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7603749 
Journal Article 
Os(VIII) - catalysis on the oxidation of some diaryl sulphoxides with bromamine-B in alkaline medium 
Meenakshisundaram, S; Markkandan, R 
2005 
1 
Indian Journal of Chemistry. Section A
ISSN: 0376-4710
EISSN: 0975-0975 
NATL INST SCIENCE COMMUNICATION-NISCAIR 
NEW DELHI 
44 
1 
71-75 
WOS:000226572400010 
The effect of substituents reveals the electronic character of Os(VIII)- catalysed N-bromobenzene sulphonamide (bromamine-B) oxidation of some diaryl sulphoxides to sulphones in a strongly alkaline (pHsimilar to11.5) t-butanol-water (1:1 v/v) medium and the conversion appears to be nucleophilic for bromamine-B (BAB). High dielectric constant of the medium favours the reactivity. The kinetic studies reveal that electron-withdrawing groups enhance the reactivity while electron-releasing ones inhibit the rate. It appears that the anion RNBr is the reactive species of bromamine-B. The possibility of the formation of Os(VI)-BAB complex causing a retarding effect on the pseudo-first-order rate coefficients is discussed. Contrary to expectations there is a marked depression in the catalytic activity of Os(VIII) in the presence of other transition metals and pyridine bases such as 2, 2'-bipyridyl and 1,10-phenanthroline. The probable reaction mechanisms are discussed on the basis of above results.