Hydrophobically modified inulin from alkenyl succinic anhydride in aqueous media

Medium and long chain esters of inulin have been prepared by reaction of alkenyl succinic anhydrides (ASA) such as 2-octen-1-ylsuccinic anhydride (OSA), and 2-dodecen-1-ylsuccinic anhydride (DDSA) in aqueous media and aqueous surfactant media, respectively. The design of the chemical process was based on the study of the influence of several reaction parameters on reaction efficiency (estimated by 1H NMR analysis of the pure end product) and reaction time. Inulin concentration, pH range, temperature, and the addition of a cationic surfactant such as dodecyltrimethylammonium bromide (DTAB) to the reaction media were evaluated for both OSA and DDSA anhydrides.Inulin slurry aqueous systems were found the best reaction media to carry out the esterification with OSA. In case of DDSA, the addition of a cationic surfactant such as DTAB was required to convert 65% of anhydride. Inulin precipitation was prevented at pH range 8.5–9.0 by the addition of DTAB. The reaction time for the synthesis of dodecenyl succinic esters of inulin, estimated as the total time required to consume all DDSA, was reduced dramatically from 24 h (without DTAB) to less than 1 h in presence of cationic surfactant. The use of micellar basic catalysis resulted in a useful way to obtain long chain alkenyl succinic esters of inulin.