Synthesis of Bisphenol A with Heterogeneous Catalysts by Liliana Neagu A thesis submitted to the Deparment of Chernical Engineering in conforrnity with the requirements for the degree of Master of Science (Engineering) Queen' s University Kingston, Ontario, Canada August, 1998 Copyright O Liliana Neagu, October 1 998
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Synthesis of Bisphenol A with Heterogeneous Catalysts
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Synthesis of Bisphenol A with Heterogeneous Catalysts
by
Liliana Neagu
A thesis submitted to the Deparment of Chernical Engineering in conforrnity with the requirements for the degree of
Master of Science (Engineering)
Queen' s University Kingston, Ontario, Canada
August, 1998
Copyright O Liliana Neagu, October 1 998
National Li b rary 1*m of Canada Bibliotheque nationale du Canada
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Abstract
The synthesis of bisphenol A (BPA) with heterogeneous catalysts was uivestigated in a batch system and in a plug flow reactor. Gibbs reactor simulations contributed to a better understanding of the reaction which leads to BPA formation. Experiments were conducted with ~mberlyst@-15, Nafion@ NR-50, Nafione SAC-13. and activated alumina acidified with concentrated hydrochloric acid (AA300/HCl). An experùnental design was used to investigate the effects of temperature, catalyst concentration, molar ratio of acetone and phenol in the initial reaction mixture, and the size of the catalyst bead. Al1 the factors significandy innuence some or al1 the aspects of the process of BPA formation.
Al1 three new catalysts: AA300/HC1, Nafion@ NR-50, and Nafion@ SAC-13, were found suitable to catalyze the production of bisphenol A, using phenol and acetone as starting materials. Both yield and selectivity are significantly higher for the processes that use the newly identined catalysts than the yield and selectivity obtained in the process that uses Amberlyst@ 1 5.
Acknowledgments
There are many people 1 want to thank in this section, people who offered me their support and their fnendship, for which 1 am grateful.
I would like to thank my supervisors Dr. Tom Harris and Barrie Jackson for their support, encouragement and understanding throughout the completion of this project. 1 would also like to thank Dr. Whitney and Dr. Brian Hunter for the meaningfid conversations, Steve Hodgson, Lisa Prior and Martin York for the& technical assistance with my research equipment.
1 am grateful to my office mate Shannon Quinn for her sincere fiiendship and her computïng knowledge. 1 thank Gregg Logan for his Eendship, for the endess conversations about food, and for introducing me to graduate student life in the department. Thankç to everybody in the department for creating such a pleasant work place.
1 would like to thank my husband for being supportive and understanding sometimes and to rny daughter for being a good and happy child, for sleeping overnight and for not crying as much as she could have.
Many thanks to the Queen's Day Care Centre staff, Halina, Donna, Pada, Sean, Karen, Lori, Sandra, for taking such a good care of my daughter and for spoiling her more than I did.
As vrea sa multumesc parintilor mei Voica si Aurel Monea pentru ca mi'au dat puterea sa visez si aripi sa zbor.
Table of Contents
.......................................................................... 1 Introduction 2 Basic Chemistry and Production of BPA ......................................
2.1 Preparation of Bisphenol A ................................................. 2.1.1 Acetone Process ..................................................
2.2.2.1 Methods of Separating BPA fiom the 1 : 1 BPA- ............................................... Phenol Aduct
2.2.2.2 By-Products Isomerization to BPA ................. 2.3 Manufacturing ...............................................................
2.3.1 Resin-Catdyzed Process ........................................ 2.3.2 Hydrogen Chloride-Catalyzed Process ........................ 2.3.3 Resin-Catalyzed Process II ......................................
...................................................................... 2.6 S u m m q 3 Gibbs Reactor Simulations ........................................................
3.1 The PRO II@ Gibbs Reactor ................................................ 3.2 Simulation of the Bisphenol A Reaction ..................................
3.2.1 Analysis of the Simulation Results ............................. 3.2.1.1 Effect of Temperature and Acetone:Phenol
Molar Ratio on BPA Formation .......................... ............................... 3.2.1.2 By-Products Formation
3 -3 Surnmary of the Sunulation ................................................ 3 -4 Conclusions ..................................................................
5.1 Prelimioary Investigation ................................................... 5.1.1 Evaluation of S ystem Reactivity and Blank Reactions ......
............................ 5.1 -2 Evaluation of Experimental Region 5.1 -3 Scheme of Reaction ..............................................
................................... 5.1.4 Experimental Reproducibility 5.1.5 Validity of Simulation Prediction for Depletion of
Acetone .............................................................. 5.2 Investigation of Suitability of New Catalysts ............................
.............. 5.3 Performance Comparison of ~ a f i o n @ and Amberlysta 15 5 -4 Experimental Design ........................................................
5.4.1 Factors Chosen and Responses ................................. ............ 5.4.2 Evaluation of Results corn Experimental Design
................................. 5.4.3 Precision of Caiculated Effects .................................................. 5.4.4 Effects Analysis
...................... 5.4.4.1 Selectivity of BPA Formation ............... 5.4.4.2 Selectivity of O-p Isomer Formation ............... 5.4.4.3 Selectivity of Chromanes Formation
5.4.4.4 Yield in BPA ........................................... ............................................. 5.4.5 Regression Analysis
5.4.5.1 Mode1 for Selectivity of BPA Formation .......... 5.4.5.2 Model for the Selectivity of O-p Isomer
Formation ................................................... 5 4 - 5 3 Model for the Selectivity of Chromanes
................................................... Formation 5.4.5.4 Mode1 for the Yield in BPA ................... -... ...
..................................................... 5.6 z4 Experimental Design ................... 5.7 Regression Analysis for the z4 Experimental Design
5.7.1 Mode1 for Selectiviw of BPA Formation ..................... 5.7.2 Mode1 for Selectiviv of Chromanes Formation .............
......................................... 5.7.3 Model for Yield in BPA 5.8 Summary ......................................................................
......... 6 Reactions in the Plug Flow Reactor ................................... .. ................................ 6.1 Reactions with Acidic Activated Alumina
............................................ 6.2 Reactions with ~ a f i o n @ NR-50 ........................................... 6.3 Reaction with ~a f ion@ SAC-13
6.4 S u m m q ...................................................................... ..................... ..................... 7 Conciusions and Recommendations ,,
A Health and Safety Regdations .................................................... @ B PRORI Input File .................................. .... ..............................
C Summary of Simulation Resuits .................................................. D The NMR Phenornenon ............................................................
List of Tables
........... -1 Quality characteristics for BPA as raw matenal for polycarbonates ............. 1 Equilibrium constant for the BPA f o. p-isomer transformation .
. 2 Results of the reaction of acetone with phenol in the presence of zeolites ............................... and cation-exchange resin ............. .. ............ ..
.............. 2.3 Solubilities of bisphenol A in various solvents (g/100g solvent) ..................................... 2.4 Variation of vapor pressure with temperature
.............................. Gibbs reaction simulation with reaction parameters Equilibrium constant for the BPA = o. p4somer transformation based on
......................................................................... simulated data ............................................ Materials used in experiments .. .... .. ...
.................................... Acquisition method on the mass spectrometer ............ Peak table with retention times and boiling points of the products . . . ......................................................... Data acqursrtion parameters
........................................................ Summary of the experiments ........................................... Results of the second set of experirnents
Results of the experiments performed with AmberlystB-1 5 in the batch ................................................................................... reactor
Results of performance cornparison between ~ a f ï o n @ and ~mberlyst@- 15 ... High value, low value, midpoint, range and half range for each factor ........ Experimental runs used to investigate the efTect of catalyst concentration (C), temperature (T) and molar ratio of acetone and phenol (R) ...............
..... Responses for the experiments perfomed in the 23 experimental design ..................................................................... Calculated effects
....................................................... Precision of calculated effects 5.10 Results of the regression analysis for the selectivity of BPA formation ..... 5.1 1 Results of the regression analysis for the selectivity of O-p isomer
............................................................................... formation 5.12 Resdts of the regression analysis for the selectivity of chromanes
............................................................................... formation ........................ 5.13 Results of the regression analysis for the yield in BPA
5.14 Additional runs ....................................................................... ......................................... 5.15 Calculated effects for the additional runs
5.16 Cornparison between the calculated effects in the fkst set and the second set of experiments ....................................................................
............................................... 5.1 7 Data for the z4 experimental design ............................................... 5.18 Calculated effects for the 24 design . .
5.19 Sigmficant effect S. .................................................................. 5.20 Results of the regression analysis for the selectivity of BPA formation .....
5.21 Results of the regression analysis for the selectiviv of chromanes .............................................................................. formation.
5.22 Results of the regession analysis for the yield in BPA.. ...................... ....................................................... 6.1 Summary of the experiments.
6.2 Results of the experiments with AM001 HCl. .......................... .. ........ ............................... 6.3 Results of the experiments with Nafion@ NR-50.. ............................... 6.4 Results of the experiment with Nafion@ SAC- 13..
A. 1 Chernicals used in experiments! associated hazards and safety ........................................................................... requirements
@ ........................................................ B. 1 PRO/LI keyword input file.. C.l Variation of bisphenol A, o,p-isomer, and triphenol formation with the
acetone:phenol molar ratio at 323.15 K. The results are presented in mol % ........................................................................................
C.2Variation of bisphenol A, og-isomer, and triphenol formation with the acetone:phenol molar ratio at 333.15 K. The results are presented in mol
C.3Variation of bisphenol A, op-isomer, and triphenol formation with the acetone:phenol molar ratio at 343.15 K. The results are presented in mol
CAVariation of bisphenol A, 07p-isomer, and triphenol formation with the acetone:phenol molar ratio at 353.1 5 K. The results are presented in mol
........................................................................................ % CSVariation of bisphenol A, og-isomer, and triphenol formation with the
acetone:phenol molar ratio at 363.15 K. The results are presented in mol ........................................................................................ %
C.6Variation of selectivity of bisphenol A 0, 07p-isomer (II), and triphend (III) with the temperature at various acetone:phenol molar
.......................... 2.1 Conversion of phenol versus time for various catalysts ........... 2.2 Product selectivity versus time for the reaction catalyzed by Re-Y
... 2.3 Product selectivity versus time for the reaction catalyzed by Hmordenite 2.4 Product selectivity versus time for the reaction cataiyzed by Amberlyst.15 .. 2.5 Mechanism of condensation of acetone with phenol s a hydrogen bonds ..... 2.6 Reactor configuration .................................................................
