Esterification of maleic acid and butanol using cationic exchange resin as catalyst

Article abstract of DOI:10.1007/s12039-017-1375-2

Abstract : Dibutyl maleate is a perfumery ester used as an intermediate in the production of paints, adhesives, and copolymers. Esterification of maleic acid and butanol was studied in presence of acidic cation exchange resin as a catalyst. The objective of this work was to test the suitability and efficacy of heterogeneous catalysts such as Indion 225H and Amberlyst-15 in the synthesis of dibutyl maleate. Various parameters deciding the conversion of reaction such as mole ratio, catalyst loading, molecular sieves, speed of agitation and effect of temperature were optimized for the maximum rate and conversion. The activation energy was calculated as 71.5?kcal/mol. Diffusivity value D _AB (maleic acid in n-butanol) at 80°C was calculated as 5.08×10-10m2/s and effective diffusivity (D _e-A) was calculated as 5.08×10-11m2/s. Solid–liquid mass transfer coefficient (k _sl-A) was calculated as 6.77×10-6m/s for the particle size of Amberlyst-15 as 0.5 mm. Graphical Abstract: Synopsis. Synthesis of dibutyl maleate was carried out using ion exchange resin as a catalyst. Effect of various parameters on the conversion of reaction like mole ratio, catalyst loading, molecular sieves, the speed of agitation and effect of temperature was studied. [Figure not available: see fulltext.].

Full text of DOI:10.1007/s12039-017-1375-2

J. Chem. Sci. Vol. 129, No. 11, November 2017, pp. 1713–1720.
© Indian Academy of Sciences
https://doi.org/10.1007/s12039-017-1375-2
REGULAR ARTICLE
Special Issue on Recent Trends in the Design and Development of Catalysts and their Applications
Esterification of maleic acid and butanol using cationic exchange
resin as catalyst
∗
AARTI MULAY and V K RATHOD
Department of Chemical Engineering, Institute of Chemical Technology, Matunga (E), Mumbai 400019, India
E-mail: vk.rathod@ictmumbai.edu.in
MS received 25 April 2017; revised 7 August 2017; accepted 8 August 2017; published online 15 November 2017
Abstract. Dibutyl maleate is a perfumery ester used as an intermediate in the production of paints, adhesives,
and copolymers. Esterification of maleic acid and butanol was studied in presence of acidic cation exchange
resin as a catalyst. The objective of this work was to test the suitability and efficacy of heterogeneous catalysts
such as Indion 225H and Amberlyst-15 in the synthesis of dibutyl maleate. Various parameters deciding the
conversion of reaction such as mole ratio, catalyst loading, molecular sieves, speed of agitation and effect of
temperature were optimized for the maximum rate and conversion. The activation energy was calculated as
◦
−10
2
7
1.5kcal/mol. Diffusivity value DAB (maleic acid in n-butanol) at 80 C was calculated as 5.08 × 10
m /s
−11
2
and effective diffusivity (De-A) was calculated as 5.08 × 10
m /s. Solid–liquid mass transfer coefficient
ksl-A) was calculated as 6.77 × 10 m/s for the particle size of Amberlyst-15 as 0.5 mm.
−6
(
Keywords. Esterification; dibutyl maleate; ion exchange resin; Indion 225H; Amberlyst-15.
1
. Introduction
manufactured mainly by sulfonation of ethylbenzene
first, followed by cross-linking with divinylbenzene.
Sulphonic acids have an effective catalytic activity and
cause fewer side reactions. These co-polymer beads
are prepared by pearl polymerization technique to get
macroreticular or macroporous resin. The application
of ion exchange resin as a catalyst for esterifica-
tion reaction is well explored earlier by researchers.
Various researchers have investigated the mechanism
of heterogeneous catalysts using ion exchange resin.
