Zirconyl chloride as a novel and efficient green Lewis acid catalyst for direct acetylation of cotton cellulose in the presence and absence of solvent

Abstract

An efficient synthesis of cellulose acetates in the presence and absence of solvent from commercial cotton cellulose, and acetic anhydride using catalytic amounts of ZrOCl2.8H2O as a novel and green Lewis acid catalyst were reported. The optimal reaction conditions for microwave irradiation in solvent-free conditions were achieved using 400 mg of ZrOCl2.8H2O, 50 mL acetic anhydride and 16 min reaction time to yield ~100% (DS = 3.0) of cellulose triacetate. Under the reflux conditions, the highest degree of substitution, DS = 2.96 was obtained after 24 h. Simple equations for converting the elemental analysis results of C and H% into the degree of substitution (DS) values for cellulose ester were proposed. Furthermore, the synthesized products were characterized by FT-IR, 1H-NMR, along with melting temperature, BET surface area, and particle-size distribution.