.................................... 2.7 Production of bisphenol A with resin catalyst 2.8 Production of bisphenol A with hydrogen chlonde catalyst ....................
.................................. 2.9 Production of bisphenol A with resin catalyst II 3.1 Variation of BPA formation with molar ratio acetone.pheno1 .................. 3.2 Variation of BPA formation with temperature and acetone:phenoI molar
ratio .................................................................................... 3.3 Variation of selectivity of BPA with temperature and acetone:phenol molar
................................................................................. ratio ........... 3.4 Variation of og-isomer formation with acetone:phenoI molar ratio
3.5 Variation of o,p &orner formation with temperature at various rnolar ratios acetone.pheno1 ..................... .. ...... .. ............................. .. ..........
3.6 Variation of selectivity of og-isomer with temperature at various molar ratios acetone: phenol .................................................................
............. 3 -7 Variation of triphenol formation with molar ratio acetone.pheno1 3 -8 Variation of triphen01 formation with temperature at various molar ratios
acetone.pheno1 ......................................................................... 3.9 Variation of selectivity of triphenol with temperature at various molar
ratios acetone.pheno1 ................................................................. 3.10 Variation of BPA formation with temperature and acetone:phenol molar
................................................................................... ratio 3.1 1 Variation of 0.p 4somer formation with temperature and molar ratio
acetone.pheno1 ..................... .. .................................................. 3.12 Variation of triphenol formation with temperature and acetone:phenol
molar ratio ............................................................................. 3.13 Variation of BPA, o.p.isomer. and triphenol formation with molar ratio
acetone:phenol at 353.15 K .......................................................... ... 3.14Variation of BPA. opisomer. and triphenol formation with temperature
4.1 Plug flow reactor ...................................................................... .......................... 4.2 Nanon@ structure; m = 6 or 7, n 1000. x = 1. 2. or 3
4.3 Electron withdrawing effect ......................................................... 4.4 Styiized view of polar/ nonpolar microphase separation in a hydrated
ionomer ................................................................................ ................................... 4.5 The Yeager 3 phase mode1 of Nafion@ clusters
viii
....................................... 4.6 Temperature profile of method used on GC 4.7 Chromatogram of the products obtained in the condensation process ......... 4.8 NMR spectrurn of acetone (CDCl, ) ...............................................
................................................. 4.9 NMR spectrum of phenol (CDCI, ) ......................................... 4.10 NMR spectrum of bisphenol A (CDCl, )
-4.1 1 NMR s p e c t m of the initial mixture of reaction (fiom 0.4 pprn to 3 . 0 ................................................................................... ppm)
4.12 NMR spectnun of the initial mixture of reaction (fiom 1 . 0 pprn to 3.0 ................................................................................... ppm)
4.13 NMR spectrum of the final mi>aure of reaction (firom 0.4 pprn to 3.0 ppm) ....... 5.1 Analysis of the reaction with hornogeneous catalyst (after three days)
......... 5.2 Analysis of the reaction with homogeneous catalyst (after six days) 5.3 Analysis of the reaction with homogeneous catalyst (afier nine days) ........ 5.4 Analysis of the reaction with homogeneous catalyst (after twelve days) .....
....................................................................... 5 -5 Crystals of BPA 5.6 Analysis of the reaction with heterogeneous catalyst (after nine days) .......
.................... 5 -7 Analysis of the reaction with no catalyst (after three days) .............................................. 5.8 Variation of BPA selectivity in tirne.
..................................... 5 -9 Variation of selectivity of O-p isomer in tirne ...................................... 5.10 Variation of chromanes selectivity in time
.................................. 5.1 1 Variation of BPA selectivity with temperature ........................... 5.12 Variation of +p isomer selectivity with temperature .......................... 5.13 Variation of chromanes selectivity with temperature
........................................ 5.14 Variation of BPA yield with temperature .......................................................... 5.15 Disappearance of acetone
5.16 Chrornatogram of the products for the process catalyzed by Amberlyst- 15 ...................................................... ...................... [6 h] .....
5.17 Chromatogram of the products for the process catalyzed by Nafion@ NR- ................................................................................ 50 [3 hl
5 . ; S Chromatogram of the products for the process catalyzed by AA 300/ HCL .................................................................................... [6 hl
5.19 Effects of considered factors on selectivity of BPA formation and their ............................................................................ significance
5.20 Effects of considered factors on selectivity of O-p isomer formation and their significance .....................................................................
5.2 1 Effects present in the molecule of phenol and the nucleophilic attack ....... 5.22 Effects of considered factors on selectivity of chromanes formation and
..................................................................... their significance ........ 5.23 Effects of considered factors on yield in BPA and their significance
List of Abbreviations
amu ASOG atm BPA BSPHNOLA C Cal cal cat.
cm c m Co. conc. DDT DGEBA DMSO e.g . exp. FID Fig. fin
1.e. I.U.P.A.C. in ioniz. IR K
US dollars micro litre Angstrom activated alumina activated with hydrochloric acid acetone atomic mass unit Analyticd Solution of Groups atmosphere bisphenol A bisphenol A Celsius calibration calorie cataly st cubic centimetre centimetre carbon number Company concentration 1,1,1 -tnchloro-2,2-bis-(p-chloropheny1)-ethane diglycidyl ether bisphenol A dimethyl sulfoxide exempli gratia experiment Free Induction Decay Figure fmal gram Gas Chromatography/ Mass Spectroscopy hour hydrochloric acid mercury Hertz ist est International Union of Pure and Applied Chemistry initial Ionization Infia red Kelvin
kcai kj km01 1 b LIBID h4AF'P max MHz min niin ml
m u MSDS NIA NBP nnl NMP NMR NONLIB NRTL O
P PFR Ph PID
psi PVC rad r f
s/n SANS SAXS SI. SIMSCI SOLUPARA SSE SSR STDPRES STDTEMP T Temp. TFE
kilocalorie kilojoul kilomol pound library methylacetylene and propadiene maximum
mega Hertz minimum minute millilitre mi llimetre milli mass unit Matenal Safety Data Sheet not applicable normal boiling point nanome tre normal melting point Nuclear Magnetic Resonance non-library non-random two liquid ortho Para plug flow reactor phenol proportional integral denvative parts per million pound per square inch poïyvinyl chloride radians radio fiequency seconds signal to noise small angle neutron scattering small angle X-ray scattering System International Simulation Sciences solubility parameter Surn of Squared Errors Sum of Squared Residuals standard pressure standard temperature Tesla temperature tetrafluoroethylene
TMS TPPI TSS U.K. UNiFAC us mec wt ZNUM
tetramethylsi f ane Time Proportional Phase increments Total Sum of Squares United Kingdom universai functionai activity coefficient United States micro seconds weight hydrogen deficiency nurnber
xii
Chapter 1
Introduction
Bisphenol A (BPA) is the commercial name used in the United States for 4,4'-
isopropylidenediphenol. In Europe I.U.P.A.C. nomenclature and other unsystematic
names are still used. Its commercial name indicates the preparation fkom two molecules
of phenol and one of acetone. The molecule of BPA c m be described as two phenolic
rings joined together by a bridging isopropylidene group (Chernical Abstract now calls
the radical 1 -methy lethy lidene) (McKetta and Cunningham, 1 976).
Dianin prepared bisphenol A for the first time in 1891 via condensation of acetone and
phenol catalyzed by hydrochloric acid. The method was not patented until 1917.
Bisphenol A was manufactured on an industrial scale for the first time in 1923 by a
German f-, Chemishen Fabriken, to be used a s intermediate for producing coating
resins (McKetta and Cunningham, 1976).
Since then, the production of BPA as an intermediate for epoxy resins continued to grow.
Some of the first large-scale producers were Firma Resins & Vernis Artificiels in France,
Farbenfabriken Bayer in Germany, Dow Chemical Company (since I941), General
Aniline and Film (fiom 1941 to 1954), Shell Chemical Co. (since 1954), Monsanto Co.
(fiom 1956 to 1971): Union Carbide (from 1960 to 1982) and General Electric Co. (since
1967) in the United States, Shawinigan Chemicals in Canada, Esquirn in Mexico, Shell
Chernicals U.K. and R. Graesser and Co. in England, Ketjen and Shell in the Netherlands,
Mitsui Toatsu Chemicals, Honshu Chemical Industries and Nippon Steel Chemical Co. in
Japan, Raghanandan Chemical Indumies in India and others (McKetta and Cunningham,
1976).
Bisphenol A is generally used as a reagent for producing polycarbonates, epoxy resins,
phenoxy resins, acrylic resins, polysdfone resins, and other polyesters and as an
intermediate for semi-synthetic wax (mc.vanderbiIt.edu/vumcdept/derm/contact 1008).
Halogenated foms are used as flame retardants, and alkylated foms are used as
stabilizen and antioxidants for rubber and other plastics, like PVC for example
(essential.org/listproc/dioxin-l/msgO0464.h) It is also used as a component of food-
packaging adhesives, as a fungicide and as a component of dental filling compositions.
Recently a toner for developing electrostatic images, that contains BPA, was developed
(Unno et al., 1997).
BPA production in the US in 1974 was only 415 million lb (McKetta and Cunningham,
1976), compared with 1.65 billion Ib of BPA in 1996 (Hileman, 1997). This four fold
increase of the production over the period of 20 years proves a high demand on the
market for the product in question. The price for BPA in 1974 was by average 0.45$/lb
(McKetta and Cunningham, 1 976). Considering the inflation (Consumer Pnce Index),
the BPA pnce in 1998 should have been 1.52$/lb. The actual price for BPA in 1998 was
by average 0.94$/lb (Chemical Market Reporter, 1998). This "decrease" c m be related to
the increase in production and interpreted with "The Boston Leamhg Curve" which
States that: "Average Unit Selling Pnces, in Constant Dollars, Characteristicaliy Decline
20 to 30 Percent in Real Terrns Each Time Accumdated Experience Doubles" (Jackson,
1997). Considering that the production in 1998 is the same as the production in 1996,
that it doubled twice since 1974, and each t h e it doubled the average unit selling price in
constant dollars declined 25% by average, the calculated price of BPA is 0.86 $Ab. This
is slightly lower than the actuai price for BPA in 1998.
