J. P. Stanley

Autoxidation of polyunsaturated fatty acids: II. A suggested mechanism for the formation of TBA-reactive materials from prostaglandin-like endoperoxides

The nature and mechanism of formation of the thiobarbituric acid (TBA)-reactive material produced in the autoxidation of polyunsaturated fatty acids (PUFA) or their esters has been studied. On the basis of chemical studies and

Autoxidation of polyunsaturated fatty acids. Part I. Effect of ozone on the autoxidation of neat methyl linoleate and methyl linolenate.

Neat samples of polyunsaturated fatty acids were exposed to ozone in air in a flow system, and the formation of peroxides, conjugated dienes and thiobarbituric acid (TBA)-reactive material was followed as a function of time. The effect of ozone is to shorten the induction period normally observed in autoxidation studies, but the ozone, at the concentrations used here (0-1.5 ppm), appears to have no effect on the rates of product formation after the induction period. During the induction period, increasing ozone concentrations give rise to substantially increased rates of peroxide (or materials which titrate like peroxide) formation, a slightly increased rate of conjugated diene formation, and no significant increase in the rate of production of TBA-reactive material. Vitamin E lengthens the induction period but appears to have no other effect. Some of these data are in conflict with earlier reports of Menzel et al.

Kinetic Isotope Effects in Reactions of Thiols with Radicals Formed by Radiolysis

A novel method is described for determining the kinetic isotope effect on the reaction in which a free radical abstracts a hydrogen atom from a H-donor such as a thiol, RSH. The radical is generate...

The Hydrogen Atom and Its Reactions in Solution

Hydrogen atoms have been generated in solution by photolysis of thiols in solutions of organic compounds, and the relative rate constants, kH, have been measured for the reaction H• + QH → H2 + Q•, where QH is any organic compound which contains hydrogen. This represents the first kinetic study of the hydrogen atom in which it is generated in solution by a technique not involving ionizing radiation. The relative values of kH are in agreement with the values from radiolysis for most of the substances studied; however, for some compounds significantly different results have been obtained.