Research Of Synergistic Effect Of Microwave And Ionic Liquids On Novozym435Catalyzed Transesterification In Non-aqueous

Ionic liquids (ILs) and Microwave irradiation (MW) are two important and rapiddeveloping technologies in the field of green catalysis. Microwave technology’sheating effect and catalytic effect can make reaction’ time shorter, enhance product’syield significantly. Besides, microwave irradiation also can achieve some reactionswhich can’t be made by many conventional methods. ILs have many advantageswhich traditional organic solvents don’t have, such as excellent microwave absorbingability, negligible vapor pressure and high thermal stability, so in the last decade ILsare more and more used as solvent, co-solvent instead of organic solvent in catalysissynthesis area. Microwave-assisted ionic liquid method can play both their advantages,and open a new era for the enzymatic catalytic reaction in non-aqueous phase.Although microwave-assisted IL method is a good way for reaction, their combinationuse is rather limited up to now, our responsibility is make them used better.In this study we wish to demonstrate that the combination use of IL and MW is anefficient method for enzymatic transesterification in non-aqueous phase. The chiral(S)-2-octanol is an important synthetic intermediate for medicaments, agriculturalchemicals, liquid crystal, organic on-linear materials and natural products. Biodiesel(monoalkyl esters of fatty acids) produced from vegetable oils, animal fats andmicroalgal oils by transesterification or esterification with shortchain alcohols hasbeen viewed as promising renewable sources of fuel. Acid and base catalysts wereadopted in the conventional method for biodiesel production to form fatty acid alkylesters. Downstream processing costs and environmental problems associated withbiodiesel production and by products recovery have led to the search for alternativeproduction methods and alternative substrates. The Novozym435(EC3.1.1.3) used inour reaction, Antarctic Candida lipase B (CALB), has been proved to be an excellentbio-catalyst for kinetic resolution of sec-alcohols in non-aqueous environments. A synergistic effect of MW and IL [EMIM][NTf2] improved the reaction’senzyme activity and enantioselectivity. The activity and enantioselectivity ofNovozym435in [EMIM][NTf2] under MW were much higher than that in solventfree system under conventional heating, in solvent free system under MW, and in[EMIM][NTf2] under conventional heating, respectively. Under the optimumconditions,50%yield of (S)-2-octanol with99%enantiomeric excess was obtained in6h. Furthermore, increased hermalstability and reusability of Novozym435under thecombination use of MW and IL condition were also observed.Under microwave irradiation (MW), an ionic liquid (IL) was used as reactionmedium to produce biodiesel (fatty acid methyl ester, FAME) with soybean oil andmethanol through transesterification by Novozym435.[EMIM][PF6] was proved tobe a good reaction medium for biodiesel production because the enzyme exhibitedexcellent transesterification activity in it. Under MW, the enzyme activity in[EMIM][PF6] was about1.8folds higher than that in tert-butanol, and underconventional heating, about1.2folds higher than that in tert-butanol. Under theoptimum conditions (microwave power of480W,[EMIM][PF6]/oil volume ratio of2:1, methanol/oil molar ratio of6:1,6%amount Novozym435based on soybean oilweight, water activity of0.33, agitation speed of200rpm, and60°C), a92%yield ofFAME was achieved in6h in [EMIM][PF6] under MW, whereas the yield of FAMEin [EMIM][PF6] without MW and in a solvent-free system with MW was70%and28%, respectively. The results suggested that MW and IL might have a synergisticeffect on improving enzyme activity. The enhancement of enzyme activity might bethat the microwave acted directly on the IL because of its excellentmicrowave-absorbing ability, which created a compatible system for both thesubstrate and the product, and prevented the deactivation of enzyme with methanoland glycerol. The introduction of IL in microwave system might also increase thevelocity of transacylation, and increase the enzyme activity indirectly. Furthermore,recovered IL and enzyme were used for five successive reaction cycles without any significant loss of enzyme activity.Herein we demonstrate that the combination of IL and MW is an efficient methodfor enzyme-catalyzed transesterification, it can improve the reaction rate and enzymeactivity, increase in product conversion rate etc.