It is well known that for obtaining light-coloured hi& rnolecular weight poIymers via
linear condensation, the PLU@ of the monomers m u t be high. Ordinary BPA is adequate
for making most epoxy resins, while BPA of very high puity is needed for
polycarbonates (99.8% purity has been mentioned as a minimum requirement (McKetta
and Cunningham, 1 976)).
The characteristics of BPA used as a raw material for producing polycarbonates are
presented in Table 1.1 (Catana et al., 1993):
Table 1.1: Quality characteristics for BPA as raw materiai fer polycarbonates (Catana et
al., 1993)
- -
Specification 1
Aspect, pallets or crystals Melting rioint, OC
I - ~ron. D D ~ . max I l l
Vaiue white
156 Colour of melt, "Hz
Light transmission, %, min Water, wtY0, max Ash. wt%. max
There are several methods of evaluating the quality of BPA. The most important
50 98 O. 1 0.005
parameter that characterizes the quality of BPA is its colour, and it was found that iron is
one of the agents that changes the colour of BPA, due to the coloured complexes that are
formed (Wasilewska, 1997). The colour can be estimated by analyMg the percentage
transmission of a 50% solution of BPA in methanol or acetone and comparing it to a
blank at 350 nm (McKetta and Cunningham, 1976) or 420 MI (Shinohara, 1971).
The technique that is most used for estimating the pur@ of BPA is the melting point
(McKetta and Cunningham, 1976). Cnide products have wide-range melting points
starting at about 140°C. The rnelting point of the pure compound is 157OC. Good
commercial grades melt at 154 to 155°C. The cryoscopic constant has been reported as
10°C (McKetta and Cunningham, 1976), and 17°C (Challa and Hermans, 1960). Another
simple test is to measure the percent of impurities that easily dissolve in a paraffinic
solvent, cyclohexane for example (McKetta and Cunningham, 1976).
Since obtaining high purity BPA is of great importance, improvement of the
manufacniring process \vas continuously investigated by researchers. Either the yield or
the selectivity of the process, or both, were considered for improvement and several
modification of the original method were studied: different catalysts, homogeneous and
heterogeneous, alternatives to acetone as feedstock, and alternatives to acetone and
phenol as feedstock.
The purpose of this investigation is to outline the bais of a search for new solid catalysts
that could be used in a catdytic distillation unit for produchg bisphenol A to improve
yields and selectivities. Catalytic distillation is a process where a reaction takes place
simultaneously with a separation process in the same unit (Podrebarac et al., 1997). The
major advantage of this type of system over traditional systems are the potential savings
in production costs, since not only one operational unit is eliminated, but also the
associated piping and instrumentation that are required to connect the reaction unit with
the separation unit are eliminated.
Catalytic distillation is a process that has the potential of producing bisphenol A at lower
production costs. With this purpose in mind, the investigation of more suitable catalysts
for the process is of great interest. Prior to the final goal of producing BPA by catalytic
distillation, prelirninary investigations m u t be performed to eventually identie new,
more suitable catalysts, and to £ïnd appropriate reaction conditions. The purpose of this
thesis is to examine the curent technologies available to produce BPA, to invetigate the
fesib-ity of new cataiysts, and to perform experiments to investigate the effects of
selected reaction parameters, using these catalysts.
In Chapter 2 a criticai literature review is conducted, which details the existing processes
used in the BPA manufacniring and purification, the alternatives that have been evaluated
with the purpose of improving the process. Also included are some physical and
chernical properties of bisphenol A.
In Chapter 3 the Gibbs reactor simulations are investigated and the results are compared
to the results in the literature. This simulation provides insight about the reaction
mechanism which leads to BPA formation. The results of these simulations are used to
determine the levels, the factors and the responses chosen for the subsequent
expenmentd designs.
In Chapter 4 the experimental apparatus and the instrumentation employed to analyze the
products, also the methods used for data processing are described. Safety procedures are
detailed as well.
In Chapter 5 the results obtained in the preliminary runs and the results obtained from the
experiments performed in the batch reactor are presented. A two factorial design is used
to examine the effects of the chosen factors on the selected respcnses.
In Chapter 6 the results obtained in the expenments performed in the plug flow reactor
are presented. This setting was used for the systerns which could not be investigated in
the batch reactor, and also for one of the new identified catalysts, which was investigzted
in the batch reactor as well. Although the nurnber of reactions in the plug flow reactor
was kept to a minimum, important conclusions and lines of fùture work emerged.
Finally, in Chapter 7 the concIusions derived fiom the experimental work are presented.
Recommendations for future investigations are given.
Chapter 2
Basic Chemistry and Production Process for BPA
The intent of this chapter is to give an overview of the existing rnethods and reaction
schemes for producing crude BPA and to ernphasize the ones that are used industrially.
General purification issues will be presented. The physicd and chernical properties of
bisphenol A will be summarized. This background material is necessary to expiain
process alternatives. Most of the information presented in this chapter is £tom McKetta
and Cunningham, 1 976.
2.1 Preparation of Bisphenol A
This subsection describes the chemistry of BPA formation including mechanisms,
possible reactions, by-products, and order of reaction.
2.1.1 Acetone Process
2.1.1.1 Primary Reaction
The acid catalyzed condensation of acetone with 2 moles of phenol is the oldest process
for producing BPA.
Phenol Acetone Bisphenol A
The heat of reaction, for reactants and products in their natural physical state at 25OC, is
calcdated fiom heats of formation as + 18 -4 kcdmol. Severe conditions are not required;
a 1:2 molar ratio mixture of acetone and phenol, in the presence of concentrated
hydrochloric acid or sulfuric acid 70% at room temperature deposits a mass of crude BPA
crystals (McKetta and Cunningham, 1976). The reaction conditions predominantly
favour the formation of the products (Nenitescu, 1980).
Some sources claim that the presence of 10% water in the reaction mixture greatly
increases the rate of the reaction catalyzed by hydrochloric acid (Scheibel, 1974). Other
sources claim that processes catalyzed by suIfonic acid ion exchange resins rnodified with
-1-SH groups are also improved by the presence of 0.6 to 5% by weight water in the
initial reaction mixture @erg and Buysch, 1994). On the other hand, since water is a
product of the desired reaction, its presence decreases the yield of BPA. To
counterbaiance this effect, dehydration by various water-binding agents (such as calcium
chlonde or phenyl acetate) or by azeotropic distillation have been suggested (McKetta
and Cunningham, 1976).
The reaction proceeds with an electrophilic attack of the proton fYom the acidic catalyst
on the molecuie of acetone. This first step of the mechanism is very similar to the one in
the production of phenolphthalein and DDT and in the akylation of phenol with olefins
(McKetta and Cunningham,
2.1.1.2 By - Products Formation
For reactions involving the substitution of a proton in an aromatic ring, both the rate of
reaction and the equilibrium distribution of products are influenced by the density of
electrons at the centre of reaction (Nenitescu, 1980). This only applies if there are no
stenc effects. Thus the pp-isorner (BPA) is the most likely to f o m since the density of
electrons in the para position of the phenol is higher than in the ortho position. Aiso, the
p,p-isomer formation is favoured fiom the thermodynarnic point of view (McKetta and
Cunningham, 1976). Still, opisomer and some o,o-isomer are observed.
OH
It was observed that the o,o-isorner is produced in negligible amounts. Another possible
product that can result fiom the reaction of the already formed BPA with the tertiary
carbonium ion @-phenyl isopropylidene) (McKetta and Cunningham, 1976) is the so
called "triphenol 1" (4,4'-(4-Hydroxy-m-phenyIenediisopropylidene)diphenol):
TnphenolI
P-isopropenyl phenol can be obtained when the p-phenyl isopropylidene ion loses a
proton. The p-isopropenyl phenol fonned can dimerize and the dimer c m add phenol to
yield another triphenol ("triphenol II" or 4,4',4" -(1,1,3-Trimethyl- 1 -propanyl-3-ylidene)
triphenol) (McKetta and Cunningham, 1 976):
OH OH Triphenol II
An irreversible cyclization of the dùner to 4'-hydroxy-2,4,4-trimethylflavan (flavan) can
occur if the hydroxyl group in the dimer is in the ortho position relative to the carbon
bearing the methylene group (McKetta and Cunningham, 1976):
Fl avan
If both hydroxyl groups in the dimer are in the ortho position relative to the aliphatic
chain, the 2'-hydroxy isomer is formed (McKetta and Cunningham, 1976):
The acetone can dimerize with itself and form mesityl oxide. The mesityl oxide formed
can M e r react with two molecules of phenol to give a product isomeric with flavan, a
chroman (McKena and Cunningham, 1976):
Acetone Acetone Mesrtyl Oxide
H~C' 'CH, Phenol
chroman 1 chroman il
The dimer resulted from the dimerkation of p-hydroxy-a-methyl styrene, triphenol II and
flavan can be obtained as a result of the reaction between mesityl oxide and phenol as
well. The reaction conditions that favor the formation of al1 the by-products presented so
far, are the same as the conditions that favor the BPA formation.
No unsaturated products were observed in the cmde product, leading to the idea that al1 of
the unsaturated products formed M e r react to give other by-products. The o,p-isomer,
melting point 1 1 l O C , triphenol 1, melting point 19 1 OC and chromane, rnelting point
158°C were al1 isolated fiom cmde BPA (McKetta and Cunningham, 1976).
Due to the high reactivity of the system, many other components can be produced and are
present in the reaction mixture. A likely one is the spirobiindan (Curtis, 1962), which c m
be obtained fkom two molecules of phenol and one molecule of phorone. The phorone is
the resdt of the condensation of three molecules of acetone, which c m occur in the acidic
medium provided for the process of BPA formation:
H,C ' Acetone
HG,
O phorone
phorone
Phenol
2. 1.1.3 Reaction Order
The BPA formation is a condensation in two steps. First a molecule of acetone reacts
with a molecule of phenol, then the product, or the corresponding ion, reacts with the
second molecule of phenol. The reaction was reported first order in both acetone and
phenol, which indicates that the first step is slower than the second step, therefore it is
rate determining (McKetta and Cunningham, 1976). In another study (Kato, 1963), the
HC1-catalyzed reaction was second order in phenol. According to de Jong and Dethmers
(Dethmers and de Jong, 1965) the activation energy for the overail process is 15 kcdmol.
