Successful Application of an Ionic Liquid Carrying the Fluoride Counter-ion in Biomacromolecular Chemistry: Microwave-Assisted Acylation of Cellulose in the Presence of 1-Allyl-3-methylimidazolium Fluoride/DMSO Mixturesa

摘要

The use of ionic liquids with fluoride anion (IL-F) is challenging because of side reactions. Neat 1-allyl-3-methylimidazolium fluoride (AlMeImF) is used as a solvent in microwaveassisted acylation of cellulose. The results are disappointing due to side reactions in the IL proper, and F~–-mediated hydrolysis of the produced ester. A dramatic improvement is observed, when AlMeImF/DMSO mixture is employed. The results are comparable to those obtained when pure 1-allyl-3-methylimidazolium chloride is employed. FTIR spectroscopy shows that dissolving a carboxylic acid anhydride in IL-F leads to the formation of acyl fluoride. Thus ILs are far from being ‘‘spectator’’ solvents. The new approach (use of IL-F/DMSO) is attractive because of its efficiency, low cost, and applicability to the derivatization of any polymer.