Yadav and Thathagar studied the kinetics of ester-
ification of maleic acid with ethanol over various
cationic exchange resins like Amberlyst-36, Amberlyst-
Esters are derived from the reaction between carboxylic
acids and organic alcohols. The liquid phase esterifica-
tion reaction has a significant role in chemical industry
due to its wide applications as plasticizers, adhesives,
pharmaceutical intermediates, pesticides and in poly-
merization of monomers.1 In the past few years,
various esterification reactions catalyzed by inorganic
acid, Lewis acid, organometallic compounds, and solid
acids, were investigated by researchers to understand
the reaction mechanism. Earlier, homogenous catalysts
4,6
–6
suchasH SO , p-toluenesulphonicacid, sodiumhydro-
2
4
gen sulphate and HCl were used for producing the ester
at a faster rate. However, separation of this catalyst
requires more steps and also it generates a large amount
of waste that made the process tedious. Hence ion-
exchange resin is a versatile material for the replacement
of the homogeneous acid catalysts. Use of heteroge-
neous catalysts are of high importance due to their
non-corrosive and eco-friendly nature, easy to separate
and no washing as of homogeneous acid is required.
These catalysts affect the equilibrium conversion due
to their selective adsorption of reactants.4 Cation-
exchange resins such as Dowex, Amberlyst series are
1
5, Indion-170, Amberlyst-18, Amberlite IR 400, and
1
DTP/K-10. Dange and Rathod reported esterification
reaction involving butyric acid and methanol over the
Amberlyst-15 catalyst. Kinetic data were tested for
pseudo-homogeneous model, Langmuir-Hinshelwood
model and Eley-Rideal model. State of art work
has been published by M. M. Sharma on the use of
cationic ion exchange resin as catalyst. Gangadwala
et al., have determined the intrinsic reaction kinet-
ics of esterification of acetic acid with n-butanol in
presence of Amberlyst-15. Yadav and Krishnan have
2
4
–12
5
investigated the synthesis of methyl anthranilate from
*
For correspondence
1713

1714
Aarti Mulay and V K Rathod
anthranilic acid and methanol using eco-friendly hetero- 2.3 Methods of analysis
geneous catalysts like ZSM-5, acid treated clays such
as filtrol-24 and K-10, ion exchange resins such as
2
.3a Gas chromatographic analysis: The liquid sam-
pleswereanalyzedusingagaschromatographModelGC2010
Shimadzu Plus for quantitative determination of dibutyl
maleate and water formed in the reaction. Column SH-RXi-5
Sil MS (30 m × 0.25 mm i.d, 0.25 μm film thickness) was
used. Helium was used as carrier gas. The initial column
temperature was set at 50 C with a hold time of 1 min to
obtain prolonged retention for early eluting peaks. The col-
umn temperature was increased to 280 C with temperature
Nafion–H, Indion-130, Amberlyst-15 and Amberlyst-
8
1
8. Although various reports are available on syn-
thesis of ester using ion exchange resin, a limited
work has been carried out on synthesis of dibutyl
maleate with ion exchange resin as catalyst. Dibutyl
maleate has wide applications as a plasticizer for vinyl
resins and used for various copolymer applications.
It is also used in plastisols, dispersions, coatings and gradient maintained at 30 C/min. At final column tempera-
adhesives.
M Bengi Taysun et al., compared the performance of 15 C/min, dibutyl maleate eluted at a retention time ranging
Amberlyst-15-dry, Amberlyst-5-wet, Amberlyst-131H+
◦
◦
◦
◦
ture of 310 C, hold time of 5 min and temperature gradient at
◦
from 11.73 to 12.96 min.
for esterification of maleic acid with butanol using
deep eutectic solvents with 1:10 molar ratio of maleic
acid to butanol. However, the effect of various param-
eters was not well-explored and fixed to comparison at
only one condition.13 Hence the current investigation
2
.3b Infra-red spectroscopy: The product liquid sam-
ples were analyzed using infrared spectrometer (FTIR 1-S
Affinity- Shimadzu make) to determine the functional groups
present, through infrared spectrum. Spectrometer details
−1
is an attempt to explore the utilization of ion exchange are; wavenumber range is 400–4000 cm with Michelson
resin for the synthesis of dibutyl maleate by a possi- interferometer (30 incident angle) and DLATGS detector
◦
ble screening of various ion exchange resins and to equipped with temperature control mechanism.
maximise the conversion by optimizing the various
parameters.
2
.3c Titrimetric analysis: Samples were taken out at
known intervals of time from the reaction mixtures and were
titrated using alcoholic 0.01 N KOH using phenolphthalein
indicator to calculate the acid value. Acid value was calcu-
lated for each sample taken out at intervals. Dibutyl maleate
obtained was expressed in terms of percent conversion as
given in equation 1.
