PEROXIDASE-CATALYZED POLYMERIZATION OF P-CRESOL IN SUPERCRITICAL CO2

The feasibility of the catalysis of horseradish peroxidase (HRP) in su percritical CO2 was studied for the polymerization of p-cresol in the presence of H2O2. The reactions were performed at 40 degrees C and 74. 8 arm (1100 psia) above the critical conditions of CO2. In the initial tests with 2 mM of p-cresol and 1 mM of H2O2, more oligomers of p-cre sol were produced as more HRP was added. This indicates that HRP is ac tive in supercritical CO2. HRP was not completely inhibited by H2O2, a t concentrations up to 20 mM. Increasing the initial concentrations of p-cresol and H2O2, to 20 mM, respectively, resulted in the formation of precipitates which were undissolved either in water or in dimethylf oramide (DMF). The effects of adding water and/or methanol as cosolven ts on the reactivity of HRP were studied subsequently. When more than 13.3 mt of water per liter of reaction volume was added, the formation of precipitates was not. observed. The reactivity of HRP was sustaine d when up to 11.8 mt of methanol per liter of reaction volume was adde d. In most cases conversion of p-cresol was less than 50% for 5 hours of reaction time.