MANGANESE-PORPHYRINS AND IRON-PORPHYRINS EMBEDDED IN A POLYDIMETHYLSILOXANE MEMBRANE - A SELECTIVE OXIDATION CATALYST

The use of ,10,15,20-tetrakis(2,6-dichlorophenyl)porphyinato] Mn(III) and Fe(III) chloride [TDCPP(Mn)Cl and TDCPP(Fe)Cl] encapsulated in a p olydimethylsiloxane (PDMS) membrane is reported for the oxidation of c yclic alcohols to ketones with t-butylhydroperoxide from an aqueous so lution. Two major conclusions can be drawn from the comparison with ca rbon black (CB) supported complexes. Firstly, both hydrophobic carrier s enhance the turnover numbers (TON) of the reaction by sorption of th e reagents near the active site. Secondly, the support material requir es a specific morphology to promote reaction selectivity. Indeed, the CB-supported complexes can be considered as an improved version of the homogeneous catalyst, whereas PDMS adds an extra dimension-selectivit y-to the heterogeneous catalyst. (C) 1998 Elsevier Science B.V. All ri ghts reserved.