Mechanism of addition of singlet oxygen to olefins and other substrates

Abstract

Abstract

Spectroscopic Study of Photosensitized Oxidation of 1,4-Polybutadiene

“…Normally the use of MB as sensitizer results in a minor additional absorption at ~6.2 μχη, but this may be removed by washing a film of the O2-reacted CB (supported on an NaCl plate) with methanol. Spectra similar to Figure 1 were obtained with chloro phyll (CL) as sensitizer, but Rose Bengal (RB) tended to give extraneous peaks caused by autoxidative side reactions just as in the case of 1,4-poly isoprene (8). The significant changes observed in Figure 1 are the growth of the 2.9-^m band (02H), the development of a moderately strong band A suitable spectroscopic means of following the degree of hydro peroxidation is provided by the absorbance ratio A2.9/A6.9 == A' (8).…”

“…Spectra similar to Figure 1 were obtained with chloro phyll (CL) as sensitizer, but Rose Bengal (RB) tended to give extraneous peaks caused by autoxidative side reactions just as in the case of 1,4-poly isoprene (8). The significant changes observed in Figure 1 are the growth of the 2.9-^m band (02H), the development of a moderately strong band A suitable spectroscopic means of following the degree of hydro peroxidation is provided by the absorbance ratio A2.9/A6.9 == A' (8). A smooth correlation of A' with oxygen uptake for MB-and CL-photosensitized oxidation of CB is given in Figure 3.…”

“…The procedures for the photosensitized oxidation of purified samples of the 1,4-polybutadienes, using visible light and methylene blue, chlorophyll and Rose Bengal as sensitizers, the procedures for the reduction of the hydroperoxidized polymers to the corresponding alcohols, as well as the procedures for the spectroscopic analysis of the reaction products, were similar to those described previously (8).…”

“…Paramagnetic shift reagent experiments were carried out using tris- ( 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyloctanedionato ) europium ( Eu-(fod)3). Portions of the Eu(fod) 3 were added to a CDC13 solution of the reduced product obtained from the singlet oxygenation of cis-1,4-polybutadiene having about 0.2 02/monomer unit.…”

The Isomeric Compositions of Hydroperoxides Produced by Oxidation of Arachidonic Acid with Singlet Oxygen

“…The 1 0 2 oxidation mechanism of unsaturated fatty acid was proposed to be an "ene type" reaction via a six-membered transition state 27 ) or perepoxide intermediate. 28 ) The eight regioisomers of MHP, that is 5-, 8-, 9-, 11-, 12-and 15-isomer (conjugated diene isomer), and 6-and 14-isomer (nonconjugated diene isomer), are formed from arachidonic acid as the result of the binding of 1 0 2 to the double bonds at LIS, 8, 11, 14 position.…”