLORAMINE-T
(POTENTIOMETRIC TITRATION)
Expt. Nickel anttJaNo. nilate taken
mmol
Dichloramine-Tconsumedmeq
Equivalents ofdichloramine-Tconsumed permole of nickelanthranilate
----------------------------------------------------------------------------------------*Assuming that 12 eqUivalents of oxidant are consumed per mole of
zinc antr~anilateo
---Po'..0
TABLE 73
DET~IINATION OF CADMIID~ ANTHRANILATE WITH DICHLORAMINE-T
(POTENTIOMETRIC TITRATION)
Expt.No.
Cadmiumanthranilatetakenmmol-
Dichloramine-Tconsumedmeg
Equivalents ofdichloramine-Tconsumed permole of cadmiumantliranilate
Cadmiumantr-!Xanilatefound*mmol
Error%
1• 0.05900 0.7072 11.98 0.05893 - 0.12
2. 0.07220 0.8674 12.01 0.07228 + 0.11
3. 0.09551 1.146 11.99 0.09550 - 0.01
4. 0.1021 1.223 11.97 0.1019 - 0.19
5. 0.1144 1.382 12.0$ 0.1151 + 0.61
6. 0.1322 1.589 12.02 0.1324 + 0.15
---------------------------------------------------------------------------------------*Assuming that 12 equivalents of oxidant are consumed per mole of
cadmium anthranilate.
~
IJIo
TABLE 74
STATISTICAL DATA FOR TITRATIONS WITH DICHLOF~INE-T
(POTENTIOMETRIC TITRATIONS)
------------------------------------------------------------------------------------------Reductant No. of experi
6. 0.2233 1.343 6.014 0.2238 +0.22 "----------------------------------------------------------------------------------------*Assuming that 6 equivalents of oxidant are consumed per mole ofantr~anilic acid.
->\5!..p.
!ABLE 76
DETERMINATION Oli' WlANGANESE ANTHRANILATE WITH DICHLORAMINE-T
(DIRECT TITRATION USING VISUAL INDICATOR)
Expt.No.
Manganeseantb.ranilatetakenm!!!.Q1
Dichloramine-Tconsumedmeg
Equivalents ofdichloramine-Tconsumed permole of manganese anthranilate
-------------------------------------------------------------------------------------------*Assuming that 12 equivalents of oxidant are consumed per mole of
zinc antt~anilate.
-'\J11..0
TABLE 81
DETERMINATION OF CADMIUM ANTHRANILATE WITH DICHLORAMINE-T
(DIRECT TITRATION USING VISUAL INDICATOR)
Expt. CadmiumNo. antr.1Xanilate
taken~
Dichloramine-Tconsumedmeq
Equivalents ofdichloramine-Ifconsumed permole of cadmiumanthranilate