Oxidation of alcohols by “activated” dimethyl sulfoxide. a preparative, steric and mechanistic study

CHAPTER 3 – Photosensitized Oxidation and Singlet Oxygen: Consequences in Biological Systems

https://science.sciencemag.org/content/sci/162/3857/963.full.pdf

Mechanisms of Photosensitized Oxidation

In order to predict hydroxy radical initiated degradation of new proton conducting polymer membranes based on polystyrene, polyethersulfone, polyetheretherketone, or on polymers obtained by radiation grafting of styrene on different fluoropolymers, eight sulfonated aromatics were chosen as model compounds for EPR experiments, aiming at the identification of products of HO/ radical reactions with these polymers. Photolysis of H
 2
O
 2
 was employed as the source of hydroxyl radicals. A detailed investigation of the pH profile was carried out for p-toluenesulfonic acid. Besides benzyl- and hydroxy-cyclohexadienyl radicals at lower pH values, phenoxyl radicals were identified, predominating in the pH range 10.5-13.0. A large number of new radicals give evidence of multiple hydroxylation of the aromatic rings, confirming reaction mechanisms proposed on the grounds of product analysis, but no evidence of dimerisation was found. The result as regards stability of organic proton exchange membranes for fuel cells is, that all unsaturated bonds and weakly bound atoms are subject to immediate attack by HO/. Ether links open by HO/ ipso addition. Strategies for the reduction of membrane degradation should focus on a minimisation of HO/ formation and of its access to the interior of the membrane.

EPR investigation of HO/ radical initiated degradation reactions of sulfonated aromatics as model compounds for fuel cell proton conducting membranes

— The photophysics and photochemistry of tryptophan and its simple derivatives is comprehensively reviewed with special emphasis on excitation by near-UV radiation. Topics explicitly discussed include the origins of large Stokes shifts in the fluorescence spectra, photoionization, the puzzle of multiple tryptophan fluorescence decay time, photochemical reactions in the presence and absence of oxygen, and the possible mechanisms of these reactions. A separate section reviews the photosensitizing properties of N-formylkynurenine, an important photooxidation product of tryptophan.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097.1984.tb03890.x

The photophysics and photochemistry of the near-uv absorbing amino acids–ii. tyrosine and its simple derivatives

Dimethyl sulfoxide-trifluoroacetic anhydride. New reagent for oxidation of alcohols to carbonyls

Oxydation des tri-t-butyl-2,4,6-, di-t-butyl-2,6 methyl-4-, trimethyl-2,4,6- di-t-butyl-2,4 et methyl-4 phenols et du cacalol, par I 2 dans le methanol-KOH

Kanji Omura

Papers

Dimethyl sulfoxide-trifluoroacetic anhydride. New reagent for oxidation of alcohols to carbonyls

Oxidation of phenols with iodine in alkaline methanol

Photoinduced reactions—L

Photo-induced Reaction. II. The Photo-sensitized Oxidation of Hindered Phenols

Photo-induced reactions—IX