45 KB446 KB40 KB199820252009Knez, ŽeljkoLeitgeb, MajaPaljevac, Muzaferaštevilka:4letnik:56str. 815-825ISSN:1318-0207COBISSID:13823766URN:URN:NBN:SI:doc-FBQ8SDWLenSlovensko kemijsko društvoActa chimica slovenicaCandida antarcticafeniletanolionske tekočinelipazeogljikov dioksidtransesterifikacijavinil acetatLipase-Catalyzed transesterification of (R,S)-1-Phenylethanol in SC COsub2 and in SC COsub2/Ionic Liquid Systems|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 bmimBFsub4 was studied. The addition of 50 mmol (70% w/w reaction mixture) of bmimBFsub4 to the reaction system gave the best result in terms of transesterification rateTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaSlovensko kemijsko društvo