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: