HIGH-YIELD, RADICAL-INITIATED OXIDATIVE FUNCTIONALIZATION OF ETHANE BY PERFLUOROCARBOXYLIC ACID ANHYDRIDES - ROLE OF METAL-IONS IN CATALYTIC ALKANE OXIDATIONS IN THE PRESENCE OF PERFLUOROCARBOXYLIC ACID ANHYDRIDES

Hydrogen peroxide and a trace of either ethene or propene initiated th e conversion of ethane to propionic acid and its mixed anhydride (CH3C H2CO2H + CH3CH2COOCOCF3) and trifluoromethyl ethyl ketone, CH3CH2COCF3 , by trifluoroacetic anhydride at 80 degrees C. For a fixed amount of H2O2, the amount of products formed increased with increasing amount o f trifluoroacetic anhydride employed and was always higher than the am ount of H2O2 added. These products. were also obtained when H2O2 was r eplaced by other radical initiators: m-chloroperbenzoic acid, azobisis obutyronitrile, and PbEt(4). With PbEt(4), ethene or propene was not r equired for product formation and close to 500 equiv of products was f ormed for every equivalent of PbEt(4) employed! Longer chain perfluoro carboxylic acid anhydrides reacted analogously; however, as the RI gro up increased in length, a corresponding increase in mixed anhydride to ketone selectivity was observed. Methane gave very little product und er the reaction conditions whereas propane underwent simple stoichiome tric oxidation to 2-propanol and acetone by H2O2. The addition of (CF3 CO2)(2)Pd to the ethane reaction resulted in simple oxidation to ethan ol and acetaldehyde in amounts lower than that corresponding to the H2 O2 present. In complete contrast to the ethane reaction, the yield of products from methane increased significantly (although less than the H2O2 added) upon the addition of (CF3CO2)(2)Pd, with methanol being th e principal product.