THE OXIDATION OF ALCOHOLS USING RUTHENIUM CATALYSTS AND IMIDAZOLIUM IONIC LIQUIDS

摘要

The ionic liquids [bmim][BF_4], [bmim][(CF_3SO_2)_2N] and [bmmim][(CF_3SO_2)_2N] have been used as alternative solvent media for the selective oxidation of alcohols to their respective aldehydes and ketones. The ruthenium catalyst tetrapropylammonium perruthenate ('TPAP') has been used in conjunction with both N-methylmorpholine-N' -oxide and molecular oxygen as oxidants. It has been demonstrated that benzylic alcohols are oxidized smoothly to give good to quantitative yields of aldehyde, whereas aliphatic alcohols react sluggishly to give poor yields of their oxidation product. The products are extracted from the reaction mixture with diethyl ether. The oxidation of the imidazolium ring to the azolone and trione has been detected by GCMS as a by-product of the oxidation process. It has not been possible to quantify or isolate these products.