Study of the selective catalysis of metalloporphyrins for 2-methyl-butane oxidation with PhIO under mild conditions

Nine ironporphyrins and eight manganeseporphyrins were synthesized, and the ir selective catalysis for the oxidation of the secondary and tertiary carb on-hydrogen bonds of 2-methyl-butane with PhIO was studied. The proportion of the oxidation product of tertiary carbon-hydrogen bond to the one of sec ondary carbon-hydrogen bond was 3:1 when ironporphyrins were used as cataly sts, and 2.3:1 when manganeseporphyrins were used as catalysts. The researc h showed that the substituting groups on the porphyrin rings influenced the catalytic selectivity of metalloporphyrins for the oxidation of the second ary and tertiary carbon-hydrogen bonds as well as the reaction yields. The electron-attracting groups on benzene rings of ironporphyrins increased the catalytic selectivity of ironporphyrins for the tertiary carbon-hydrogen b ond oxidation and the reaction speeds, and the electron-releasing groups in creased the catalytic selectivity for secondary carbon-hydrogen bond oxidat ion and reduced the reaction speeds. Both electron-attracting and -releasin g groups on benzene rings of manganeseporphyrins enhanced the catalytic sel ectivity of manganeseporphyrins for the secondary carbon-hydrogen bond oxid ation. (C) 2001 Elsevier Science B.V. All rights reserved.