Analysis of positions of substitution of O-acetyl groups in partially O-acetylated cellulose by the reductive-cleavage method

Described herein are methods for determining the degree of substitution (ds) and the positions of substitution of O-acetyl groups in commercial samples of partially O-acetylated cellulose. Sequential neutral methylation of the polymers, base-catalyzed ethylation, and reductive cleavage gives eight products that are analyzed as their O-acetyl derivatives by gas-liquid chromatography. Alternatively, the permethylated polymers are subjected to reductive cleavage directly, under conditions that reduce O-acetyl groups to O-ethyl groups, to give the same eight products. The ds values obtained by these two methods were in good agreement with values obtained by integration of the O-acetyl and O-trimethylsilyl resonances of the fully O-trimethylsilylated polymers.