Product identification of guaiacol oxidation catalyzed by manganese peroxidase

The mechanism underlying the oxidation of guaiacol (2-methoxyphenol) by manganese peroxidase (MnP) was studied by structural identification of the products. After separation by TLC, the products were characterized by NMR, GC-MS, and LC-MS. They were determined to be 3,3'-dimethoxy-4,4'-biphenol, a mixture of 3,3'-dimethoxy-4,4'-biphenoquinone and 3,5'-dimethoxy-4,4'-biphenoquinone, 6-methoxy-4-(4-hydroxy-3-methoxyphenyl)-1,2-benzoquinone, 3-(4-hydroxy-3-methoxy-phenyl)-5,3'-dimethoxy-4,4'-biphenol, and a mixture of 5-(4-hydroxy-3-methoxyphenyl)-3,3'-dimethoxy-4,4'-biphenoquinone and 3-(4-hydroxy-3-methoxyphenyl)-5,3'-dimethoxy-4,4-biphenoquinone. From the direct GC-MS analysis, two other products were identified as 3-methoxy-catechol and 2-methoxy-1,4-benzoquinone. The reaction mechanism of MnP-catalyzed guaiacol oxidation is suggested on the basis of the structural information obtained for these products. (C) 2008 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.