According to Kato (Kato, 1963) the activation energy is19 kcal/mol. These processes are
reversible fike most other electrophific substitutions. In the presence of an acid, an
equilibrium c m be established between BPA and the main by-product, the o,p-isomer.
2.1.1.4 Equilibrium Data
The ortho-para ratio increases by increasing the temperature therefore temperatures as
low as possible are preferred in order to maximize the BPA formation (McKetta and
Cunningham, 1976).
Using phenol as a solvent for the process, the data presented in Table 2.1 were generated
for the equilibrium constant for the BPA+o,p-isomer transformation. 0.067 at 40°C,
0.08 at 60°C, 0.1 1 at 80°C, and 0.16 at 100°C (Dethmers and de Jong, 1965).
Table 2.1: Equilibrium constant for the BPA 0.p-isomer transformation
2.1.1.5 Catalysts
Temperature (OC)
K
For the process catalyzed by gaseous hydrochloric acid, the reaction of BPA formation is
reported to be first order in catalyst. E s is the reason why it was recommended to nin
the process at several atmospheres (Takenaka et al., 1968).
The first catalyst used to produce BPA was concentrated hydrochloric acid. Processes
that use gaseous hydrochloric acid or acid ion-exchange resins are also operated in the
United States. Aithough the process is slower and the product more difficult to puri@
than in the hydrochlonc acid catalyzed process, sulfuric acid 70% to 75% concentration
can be used as catalyst. In this case the concentration of the acid m u t not exceed the
40
0.067
60 80 100
0.08 0.1 1 0.16
above mentioned b i t s in order to minimize the sulfonation. There are some advantages
in using sulfunc acid as catalyst for the process: the apparatus is simpler and the
corrosion is less severe (McKetta and Cunningham, 1976).
Other homogeneous catalysts that can be used but do not seem to have practicai
The data in Table 2.2 are plotted and the graphs are illustrated in Figures 2.1,2.2,2.3, and
2.4. They show that in the case of zeolites, Re-Y gives the highest activity (Fig. 2.1).
This rnight be due to its highest concentration of acid sites compared to the other zeolites
used (H-Y, H-mordenite and H-ZSM-5).
The relative activities of various catalysts decrease in the order:
~ r n b e r l y f 15 > Re-Y > H-mordenite > H-Y > H-ZSM-5
The concentration of the undesired products increase in the order:
Amberlyst" 1 5 c Re-Y c H-mordenite
Fig. 2.1 Conversion of Phenol versus Time for Various Catalysts
Reaction Time [hl
-+ H-mordenite -e- Arnberiyst-15
Fig. 2.2 Product Selectiviry versus Time for the Reaction CataIytcd by Re-Y
Reactian Timc [hl
op-isomer [II] + Chroman 1 and Chroman II [III+IV]
Fig. 2 3 Rodud Seleaivity versuç T i for the Readon Catalyzed by H-mordenite
+ BPA m -C opkamer [lq + amxrian 1 and Chroman II [m+W -.-OthcrS
Fig. 2.4 Product Selcctivity venus Time for the Reaction Catalyzed by Amberlyst-15
Rcaction Timc [hl
+ BPA [q -t opisomer [lu
Chroman 1 and Chroman II [III+IV]
The conversion of phenol increases monotonie with time and the higher the concentration
of acid sites in the catalyst the higher the conversion (Fig.2.1). However, the activity of
the tested zeolites for the formation of BPA is lower than that of the cation-exchange
resins. The data also show that the more acidic the catalyst is, the selectivity of the BPA
formation is higher (Fig. 2.2,2.3, and 2.4).
The conversion of acetone and phenol to BPA is catalyzed by bases as well as acids;
sodium phenoxyde (C,H,ONa) is particularly specified (McKetta and C m g h a m ,
1976). However, the method is of no use because both yield and quality of product are
inferior.
2.1.1.5.1 Catalyst Enhancers
Both rate of formation and yield in BPA c m be improved by using 1% or less by weight
compounds that contain mercapto groups (McKetta and Cunningham, 1976). Some of
the compounds containing mercapto groups are su1 fur dichloride, sodium thiosul fate,
hydrog en sulfide, iron suifide, alkanethiois, arenethiols, thioglicolic acids,
mercaptoalkanesdfonic acids, alkali alkyl xanthates, 2-mercaptobenzothiazote and others
(McKetta and Cunningham, 2 976).
This improvement in rate and yield is possible due to the fact that the carbonium ion
containing sdfûr (CHJIC+SR is more stable than (CH&2+OH. Being more stable, it can
exist in higher concentration in the reaction rnixtare and consequently dkylate faster the
phenol ring (McKetta and Cunningham, 1976).
Sulfonated aromatic organic polymers, such as sulfonated polysiyrene, havîng organic
mercaptan groups , aminoorgano mercaptan groups (Faler and Loucks, 198 1, 1982,
1984), N-alS.laminoorgano mercaptan groups (Faler and Loucks, 1983) attached to
backbone sulfonyl radicals by covalent nitrogen-sulfur Iinkages have been used as ion-
exchange resins for making BPA. Also a sulfonated polystyrene ion-exchange resin
having ionically bound N-allcylaminoorgano mercaptan groups was developed (Pressman
and Willey, 1986). These polymers have been developed with the intention of improving
the degree of activity, selectivity and stability of these sulfonated aromatic organic resins.
In 1994 Rudolph developed a catalyst modified with mercapto amines to be used for BPA
and other bisphenols formation (Rudolph et al., 1994). This continuous search for new
and enhanced catalysts demonstrates the serious need for improved yields and
selectivities in the process of BPA formation.
2.1.1.6 Bisphenols Stabilizers
Malic, glyceric and lactic acids have been found to be highly efficient for the stabilization
of bisphenols. These hydroxy carboxylic acids or their ammonium or alkali metal salts
cm be added to the feed reactants used to make the bisphenols or to the reaction mixture
after the reaction is complete or at any time in between. They are particularly useful
when the bisphenol is exposed to high temperatures, such as during the separation of the
bisphenol £tom the reaction mixture , which, in most cases, involves a melting stage
(Dachs et al., 1982).
2.1.1.7 Solvents
The viscosity of the reaction mixture may increase as the process advances. Thus it is
preferable to perfonn the reaction in a solvent, which ha to be inert in the given reaction
condition, to avoid the formation of even more by-products. Suggested solvents are
chlorinated aliphatic hy drocarbons, acetic acid, or aromatic hydrocarbons (McKetta and
Cunningham, 1976). Excess phenol is preferred since it suppresses the condensation of
acetone with itself and it is easy to recover and recycle. Feeding acetone at successive
stages in multistage or cascade reactors rnawnizes the advantages of excess phenol
(McKetta and Cunningham, 1976).
2.1.1.8 Reaction Mechanism
Reinicker and Gates (Catana et al,, 1993) suggested a mechanism for the condensation
process, for the reactions catalyzed by sulfonic resins. This mechanism involves the
formation of hydrogen bonds between the ketone and the sulfonic resin. These bonds
were observed experirnentally by IR spectroscopy.
The proposed mechanism consists of the electrophilic attack of a polar reactive
intermediate, which c m be a carbonium ion, on the aromatic ring. In the fus1 step the
hydrogen bonds are formed between the carbonyl group of the ketone and the sulfonic
group of the resin (1). This intermediate is expected to react with the phenol in the non-
polar surrounding medium, forming a tertiary alcohol (II), which transforms rapidly into a
carbonium ion (III). The final step, the formation of the BPA molecule, takes place
through hydrogen bonds (Fig.2.5). This type of mechanism also explains the formation
of some of the by-products which can appear during the synthesis or during subsequent
processing of the BPA.
Fig. 2.5 Mechanism of Condensation of Acetone with Phenol via Hydrogen Bonds
(Catana et ai., 1993)
2.1.1.9 Reactor Configuration
If the reaction for producing BPA fiom phenol and acetone is conducted in a fixed bed
reactor containing gel-form or macroporous sulfonic acid ion exchanger resins, the
volume/time yield c m be improved by providing the resin as a two-layer bed (Berg et al.,
1995) (Fig.2.6):
the lower layer of the bed comprises an unrnodified resin having a low degree
of crosslinking, less than or equal to 2%, and comprises 75 to 85% of the bed
volume as a whole; and
the upper layer of the bed, which comprises 15 to 25% of the bed volume as a
whole, comprises either:
* a resin having a higher degree of crosslinking than the lower bed, fiom
equal to or greater thm 2% to less than or equal to 4%, in which 1 to
35 mol % of the sulfonic acid groups are optionally covered with
species containing alkyl-SH groups by ionic fixing, or
* a resin having a low degree of crosstirking, less than or equal to 2%,
in which 1 to 25 mol % of the sulfonic acid groups are covered with
species containhg alkyl-SH groups by ionic fixing.
.L
Fig.2.6 Reactor Configuration
2.1.2 Alternatives to Acetone as Feedstock
Compounds that react with acid to generate the isopropylic carbonium ion can be
generally used instead of acetone. One of the processes semicommercially applied in
Russia used propyne (methylacetylene), or a commercial mixture of propyne and
propadiene (MAPP), as an alternative to acetone as feedstock (McKetta and Cunningham,
1976). Other processes clairn the use of isopropenyl acetate or 2-chloropropene instead
of acetone (McKetta and Cunningham, 1976):
Use of these, like that of (CH3)2C(SR)I types (from acetone and thiols) (McKetta and
Cunningham, 1976), avoids the formation of water as a by-product.
Industrially, the phenol and the acetone are obtained together in the acid cataiyzed
decomposition of cumyn hydroperoxide (C,H,C(CH3)200H). It is thus namal that cmde
reaction mixtures, either enriched in phenol by addition or depleted in acetone by
distillation thereof (to produce a more suitable ratio of reactants), were used to make BPA
(Kiedik et al., 1993). The simplification achieved in this manner is compensated by
inferior yields and selectivities.
BPA can be produced with good yields by adding phenol to p-isopropenyl phenol. The
p-isopropenyl phenol necessary for the process is obtained together with phenol fiorn the
by-products of BPA manufacture via alkaline cracking at 220°C and 55 mm Hg. This
way by-products of the BPA formation process c m be transformed in the desired product,
BPA, for an overall improvement of the yield and the selectivity of the process (McKetta
and Cunningham, 1 976).
