Water‐insoluble dextran polymers by grafting of hydrophobic groups. I. Reaction with butyric anhydride and heterogeneous hydrolysis of the partially modified dextran

Abstract

AbstractA study has been made on the modification reaction of dextran with butyric anhydride using pyridine as catalyst. The structures of the modified polymers were determined by means of IR and 1H‐NMR spectroscopy as well as by chemical analysis. It has been found a linear dependence of the reaction rate on the product of butyric anhydride and pyridine concentrations and a more complex dependence on the alcoholic groups concentration. The activation energy was found to be 7.0 kcal/mol. A partially modified dextran (D.S. 1.34) was hydrolyzed at several pH values and temperatures. The experimental data have been treated as a pseudo‐first‐order reaction with respect to the butyrate concentration. The activation energies obtained from the acid and base catalyzed hydrolysis reactions were 12.5 and 12.0 kcal/mol, respectively.