2908 Herliati et al.
Asian J. Chem.
hydrogen chloride of 28 to 37 % by weight can also be used
as a chlorinating agent under atmospheric condition. The
reaction can be carried out in either batch or continuous mode
by vigorously stirring within temperature range of 100 to
120 °C. However, other hydrochlorination studies to produce
dichloropropanol were poorly developed around aqueous
hydrogen chloride as a chlorination agent.
Sample preparation and analysis:About 3 mL of sample
was treated with 0.5 g of the mentioned salt and kept at 100 °C
for 0.5 h in order to remove the entire water residues7. The
sample was then filtered with Whatman filter paper in order to
separate the precipitate formed and the clarified solution was
then analyzed by using gas chromatographic/mass spectro-
metry (GC/MS).
The main objective of this study was to develop a process
for the synthesis of 1,3-dichloropropanol through hydrochlo-
rination glycerol and HCl in the presence of carboxylic acid.
The HCl selected was muriatic acid (hydrogen chloride, 37 %
Quantitative analyses were carried out using GC/MS under
the following conditions: column, Capillary HP Wax; statio-
nary phase; length = 25 m; i.d. = 0.25 mm; film thickness =
0.25 µm; Ionization mode; helium as gas carrier; injector
temperature = 250 °C; detector temperature = 230 °C; tempe-
rature ramp = 1 min at 80 °C; heating rate = 6 °C/min to 150 °C,
then 3 °C/min up to 190 °C, then hold for 1 min at finally =
240 °C. The sample of the reaction mixture was first diluted
with methanol in a volumetric ratio of 1:20. The injected
volume of the obtained solution was 1 µL.
w/wt.) due to its good performance as chlorinating agent9,10
.
Firstly, our experimental work focused on the performances
of catalysts containing carboxylic acid groups of which having
a lower volatility than acetic acid, such as propionic acid,
malonic acid and lactic acid.After identifying the best catalyst
for the synthesis, the experiments were then directed towards
investigating the effects of operating parameters such as
reactant molar ratio and temperature of reaction on the reaction
yields. Our present results were also compared with experi-
The effects of reactant mol ratio and operating temperature
on both conversion of glycerol and selectivity of 1,3-dichloro-
propanol were examined by using aforementioned procedure.
Eqn (i) and (ii) were used to calculate the conversion of glycerol
and selectivity of dichloropropanol respectively:
mental data 7 and simulation study using Aspen PlusTM 11
.
EXPERIMENTAL
Moles of glycerol reached
Mole of glycerol supplied
Conversion of
glycerol (%)
=
× 100
(1)
Commercially available carboxylic acid catalysts namely
acetic acid, propionic acid, lactic acid and malonic acid, glyce-
rol and muriatic acid were purchased from Merck Chemical
Co. While 1,3-dichloropropanol for GC standard calibration
was obtained from Sigma Aldrich Co. Singapore.
Moles of dichloro-
propanol produced
Selectivity of
DCP (%)
=
× 100 (2)
Mole of glycerol reacted
Experimental run: First set of experimental runs focused
on screening of the best catalyst which were conducted at a
molar ratio of glycerol and muriatic acid of 1:16 and 8 %
catalyst by mole as recommended byYunus et al.11. Four types
of carboxylic acid, namely propionic acid, malonic acid, lactic
acid and acetic acid, were investigated at 90 °C with respect
to the acetic acid low volatility (117 °C). Then experiments
were done to observe the effects of reactant molar ratio on the
process at values ranged from 1:16 to 1:32.The experiments
were conducted at 120 5 °C using the best selected catalyst
from the previous screening experiments. After which, the
experiments were performed to examine the effect of tempe-
rature on conversion of glycerol and selectivity of 1,3-dichloro-
propanol at 80, 90, 100 110 and 120 °C.
RESULTS AND DISCUSSION
Screening of catalyst: The selection of the best catalyst
from carboxylic acid groups is crucial to obtain a good selec-
tivity from the reaction. To observe the performances of the
selected carboxylic acid catalysts on the conversion and also
selectivity, four experiments were conducted using acetic acid,
propionic acid, lactic acid and malonic acid.
The screening of the catalyst was conducted initially by
running the reaction between aqueous hydrogen chloride and
glycerol without the presence of catalyst. It was observed that
without catalyst there was no conversion of glycerol at all.
After that, the experimental runs were directed towards finding
the best catalyst among the four selected carboxylic acids of
which having a lower volatility than acetic acid (Table-1). From
the results, it was observed that malonic acid was the best
catalyst for the conversion of glycerol to 1,3-dichloropropanol.
Malonic acid has relatively lower volatility of which enabled
the reaction to be conducted at higher temperatures without
appreciable loss of catalyst. In general, the conversion of
glycerol was almost complete after 3 h using these catalysts.
In addition, the selectivity of the reaction was also analyzed
based on the concentration of 1,3-dichloropropanol which was
at 44 % by moles using malonic acid catalyst. The maximum
selectivity of dichloropropanol obtained in the earlier work
was 21 % higher compared to the earlier study by Tesser et al.7.
On the other hand, Yunus and Herliati11 demonstrated that up
to 70 % selectivity of dichloropropanol could be obtained from
simulation study using Aspen PlusTM. However, the previous
result was obtained using gaseous hydrogen chloride as a
Experimental setup:The reactions were performed in a
250 mL three-neck flask equipped with a thermometer, a samp-
ling port and a reflux condenser. The condenser was connected
to an accumulator. The reactor was immersed in a temperature
controlled oil bath at constant stirring by the magnetic stirrer.
Initially, the reactants comprised of glycerol and aqueous
hydrogen chloride solution 37 % w/w (chlorination agent) was
loaded into glass reactor. After the homogeneous solution
reached certain temperature (in the range of 80 to 120 °C)
under vigorous stirring, aqueous hydrogen chloride, chlori-
nation agent, were slowly added to the mixture followed by
the catalyst. In this way, the catalyst would be uniformly
distributed in the reaction media which increase the effective
surface area provided by the catalyst for the reaction. The
reaction in the presence of catalyst was conducted for 3 h. For
analysis of reaction products, gas chromatography method was
used throughout the experiments.