Determination of Galactosediethylmercaptal and 3,6 Anhydrogalactosediethylmercaptal with the Anthrone and Seliwanoff Reagents

Abstract

SOME pure 3,6 anhydro-L-galactose was required as standard to determine the concentration of this sugar in several algal polysaccharides. Efforts to prepare it in a crystalline form were unsuccessful. Therefore the standard solution was made up from the 3,6 anhydro-L-galactosediethylmercaptal. Unfortunately the ethylmercaptan liberated on acid hydrolysis of the mercaptal interfered with colour formation in the anthrone and Seliwanoff tests. A similar interference was obtained with the diphenylamine reagent¹. A method was developed to obtain from 3,6 anhydro-L-galactosediethylmercaptal, in quantitative yield, a solution of 3,6 anhydro-L-galactose free of ethylmercaptan. The object of this communication is to describe the method whereby sugar mercaptals can be analysed with colorimetric sugar reagents.