Determination of terminal hydroxyl groups in polyethyleneoxy compounds

Abstract

The 3, 5-dinitrobenzoyl chloride method has been adapted for the semi-micro analysis of hydroxyl groups in polyethylene glycol and non-ionic surfactants of the polyethylene oxide type. The 3,5-dinitrobenzoates are determined colorimetrically after removal of the excess of acid chloride by column chromatography.

By this method 100 µg of hydroxyl can be determined with a relative accuracy of 4·5 per cent. Products containing fewer than ten ethylene oxide units per molecule do not respond adequately.

Results of the analyses of some technical non-ionic detergents and polyethylene glycol are reported.