Oxidation triplet oxygen

Some of the earliest studies of triplet carbenes in frozen media by epr spectroscopy revealed that these intermediates react rapidly with molecular oxygen (Trozzolo and Gibbons, 1967). This should not come as a surprise since the combination of a triplet carbene with triplet oxygen is a spin-allowed process. Indeed, recent measurements show that this reaction proceeds with a rate that is approximately at the diffusion limit. The product of this reaction (17) is the expected carbonyl oxide (Werstiuk et al., 1984 ... 

Type II involves electron transfer from the excited triplet state of the sensitiser to triplet oxygen producing the highly oxidative singlet oxygen. This mechanism has already been discussed (see Figure 4.14). 

Disilenes have much lower oxidation potentials than olefins , and consequently they are much more reactive toward 02. Typically, disilenes 93 react in solution with triplet oxygen to give 1,2-disiladioxetanes 94 as the major product, accompanied at room temperature by a smaller amount of disilaoxirane 95 (equation 93) °. ... 

Selenophenes, dioxirane oxidation, 1157 Selenyl radicals, triplet oxygen domino reactions, 223, 227... 

Thiophene, dioxirane oxidation, 1156 Thiourea, dialkyl peroxide synthesis, 706 1,4-Thioxane, oxidation, 805-6 Thiyl radicals, triplet oxygen domino reactions, 221-3, 224, 225, 226 THPO (1,2,3,4-tetrahydronaphthyl hydroperoxide), 331-2 Thromboxanes, from arachidonic hydroperoxides, 612... 

An interesting case has been reported by Turro where triplet oxygen oxidation of dimethylketene is suggested to involve a dual pathway a diradical intermediate on the path to polyester formation and a zwitterion leading to dimethyldioxetanone (Scheme 98) (78JA5580). 

---