Steric and electronic control of iron porphyrin catalyzed hydrocarbon oxidations
The yields and product distributions in the oxidation of hydrocarbons (cyclohexane, n-pentane, n-octane, methylcyclohexane, tert-butylcyclohexane, and ethylbenzene), using substituted iron tetraphenylporphyrins and iodosobenzene, are shown to be markedly affected by nature and location of phenyl ring substituents. These substrates were used to measure the activity, regioselectivity, substrate selectivity, and stereoselectivity of the substituted iron porphyrin catalysts. Higher yields are observed with iron porphyrins having bulky substituents near the iron center. Kinetics measurements and concentration studies show that these substituents improve lifetimes by hindering the catalyst's bimolecular self-destruction. Higher yields are also observed with electron-withdrawing substituents. A new iron fluoro-pocket porphyrin shows higher activity due to this electronic effect. Substrate and regioselectivity are also influenced by steric and electronic effects of the iron porphyrin's phenyl ring substituents. Bulky porphyrins also affect the stereoselectivity at the 2-, 3-, and 4-positions in tert-butylcyclohexane oxidation. A mechanism supported by kinetic modeling studies is proposed for the oxidation reactions. 48 references, 14 figures, 5 tables.
- Research Organization:
- E.I. du Pont de Nemours and Co., Wilmington, DE
- OSTI ID:
- 5974378
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 24:26; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
AROMATICS
BENZENE
CARBOXYLIC ACIDS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CYCLOALKANES
CYCLOHEXANE
DATA
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
INFORMATION
IRON COMPOUNDS
KINETICS
MATHEMATICAL MODELS
NUMERICAL DATA
OCTANE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
PENTANE
PORPHYRINS
REACTION KINETICS
STEREOCHEMISTRY
THERMODYNAMIC ACTIVITY
TRANSITION ELEMENT COMPOUNDS
YIELDS