A theoretical and experimental study on etherification of primary alcohols with the hydroxyl groups of cellulose chain (n = 1–3) in acidic condition

•The SN2 etherification reaction of the primary alcohols with the hydroxyl groups of cellulose chain (n = 1–3) in acidic condition were investigated by using density functional theory (DFT) and two-layer ONIOM approach.•During the etherification reaction, reactant complex and product complex are formed, where H+ ions are shared by both alcohol and water or by both ether and water.•The energy barrier of H3O+ releasing step is much higher than that of activation step.•The effect of substituent r on the reactivity is significant.