Cellulose Studies

Abstract

In an attempt to establish unambiguously the presence of the nonreducing end group in cellulose when treated under nondegrading conditions, different celluloses were sub jected to exhaustive methylation, using sodium hydroxide and dimethyl sulfate in toluene. Other methods of methylation were also investigated. Samples with 43.8% methoxyl content were obtained which were found suitable for this investigation. Identification and quantitative estimation of tetramethyl glucose, which originates from the nonre ducing end of the cellulose chain, involved hydrolysis, extraction of the tetramethyl glucose from the main component, trimethyl glucose, and chromatographic analysis. Paper, thin-layer, and gas chromatography were used in the analysis and special techniques were developed for each method. Identification and quantitative estimation by gas chromatography were accomplished for the methyl glucosides and the trimethyl silyl derivatives of the methylated glucoses. Isolation of crystalline tetramethyl glucose and the preparation of its anilide derivative provided unambiguous proof of the presence of nonreducing end groups in cellulose when treated under nondegrading conditions. It was observed that methyl tetramethyl glucoside is volatile at room temperature and atmospheric pressure. This is advanced as a probable reason for the previously reported absence of nonreducing end groups in cellulose. The quantitative method of tetramethyl glucose estimation, in relation to the tri methyl glucose content, was used for the determination of the number average degree of polymerization of cellulose. For methyl celluloses of different origins, these were found to be: 908% ± 18% for cotton cellulose, 465% ± 21% for a commercial methyl cellulose, and 197% ± 20% for viscose rayon cellulose.