Substituent effect on iron phthalocyanines as cyclohexene oxidation catalysts

Abstract

The effect of electron withdrawing vs electron donating substituents on the catalytic activity of iron phthalocyanines was investigated using cyclohexene oxidation as a model reaction. We demonstrate that iron phthalocyanine with electron-withdrawing substitutents showed better conversion and selectivity into 2-cyclohexen-1-one (ON) oxidation products. Two iron phthalocyanines peripherally octasubstituted either with electron-withdrawing isobutylsulfonyl moities or electron-donating isobutoxy moieties were designed to investigate the effect of the substitution pattern on their oxidation catalytic activity, and were then tested in oxidation of cyclohexene as a reaction model. For both catalysts, the main product of oxidation was 2-cyclohexen-1-ol which is an allylic oxidation product. The electron-withdrawing isobutylsulfonyl substituted iron phthalocyanine 1 exhibited better catalytic activities than the electron-donating isobutoxy substituted iron phthalocyanine 2.