1966 Volume 39 Issue 10 Pages 2202-2205
The assignments of the erythro-threo configuration to isomeric 2-methyltartaric acids and the-cis-trans configuration to isomeric 1,2-dihydroxycyclohexane-1,2-dicarboxylic acids were made on the basis of the infrared absorption spectra of their calcium salts. Thus, the isomer of 2-methyltartaric acid, with a m. p. of 146°C, corresponds to the erythro form, and the other isomer, with a m. p. of 161°C, to the threo form; also the one isomer of isomeric 1,2-dihydroxycyclohexane-1,2-dicarboxylic acids with a m. p. of 154°C corresponds to the cis (meso) form, and the other, with a m. p. of 180°C, to the trans (racemic) form. The configurations of the compounds are discussed in comparison with those of tartaric acid and 2,3-dimethyltartaric acid, the latter of which was recently decided by optical resolution by present author (S. Tatsumi, This Bulletin, in press.).
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