The enantioselective hydrolysis of racemic naproxen methyl ester in supercritical CO2 using Candida rugosa lipase

The enantioselective hydrolysis of racemic naproxen methyl ester by Candida rugosa lipase (CRL) was studied in aqueous buffer solution/isooctane reaction system in the presence of supercritical CO2. The effects pressure (75–160 bar), temperature (32–42 °C) and reaction time (0.5–12 h) on the enantiomeric excesses of the product (eep) and the substrate (ees), enantiomeric ratio (E), conversion (x) and enzyme activity were investigated in a batch reactor system. The highest enantiomeric ratio achieved at 120 bar of pressure, 37 °C of temperature and 2 h of reaction time was E = 193 with x = 41.3%, eep = 97.9% and ees = 68.8%. CRL remained active at least for 12 h at 37 °C and 120 bar in supercritical CO2 medium. Furthermore, enantiomeric ratio increased with increasing reaction time and reached the value of E = 236 with eep = 98.2%, ees = 70.0% and x = 41.6% after 12 h of hydrolysis.