Oxidations by the system "hydrogen peroxide-manganese(IV) complex-carboxylic acid" Part 3. Oxygenation of ethane, higher alkanes, alcohols, olefins and sulfides

The manganese(IV) complex salt [L2Mn2O3](PF6)(2) (L = 1,4,7-trimethyl-1,4,7 -triazacyclononane) (compound 1, see Scheme 1) very efficiently catalyzes t he hydroperoxidation of saturated hydrocarbons, including ethane by H2O2 in acetontitrile or nitromethane solution at low (room or lower) temperature, provided a carboxylic (typically acetic) acid is present. The hydroperoxid ation of tertiary positions in disubstituted cyclohexanes proceeds with par tial retention of configuration in nitromethane or acetonitrile solution, w hile the stereoselectivity of the reaction is only negligible in acetone so lution. The system "H2O2-compound 1-MeCO2H" also transforms secondary alcoh ols into the corresponding ketones with quantitative yields at room tempera ture within a few minutes; the yields of aldehydes and carboxylic acids in the oxidation of primary alcohols are lower. Terminal aliphatic olefins suc h as hexene-1 are quantitatively epoxidized by the same system in acetonitr ile at room temperature within 20 min, while the epoxide yield in the analo gous reaction with styrene attains only 60% under the same conditions. Fina lly, dimethylsulfide can be quantitatively and selectively converted into d imethylsulfoxide within 3h at room temperature. The system "tert-BuOOH-comp ound 1" also oxidizes alkanes, addition of acetic acids has less pronounced effect on the direction and efficiency of the reaction, Two other checked derivative of Mn(IV) (compounds 2 and 3) as well a porphyrin complex of Mn( III) (compound 4) exhibited lower activity in catalysis of alkane oxidation with tert-BuOOH. (C) 2001 Elsevier Science B.V. All rights reserved.