6251-34-9Relevant articles and documents
A kinetic investigation, supported by theoretical calculations, of steric and ring strain effects on the oxidation of sulfides and sulfoxides by dimethyldioxirane in acetone
Hanson, Peter,Hendrickx, Ramon A. A. J.,Lindsay Smith, John R.
supporting information; scheme or table, p. 65 - 84 (2011/01/07)
The oxidations of alkyl 4-nitrophenyl, and dialkyl, sulfides and sulfoxides by dimethyldioxirane in acetone occur by concerted mechanisms but the sulfides respond differently from the sulfoxides to variation in the alkyl group. The reactions of the sulfides are inhibited by the steric effects of alkyl groups and these predominate over their inductive effects. By contrast, the reactions of these limited sets of sulfoxides are insensitive to alkyl steric effects but there is an indication of steric acceleration when a broader set of sulfoxides is considered. This behaviour is rationalised in terms of the differences in dipolar charge and its solvation between the ground state and transition state for the two types of substrate. The oxidations of cyclic sulfides and sulfoxides also exhibit contrasting behaviour. The reactivity of the sulfides is insensitive to ring strain but is explicable in frontier orbital terms whereas that of the sulfoxides is partly dependent upon the change in ring strain between reactant and product on oxidation, a difference rationalised in terms of the relative positions of the transition states in the reaction coordinates of the two oxidations. The reactivity of 4-, 5- and 6-membered cyclic sulfoxides is also dependent on a ring-size related property of the transition state. Calculations at the B3-LYP/6-31G* level of density functional theory on both ground states and transition states, including simulation of solvation by acetone, strongly support the mechanistic conclusions reached in this and earlier work.
Selective Autoxidation of Electron-Rich Substrates under Elevated Oxygen Pressures
Correa, Paul E.,Hardy, Gordon,Riley, Dennis P.
, p. 1695 - 1702 (2007/10/02)
We report here the observation of a novel autoxidation pathway which occurs with electron-rich substrates.Tertiary amines, dialkyl thioethers, olefins, and alkynes under high oxygen pressures (>20 bars of O2), in polar solvents, and at elevated temperatures (>90 deg C) yield in good to excellent selectivity amine oxides, sulfoxides, and site-specific olefin and alkyne cleavage products, respectively.The results of mechanistic studies, including high oxygen pressure electrochemical studies, are discussed.A mechanism for this novel oxygenation reaction pathway that is consistent with the observed results is proposed.It involves an initial unfavorable electron transfer from the electron-rich substrate to oxygen to yield superoxide and the radical cation, which reacts with triplet oxygen to yield the oxygenated radical cation intermediate, a suspected potent oxidant.Electron transfer to the oxygenated radical cation from additional substrate (chain reaction) or superoxide yields a zwitterionic intermediate.This intermediate either reacts with additional substrate (O-atom transfer) to yield product (sulfoxide and N-oxide, in the case of thioethers and tertiary amines) or is converted with unimolecular reactivity to dioxetane-like (in the case of alkenes) or dioxetene-like (in the case alkynes) derived products.
Mechanism of the Oxidation of Sulphides with Sodium Periodate
Ruff, Ferenc,Kucsman, Arpad
, p. 683 - 688 (2007/10/02)
The kinetics of the oxidation of RSAr, R2S, and (CH2)nS sulphides with NaIO4 yielding sulphoxides were investigated in ethanol-water solutions, and the rate equation v = k2 was found to be valid.The observed substituent (ρ -1
