Reactions of iron porphyrins with CF/sub 3/, CF/sub 3/O/sub 2/, and CBr/sub 3/O/sub 2/ radicals

Journal Article · Thu Jul 16 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100299a041· OSTI ID:6389202

Brault, D; Neta, P

The reactions of ferric and ferrous deuteroporphyrin (PFe/sup III/, PFe/sup II/) with alkyl and peroxyl radicals derived from CF/sub 3/Br and CBr/sub 4/ were studied by kinetic spectrophotometric pulse radiolysis in aqueous alcohol solutions. PFe/sup II/ reacts with CF/sub 3/ radical at nearly diffusion controlled rate (k = 2 x 10/sup 9/ M/sup -1/ s/sup -1/) to form a metal-carbon bonded complex. The PFe/sup III/CF/sub 3/ adduct subsequently reacts with another PFe/sup II/ (k = 5 x 10/sup 6/ M/sup -1/ s/sup -1/) presumably to form the carbene intermediate PFe/sup II/CF/sub 2/ which further hydrolyzes. The final products are PFe/sup III/ and PFe/sup II/CO. CF/sub 3/ radicals also react with PFe/sup III/ (k = 4.5 x 10/sup 8/ M/sup -1/ s/sup -1/) to yield an oxidized product. The initial product undergoes a slow reaction (k = 2.8 x 10/sup 3/ s/sup -1/) ascribed to ligand exchange. CBr/sub 3/ radicals do not react with PFe/sup III/ with reaction rate constants of 3.9 x 10/sup 8/ and 2.8 x 10/sup 8/ M/sup -1/ s/sup -1/, respectively. Similar reactions were reported for other peroxyl radicals. These reactions were used in competition kinetic experiments to obtain the rate constants for hydrogen abstraction from linolenic acid. The rate constants for the reaction of linolenic acid with CF/sub 3/O/sub 2/ and CBr/sub 3/O/sub 2/ are 6.9 x 10/sup 6/ and 1.2 x 10/sup 6/ M/sup -1/ s/sup -1/, respectively. The reactions are discussed with regard to the reactivity and possible toxicity of halogenated compounds.

• Research Organization: National Bureau of Standards, Gaithersburg, MD
• OSTI ID: 6389202
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:15; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400600 -- Radiation Chemistry
ALCOHOLS
ALKYL RADICALS
AQUEOUS SOLUTIONS
BROMINE COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
DECOMPOSITION
DEUTERIUM COMPOUNDS
DIFFUSION
DISPERSIONS
EXPERIMENTAL DATA
FLUORINE COMPOUNDS
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IRON COMPLEXES
KINETICS
MIXTURES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEROXY RADICALS
PORPHYRINS
PULSE TECHNIQUES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION KINETICS
SOLUTIONS
SPECTROPHOTOMETRY
TRANSITION ELEMENT COMPLEXES