Lipase-catalyzed synthesis of oleyl oleate in pressurized and supercritical solvents

Supercritical and pressurized solvents were used as a biochemical reaction media. As a model system esterification of oleic acid with oleyl alcohol ca talyzed by lipase from Rhizomucor miehei (Lipozyme(IM)) was used. Due to th e limitation of the process that may arise from the non-polarity of carbon dioxide, which preferentially dissolves hydrophobic compounds, studies were performed also with other gases (n-butane. n-propane, n-propane:n-butane m ixture). The initial reaction rates at 20 degrees C are in n-butane around 5 mmol/(g *h) and in the mixture n-propane:n-butane around 6 mmol/(g*h). They are app roximately 2-3 times higher than in CO2. At 50 degrees C the reaction rates in n-butane and in n-propane:n-butane mixture are higher in comparison wit h CO2 only at the pressure. which is subcritical for CO2. The maximal initial reaction rate of 13 mmol/(g*h) was observed in SC-CO2 a t 250 bar and 50 degrees C. The maximal conversion of 87.1% was observed in n-butane at 20 degrees C and 20 bar bur the reaction lime n as 5 h. 86% co nversion was reached in only one hour at 50 degrees C and 100 bar in SC-CO2 .