The primary products formed from the autoxidation of lipids can be understood based upon a mechanism that involves five different reaction types. These reactions are: reaction of a carbon radical and molecular oxygen, atom transfer of a hydrogen from substrate to the chain carrying peroxyl, fragmentation of the chain carrying peroxyl to give oxygen and a carbon radical, rearrangement of the peroxyl, and cyclization of the peroxyl. The mechanism of these primary reaction steps has been the focus of extensive research over the past fifty years, and the current level of understanding of these transformations is the subject of this review.

The mechanism of methyl oleate autoxidation was investigated. HPLC techniques were developed to analyze the products of autoxidation (hydroperoxides and the corresponding alcohols). The alcohols could be completely resolved by normal-phase chromatography, six products being characterized having oxygen substitution and double position as follows: 1 l-OOH-Zranr-Ag-io, 1 l-OOH-cis-Ag-io, 10-OOH-íroztr-Ag-g, 9-OOH-Zre/zi-Aio-n, 8-OOH-f/ww-Ag-m, 8-OOH-czi-Ag-io As the hydrogen atom donor concentration of the medium of autoxidation is increased, increased 11 -cis, 8-cis, 9-trans, and 10-trans hydroperoxides and decreased 11 -trans and 8-trans hydroperoxides were obtained, consistent with a mechanism in which peroxyl H-atom abstraction and [2,3] allylperoxyl rearrangement are in competition. An iterative computer kinetic analysis was developed which modeled the oleate autoxidation mechanism, and rearrangement rate constants were determined. Allylperoxyl radicals undergo rearrangement with different rates depending on the geometry of the allylperoxyl.Autoxidation, the radical chain reaction of molecular oxygen and organic substrates, results in the formation of hydroperoxides.1

No abstract

No abstract

Rigid immobilization of 2,2',4-trihydroxyazobenzene on triazine modified cellulose is shown to extend the pH range over which this ligand forms a fluorescent complex with Al+3. In the nonimmobilized form a nonfluorescent two-to-one complex competes with the fluorescent one-to-one complex and is favored under neutral conditions. The substrate and immobilization linkage used here are demonstrated to be sufficiently rigid to inhibit the formation of the spectroscopically undesirable bis complex. This phenomenon increases the potential applicability of the ligand as a spectrofluorometric reagent for Al+3. This result 403