It was reported that BPA is formed in a reaction between phenol and a urea-acetone
condensation product (McKetta and Cunningham, 1976). The urea-acetone condensation
product is presented below:
2.2 Purification
The process used to produce BPA influences the composition of the mixture fiom the
reactor. It is still expected to contain phenol, acid cataiyst (unless an acid ion-exchange
resin was used), water, BPA, by-products, a thiol promoter, and sorne acetone (if the
reaction was not carried out to depletion of acetone) (McKetta and Cunningham, 1 976).
For exampie, a cmde product Stream consisted of 4 1% BPA, 36.2% 07p-isomer, 1.1% o,o-
isorner, 14.2% phenol, 3.5% chromane, 0.05% flavan, and 12% of unidentified
compounds (Verkhovskaya et al., 1973). The ratio of BPA to 07p-isomer to chromane in
another crude product meam ws 90:7:3 (McKetta and Cunningham, 1976). The
composition of the BPA usually available on the market is 94% BPA, 4% og-isomer, 3%
triphenol1, and 1 % chromanes (Anderson et. al., 1959).
Small differences in the operating conditions may have considerable effect on the process
of BPA formation, and different purification processes may be necessary. This results in
purification procedures that are numerous and diverse. Since excess phenol is generally
used, its removal and recycling is a step found in most purification processes (McKetta
and Cunningham, 1976).
2.2.1 Catalyst Separation
No catalyst separation is required for the resin catalyzed processes. If a homogeneous
catalyst was used than this has to be neutralized, or washed with water, or distilled out in
the case of hydrochloric acid. The hydrochloric acid is the most preferred one among the
homogeneous catalysts, because it can be recycled and the waste disposal problems are
thus reduced.
The water has to be removed fiom the system whether homogeneous or heterogeneous
catalyst was used. It can be removed by stripping with inert gas such as carbon dioxide
or nitrogen, or with benzene. The addition of benzene facilitates the water removal
without the use of vacuum equiprnent (McKetta and Cunningham, 1976). In 1992
Cipullo announced a more effective way of removing the water fiom the cataiyst bed
(Cipullo, 1992). The process involves two steps. In the first step 25 to 90% of the water
is removed by vaporization. In the second step the dehydration is completed by
saturating the catalyst with pllenol.
Sometimes the resin catalyzed processes nui to 50% conversion of acetone and in such
cases dong with water the h p p i n g removes acetone and some phenol as well. The
acetone and phenol removal c m be minimized by adding a trace of a metal complexing
acid before stripping (oxalic, citric, or tartric acid) (McKeîta and Cunningham, 1976).
2.2.2 BPA Separation from Crude
The crude is the mixture of products and unreacted reagents that corne out of the reactor.
Most of the BPA produced separates as a 1: 1 adduct with phenol afier partially stripping
and cooling the crude. This adduct c m be separated by filtration, centrifugation or both.
The phenol adduct can be M e r subjected to a series of processes with the purpose of
separating the BPA fiom the phenol. These processes may be remelting,
recrystallization, melting and passing over an ion exchange resin (Faler and CipiifIo,
1988), heating in vacuum to distill out the phenol or heating with excess water (McKetta
and Cunningham, 1976). The product may be M e r refined by soIvent treatment or
vacuum distillation.
Strong acids can leach fiom the acidic ion exchange resin catalyst into the reaction
mixture during the reaction. These acids can decrease the yield and the selectivity of the
overall process by cataiyzing the cracking of BPA during purification and finishing steps.
Therefore it is important to remove them before starting the purification of the product,
and this can be done effectively by an inorganic oxide (Powell and Uzelmeier, 1991).
Formation of the 1 : 1 BPA-phenol adduct c m be prevented by:
operating the process with very little excess phenol,
operating the process with acetone and phenol in a molar ratio close' to
stoichiometry in inert solvent or to a less than 100% conversion of acetone,
vacuum-stripping phenol fiom the crude, or
treating the acid-stripped crude, partiy crystallized or not, with excess water, and
steaming to remove remaining thiol promoter (McKetta and Cunningham, 1976).
2.2.2.1 Methods of Separating BPA from the 1: 1 BPA-Phenol
Adduct
Since most of the modem processes for obtaining BPA operate with a high excess of
phenol, the formation of the 1:1 BPA-phenol adduct is inevitable; and so new ways of
obtaining high quality BPA fiom the said adduct have been investigated. Such a method
has been reported and consists of fusing the adduct in an atmosphere having a maximum
oxygen content of 0.005% by volume, followed by evaporation of liberated phenol
(Asaoka et al., 1 994 and 1995).
Selective solvents that dissolve the maximum of by-products and a minimum of BPA are
used to separate the BPA fYom the 1 :1 8PA:phenol adduct. Such solvents are berizene,
heptane, cold ethylene dichlonde, a mixture of an aromatic and an aliphatic solvent, weak
aqueous alkalies (NaCo,, W O H ) and organic solvent-water emulsions (McKetta and
Cunningham, 1976).
Recrystallization is another effective procedure. The solvents usually used are aromatic
solvents like toluene and chlorobenzene, a mixture of an aromatic solvent with a polar
solvent, methanol or a mixture of methanol and ethylene dichloride, 1,1,2,2-
tetrachloroethane, acetic acid, and isopropyl alcohol (McKetta and Cunningham, 1976).
A newly developed process purifies the BPA by a two stage crystallization procedure
(Sakashita et al., 1993). A system that uses the combined efTect of a filter and a
centrifuge was considered in order to minimize the liquid impurities that rernain on the
crystal cake. The crystals are also washed to reduce the surface adherent impurities on
the final crystals.
The dissolution of cmde BPA in caustic alkali, filtration and precipitation with a strong
acid or carbon dioxide (Flippen et al., 1970) is another possibility. Decoiorizing carbon
and inorganic salts c m be added, also a reducing agent (sulfite or hydrosulfite) is
advisabIe to add to prevent the BPA f?om becoming coloured, as a result of oxidation by
air (McKetta and Cunningham, 1976). Anhydrous ammonia can be used to precipitate
adduct "salts" that can be isolated and dissociated to yield pure BPA (McKetta and
Cunningham, 1976).
Vacuum distillation has already been mentioned (Kiedik et al., 1993) in spite of the
special equipment required. Another disadvantage of this procedure is the tendency of
BPA to decompose at pot temperatures above 200°C, especially if acidic or basic
irnpurities are present (McKetta and Cunningham, 1976). In order to avoid
decomposition, thin-film distillation can be performed instead of vacuum distillation
(Pahl et al., 1965). The decornposition can also be reduced by distilling under a nitrogen
atmosphere and dding polypropylene glycol. a secondary or tertiary aikaline earth
phosphate, or diethyl malonate before distillation (McKetta and Cunningham, 1976).
2.2.2.2 By-Products Isomerization to BPA
BPA by-products can be isomerized to BPA in the presence of an acid catalyst (which
can Se an ion-exchange resin or hydrogen chloride) and a fiee mercaptan CO-catalyst (Li,
1989). The alkaline cracking at 220°C and 55 mm Hg of the by-products to yield phenol
andp-hydroxy-isopropenynil phenol that c m be recycled to the process has aiready been
mentioned (McKetta and Cunningham, 1 976). This high temperature is necessary
because the chromanes are relatively refractory and tend to build up in recycle strearns
(McKetta and Cunningham, 1976). The chroman can also be isolated and purified as a
crystalline ciathrate. The BPA can also be regenerated with good yields fiom scrap resins
(McKetta and Cunningham, 1 976).
2.3 Manufacturing
The most industrially used processes for making BPA in the 'Jnited States and Western
Europe are the acetone-phenol ones, in homogenous as weIl as heterogeneous catalysis.
Considering the costs involved and the net advantages the heterogeneous catalysis offers,
the resin-catalyzed process is preferred and it has been improved continuously.
A process which considers reacting acetone with very Iittle excess phenol (1:4 to 1:12
molar ratio acetone:phenol in the initial reaction mixture) was reported (Iimun, et al.,
1990). The reaction stage of this process comprises of two steps. In the fust stage the
acetone is reacted with very little excess phenol in the presence of a sulfonated cation
exchange resin catalyst modified with a rnercapto goup-containing compound to convert
20 to 60% of acetone. In the second stage the reaction mixture fiom the first step is
reacted in the presence of hydrochloric acid as catalyst.
Although the literature shows that processes using alternative feeds, such as a post-
reaction mixture resulting fiom the synthesis of phenol and acetone, are not convenient
because of the great variety of by-products and the infenor yields, such a process has
been developed and it is now industrially used in the United States.
Accordingly, three flow sheets are presented in this chapter:
a) the resin-catalyzed process using acetone and phenol;
b) the hydrogen c hloride-cataly zed process ; and
c) the resin-catalyzed process using a post-reaction mixture of the cumyl-
hydroperoxide decomposition.
2.3.1 Resin - Catalyzed Process
A process catalyzed by a sulfonated cation exchange resin modified with 2-
mercaptoethmol is presented in Fig. 2.7 (McKetta and Cunningham, 1976). A mixture
consisting of 83.4% phenol, 5.1% acetone. 0.1% water, 3.4% recycled BPA and 8.0%
recycled by-products are preheated and fed to the reactor. The reactor is operated at
about 75°C. The residence time is set at one hour. The process runs to a 50% conversion
of acetone (McKetta and Cunningham, 1976). Aithough not stated in the reference. the
units for product distribution are most likely to be wt'X0. If the units were mol%, the
molar ratio of acetone to phenol would be about 1 : 16, which is undesirable since it would
favour the adduct formation.
