However, homogeneous functionalization pathways are required for a better control of the distribution of the functional
groups and the degree of substitution (DS) of the ester moieties as well as in order to introduce complex and sensitive ester moieties. Homogeneous conversion of cellulose applying in situ activation of carboxylic acids is a very promising and efficient route for esterification. p-Toluenesulfonyl chloride, acyl-1H-benzotriazole, 1,3-dicyclohexylcarbodiimide (DCC) in
combination with 4-pyrollidinopyridine or N,N-carbonyldiimidazole are applied as activating agents. The method of in situ activation of carboxylic acids has various advantages including the fact that a variety of new esters are accessible in cases where reactive derivatives of the acids (anhydrides or chlorides) cannot be easily synthesized.