2
. Experimental
2.1 Materials
Maleic acid and n-butanol were procured from S.D. Fine
Chem Mumbai, India and Loba Chemie respectively. Acidic
ion exchange resin (Indion 225H & Amberlyst-15 of Rohm
and Haas Co.) was obtained from S.D. Fine Chem Mumbai.
Molecular Sieves (4A type), from S.D. Fine Chem Mumbai
was used in the reaction.
(
av1 − av2)
%
conversion =
× 100
(1)
av2
◦
Whereav1 isanacidvalue(mgKOH/g)ofthereactionmixture
at beginning and av2 is an acid value (mg KOH/g) of the
reaction mixture at an individual time interval.
2.2 Experimental setup and method
The reactions were carried out in a batch reactor of 100 mL
capacity equipped with 4 baffles. The reactor was continu- 3. Results and Discussion
ously stirred by using a three blade glass turbine impeller
driven by an electrical motor. The reaction contents were In the present work, a dicarboxylic acid i.e., maleic acid
well-stirred and the speed of agitator was varied using a speed
reacts with n- butanol in presence of an acidic cata-
controller. Thetemperatureofthereactionwasmaintainedata
lyst to produce monobutyl maleate and further reacts
constant value by using a thermostatic water bath. The catalyst
with n-butanol to produce dibutyl maleate. As per the
◦
was dried at 70 C for 2 h before use. A measured quantity of
reaction stoichiometry, one mole of maleic acid reacts
maleic acid and butanol were added to the reactor and allowed
with two moles of n-butanol to give the product of one
mole of dibutyl maleate along with one mole of water,
to reach a desired temperature. Cationic exchange resin and
molecular sieves were added and zero time sample was col-
where water is the by-product of the reaction. As men-
lected. Butanol was taken in far excess over maleic acid to
tioned earlier, butanol was used in excess of maleic
acid to shift the equilibrium towards the forward direc-
drive the equilibrium of the reaction towards ester formation.
Very small amount of sample was withdrawn at a higher fre-
quency at first half hour and at a definite interval thereafter tion of ester formation. The reaction is represented as
for 4 h of time. below:

Esterification of maleic acid and butanol
COOH-HC = CH-COOH + 2C H OH
1715
225H and Amberlyst-15 are 1.8 and 4.7 respectively
whichmeansAmberlyst-15wasfoundtobemoreactive.
Yadav and Thathagar carried out the esterification reac-
tions of maleic acid and ethanol on Amberlyst-15 and
Indion-130 as well as Dange and Rathod investigated
the esterification reaction involving butyric acid and
methanol over Amberlyst-15 as a catalyst. Yadav and
Kulkarni also performed the synthesis of isopropyl lac-
tate using Indion -130, Amberlyst-36, Amberlyst-15,
Amberlite-120, Dowex 50W, Filtrol-44, DTPA/K-10,
where they observed that Amberlyst-36, Amberlyst-
4
9
(Maleic acid)
(Butanol)
ꢀ
(
COOC H -HC = CH-COOC H + H O
4
9
4
9
2
Dibutyl Maleate)
(Water) (2)
Various reactions were carried out with reaction condi-
tions altered to study the effect of catalysts, temperature,
thespeedofagitation, acidtoalcoholratio, catalystload-
ing and amount of molecular sieves.
All experiments were performed thrice to check
the reproducibility of the experiments. The conversion
obtained with this analysis for the effect of various
parameters was found with 2% deviation in the results
which are reported in appropriate figures.
14
1
5 and Indion-130 were most effective. Although M.
Bengi Taysun et al., used Amberlyst-15 for esterifica-
tion of butanol and maleic acid, the conversion obtained
was only 8% as they have not performed the reaction at
13
optimized conditions.
3.1 Screening of catalysts
Further reactions in this present work were carried
out with Amberlyst-15 as the catalyst where only one
parameter was varied at a time under the otherwise sim-
ilar experimental conditions. The properties of cation
exchange resins like Indion 225H and Amberlyst-15 are
given in Table 1.
