Ionic liquid-assisted solublization for improved enzymatic esterification of phenolic acids

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  • Zhiyong Yang, Danmark
  • Zheng Guo
  • Xuebing Xu, Danmark
Phenolic acids are very difficult to dissolve in most of solvent, which lead to low yield and long reaction time for production of lipophilic phenolic derivatives according to previous studies.This work is focused on increasing production of lipophilic phenolic derivatives catalyzed by Novozym 435 in a binary system, which is composed of ionic liquid tOMA•TFA (trioctylmethylammonium Trifluoroacetate) and octanol. Ionic liquid tOMA•TFA has great solubility towards most of phenolic acid. The strategy of increasing the solubility of phenolic in ionic liquid tOMA•TFA was proved to be an efficient way for increasing conversion of phenolic acids. The mixture ratio between tOMA•TFA and octanol was varied from 1:4 to 1:16 (v/v), it was found that the highest conversion of dihydrocaffeic acid (DHCA) was achieved when tOMA•TFA and octanol was mixed as 1:12 (v/v). It was also found that conversion of DHCA at 70 oC was slightly higher than at 60 oC and 80 oC. Removing water by molecular sieves and vacuum has significant improvement on the conversion. Even though the conversion was much higher when the concentration of DHCA was 0.4 M, the highest reaction rate was observed when the concertration of DHCA was 1.6 M, which was also higher than the parallel experiment where no ionic liquid was applied for increasing solubility of DHCA. Relative high conversion of ferulic and caffeic acids was achieved when similar reactions were conducted with these two phenolic acids, and the conversion in the system containing ionic liquid was significant higher than the system without ionic liquid.
TidsskriftJournal of the American Oil Chemists' Society
Sider (fra-til)1049-1055
Antal sider7
StatusUdgivet - 2012

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