Mechanisms of hydrogen-, oxygen-, and electron-transfer reactions of cumylperoxyl radical
Rates of hydrogen-transfer reactions from a series of para-substituted N,N-dimethylanilines to cumylperoxyl radical and oxygen-transfer reactions from cumylperoxyl radical to a series of sulfides and phosphines have been determined in propionitrile (EtCN) and pentane at low temperatures by use of ESR. The observed rate constants exhibit first-order and second-order dependence with respect to concentrations of N,N-dimethylanilines. This indicates that the hydrogen- and oxygen-transfer reactions proceed via 1:1 charge-transfer (CT) complexes formed between the substrates and cumylperoxyl radical. The primary kinetic isotope effects are determined by comparing the rates of N,N-dimethylanilines and the corresponding N,N-bis(trideuteriomethyl)anilines. The isotope effect profiles are quite different from those reported for the P-450 model oxidation of the same series of substrates. Rates of electron-transfer reactions from ferrocene derivatives to cumylperoxyl radical have also been determined by use of ESR. The catalytic effects of Sc(OTf)3 (OTf = triflate) on the electron-transfer reactions are compared with those of Sc(OTf)3 on the hydrogen- and oxygen-transfer reactions. Such comparison provides strong evidence that the hydrogen- and oxygen- transfer reactions of cumylperoxyl radical proceed via a one-step hydrogen atom and oxygen atom transfer rather than via an electron transfer from substrates to cumylperoxyl radical.
Photosensitized oxidation of furans; Part 18: A simple method for a one-pot synthesis of functionalized methyl cis-4-oxoalk-2-enoates
Functionalized methyl cis-4-oxoalk-2-enoates 2 are synthesized in a one-pot procedure by singlet oxygen oxygenation of the corresponding 2-methoxyfurans 1 in methanol and reduction of the resulting hydroperoxides 4 and 5 by the sulfides 6 which are selectively oxidized into the sulfoxides 7. The synthetic method has a wide range of applicability and affords compounds 2 stereoselectively and in good yields; concomitantly the sulfoxides 7 are obtained in excellent yields.
Iesce,Cermola,Piazza,Scarpati,Graziano
p. 439 - 443
(2007/10/02)
The Titanium Dioxide Sensitised Photo-Oxidation of Sulphides
Titanium dioxide has been shown to photosensitise the oxidation of sulphides to give sulphoxides and sulphones.Evidence is presented against the involvement of singlet oxygen and in favour of the sulphide radical cations as being intermediates.
Davidson, R. Stephen,Pratt, Julie E.
p. 5903 - 5906
(2007/10/02)
More Articles about upstream products of 2211-92-9