Iron (III) porphyrin biomimetic catalyst supported on ionic liquid modified SBA-15 for epoxidation of 1-octene

Abstract

Ionic liquids (ILs) have attracted much attention as an alternative reaction media to conventional organic solvents due to their unique physicochemical properties especially their low vapor pressure which can be considered as non-volatile compound. Furthermore, it has been shown that ILs provided more suitable environment for enzymes, making it a suitable candidate as green catalysts for biotransformation. Synthetic metalloporphyrins have been used as functional molecules and mimic of enzyme like catalase, peroxidases and cytochrome P-450. However, there is lack of report on the synthesis of metalloporphyrins supported ILs because of reduction of mass transfer ability from their toxicity and high viscosity. In this study, the metalloporphyrin, iron(III)-5,10,15,20-tetra-(4-pyridyl)porphyrin (FeTPyP) which able to mimic the reactions mediated by cytochrome P450 enzyme, was synthesized from the reaction of free-base porphyrin, 5,10,15,20-tetra-(4-pyridyl)porphyrin (TPyP) with iron(III) chloride hexahydrate. Ionic liquid grafted mesoporous silica SBA-15 (IL-SBA-15) was prepared through functionalization of ionic liquid 1-(3-triethoxysilylpropyl)-3-methylimidazolium chloride (IMI+Cl-) onto the surface hydroxyl of mesoporous silica SBA-15. FeTPyP acts as a homogeneous catalyst was then immobilized onto IL-SBA-15 to afford a heterogeneous catalyst, FeP-IL-SBA. The catalytic activity of the heterogeneous catalysts was tested in the epoxidation of 1- octene and the reaction was carried out in acetone using tert-Butyl hydroperoxide (TBHP) as oxidant at 70 °C for 24 hours. It was found that 1,2-epoxyoctane was the main product and were analyzed using GC-FID and GC-MS.