Peroxidase-catalyzed polymerization ofp-cresol in supercritical CO2

摘要

The feasibility of the catalysis of horseradish peroxidase (HRP)in supercriticalCO2was studied for the polymerization ofp-cresol in the presence of H2O2. The reactions were performed at 40‡C and 74.8 aim (1 100 psia) above the critical conditions ofCO2. In the initial tests with 2 mM ofP-crcsol and 1 mM of H2O2, more oligomers ofp-cresol were produced as more HRP was added. This indicates that HRP is active in supercritical CO2. HRP was not completely inhibited by H2O2at concentrations up to 20 mM. Increasing the initial concentrations ofp-cresol and H2O2to 20 mM, respectively, resulted in the formation of precipitates which were undissolved either in water or in dimcthylforamide (DMF). The effects of adding water and/or methanol as cosolvents on the reactivity of HRP were studied subsequently. When more than 13.3 mL of water per liter of reaction volume was added, the formation of precipitates was not observed. The reactivity of HRP was sustained when up to 11.8 mL of methanol per liter of reaction volume was added. In most cases conversion ofP-cresol was less than 50 for 5 hours of reaction tim