Role of Hydroxyl Functionalized Ionic Liquids in Oxygenation and Oxidation of Phenols with H2O2 Catalysed by Iron(III) Porphyrins

Sohail      Ahmad; Kumar      Karitkey Yadav; S.      M. S. Chauhan

doi:10.2174/138527212804546787

Abstract

The formation of oxygenated (quinone) and oxidative (polymer) products in the reaction of selected phenols with hydrogen peroxide catalysed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides ((TAP)FeIIICl) in 3:1 mixture of dichloromethane and hydroxyl ionic liquids (1-(2-hydroxyethyl)-3-methyl imidazolium and 2-hydroxyethyl ammonium ionic liquids) depend on the electron donating and withdrawing group on porphyrin rings, type of ionic liquids and phenols. Oxygenated products were obtained from iron(IV) oxo radical cationic intermediate by heterolytic cleavage of the O-O bond of (TAP)Fe(III)-OOH in the reaction of iron(III) porphyrin with H2O2 in [HOEMIm]PF6 and [HOEMIm]BF4 based hydroxyl ILs. Polymeric products were obtained from homolytic cleavage of the O-O bond of (TAP)FeIII-OOH in the reaction of iron(III) porphyrin with H2O2 in [HOEMIm]OH and [HOEMIm]OAc based hydroxyl ILs. The catalytic efficiency of iron(III) porphyrin increases in 3:1 binary mixture of dichloromethane and imidazolium based hydroxyl IL in comparison with 3:1 binary mixture of dichloromethane and ammonium based hydroxyl ionic liquids. The coordination of [HOEMIm]+ cation in [HOEMIm]PF6 and [HOEMIm]BF4 ILs and OH- and OAc- anions in [HOEMIm]OH and [HOEMIm]OAc ILs with (TAP)FeIIICl have been studied by UV-vis and 1H NMR spectroscopy.

Keywords: Axial ligand, Heterolytic-homolytic cleavage, 2-hydroxyethyl imidazolium and ammonium ionic liquids, Iron(III) porphyrins, Halogenated phenols, Phenol polymerization

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