46305-58-2Relevant academic research and scientific papers
Probing for Electronic and Steric Effects in the Peracid Oxidation of Thianthrene 5-Oxide
Adam, Waldemar,Golsch, Dieter
, p. 115 - 119 (1997)
A systematic examination of the electronic and steric effects in the peracid oxidation of thianthrene 5-oxide (SSO) was undertaken and has revealed valuable information on the oxidative reactivity of the SSO mechanistic probe toward peroxidic oxidants. Thus, no significant steric effect was found on the bisulfoxide (SOSO)/sulfone (SSO2) product ratio for aliphatic peracids with varying size of alkyl groups [R = Me, Et, i-Pr, t-Bu, (n-Bu)(Et)CHCH2]. However, a significant electronic effect was observed for CH3CO3H and CF3CO3H, for which the Xso values were 0.16 and 0.01, i.e., predominant oxidation of the sulfide functionality to the SOSO product by these oxidants. In addition, substituted perbenzoic acids displayed this trend. In contrast, the nucleophilic peracid anion led exclusively (Xso = 1.00) to oxidation of the sulfoxide site to the SSO2 product. The oxygen transfer appears to be orbital-controlled since the more electrophilic oxidant is clearly the more reactive as well as more chemoselective, i.e., preferred attack at the more nucleophilic sulfide site in SSO.
Radical Ions, 81. ENDOR Spectroscopic Investigations of Radical Cations of Aromatic Organosulfur Compounds
Bock, H.,Hierholzer, B.,Rittmeyer, P.
, p. 187 - 204 (2007/10/02)
Conditions for ENDOR measurements of organosulfur radical cations are discussed and tested.The one electron oxidation of a variety of aromatic sulfur compounds comprising benzene-1,2-dithiole, 1,4-dithiine, thianthrene and diphenylsulfide derivatives as well as 33S isotope-marked bis(2,5-dimethoxyphenyl)disulfide is accomplished using the oxygen-free, powerful and selective AlCl3/H2CCl2 reagent.Partly with substantial structural changes, paramagnetic M.+ species of 1,2-benzodithiete, 1,4-dithiine, thianthrene and diphenyl sulfide result.Their temperature-dependent ENDOR signal patterns provide numerous information e.g. on radical cation structure and dynamics, on the rather high sulfur spin populations or on the spin rotation interaction dominated relaxation behaviour.Accordingly, to obtain optimum ENDOR effects in organosulfur radical cations low temperature measurements are required, and especially for still undiscovered 33S ENDOR couplings, small g factor anisotropies and 33S spin densities appear to be necessary. - Keywords: ENDOR (Special, General Triple) Spectra, Temperature Dependence, Organosulfur Radical Cations, Structural Changes, Molecular Dynamics
ESR Investigation of Radical Cations Formed from Aromatics and Heteroaromatics Adsorbed on Mo-Al2O3 Surfaces
Petrakis, L.,Meyer, P. L.,Jones, Gerald L.
, p. 1029 - 1038 (2007/10/02)
Molybdena-alumina is an important model catalyst system that has attracted considerable attention over the years.The behavior of adsorbed species on catalytic surfaces is also of interest because this may lead to a better understanding of the reaction mechanisms involved in the catalytic process.Using electron spin resonance, we have continued our systematic study of the molybdena-alumina system to which various aromatics and heteroaromatics have been added.We have investigated electron-transfer reactions with the molybdena-alumina surface and have also investigated the structural and dynamical aspects of the resulting adsorbed cations.Computer fitting of the cation ESR spectra has been carried out for a more precise determination of spectral parameters, and a comparison with solution spectral parameters has also been made.
