Mechanism of catalytic oxygenation of alkanes by halogenated iron porphyrins.
Halogenation of an iron porphyrin causes severe saddling of the macrocyclic structure and a large positive shift in the iron(III)/(II) redox couple. Although pre-halogenated iron(II) porphyrins such as Fe(TFPPBr8) [H2TFPPBr8, beta-octabromo-tetrakis(pentafluorophenyl)-porphyrin] are relatively resistant to autoxidation, they rapidly reduce alkyl hydroperoxides. These and related reactivity studies suggest that catalysis of alkane oxygenation by Fe(TFPPBr8)Cl occurs through a radical-chain mechanism in which the radicals are generated by oxidation and reduction of alkyl hydroperoxides.
Grinstaff
M W
MW
Arthur Amos Noyes Laboratory, California Institute of Technology, Pasadena 91125.
Hill
M G
MG
Labinger
J A
JA
Gray
H B
HB
D000473:Alkanes / Q000737:chemistry*; D002384:Catalysis; D010084:Oxidation-Reduction; D010420:Pentanes / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D005466:Fluorocarbons
D000473:Alkanes; D010420:Pentanes; D011166:Porphyrins; C087332:2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato-iron(III); D005466:Fluorocarbons; C087331:3-methylpentane