An efficient esterification of pullulan using carboxylic acid anhydrides activated with iodine

Abstract

Acylation of alcohols (esterification) with anhydride is an important and routinely utilized transformation in organic synthesis. Iodine is a cheap and one of the most powerful anhydride activating agents for the esterification of alcohols. Therefore, an efficient and cost effective method was developed for the acylation of pullulan polysaccharide by using different acid anhydrides activated with iodine. A series of organo-soluble pullulan esters were successfully synthesized, purified and characterized. Under solvent free conditions, it was feasible to fabricate pullulan nonaacetate and pullulan stearate. Attachment (covalent) of the pendant groups onto polymer backbone was verified by spectroscopic techniques. All of the products were characterized by using thermal analysis, FTIR and 1H NMR spectroscopy.