Synthesis of FeBr3-cyclodextrin complexes in non-aqueous solution

Mixing FeBr₃ either solid or dissolved in ethyl ether, in acetonitrile or in dichloromethane with solid β-cyclodextrin, form different type of FeBr₃-cyclodextrin complexes as indicated by their stoichiometric composition and thermal and spectroscopic properties. The complexes are stable under usual atmospheric conditions. Water solutions of FeBr₃ at pH 12 containing cyclodextrin are stable over 24 h. The solid complexes were characterized by DSC and TGA analysis as well as by IR spectroscopy. It is shown that the complexes obtained from the reaction of solid cyclodextrin with FeBr₃ dissolved in ethyl ether, acetonitrile, or dichloromethane catalyze the oxidation of methyl phenyl sulfide to methyl phenyl sulfoxide although in different yields. The best complex for this purpose is the one prepared in CH₂Cl₂ which afforded the sulfoxide in good yield.