Synthesis of cellulose dehydroabietate in ionic liquid [bmim]Br

► Cellulose dehydroabietate (CDA)-a new type of cellulose derivative was synthesized. ► Ionic liquid [bmim]Br was used as an effective green reaction solvent. ► CDA has better solubility, water-repellency and the resistance to acids and bases. ► These properties increase with the degree of substitution of CDA.