Conversion of bromobenzene to 3-bromophenol. A route to 3- and 4-bromophenol through sulfur-series intermediates derived from the 3,4-oxide.

Premercapturic acids derived from bromobenzene 3,4-oxide were found to act as precursors of 3- and 4-bromophenol in the rat and guinea pig. The 4-S- and 3-S- positional isomers used in this study were rat urinary metabolites and were prepared in unlabeled, radioactive, and 2,4,6-d3-labeled forms. These are not guinea pig urinary metabolites; the guinea pig does not completely acetylate cysteine conjugates, and this effect leads to urinary products arising from deamination of the cysteine moiety rather than to urinary premercapturic acids. Conversion to phenols was found to be much greater in the guinea pig than in the rat. We interpret our results as indicating that cysteine adducts, rather than the N-acetylcysteine adducts which were administered, are required intermediates in this metabolic route to 3- and 4-bromophenol. This route to phenols may be the major mode of phenol formation for many aromatic compounds. Sulfur-series metabolic products from bromobenzene also include thiocatechols, and these metabolites may be responsible for the hepatotoxicity of bromobenzene in high dosage.