Biocatalytic separation of (R, S)-1-phenylethanol enantiomers and fractionation of reaction products with supercritical carbon dioxide

The continuous kinetic resolution of (R, S)-1-phenylethanol via enzymatic transesterification was chosen as a benchmark reaction for the study of a complete reaction/separation process using supercritical carbon dioxide. Phase equilibrium data for binary and ternary systems was acquired as a starting point to determine the best conditions of operation. Total conversion of the (R)-isomer of the alcohol was achieved using a 10% molar excess of vinyl laurate. Three separators operating at given temperatures and pressures allowed the recovery of (S)-1-phenylethanol with a purity of 86%. The phase equilibrium data obtained indicates that an additional separation step should allow the recovery of both (S)-1-phenylethanol and (R)-1-phenylethylaurate with over 95% purity. Due to the low solubilities of the target compounds, CO₂ from the outlet gas stream of the last separator must be recycled to ensure the technical viability of the integrated reaction/separation of (R, S)-1-phenylethanol.