Muzafera Paljevac, Željko Knez and Maja Habulin*
University of Maribor, Faculty of Chemistry and Chemical Engineering,
Laboratory for separation processes and product design, Smetanova 17, SI-2000
Maribor, Slovenia
* Corresponding author: E-mail: maja.habulin@uni-mb.si;
Tel.: +38622294462, Fax.: +38622527774
Abstract
Commercial immobilized lipase B from Candida antarctica (CALB) was successfully
applied to catalyzing the transesterification
of (R,S)-1-phenylethanol in supercritical carbon dioxide and in supercritical
carbon dioxide/ionic liquid biphasic
system. Firstly, the variables affecting the performance of CALB in
transesterification reactions in supercritical
carbon dioxide, such as CALB concentration, temperature and pressure, were
studied. An increase in the conversion and
in the reaction rate was observed as the CALB/substrate ratio, temperature and
pressure, were increased from 4.3 to
19.9, from 40 °C to 80 °C and from 8 MPa to 10 MPa, respectively. Further
increase in temperature from 80 °C to 120
°C and pressure from 10 MPa to 30 MPa resulted in lower conversion and lower
initial reaction rate. Furthermore, different
vinyl esters were used as acyl donors for CALB-catalyzed transesterification of
(R,S)-1-phenylethanol in supercritical
carbon dioxide. The highest initial reaction rate was attained with vinyl
butyrate, although 50% conversion was
attained faster when vinyl acetate was used as acyl donor.
Secondly, in transesterification of (R,S)-1-phenylethanol, performed in
supercritical carbon dioxide/ionic liquid biphasic
system, influence of concentration of 1-butyl-3-methylimidazolium
tetrafluoroborate [bmim][BF4] was studied. The
addition of 50 mmol (70% w/w reaction mixture) of [bmim][BF4] to the reaction
system gave the best result in terms of
transesterification rate.
Keywords: Candida antarctica lipase B, transesterification, (R,S)-1-phenylethanol, vinyl acetate, supercritical carbon dioxide, ionic liquids