The Investigation Of Deoximation By Ionic Liqiuds

Recovery of ketone and aldehyde from oximes is an important reaction because oxime serves as an efficient protective group for carbonyl compounds, and the regeneration of carbonyl compounds from oximes represents a potential route for syntheses of ketones and aldehydes. But most of deoximation methods are not free from drawbacks: toxic and hazardous oxidants or reductants and large amounts of strong Lewis and Br?nsted acids used in these systems, longer reaction period, low yield of products, difficult in isolating the products and formation of over-oxidized products were also the problems.Here, a new method for deoximation with room temperature ionic liquids as both catalyst and solvent was successfully developed under mild reaction conditions. Metal chloride ionic liquids based on 1-alkyl-3-methylimidazolium and triethylene ammonium cations, such as AmimBr(Cl)- MClx (A = ethyl, butyl, benzyl; M = Al, Fe, Cu, Sn and Zn; x = 2, 3) and Et3NHCl-FeCl3 were prepared, and served as both catalyst and used for green deoximation converted to the corresponding carbonyl compounds. Ferrate chloride ionic liquid proved to be an effective catalyst in satisfying exhibition.The results showed that this type of ionic liquids were effective catalyst, wich could catalyse deoximation of cyclohexanone oximes effectivlye under mild reaction conditions. Moreover, the new catalytic technology are easy-clean, convenient and rapid, and easy in isolating the products. We discussed the effect of metal chloride, cations in ionic liquids and bmimBr/FeCl3 molar ratio on the deoximation. Besides, reaction temperature, time and amount of cyclohexanone oxime were also analysised. Controlling of acid range and improving the solubility of substrate is the key of the deoximation. A good catalytic performance was obtained with nearly 100.0 % yield of cyclohexanone and selectivity of above 99.9 %, and the catalyst could be reused for three times.In addition, We speculated the possible mechanism of the reaction.At last, the catalyst also showed high catalytic activity for deprotection of other oximes. These achievements are higher in the literature.