On the Oxidation of Mercaptans and Tiiio Acids to the Corresponding Sulfonic Acids.*

The object of the work on the oxidation of optically active thio compounds to the corresponding sulfo derivatives was discussed in the preceding series of articles.’ It will be referred to in this place very briefly. It is desired, first, to follow the effect on optical rotation of the change in polarity of a single group attached to the asymmetric carbon atom; second, to observe in substituted carboxylic acids the difference in the rotations of the free acids and of their salts. With regard to the first point of interest, the following observations have been made up to the present. In the series of secondary mercaptans, all showed a change in direction of their optical rotations on oxidation to the corresponding sulfonic acids. The mercaptans thus far analyzed in this respect are, 2-mercaptobutane, 2-mercaptoisohexane, 2-mercaptohexane, and benzylphenyl mercaptomethane. From these observations it is evident that derivatives of secondary alkyls analogous in configuration, but differing markedly in the polarity of the significant groups, rotate polarized light in opposite directions. On the basis of these considerations the conclusion was drawn that secondary alcohols and secondary halides rotating in opposite directions are configurationally related. To these data and to the conclusions previously published we may now add the data on the oxidation of methylphenyl thiome-