Cellulose acylation in homogeneous and heterogeneous media: Optimization of reactions conditions

The dependence of the DS on the acid anhydride/anhydroglucose unit ((RCO)2O/AGU) molar ratio was correlated using second-order polynomials. The regression coefficients of the (RCO)2O/AGU terms showed that increasing the length of the RCO group of the anhydride led to lower values of DS. For acylation under heterogeneous reaction conditions, the following were employed: acid anhydrides and butyryl chloride as acylating agents; iodine as a catalyst; N,N-dimethylformamide (DMF) as a solvent, pyridine, and triethylamine as solvents and catalysts. For acylation using acetic anhydride plus iodine, the values of DS correlate with reaction time by a second-order polynomial. Due to its role as a polar solvent and a nucleophilic catalyst, pyridine was the most effective base catalyst, independent of the acylating agent (butyric anhydride and butyryl chloride).