ENZYME-CATALYZED REACTIONS IN IONIC LIQUIDS AND IN SUPERCRITICAL CARBON DIOXIDE

Namen doktorske disertacije je bil razviti nove, alternativne metode encimsko katalizirane kinetične resolucije sekundarnih alkoholov v ne-konvencionalnih topilih, kot so ionske tekočine in superkritični ogljikov dioksid. Ionske tekočine predstavljajo zanimiv razred topil za encimsko katalizirane reakcije. Uvodoma smo sintetizirali tri različne ionske tekočine, in sicer 1-butil-3-metilimidazolijev klorid, 1-butil-3-metilimidazolijev heksafluorofosfat in 1-butil-3-metilimidazolijev tetrafluoro-borat, z namenom, da v ionskih tekočinah določimo aktivnost in stabilnost prostih in imobiliziranih encimov različnega izvora. Nadalje smo ionske tekočine uporabili kot reakcijski medij za encimsko katalizirano transesterifikacijo (R,S)-1-feniletanola z vinil acetatom, kjer smo pri atmosferskem tlaku določili 1-butil-3-metilimidazolijev tetrafluoroborat kot najprimernejši reakcijski medij in imobilizirano lipazo B iz Candida antarctica kot najprimernejši biokatalizator za omenjeno reakcijo. Za transesterifikacijo (R,S)-1-feniletanola z vinil acetatom, izvedeno v 1-butil-3-metilimidazolijevem tetrafluoro-boratu pri atmosferskem tlaku in katalizirano z imobilizirano lipazo B, smo optimirali reakcijske parametre, kot so koncentracija biokatalizatorja, substratov in topila, temperatura in hitrost mešanja reakcijske zmesi. Imobilizirano lipazo B iz Candida antarctica smo uspešno uporabili kot biokatalizator za encimsko katalizirano transesterifikacijo (R,S)-1-feniletanola tudi v superkritičnem ogljikovem dioksidu in v dvo-faznem sistemu superkritični ogljikov dioksid/ionska tekočina. V superkritičnem ogljikovem dioksidu smo proučili vpliv koncentracije lipaze, temperature, tlaka in vrste donorja acilne skupine na aktivnost lipaze. V dvo-faznem sistemu superkritični ogljikov dioksid/ionska tekočina pa smo proučili vpliv koncentracije ionske tekočine 1-butil-3-metilimidazolijevega tetrafluoroborata na potek reakcije.The aim of the PhD thesis was to develop new, alternative methods for the enzyme-catalyzed kinetic resolution of secondary alcohols in non-conventional media, such as ionic liquids and supercritical carbon dioxide. Ionic liquids represent an exciting new class of reaction solvents for catalysis, which have been used successfully for enzyme-catalyzed reactions. Firstly, three different ionic liquids, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methyl-imidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium tetrafluoroborate, were synthesized in order to determine enzyme activity and stability of free and immobilized enzymes from different sources in ionic liquids. Next, ionic liquids were used as reaction media for enzyme-catalyzed transesterification of (R,S)-1-phenylethanol with vinyl acetate at atmospheric pressure, where 1-butyl-3-methylimidazolium tetrafluoroborate was determined as the most suitable reaction medium and immobilized lipase B from Candida antarctica as the most suitable biocatalyst for the abovementioned reaction. The optimisation of reaction parameters, such as biocatalyst concentration, substrate concentration, solvent concentration, temperature and mixing rotational speed, for the immobilized lipase B-catalyzed transesterification of (R,S)-1-phenylethanol with vinyl acetate in 1-butyl-3-methylimidazolium tetrafluoroborate at atmospheric pressure was carried out, as well. Immobilized lipase B from Candida antarctica was successfully applied to catalyze the transesterification of (R,S)-1-phenylethanol in supercritical carbon dioxide and in the biphasic system supercritical carbon dioxide/ionic liquid. The variables affecting the lipase activity, such as lipase concentration, temperature, pressure and type of acyl donors, were studied in supercritical carbon dioxide. In the biphasic system supercritical carbon dioxide/ionic liquid the influence of 1-butyl-3-methylimidazolium tetrafluoroborate concentration on reaction performance was studied