MAKE-UP , ACETONE , 1 4
PHENOL
3
ACETONE ACETONE PHENOL WATER
+t - 3 8
PHENOL ACETONE - ACE3ONE WATER
l PMNOL
\ I
2 ,+. 3 <wASH PHENOL
BYPRODUCT
'4 '~ V
5 t BPA 1 PHENOL ADUCT
I PHENOL. BYPRODUCT, BPA - RECYCLE
Fig. 2.7 Production of Bisphenol A with Resin Catalyst (McKetta and Cunningham, 1976)
1-Feed tank; 2-Reactor; 3-Concentrator; 4-Crystallizer; 5-Solid-Liquid separator; 6-Melter; 7-Flaker; 8,9-Distillation columns; 1 0-Phenol stripper. The reactor effluent, together with some recycled phenol, BPA and by-products go to the
concentrator. The concentrator is operated at 200mm Hg. The overhead at the
concentrator is a mixture of acetone, water and phenol (18 to 20%). The boîton Stream
consists of phenol, BPA and by-products. The overhead passes through a series of
distillation columns to remove the water fiom the acetone and the phenol, which are
recycled to the reactor. The bonom Stream from the concenmtor goes to a crystdlizer
where it is cooled d o m to separate the BPA as phenol adduct. Afier crystallization the
mixture is separated in a centrifûge, washed with phenol, and fieed of phenol by melting
at 130°C, then stripping in a column at 200°C and lmrn Hg. The purity of the product
obtained with this process is over 90%. The phenol recovered in the sûipper is recycled
to the centrifuge and the centrifuge liquor is recycled to the reactor (McKetta and
Cunningham, 1976).
2.3.2 Hydrogen Chloride - Catalyzed Process
A process that uses hydrogen chloride as cataiyst is presented in Fig. 2.8 (Pahl et A.,
1965). A version of this is used by Mitsui Chemical in Japan and by General Electric in
the United States (McKetta and Cunningham, 1976). A mixture of excess phenol,
acetone, BPA and by-products fiom the recycle strearns are saturated with gaseous
hydrochlonc acid and fed to the reactor. The reactor is operated at about 50°C. The
mixture is reacted for several hours under continuous stimng. The effluent fiom the
reactor undergoes a preliminary stripping that removes a two-phase mixture of
hydrochloric acid, water and some phenol. This overhead goes to a decanter where the
two layers separate. The hydrochloric acid is recovered fiom the aqueous phase and
recycled. The water goes to the drain. The stripped crude is fed to a senes of separation
columns and successively freed of phenol in the phenol still (at about 10 mm Hg) and of
o,p-isomer in the isomer still. The phenol and by-products separated in this stage are
recycled to the reactor (McKetta and Cunningham, 1976). The impurities with higher
boiling points are separated fiom BPA by vacuum distillation in the BPA still at 1 to 5
mm Hg. The BPA overhead is mixed with some solvent (e.g. benzene) under pressure
while molten, then cooIed in the crystallizer to cause crystallization. The purified crystals
are separated in a centrifuge and then dried for a high quality product. The liquor fiom
the centrifuge goes to a solvent d l . The by-products separated at this stage are recycled
to the reactor and the solvent is stored for subsequent uses (McKetta and Cunningham,
1976).
HCL , , H a RECYCLE / -
Fig. 2.8 Production of Bisphenol A with Hydrogen Chloride Catalyst (Pahl et al., 1965) 1-Reactor; 2-HC1 still; 3-Decanter; 4-HC1 recovery column; 5-Solvent still;
Fig. 4.7 Chrornatogram of the Products Obtained fiom the Condensation Process
Chramaabgram P l o t C:~ATLIRWUILICIP(AWXP1\FEBSs4 W W 9 8 16:B1!38 C a m m e n t : EXîERIHENT 4 W I O H - FE39 - WTER 96 HOURS Scan No: 1 R e t e n t i o n T i m a ' 8!01 RIC: 8 asts Range: 8 - 8
Range: 1 ta 728 IB&A = 351694116 Plotted: 1 to 728 ieq
TOT
The calibration of the GCMS method was not possible because most of the by-products
observed in the reaction were not availabie as standards. NI the sarnples contained
relatively the same components in comparable amounts, the sarnpling procedure. The
preparation of the sample and the analysis conditions were identical. Therefore it was
decided to consider the area of the peaks proportional with the mass of the corresponding
compound. The GC/MS analysis was used to detelmine the selectivity of the process.
4.4.2 NMR AnaIysis
A Bruker ACF-200 NMR Spectrometer with a MHz frequency was used to
deterrnine
acquisition
the amount of BPA produced with heterogeneous catalysis. The data
parameters
commercial NMR data
1995).
are summarized in Table 4.4. NMR data are anaIyzed using a
processmg
Table 4.4: Data acquisition parameters
as NUTS (Acom NMR,
1 Parame ter 1 Value
Number of Points 1 8 192
Number of Acquisitions Pulse Width (usec) Recycle DeIay (sec) Frequency (MHz) Sweep Width (Hz) Dwell Titne (usec)
Acquisition Time (sec) Offset Freauencv
16 5 .O 3 .O
200.132339 4032.3 248 .O 2.032 1 104.9
4.4.2.1
this
Domain Acquisition Type
General Introduction to the NMR Procedure
Study
Time TPPI
Used in
The procedure for calculating the yield in BPA in this study is based on the fact that
acetone and BPA have peaks that do not overlap and can be integrated and compared.
The procedure for calculating the error associated with the NMR analysis is also
described. The NMR spectra of acetone, phenol, and bisphenol A are presented in
Fi-ures 4.8,4.9, and 4.10, respectively.
Fig. 4.8 NMR Spectmn for Acetone (CDCI,)
Fig. 4.9 NMR Spectnim for Phenol
Fig. 4.10 NMR Specaum for Bisphenol A (CDCI,)
4.4.2.2 Calculation of the Error Associated with the NMR
Analysis
In the NMR spectrum of the initial mixture acetone:phenol (Fig. 4.1 l), the integrai of the
acetone peak was attributed the value of 100. The portion of the spectnim where the two
methyl groups of the BPA should appear was also integrated. Since there is no BPA
initially present in the system, the value of this integral should be zero, and if it is nof
then the error is attributed to the noise level within the integrated interval of the spectrum.
Fig. 4.11 NMR Spectrum of the Initial Mixture of Reaction (fiom 0.4 ppm to 3.0 ppm)
Since the processing error seems to be under 0.01 %, it was necessary to attribute a value
of 10,000 to the integral of the acetone peak in order to calculate the processing error.
Then the integrated noise showed a non zero value (Fig. 4.12).
The signal to noise (sh) is calculated as a ratio of two ratios. The numerator is the area
of a peak divided by the frequency domain over which the peak was integrated. The
denominator is the area integrated over a region in the spectrum where no peak is
supposed to appear divided by the frequency domain over which it was integrated. The
eequency domain can be expressed both in Hertz or in ppm; ppm represents the ratio of
the resonant frequency (in Hz) and the fiequency of the magnet (in Hz). In the
caiculation presented for signal to noise the fiequency domains were expressed, by
choice, in Hertz. The ratio signal to noise (sh) is:
The error associated with NMR analysis is:
Fig. 4.12 NMR Specûum of the Initial Mixture of Reaction (fiom 1 .O ppm to 3.0 ppm)
4.4.2.3 Procedure for Calculating the Yield in BPA
Another sample, taken at the end of the reaction, was analyzed on the NMR, and
processed with NUTS (Acom NMR, 1993,1994,1995), using the same normalization
constant, as the sample shown in Figure 4.1 1. The spec- of the sample taken at the
end of the reaction is presented in Figure 4.13.
When processing spectra with the same normalization constant, by setting the value of an
integral at 100, in al1 subsequent spectra the values of the integrals considered are going
to be percentages of the set integral. It is known that both integrals considered in this
application (the acetone peak and the peak of the methyl groups in the BPA) are
accounted for six protons each, and it is also known that the integrals are proportional to
the number of moles in the mixture corrected with the ambe r of protons (a correction
not necessary since the number of protons is the same). This means that if the initial
composition of the mktwe is known, the number of moles of BPA and of acetone in a
subsequent spectnim cm be calculated.
Fig. 4.13 NMR Spectrum of the Final Mixture of Reaction (fiom 0.4 pprn to 3.0 pprn)
The initial mixture contains: 24.12 g of acetone and 75.55 g of phenol. The molecular
weights for acetone and phenol are: 58.08 g/mole and 94.1 1 g/mole respectively.
Therefore the initial rnixhue consists of 0.41 mole of acetone and 0.8 mole of phenol, or,
in mole percent, 34.1 mole % acetone and 65.9 mole % phenol.
The yield in BPA is caiculated with the following formula:
where
7 is the yieId in BPA;
q p ~ , f i n is the number of moles of BPA present in the finai reaction mixture, and it is
caiculated as the product of the initiai number of moles of acetone and the value of
the BPA methyl peak integrai in the NMR spectnun;
M ~ A is the molecuiar weight of the BPA;
mi , is the weight of îhc reaction mixture.
4.5 Summary
This chapter presented the matenals and the analytical methods used for this research,
and the apparatus employed by the experimentd part of this study. The NMR tube
reaction was used to identifi new catalysts. The batch reactor was used to perform the
experiments with ~af ion@, in order to assess the effects of the selected process parameters
on the synthesis of BPA. The plug flow reactor was employed for the reactions with
acidified activated alumina, since this catalyst was not mechanically robust enough to
undertake the mixing in the batch reactor. A significant amount of time was required to
ensure that al1 safety concerns were satisfied.
in the next chapter the experimental results are presented and discussed. Several sets of
experiments were performed to evaluate the reactivity of the system of interes& to veri&
the experimental reproducibility, and to narrow down the experimental region which will
be investigated usïng an experimental design.
Chapter 5
Experimental Results and Discussion
Eight sets of experiments were performed to examine the synthesis of bisphenol A under
various reaction conditions. The first set used homogeneous and heterogeneous catalysis
at roorn temperature. The second set used ~afTon@ at various temperatures in a batch
reactor. The third set used AmberlystB 1 5 as heterogeneous catalyst, with the purpose of
evaluating the experimental reproducibility. The fourth set consisted of one reaction with
heterogeneous catalyst, and had the purpose of validating the simulation prediction that
the reaction goes to depletion of acetone. The nfth set consisted of reactions performed
with heterogeneous catalyst in an NMR tube. The sixth set used heterogeneous catalysis
in a batch reactor with the purpose of cornparhg the performance of ~ a f ï o n @ NR-50
versus ~mberlyst@ 15. Finally, the seventh and the eighth sets employed heterogeneous
catalysis at various ternperatures, catalyst concentrations, and molar ratios acetone:phenol
in a batch reactor. Ln these experiments a two factorial design was perfomed to examine
the effects of catalyst type, catalyst concentration, temperature, and molar ratio acetone to
phenol. AU the experiments presented in this chapter are summarized in Table 5.1.
