22 ml of a dipotassium hydrogen phosphate/citric acid buffer solution of pH 4.5 (prepared by titrating a 0.2 M potassium dihydrogen phosphate solution with a 0.1 M citric acid solution and diluting to 1/4) were treated at 45° C. with 243 mg (1.60 mmol) of 3,4-dimethoxytoluene in 1 ml of ethanol. 0.180 mmol of a mediator (Table 1) was added with stirring. After approx. 10 minutes, the mixture was treated with 5 ml of an aqueous solution of 2 mg/ml laccase from Trametes versicolor (specific activity: approx. 18 IU/mg, defined with ABTS as substrate). After a reaction time of 22 hours with exposure to air, the reaction solution was extracted with chloroform and examined by N spectroscopy and gas chromatography. Yields of 3,4-dimethoxybenzaldehyde and 3,4-dimethoxybenzyl alcohol, see Table 1.
