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

Using 4-dimethylaminopyridine (DMAP) as the catalyst, highly efficient propionylation and butyralation of cellulose were successfully carried out in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) under mild conditions. Cellulose propionate (CP) and cellulose butyrate (CB) with a degree of substitution (DS) in the range from 0.89 to 2.89 were synthesized within only 30 min at 30 °C. The DS values of the products could be well controlled just by molar ratio of acid anhydride/anhydroglucose unit (AGU). More interestingly, the conversions of acid anhydrides in both propionylation and butyralation were as high as above 90%, even 96%. Therefore, this work provides a facile and highly efficient way for the synthesis of cellulose esters CP and CB.