PEROXIDASE-CATALYZED DESULFONATION OF 3,5-DIMETHYL-4-HYDROXY AND 3,5-DIMETHYL-4-AMINOBENZENESULFONIC ACIDS

Horseradish peroxidase (HRP), lignin peroxidase (LiP), and Mn(III)-malonate (a manganese peroxidase mimic) oxidized 3,5-dimethyl-4-hydroxybenzenesulfonic acid (I) to 2,6-dimethyl-1,4-benzoquinone (III) and 2,6-dimethyl-1,3,4-trihydroxybenzene (IV). Only LiP was efficient at oxidizing 3,5-dimethyl-4-aminobenzenesulfonic acid (II); LiP oxidized II to 2,6-dimethyl-1,4-benzoquinone (III) and 2,6-dimethyl-3-hydroxy-1,4-benzoquinone (V). In these reactions, the H2O2-oxidized peroxidases or Mn(III)-malonate oxidized the aromatic ring by two electrons to produce a cation. Nucleophilic attack by water on the sulfonic acid bearing carbon eliminated sulfonic acid as inorganic sulfite and produced 2,6-dimethyl-1,4-benzoquinone (III). Possible mechanisms for the formation of IV and V are discussed. © 1993 Academic Press. All rights reserved.