Effects of reaction conditions on laccase-catalyzed α-naphthol polymerization

Enzymatic oxidative polymerization of alpha-naphthol was carried out batch-wise with the laccase enzyme, produced by Trametes versicolor (ATCC 200801). The polymerization reaction was conducted in a closed, temperature controlled system containing acetone (solvent) and sodium acetate buffer for pH control. The effects of the organic solvent (acetone) composition, monomer (alpha-naphthol) and enzyme concentrations, buffer pH and temperature on the polymerization rate were investigated with respect to initial reaction conditions and depletion rate of dissolved oxygen. The optimum acetone composition, pH, monomer, dissolved oxygen and enzyme concentrations were determined as 50% (v/v), 5, 3409 gm(-3), 20.3 gm(-3) and 0.173 U cm(-3), respectively; these values provided the most desirable conditions for initial reaction rate. Temperature rise supported the rate increase up to 37 degrees C, after which the rate tended to be stable due to a drop in dissolved oxygen concentration. The product polymer, poly(alpha-naphthol), with an average molecular weight of 4920 Da was soluble in common organic solvents. (C) 2000 Society of Chemical Industry.