Cationic ion exchange catalysts like Indion 225H and
Amberlyst-15 were used to understand the efficacy of
the reaction. During the reaction, n-butanol was used
as an excess reactant and maleic acid as limiting reac-
tant to drive the equilibrium towards formation of an
ester. The condition used for screening of the catalyst
was mole ratio of 1:4 for maleic acid to butanol, the 3.2 Effect of acid to alcohol ratio
◦
temperature of 80 C with a catalyst loading of 2%
As per the reaction stoichiometry, 1:2 mole ratio of
and a speed of agitation of 300 rpm. The results are
shown in Figure 1 which is expressed as the conversion
of maleic acid for these two heterogeneous catalysts.
It was found that Amberlyst-15 gave a higher conver-
sion of 48% as compared to Indion 225H with 44%
conversion for the reaction time of 4 h. The chem-
ical activity which is expressed as meq/g for Indion
maleic acid to n-butanol is required to perform the reac-
tion. However, to alter the reaction equilibrium, use of
an excess of alcohol is recommended to increase the rate
of forward reaction and improve the formation of ester.
Thus, the mole ratio of maleic acid to n-butanol was also
varied as 1:3, 1:4, and 1:5 keeping other parameters at
a constant value. The results are plotted as shown in
Figure 2 at reactions conditions as 4% of catalyst, 4%
◦
6
5
4
3
2
1
0
0
0
0
0
0
0
molecular sieves, reaction temperature 80 C and speed
of agitation as 300 rpm.
It was found that the concentration of n-butanol has
an influence on the conversion. As the amount of alco-
hol was increased, the conversion of maleic acid also
increased from 50% to 62% with an increase in the mole
ratio of maleic acid to n-butanol at 1:3 to 1:4 at opti-
mum conditions of temperature, the speed of agitation
and catalyst loading. Beyond 1:4 there was no apprecia-
ble effect on the conversion. Thus, mole ratio of 1:4 for
maleic acid to butanol was considered to be optimum.
Indion225H
Amberlyst 15
3.3 Effect of catalyst loading
0
100
200
300
The effect of catalyst loading for Amberlyst-15 on the
conversion of maleic acid and n-butanol was investi-
gated by varying the catalyst loading from 2%, 4%
Time (min)
Figure 1. Effect of different catalyst on conversion of
◦
maleic acid at 80 C, catalyst loading 2%, the speed of agita- and 6% based on the total weight of the reactants at
◦
tion 300 rpm, maleic acid to butanol mole ratio 1:4.
a temperature of 80 C, using 4% molecular sieves and

1716
Aarti Mulay and V K Rathod
Table 1. Characteristics of cation exchange resin used.
Properties
Indion 225H
Amberlyst-15
Shape
Size (mm)
Beads
0.3–1.2
Beads
0.5
Polymer type
Matrix
Weight Capacity (mEq/g)
Porosity (%)
Surface area (m /g)
Temperature Stability
Functional group
Macro-reticular
Styrene divinylbenzene copolymer
Macro-reticular
Styrene divinylbenzene copolymer
1.8
–
4.7
36
34.85
2
–
393 K
sulfonic acid
–
393 K
sulfonic acid
20
Cross linking (% DVB)
8
0
0
0
0
0
0
0
0
0
speed of agitation as 300 rpm keeping the mole ratio
of maleic acid and n-butanol as 1:4. Fresh resin was
used for each new trial. The conversion of maleic acid
as a function of time with different catalyst loading is
shown in Figure 3. It was observed that the conversion of
maleic acid increases proportionally with catalyst load-
ing. Increase in the catalyst loading means more active
sites available for the reaction, which gave an increase in
conversion. The change in the conversion of maleic acid
was observed from 68% to 77% when catalyst loading
was varied from 4% to 6%. Thus, no significant change
in conversion was observed when catalyst loading was
varied from 4% to 6%, may be due to unavailability
of sufficient substrate for the reaction. Hence opti-
mum catalyst loading was taken as 4% for further
experiments.
