Oxygenation Reaction of Organic Sulfides with Oxochromium(V) Ion.
The selective oxidation of 19 alkyl aryl sulfides to sulfoxides with three oxochromium(V) complexes in an acetonitrile-water mixture is overall second order, first order in the oxidant and in the substrate. Sulfides containing electron-attracting substitutents retard the rate while those containing electron-releasing substitutents accelerate the rate of oxidation. The rate constant for the oxygenation reaction, k(2), is better correlated with sigma(+)/sigma(-) than Hammett sigma constants. The reactivity of different alkyl phenyl sulfides C(6)H(5)SR (R = Me, Et, n-Pr, i-Pr, n-Bu, and t-Bu) is accounted for in terms of Taft's polar, sigma, and steric, E(s), substitutent constants. These kinetic results are interpreted in terms of a mechanism involving outer sphere electron transfer from sulfide to Cr(V) as the rate-determining step. The results of Cr(V) oxidation are compared with those of Cr(VI) oxidation.
Ganesan
Tharumeya Kuppusamy
TK
Department of Chemistry, The American College, Madurai 625 002, India, and School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India.
Rajagopal
Seenivasan
S
Bharathy
Jesuraja Bosco
JB
Sheriff
Ambalam I. Mohamed
AI