Highly efficient propionylation and butyralation of cellulose in an ionic liquid catalyzed by 4-dimethylminopyridine

► Finding an effective catalyst for propionylation and butyralation of cellulose in ionic liquid. ► Synthesizing CP and CB under mild reaction conditions. ► Resultant CP and CB with DS from 0.89 to 2.89. ► Controlling DS of products by molar ratio of acid anhydride/AGU. ► Conversions of acid anhydrides in both reactions as high as 90%, even above 96%.