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Aqueous Phase One‐Electron Reduction of Sulfonium, Selenonium and Telluronium Salts
Author(s) -
Eriksson Per,
Engman Lars,
Lind Johan,
Merényi Gabor
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200400604
Subject(s) - radiolysis , sulfonium , chemistry , radical , alkyl , formate , aqueous solution , medicinal chemistry , reducing agent , solvated electron , organic chemistry , salt (chemistry) , catalysis
Triorganylsulfonium, ‐selenonium and ‐telluronium salts were reduced by carbon dioxide radical anions/solvated electrons produced in aqueous solution by radiolysis. The radical expulsion accompanying reduction occurred with the expected leaving group propensities (benzyl > secondary alkyl > primary alkyl > methyl > phenyl), although greater than expected loss of the phenyl group was often observed. Diorganyl chalcogenides formed in the reductions were conveniently isolated by extraction with an organic solvent. Product yields based on the amount of reducing radicals obtained from the γ‐source were often higher than stoichiometric (up to 1800 %) in the reduction of selenonium and telluronium compounds; it is likely that this result can be accounted for in terms of a chain reaction with carbon‐centred radicals/formate serving as the chain transfer agent. The product distribution was essentially independent of the reducing species for diphenyl alkyl telluronium salts, whereas significant variations were seen for some of the corresponding selenonium salts. This would suggest the intermediacy of telluranyl radicals in the one‐electron reduction of telluronium salts. However, pulse radiolysis experiments indicated that the lifetimes of such a species (the triphenyltelluranyl radical) would have to be less than 1 μs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)