| Abstract |
A simple system is described, which oxidizes saturated hydrocarbons either in acetonitrile or (less efficiently) in water. The system consists of 50\% aqueous hydrogen peroxide as an oxidant, sodium metavanadate, NaVO3, as a catalyst and sulfuric (or oxalic) acid as a co-catalyst. The reactions were carried out at 20-50 degrees C. In the oxidation of cyclohexane in acetonitrile, the highest yield (37\% based on cyclohexane) and turnover number (TON=1700) were attained after 3 h at 50 degrees C. The corresponding parameters were 16\% and 1090 for n-heptane oxidation under the same conditions. The oxidation of higher alkanes. RH, in acetonitrile gives almost exclusively the corresponding alkyl hydroperoxides, ROOH. Light alkanes (n-butane, propane, ethane, and methane) have been also oxygenated by the system under consideration. The highest TON (200) was attained for ethane and the highest yield (19\%) was obtained in the case of n-butane. The selectivity parameters measured for the oxidation of linear and branched alkanes are low, the reaction with cis- and trans- 1,2-dimethylcyclohexanes is not stereo-selective. These facts lead us to conclude that the oxidation occurs with the formation of hydroxyl radicals in the crucial step. (C) 2009 Elsevier Ltd. All rights reserved |
