Acetylation of β-cyclodextrin in ionic liquid green solvent

The ionic liquid (IL), 1-butyl-3-methylimidzolium bromide ([C(4)mim]Br), synthesized under supercritical CO2, was developed as a green solvent for the dissolution, regeneration and acetylation of beta-cyclodextrin (beta-CD). The dissolution of beta-CD in [C(4)mim]Br of 25 wt% could be reached at 25 A degrees C. The acetylation of beta-CD was carried out under acetic anhydride in [C(4)mim]Br in the absence of catalyst. beta-CD acetates with different degrees of substitution of 0.07-1.14 were obtained directly under the homogeneous reaction conditions. The reaction medium of IL applied can be easily recycled and reused after the synthesis of beta-CD acetate. The effects of reaction time, temperature, and acetic anhydride/AGU on the acetylation of beta-CD were investigated. The acetylated beta-CD samples were characterized by NMR, FT-IR, and X-ray diffraction (XRD) spectroscopy. It is the first time that we have demonstrated that ILs can be used as an environmentally friendly solvent for the acetylation of beta-CD, which will open a new route to acetylation of beta-CD under green solvent without catalyst.