Unified Mechanism for Polyunsaturated Fatty Acid Autooxidation. Competition of Peroxy Radical Hydrogen Atom Abstraction, β-Scission, and Cyclization

Article abstract of DOI:10.1021/ja00411a032

The autooxidation of linoleic (18:2) and arachidonic (20:4) acids with several cosubstrates was investigated.Cumene, tetralin, 1,4-cyclohexadiene, and 9,10-dihydroanthracene in benzene were used as cosubstrates for the oxidation of linoleic acid.The distribution of products, trans,cis diene hydroperoxides and trans,trans diene hydroperoxides, was dependent on the ability of cosubstrates to donate hydrogen atoms to linoleate peroxy radicals.Arachidonic acid was oxidized in mixtures of benzene/1,4-cyclohexadiene with linoleic acid internal standard.Product distribution of six hydroperoxyeicosatetraenoic acids (HPETE) derived from arachidonic acid was established at different concentrations of 1,4-cyclohexadiene in the solvent mixture.A kinetic expression is derived that is useful in describing polyunsaturated fatty acid oxidation product mixtures.By the use of this kinetic derivation, the rate of cyclization of peroxy free radicals derived from arachidonic acid was determined.