Rapid Homogeneous Acylation of Cellulose in a CO2 Switchable Solvent by Microwave Heating

The acylation modification of cellulose to make it processable is an important method to utilize this green, renewable material with broad prospects. However, it usually takes several hours or even more than 20 h to obtain products with a high degree of substitution (DS) through the methods reported in the existing literature, especially for cellulose acetate (CA). In this study, rapid homogeneous acylation of cellulose is achieved in a novel CO2 switchable solvent system by using microwave heating. CA products with DS ranging from 1.83 to 2.91 can be obtained within 3-15 min by using acetic anhydride as the acylation reagent. This strategy can also be applied for the synthesis of a series of cellulose esters with different side chain lengths, and it takes only 10 min to produce cellulose esters with a DS higher than 2.20 under microwave heating. This study suggests a facile and effective method for the synthesis of cellulose esters.