Table 5.1 Summary of the experiments Exp. # 1 Time 1 Catal yst 1 Catalyst Conc. 1 Temp. 1 Acetone:Phenol 1 Reactor Type
1.1 1.2 1.3 II. 1 11.2 11.3 11.4 11.5 IL?. 1 111.2 m.3 IV. 1
I I I I 1 I
V.4 1 6 1 AA 300/HC1 1 10 1 70 1 1 :2 1 NMR Tube
(h) 288
V. I V.2 V.3
2 16 72 96 96 96 96 96 5 5 5
240
Type HC1
6 3 3
V.5 VI. 1 VI.2 VII. 1 VIL2 VII.3 VI1 -4 VIL5 VII.6 VII.7 VII.8 VII.9 - VXI.10 VII.1 1 Vn.12 VIII. 1 VIII.2
VIII.4 VIII.5 VIII.6 VIII.7 VIIT.8
(wt %) 10
~mberlyst" 15 No Catalyst
~afion@NR-50 Nafionam-50 ~a£ ion@ NR-50 ~ a f i o n @ NR-50 Nafion@ NR-50 ~rnber lys t~ 15 ~mberIyst@ 15 ~ m b e r l y s t 15 Amberiyst@ 15 ~ m b e r l y s t ~ 15 Nafion@ NR-50 ~ a f i o n @ NR-50
6 27 27 24
25 25 63 72 83 92 102 72 72 72 72
I
10 - 10 10 10 10 10 10 10 10 10
24 24 24 24 24 24 24 24 24
(Oc)
25
10 10 10
AA 300/HCl ~ m b e r l y s t ~ 15 ~ a f i o n @ NR-50 Nafion@ NR-50
The effect of the catalyst concentration (C) becomes insignificant in the combined design.
The effect of the temperature on the yield in BPA is just slightly srnaller in the case of the
combined design in comparison with the 2' design (2.09 compared with 2.66). The
significance of the two factor interaction effect associated with the catalyst concentration
and the temperature (CT) is almost the same for both z3 and 2' designs. The two factor
interaction eEect associated with the temperature and the molar ratio of the reagents (TR)
is smaller in the case of the combined design in comparison with the 2' design (-2.51
compared with -3.92). The three factor interaction effect (CTR) is significant in both z3
and z4 designs. In the combined design some factors become significant: the molar ratio
(R), the particle size 0, the two factor interaction effect associated with the temperature
and the particle size (RI), and the two factor interaction effect associated with the molar
ratio of the reagents and the particle size (RN).
This chapter presented the results obtained for the experiments performed in the NMR
tube and in the batch reactor. These experiments investigated and evaluated the reactivity
of the system, blank reactions, and experimental reproducibility. A scherne of reaction
was set up, based on the results obtained. New catalysts were tested and found suitable
for producing BPA.
The effects of temperature, catalyst concentration, and molar ratio acetone:phenol in the
initiai reaction mixture were examined in depth, also the variation of BPA and by-
products formation and the variation of the yieId of BPA with respect to t h e were
analyzed. The results were compared to data obtained fiom Literature and simulation.
The examination of the experimental design provides a better understanding of the
operating conditions and the effects the chosen factors have on the system under
investigation. The purpose is to maximize the amount of BPA produced while
minimizing the number and the amount of by-products produced.
The analysis of the results obtained in the 2" experimental design indicate that a moderate
temperature is desirable, a 10 wt% catalyst concentration and a 1 :2 molar ratio
acetone:phenol. At temperatures close to the upper limit of the experimental range, the
yield in BPA is higher, but so is the formation of chromanes. This fact c o b s the
fîndings in the literature and the simulation results. The initial molar ratio of acetone and
phenol is significant only for the yield in BPA, and a stoichiometric ratio is defïnitely
preferred, which confirms the simulation results and contradicts the data in the literature.
The particle size of the catalyst beads also influences the production of BPA. Larger
amounts of BPA were obtained with the cataiyst with bigger particle size, and better
selectivities of the BPA formation with the catalyst with smaller particle size. This can
be explained by the fact that the occurrence of swelling of the smalier particles of catalyst
was insuffkient and the access of the reagents to the acidic sites inside the catalyst
particle was reduced. Harmer et al., 1996 indicate that the accessibility of the active sites
inside the catalyst can be improved by using as catalyst a new rnaterial instead of the
156
basic stmctural polyrner Nafion@, that is Nafion" SAC-13, which is essentially silica
irnpregnated with the basic smictural polymer ~ a f i o n ? This new material seems to
fomuiately combine the benefits of the porous structure of the silica and the super acid
capabifities of ~afion".
The next chapter presents the results of the experiments performed in the plug flow
reactor. The intent of these experirnents is to take M e r the investigation of the process
of BPA formation and to identiw Iines of future work.
Chapter 6
Reactions in the Plug Flow Reactor
Preliminary results obtained in the experiments performed in the plug flow reactor (PFR)
are presented and discussed in this chapter (see PFR diagram in Figure 4.1). The
catalysts used for these nins were:
(AA 300/HCl), Nafion@ NR-50, and
this chapter are summarized in Table
activated alumina
bJafïonm SAC- 13.
6.1.
Table 6.1: Summary of the experiments
acidified with hydrochloric acid
Al1 the experiments presented in
Exp. #
IX.2 X. 1 X.2 X.3 XI. 1
Temperature (Oc)
Tirne (h)
Acetone:Pheool Molar Ratio
24 24 24 24 24
Catalyst Type
AA 300/HC1 Nafion@ NR-50 Nafion@ NR-50 NafionmNR-50
Nafion@ SAC- 13
Flow Rate W h )
4.0 4.8 4.8 4.8 4.0
92 102 102 102 92
1:2 1:s 1 5 1 5 1:2
6.1 Reaction with Acidic Activated Alumina
Several experiments were tried with AA 300/HC1 in the batch reactor, but only after half
hour the reaction mixture became cloudy and the reactions were stopped. The activated
alumina was not robust enough to withstand mixing and it crushed. This is the reason
why a plug flow reactor was necessary to Uivestigate this system. Two reactions were
performed using as catalyst activated alumina acidified with hydrochlonc acid (AA
300MC1)-
For the first reaction, a 8x14 mesh AA 300 was acidified for two hours with a 2:l
solution of hydrochloric acid and water (volurneiric proportion) at room temperature.
The catalyst was dried in the reactor with hot nitrogen (105"C), overnight. The reactor
was fed with a 1 :5 initial mixture of acetone and phenol (molar ratio) using a syringe
pump previously calibrated, at a rate of 4.8 cch. The temperature was maintained
constant during the reaction, at 102OC, by means of a thennocouple located in the catalyst
bed, attached to a PID (proportional-integral-derivative) controller, that regulated the
power of the heater. The reaction was stopped after 24 hours.
The product was cloudy. M e r separation, a sarnple was anaiyzed on the GC-MS.
Although a BPA peak was observed, the quantity produced was small. No other products
were observed.
Taking into account the resdts of the first reaction, a second experiment was performed.
With the intent of increasing the yield in BPA, some modifications were considered. 20
grarns of a 14x18 mesh AA 300 were acidified for two hours with concentrated
hydrochloric acid at room temperature. The catalyst was dried ovemight in the reactor
with hot nitrogen (105°C). The reactor was fed with a 1:2 initial mixture of acetone and
phenol (molar ratio) using a syringe pump previously calibrated, at a rate of 4.0 cch. The
temperature was maintained constant during the reaction, at 92"C, by means of a
thermocouple located in the catalyst bed, attached to a P D controller, that regulated the
power of the heater. The changes in process conditions were intended to increase the
activity of the cataiyst and the retention time in the reactor. Both variables were changed
to increase the contact time between the catalyst and the reagents. A 1:2 molar ratio of
the initial reagents was preferred, based on the conclusions from the previous
investigations. The reaction was stopped after 24 hours. The ody product observed in
significant amount was bisphenol A. The results are presented in Table 6.2.
Table 6.2: Results of the experiments with AA 3001 HCl
The yields in BPA obtained in these two experiments are comparable to the yields
obtained for some of the experiments presented in the previous chapter (experiments
Exp. #
IX. 1 IX.2 ' I is bisphenol A; II is 2,4'-isopropylidenediphenol; III is 4'-hydroxyphenyl-2,2,4- trimethyl chroman 1; IV is 4'-hydroxyphenyl-2,4,4-trimethyl chroman II; V are other by- products.
Temp. OC 102 92
Flow cc/h 4.8 4.0
Yield wt% c 0.5 1.79
Reaction Time (h)
24 24
Molar Ratio 1:5 1:2
Product Distribution' (wtO/o) 1 n III+N V
100.00 100.00
0.00 0.00
0.00 0.00
0.00 0.00
WI. 11, VIII. 1, VIII.2, W.5 , VIII.6, VIII.7). The selectivities obtained in the
experiments performed in the PFR using AA 3 00/HC1 as catalyst are 100%, higher than
the selectivity obtained in any previous experiment These prelirninary results prove that
acidified activated alumina is a suitable catalyst for the production of bisphenol A.
6.2 Reactions with Piafion@ NR-50
The reactions with Nafion@ NR-50 (the basic polymer) were performed at 102OC. The
catalyst was dned prior to the reaction with Nz at 105OC. The reactor was fed with a 1 :5
initial mixture of acetone and phenol (molar ratio), using a syringe purnp previously
calibrated, at a rate of 4.8 cch. The temperature was maintained constant during the
reaction, at 102"C, by means of a thermocouple located in the catalyst bed, attached to a
PID controller, that regulated the power of the heater. The reaction was stopped after 24
hours. Between the two reactions the catalyst was regenerated with a 15% solution of
niûic acid, at 50°C, which was allowed to flow through the catalyst bed at a rate of 20
cc& for six hours.
Two samples fiom the fist reaction were prepared and analyzed, one on the GC-MS, the
other one on the NMR. The product fiom the second reaction separated hto two layers, a
light one and a dark one. Both layers were analyzed on the GC-MS.
nie reason for the separation is believed to be the fact that the catdyst was not washed
and dried well enough after regeneration, therefore an aqueous and an organic layer
existed in the system. Also the presence of the nitric acid made possible the formation of
some nitro compounds, which were observed in the light colored fiaction.
