Reagent effects on distribution of methylsulfonylethyl substituents in the D-glucopyranosyl unit of cotton cellulose

Abstract

The distribution of methylsulfonylethyl substituents at the 2-O-, 3-O-, and 6-O-positions of the monosubstituted D-glucopyranosyl unit of cotton cellulose was found to be a function of the specific reagent and the reaction conditions. The distribution is dependent upon the extent to which rate or equilibrium of reaction at the individual hydroxyl groups is the controlling factor. Under conditions which approach equilibrium in the reaction of methyl vinyl sulfone with cotton cellulose, the ratio of 2-O- to 6-O-substitution is 0.14:1.0. A variety of precursors for methyl vinyl sulfone (i.e., 2-(methylsulfonyl)-ethanol, [2-(rnethylsulfonyl)ethyl]pyridinium chloride, 2-bromoethyl methyl sulfone, and to-[2-(methylsulfonyl)ethyl]ether) react with cotton cellulose under non-equilibrium conditions to generate ratios of 2-O- to 6-O-substitutions as high as 0.44:1.0. The effect of diffusion of reagents into the cotton fiber upon the distribution of substituents is clearly evident in these reactions. Specific modifications of the process of reaction of methyl vinyl sulfone or 2-(methylsulfonyl)ethanol with cotton cellulose yield ratios of substituents in the 2-O- to 6-O-positions as high as 0.8:1.0; this ratio is similar to those which characterize certain rate-controlled Williamson etherification reactions with cotton cellulose.