Preparation of Cellulose Esters with Aromatic Carboxylic Acids.

Abstract

The preparation of cellulose esters with aromatic carboxylic (substituted benzoic) acids in the presence of p-toluenesulfonyl chloride (TsCl) in pyridine (Py) was investigated. Cellulose was readily acylated with substituted benzoic acids, such as nitro-, chloro-, methyl- and methoxybenzoic acid, by use of the Py/ TsCl/ acid system, and corresponding cellulose esters with high degrees of substitution (DS) were obtained. The difference among the substituents and among the isomers (o, m- and p-isomers) of the acid did not influence the reaction significantly. With an amino-substituted benzoic (p-aminobenzoic) acid, the cellulose ester could not be obtained, because acylation of the NH2 group with the other p-aminobenzoic acid took place in preference to the OH group of cellulose. When the NH2 group was protected with a methyl group, on the other hand, the corresponding ester was obtained by this method.