No BPA or any of its isomers were detected in the light colored bction. Some BPA, 0-0
isomer and o-p isorner were observed in the dark colored fraction. The product
distribution and yield for both reactions are presented in Table 6.3.
Table 63: Results of the experiments with ~ a f i o n @ NR-50
Dark colored fiaction of the product in the second reaction
Exp. #
X. 1 X.2 " x.2
Products unidentified, and obtained oniy in the reaction performed with regenerated catalyst, believed to be nitro derivatives
a Light colored fraction of the product in the second reaction
Selectivity of BPA formation, if the unidenîified products are not taken into account Selectivity of o-p isomer formation, if the unidentified products are not taken into
Yield wt% 4.1 1 - -
Reaction 1 Molar
A third experiment was tried with the sarne catalyst, but it was stopped because the
Flow c c 5 4.8 4.8 4.8
Time 24 24 24
pressure was building up rapidly. The reason appeared to be the fact that the polymer
Temp. OC 102 1 02 1 02
Ratio 1 5 i:5 1 5
Product Distribution (wt%) I II III+TV V VIc
particles swelled and expanded to the extent that they almost formed a block inside the
82.47 -
31.17 79.63d
reactor, without leaving any space for the reactants or the nitrogen to flow through. This
situation might be solved by mWng the Nafion@ NR-50 particles with g l a s beads, to
17.53 -
7.97 20.37'
ensure the flow space in the reactor. Another possible and interesting experiment to
examine is to mix the Nafion@ NR-50 with acidified activated alumina. Besides solving
0.00 -
0.00 -
0.00 -
0.00 -
-
1 O0 60.86 -
the flow problem inside the reactor. one couid also snidy the combined effect of the two
cataiysts on the process of BPA formation.
6.3 Reaction with ~ a f i o n @ SAC-13
~afion@' SAC-13 is essentially silica impregnated with the basic polymer Nafion@ NR-50.
This new materid combines the benefits of the porous structure of the silica with the
super acid properties of ~a f ion? The purpose of this reaction is to evaluate 60m the
qualitative point of view the suitability of this new material to catalyze the production of
bisphenol A.
The reaction with Nafion@ SAC-13 was performed at 92OC. The catalyst was dried prior
to the reaction with N, at Mac. The drying temperature, 155"C, was arbitrarily chosen
between 105°C and 1 60°C, since the drying process can occur ordy at temperatures above
100aC, and on the instructions that came with the catalyst drying temperatures under
160°C were indicated. The reactor was fed with a 1:2 initiai mixture of acetone and
phenol (molar ratio), using a syringe pump previously calibrated, at a rate of 4.0 cch.
The temperature was maintained constant during the reaction, at 9SaC, by means of a
thermocouple located in the catalyst bed, attached to a P D controller, that regulated the
power of the heater. The reaction was stopped after 24 hours.
The phenol used in this reaction was not the liquid form as for al1 the other experiments.
The crystals form was used instead. The reason for this was that al1 of the liquid phenol
was consurned, and Fisher Scientific stopped distributhg this product, because they could
not stabilize their b~ches . Other suppliers were contacted, but they do not fiunish the
phenol in liquid fom, with 9% water as impurity. As a result, the water content in this
system was lower and a decrease in the yield was expected, since it was found in the
Iiterature that about 10% water in the initial reaction mixture increases the rate of the
reaction (Scheibel, 1974).
The only products observed were mesityl oxide, 0-0 isomer, and BPA, in very s m d
quantities. Two samples were prepared and analyzed, one on the GC-MS, the other one
on the NMR. The product distribution and the yield for the reaction are presented in
Table 6.4.
Table 6.4: Results of the experiment with ~ a f i o n @ SAC - 13
The following 5 tables show the moi percent content of bisphenol A, og-isomer, and
triphenol in the final product Stream as a function of temperature and molar ratio over the
considered range of temperature, at 1 atm. The final table shows the variation of
selectivity of bisphenol A (I), ogisomer (II), and triphenol (III) with the temperature at
various acetone:phenol molar ratios. The initial reaction mixture consists of acetone and
phenol only.
Table C.1: Variation of bisphenol A, o,p-isomer, and triphenol formation with the acetone:phenol molar ratio at 323.15 K. The results are presented in mol %.
Temperature 1 Molar Ratio 1 Bisphenol A ( og-Isomer 1 Triphenol
Table C.2: Variation of bisphenol A, o,p-isomer, and triphmol formation with the acetone:phenol rnolar ratio at 333.15 K. The resdts are presented in mol %.
Temperature 1 Molar Ratio 1 Bisphenol A
Table C.3: Variation of bisphenol A, o,p-isomer, and triphen01 formation with the acetone:phenol molar ratio at 343.15 K. The results are presented in mol %.
Temperature 1 Molar Ratio 1 Bisphenol A
1 1
* The equilibrium was not achieved. The numbers rc the 50 iterations.
lect the result obtained at the end of
Table C.4: Variation of bisphenol A, o,p-isomer, and triphend formation with the acetone:phenol rnolar ratio at 353.15 K. The results are presented in mol %.
Temperature 1 Molar Ratio 1 BisphenoiA 1 op-Isomer 1 Triphenol
Table CS: Variation of bisphenoi A, o,p-isomer, and aiphenol formation with the acetone:phenol molar ratio at 3 63.1 5 K. The results are presented in mol %.
Table C.6: Variation of selectivity of bisphenol A (I), o,p-isomer (II), and triphenol (III) with the temperature at various acetone:phenol molar ratios.
Molar Ratio Temperature Selectivity (%)
Ac:Ph (K) 1 1 II III 0.05 323.15 69.77 30.23 0.00
Appendix D: The NMR Phenomenon
Nuclear Magnetic Resonance (NMR) spectroscopy is a method of great interest and importance for the study of chemical substances. The use of puised Fourier transform methods with spectnim accumulation made it possible to obtain high resolution spectra (Sanders and Hunter, 1 993).
Do1 Magnetic Energy Levels and Transitions
When the spin quantum number 1 of a nucleus is nonzero, the nucleus possesses a magnetic moment. This condition is met if the mass number and atomic number are not even. The proton ('H) has a spin 1 of X. When placed in a magnetic field of strength Bo, nuclei with nonzero 1 occupy quantified magnetic energy levels, cailed Zeeman levels, the number of which is equal to 21 + 1 (Sanders and Hunter, 1993). The relative population of the Zeeman levels are normally given by a Boltzmann distribution.
Transitions between energy levels can be made to occur by means of a resonant radio fiequency (rf) field B, of fiequency vo. A way of picturing the resonance phenornenon e s e s fiom the fact that when placed in a magnetic field, a nucleus undergoes Larmor precession about the field direction at a rate given by v, or a, (ao is the resonant fiequency, o, = 2nv0, rad/s). Transitions between energy levels occur when the fiequency of the rf field equals the Larmor precession frequency (Sanders and Hunter, 1993).
D.2 The Chernical Shift
Resonaxce occurs at slightly different fiequencies for each type of proton, depending on its chemical binding and position in a molecule. This variation is caused by the cloud of electrons about each nucleus, which shields the nucleus against the magnetic field, thus requiring a slightly lower value of v, to achieve resonance than for a bare proton (Sanders and Hunter, 1993). Protons attached to or near electronegative groups such as OH, OR, OCOR, COOR, and halogens expenence a lower density of shielding electrons and resonate at higher v,. Protons farther removed fiom such groups, as in hydrocarbon chains, resonate at lower v,. These variations are calied chemical shifts and are commonly expressed in relation to the resonance of the tetramethylsilane (TMS) as the zero of reference. The total range of proton chernical shifts in organic compounds is on
the order of 10 ppm, e.g. ca 1 kHz in a magnetic field of 2.34 T (Sanders and Hunter, 1993).
For any nucleus, the separation of chemically shifted resonmces, expressed in H z , are proportional to Bo. When expressed in ppm, as common, the chemical shifts are independent of Bo.
The eiectronic screening of nuclei is actually anisotropic so that the chemical shift is a directional quantity and depends on the orientation of the molecule with respect to the direction of the magnetic field. In solution, the motional averaging produces an isotropie value of the chemical shift.
D.3 Nuclear Coupling
Nuclei sficiently removed fiom each other do not feel the effects of the magnetic fields of the other nuclei. In this case, the locai magnetic field at each nucleus is essentially equal to Bo. If Bo can be made very homogeneous over the sample, the width of the resonance lines may be very small.
D.3.1Direct Dipole - Dipole Coupling
In most substances, protons contribute to local fields and are sufficiently numerous to have a marked effect. The 13c atoms also conhbute to the local fields, but their naturai abundance is very small, therefore they do not have a visible effect.
D3.2Indirect Nuclear Coupling
Magnetic nuclei may transmit information to each other concerning their spin states not only directly through space, but also through the intervening covalent bonds. This is indirect or scalar nuclear coupling, aiso known as J coupling. Rapid tumbling of the molecde does not reduce this interaction to zero. If the nucleus has n suffIcient1y close, equivalently coupled spin -% neighbors, its resonance will be split into n + 1 spin states of the neighboring group of spins. Thus one neighboring spin splits the observed resonance to a doublet, two produce a 1 :2: 1 triplet, three a 1 :3 :3: 1 quartet, and so on. The strength of the coupling is denoted by a coupling constant J and is expressed in Hz.
Referen
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Anderson, W.M., G.B. Carter and A.J. Landua, Anal. Chem., 31, 1214-1217 (1959).
Arnold-Stanton, R. and D.M. Lemal, The Journal of Orgunic Chemistry, 56, 146-151 (1991).
Asaoka, S., T. Maejima, K. Sakashita, N. Yoneda, M. Yasui, N- Onda, T. Watanabe, N. Moriya, A. Shindo, H. Nishijima, A. Kukidome, R. inaba, T. Imazeki, K. Shimogawara, U.S. Patent 5,324,867 (1 994).
Asaoka, S., T. Maejima, K. Sakashita, N. Yoneda M. Yasui, N. Onda, T. Watanabe, N. Moriya, A. Shindo, H. Nishijima, A. Kukidome, R. Inaba, T. Imazeki, K. Shimogawara, US. Patent 5,382,7 12 (1 995).
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