7
6
5
4
3
2
1
1
1
:03
:04
1:05
0
50
100
150
200
250
300
Time(min)
Figure 2. Effect of mole ratio on conversion of maleic acid
at a catalyst loading 4%, molecular sieves 4%, temperature
0 C, the speed of agitation 300 rpm.
◦
8
3
.4 Effect of agitation speed
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
In solid-liquid catalytic reaction, two types of mass
transfer resistances exist which include solid liquid
interface and other is intraparticle diffusion. Also the
diffusion of A from the bulk liquid phase to the exterior
of the catalyst surface through the liquid film surround-
ing the catalyst particle is represented by solid-liquid
7,14
8
mass transfer coefficient ksl-A. Amongst two resis-
M=2
M=4
M=6
tances, external mass transfer resistance can be reduced
by increasing the turbulence in reaction medium; that
can be done by varying the speed of agitation. Thus, the
effect of speed of agitation was studied at different agi-
tation speed between 100 rpm to 500 rpm to understand
the influence of external mass transfer resistance. The
reaction conditions were mole ratio of maleic acid to
0
100
200
300
Time (min)
◦
butanol at 1:4, 4% catalyst loading, temperature 80 C
and 4% molecular sieves. Figure 4 shows that conver-
sion increases from 55% to 62% when agitation speed
Figure 3. Effect of Catalyst Loading on conversion of
maleic acid at a mole ratio of maleic acid to butanol 1:4,
◦
temperature 80 C, the speed of agitation 300 rpm, molecular is varied from 100 rpm to 300 rpm. Further increase
sieves 4%.
in the agitation speed to 500 rpm shows an increase

Esterification of maleic acid and butanol
1717
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
80
70
60
50
40
1
3
5
00 rpm
00 rpm
00 rpm
30
20
0
percent
2 percent
4
6
percent
percent
10
0
100
200
300
Time (min)
0
0
50
100
150
Time (min)
200
250
300
Figure 4. Effect of the speed of agitation on conversion of
maleic acid at catalyst loading 4%, temperature 80 C, maleic
◦
acid to butanol mole ratio 1:4, molecular sieves 4%.
Figure 5. Effect of molecular sieves (0%, 2%, 4% and 6%)
on conversion of maleic acid at a mole ratio of maleic acid
◦
to butanol 1:4, Catalyst loading 4%, temperature 80 C, the
in conversion to 66%. This marginal increase in the speed of agitation 300 rpm.
conversion from 62% to 66% at 300 rpm and 500 rpm
may be because of the decrease in mass transfer resis-
tance due to increase in the turbulence. Hence the stirrer
speed of 300 rpm was selected as optimum and fur-
ther experiments were carried out at 300 rpm. Since
n-butanol (B) was taken in excess, there may be a possi-
bilityofdiffusionalresistanceofmaleicacid(A)through
the liquid film around the catalyst and through the pores.
Hence liquid phase diffusivity values DAB (maleic acid
in n-butanol) was required which was calculated by
with acetic acid, external mass transfer limitation was
negligible at a stirrer speed above or equal to 500 rpm,
where the stirrer speed was varied in a range from 50
to 900 rpm. Researchers also reported a negligible
impact of speed of agitation on the overall rate of reac-
tion in the range of 12 to 33 rps. Hence the esterification
16
reactions were carried out at a higher stirrer speed of
17
1
6.7 rps.
15
Wilke Chang equation.
◦
−10
2
DAB at 80 C was calculated as 5.08 × 10 m /s
and effective diffusivity (D ) is calculated as 5.08 ×
e-A
3.5 Effect of addition of molecular sieves
−11
2
1
0
m /s from D
= D ε / τ where ε and τ are
e-A
AB
1
◦
taken as 0.3 and 3, respectively. The values of solid- In this investigation, molecular sieves (4A type) were
liquid mass transfer coefficient ksl-A was calculated by added in a range of 2%, 4%, 6% (w/w) to study the
assuming Sherwood number, sh = (K d )/D = 2 effect of water produced in the esterification reaction.1
,2
sl
p
where D is diffusivity. k
was calculated as 6.77 × One experiment is also performed without addition of
sl-A
−6
1
0
m/s for the particle size of Amberlyst-15 as 0.5 molecular sieve to identify the variation in conversion.
9
,14
mm.
