Submicro-methods for the analysis of organic compounds. Part XXIV. The determination of C-methyl groups

Abstract

The determination of C-methyl groups by chromic acid oxidation has been extended for use on the submicro-scale. Difficulties encountered necessitated a detailed examination of the various factors involved and these studies were made on the micro-scale, for convenience. When the micro Kuhn–Roth method was applied, improved results and shorter oxidation periods were obtained when vanadium pentoxide or manganese(II) sulphate was added. Analysis of aliphatic, aromatic, heterocyclic, and steroid samples showed that the additives had different effects on different compounds, but no apparent effect on the rate of decomposition of acetic acid. Finally, a submicro-method based on addition of vanadium pentoxide to the chromic acid mixture in a modified apparatus was developed; the results were only slightly less reproducible than those obtained by the micro-method.