Studies in detoxication. 56. The metabolism of alkylbenzenes. Stereochemical aspects of the biological hydroxylation of ethylbenzene to methylphenylcarbinol

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Abstract
([plus or minus])-Methylphenylcarbinol is partly excreted by rabbits as ([plus or minus])-methylphenylcarbinyl glucuronide, which can be resolved into the (+)- and (-)-diastereoisomers by fractional crystallization of the triacetyl methyl esters. Acetophenone is reduced in rabbits to (-)-methylphenylcarbinol, which is excreated as a glucuronide which is identical with the glucuronide isolated after feeding with the (-)-carbinol. Ethylbenzene gives rise to both (+)-and (-)-methylphenylcarbinol in rabbits. The carbinols were characterized as the triacetyl methyl esters of the corresponding glucuronides. Ethylbenzene does not undergo oxidation in the benzene ring in vivo. Styrene and styrene epoxide do not appear to yield methylphenylcarbinol in rabbits. Phenylacetic and phenaceturic acids were not detected as metabolites of ethylbenzene, but phenaceturic acid was isolated as the main metabolite of beta-phenylethanol. The mechanism of the biological oxidation of ethylbenzene is discussed and it is suggested that this hydrocarbon is initially oxidized at the active methylene group to yield (+)-methylphenylcarbinol, which could then yield mandeiic and benzoic acids.