Yadav and Thathagar, Yadav and Krishnan All these experiments were carried out at a mole ratio
described the influence of intraparticle diffusion which of maleic acid to butanol 1:4, agitation speed of 300
was varied with particle size. They reported the values rpm and catalyst loading of 4% (w/w) at a temperature
of mass transfer coefficient k as 4.34 × 10− m/s and of 80 C. Figure 5 shows an increase in the conversion
5
◦
sl-A
−3
1
.857 × 10 cm/s respectively.
of dibutyl maleate from 40% to 68%, with an increase
Similar study was also reported for the synthesis of in molecular sieves, however the reaction conversion
diethyl maleate using Indion-170 where no external dif- is investigated to be lower at 40% without addition of
fusion effect was observed for stirrer speed ranging from molecular sieves. This indicates the adsorption of pro-
1
5
00 to 1000 rpm. Dange and Rathod also studied the duced water in the pores of molecular sieves. As there
effect of stirrer speed in the range of 100 to 400 rpm was a marginal change in the conversion of dibutyl
and found that the mass transfer coefficient was almost maleate after 4% (w/w) molecular sieves, it was taken
negligible at 300 rpm. In the study undertaken by Ali as optimum. Liu et al., reported the deactivation of cat-
12
et al., it was found that in the reaction of 2-propanol alyst occurs with water as the by-product. Dange and

1718
Aarti Mulay and V K Rathod
8
0
0
0
0
0
0
0
0
0
1.4
R² = 0.9445
7
6
5
4
3
2
1
1
.2
1
R² = 0.9315
R² = 0.9425
0
0
.8
.6
60 oC
R² = 0.9191
7
8
9
0 oC
0 oC
0 oC
0.4
0.2
0
R1
100
R2
R3
R4
0
100
200
Time (min)
300
0
200
300
Time (min)
Figure 6. Effect of temperature on conversion of maleic
acid at maleic acid to butanol mole ratio 1:4, Catalyst loading
Figure 7. Plot to calculate rate constants at various range
of temperatures 333–363K.
4%, the speed of agitation 300 rpm, molecular sieves 4%.
Table 2. Rate constant values for butanol at
different temperatures.
Rathod carried out esterification reactions using molec-
ular sieves and reported the increase in the conversion
of methyl butyrate on increasing molecular sieves to the
reaction mixture.2
−1
Temperature (K)
Rate Constant k1(min
)
−3
333
1.3 × 10
−
3
343
353
363
2.6 × 10
5 × 10
−3
3.6 Effect of temperature
−
3
6.6 × 10
Effect of temperature was studied by performing reac-
tion at 333 k, 343 K, 353 K and 363 K for 4 h with
Amberlyst-15 as a catalyst, mole ratio of maleic acid
to butanol 1:4, Catalyst loading 4%, with continuous
agitation at 300 rpm. Figure 6 depicts higher values of
conversion with increasing temperature. This is due to
more collisions within the reactants which have suffi-
cient energy to break the bonds in between the reactant
molecules to form products.
3
-1
(
1/T) x 10 , (K )
0
2
.7
2.8
2.9
3
3.1
-
-
-
1
2
3
There was no appreciable change in the conversion
beyond 353 K, therefore, it was taken as an optimum
-4
-5
value. Further, the plot of –ln (1 − X ) vs time as in
A
Figure 7 indicates a straight line behaviour alike pseudo-
8
first order behaviour. Thus, the rate constants for the
-
-
6
7
forward reaction at different temperatures are repre-
sented in Table 2.
The rate constant was expressed in terms of Arrhenius
equation, which is as follows
3
Figure 8. Arrhenius plot of ln k versus (1/T) ×10 , Catalyst
loading 4%, the speed of agitation 300 rpm, maleic acid to
butanol mole ratio 1:4.
k = k e−
E/RT
(3)
0
where k is Rate constant, k is frequency factor, E
o
is activation energy and R is Gas constant (1.98 ×
−3
−1
−1
1
0
kcal K mol ).
in Figure 7. A plot of ln K versus 1000/T was plot-
The Arrhenius plot to calculate the rate constant for ted as in Figure 8, and the energy of activation was
forward reaction in the temperature range of 333–363 calculated as 71.5 kcal/mol which represents a kinet-
K gives the regression coefficient of 0.94 as shown ically controlled reaction. There is an increase in the

Esterification of maleic acid and butanol
1719
Figure 9. IR spectrum of dibutyl maleate. IR (cm 1): ν(CH=CH), 961; ν(C-O), 1213; ν(C-O-C), 1210;
−
ν(CH and CH ), 2900.
