Initiation, rate, autoxidation linoleic acid

Furimsky E, Howard JA, Selwyn J (1980) Absolute rate constants for hydrocarbon autoxidation. 28. A low temperature kinetic electron spin resonance study of the self- reactions of isopropylperoxy and related secondary alkylperoxy radicals in solution. Can J Chem 58 677-680 Gebicki JM, Allen AO (1969) Relationship between critical micelle concentration and rate of radiolysis of aqueous sodium linolenate. J Phys Chem 73 2443-2445 Gebicki JM, Bielski BHJ (1981) Comparison of the capacities of the perhydroxyl and the superoxide radicals to initiate chain oxidation of linoleic acid. J Am Chem Soc 103 7020-7022 Gilbert BC, Holmes RGG, Laue HAH, Norman ROC (1976) Electron spin resonance studies, part L. Reactions of alkoxyl radicals generated from alkylhydroperoxidesand titanium(lll) ion in aqueous solution. J Chem Soc Perkin Trans 2 1047-1052... 

A steady-state analysis can now be performed for the autoxidation of linoleic acid. The rate of initiation is given by eqs 3-5 and can be simply written as Ri At the steady-state, the rate of... 

In our system, the rate of autoxidation of linoleic acid, is essentially zero in the absence of the initiator. (Notice the flatness of the oxygen trace at the far left in Figure 1 before the initiator is added.) Our system produces classical inhibition kinetics. Initiator can be injected into the bulk aqueous phase and the autoxidation starts instantly. When the vitamin E is injected, it also produces an instantaneous effect. The rate of autoxidation before the vitamin E is added, Roxi> is also observed after all the... 

In this article I have calculated concentrations of linoleic acid, vitamin E, the initiator, and Op in the micellef since this is where the autoxidation occurs. Thus, the concentrations quoted in the text are 100 times larger than the values that would be obtained if the solution were assumed to be a single homogeneous phase and average concentrations were used. Similarly, therefore, the value of R. I have used is 100 times larger than the value calculated fronrthe rate of... 

The relative rates of autoxidation of different unsaturated fatty acids and esters were compared on the basis of oxygen absorption measurements (Table 1.1). In neat systems without added initiator, linoleate was 40 times more reactive than oleate, linolenate was 2.4 times more reactive than linoleate, and arachidonate was 2 times more reactive than linolenate. The oxidizability of polyunsaturated fatty acid (PUFA) esters was also compared on the basis of oxygen uptake measured kinetically by the induction period method described above, in solution in the presence of azo initiators. The oxidizability of 18 2,18 3,20 4, and 22 6 was linearly related to the number of bis-aUyUc positions present in the fatty esters. From this relationship, the oxidizability of each PUFA was increased approximately two fold for each active bis-allylic methylene group. Thus, the oxidizability of 22 6 was 5 times greater than that of 18 2. 

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