Substitution in cellulose ethers. Part I. Determination of glucose units according to number and type of ether substituents using quantitative thin-layer chromatography

Abstract

A procedure for the quantitative characterisation of the distribution of substituents in cellulose ethers is presented. After total hydrolysis in dilute sulphuric acid the sample is separated by thin-layer chromatography on silica gel according to number and type of substituents attached to the glucose unit. Quantitative evaluation of the chromatograms is performed by scanning photometry in the visible range. The procedure allows the determination of the percentages of tri-, di-, mono- and unsubstituted monomeric units in alkyl and alkylhydroxyalkyl celluloses. Data on the distribution of the hydroxyalkyl substituents in mixed ethers were also obtained. The reproducibility of the thin-layer chromatographic separation and that of the entire procedure are discussed.