2
value of the equilibrium constant with an increase in 3.7 Determination of functional groups
the temperature which indicates that the reaction is
Further liquid samples were analyzed using infrared
spectrometer (FTIR 1-S Affinity- Shimadzu make)
to determine the functional groups present, through
infrared spectrum as shown in Figure 9. The charac-
endothermic in nature. The earlier work done by Yadav
and Thathagar reported the activation energy as 14.2
kcal/mol for the esterification reactions of maleic acid
1
and ethanol carried out with Indion-170. Yadav and
−1
teristic peak at 961 cm can be attributed to =CH- out-
of-plane deformation in CH=CH- structure. The band
Krishnan calculated the activation energy as 18.176
kcal/gmol for the synthesis of methyl anthranilate from
anthranilic acid and methanol using heterogeneous cat-
−1
near 1168 cm may be due to C-O-C anti-symmetric
−1
8
stretch for the ether linkage. The band at 1210 cm con-
firms the C-O-C stretching in dibutyl maleate as ester
linkage. The presence of carbonyl group is confirmed
alysts like Indion-130. The activation energy for the
current investigation is quite high that indicates the sen-
sitivity of the reaction rate with temperature.

1720
Aarti Mulay and V K Rathod
from the peak near 1722 cm−1 which appears relatively
5. Gangadwala J, Mankar S and Mahajani S 2003 Esteri-
fication of Acetic Acid with Butanol in the presence of
ion-exchange resins as catalysts Ind. Eng. Chem. Res. 42
−1
red shifted from the expected position of 1740 cm
because of the presence of unsaturation in the molec-
2
146
−1
ular structure. The peak near 2900 cm is attributed to
the symmetric and asymmetric stretching of –CH and
6
. Chakrabarti A and Sharma M M 1993 Cationic ion
exchange resins as catalyst React. Polym. 20 1
–
CH groups in aliphatic chain. This result confirms the
7. Ali S H, Tarakmah A, Merchant S Q and Al-Sahhaf T
2007Synthesisofesters:Developmentoftherateexpres-
sion for the Dowex 50Wx8-400 catalyzed esterification
of propionic acid with 1-propanol Chem. Eng. Sci. 62
2
synthesis of dibutyl maleate by using Amberlyst-15.
3197
4
. Conclusion
8
. Yadav G D and Krishnan M S 1998 An ecofriendly
catalytic route for the preparation of perfumery grade
methyl anthranilate from anthranilic acid and methanol
Org. Process. Res. Dev. 2 86
9. Yadav G D and Mehta P H 1994 Heterogeneous catal-
ysis in esterification reactions: preparation of phenethyl
acetate and cyclohexyl acetate by using a variety of solid
acidic catalysts Ind. Eng. Chem. Res. 33 2198
The esterification of maleic acid and butanol in presence
of cationic ion exchange resin was successfully carried
out in presence of Amberlyst-15. The rate of esterifi-
cation increases with an increase in temperature over
a range from 60 C to 90 C where 80 C was found to
be optimum. The conversion was optimum at a stirrer
speed of 300 rpm, which was found to be effective for
eliminating external diffusion effect. A maximum con-
version of 76% was found for catalyst loading and the
addition of molecular sieves as 4% (w/w). Diffusivity
◦
◦
◦
1
0. Sejidov F T, Mansoori Y and Goodarzi N 2005 Esterifi-
cation reaction using solid heterogeneous acid catalysts
under solvent-less condition J. Mol. Catal. A Chem. 240
186
1
1. Peters T, Benes N E, Holmen A and Keurentjes J T 2006
Comparison of commercial solid acid catalysts for the
esterification of acetic acid with butanol Appl. Catal. A
Gen. 297 182
values D (maleic acid in n-butanol) was calculated at
AB
◦
−10
2
8
5
0 C as 5.08 × 10 m /s and effective diffusivity as
−11
2
.08×10 m /s. The energy of activation was found to 12. Liu Y, Lotero E and Goodwin J 2006 Effect of water on
be 71.5 kcal/mol. Mass transfer coefficient (ksl-A) was
sulphuric acid catalyzed esterification J. Mol. Catal. A
Chem. 245 132
−6
calculated as 6.77 × 10 m/s for the particle size of
1
3. Taysun M B, Sert E and Atalay F S 2014 ISITES 2014:
Amberlyst-15 as 0.5 mm.
2nd International Symposium on Innovative Technolo-
gies in Engineering and Science, June 18–20, Karabuk,
Turkey, p. 1325
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4