Kinetics and mechanism of the oxidation of some organic sulfides by morpholinium chlorochromate

Abstract

The oxidation of organic sulfides by morpholinium chlorochromate (MCC) resulted in the formation of the corresponding sulfoxides. The reaction is first order with respect to both MCC and the sulfide. The reaction is catalyzed by toluene-p-sulfonic acid (TsOH). The oxidation was studied in 19 different organic solvents. An analysis of the solvent effect by Swain's equation showed that both the cation-and anion-solvating powers of the solvents play important roles. The correlation analyses of the rate of oxidation of 34 sulfides were performed in terms of various single and multiparametric equations. For the aryl methyl sulfides, the best correlation is obtained with Charton's localized-delocalized-resonance and localized-delocalized-resonancesteric equations. The oxidation of alkyl phenyl sulfides exhibited a very good correlation in terms of the Pavelich-Taft equation. The polar reaction constants are negative, indicating an electrondeficient sulfur center in the rate-determining step. A mechanism involving formation of a sulfonium cation intermediate in the slow step has been proposed.

Oxidation of Aliphatic Aldehydes by Tetraethylammonium Chlorochromate: A Kinetic and Mechanistic Study

“…Formation of a protonated Cr(VI) species has earlier been postulated in the reactions of structurally similar PBC [11] and MCC [12].…”

Kinetics and thermodynamics of oxidation of some thio acids by tripropylammonium fluorochromate in N , N -dimethyl formamide and acetic acid mixture

“…Dithiodiglycolic acid is obtained from Sigma Aldrich. Dithiodimalic and dithiodilactic acids were prepared by the oxidation of the corresponding thiols by ferric alum (Malini et al, 2008). Acetic acid purified by a standard method and the fraction distilling at 118°C was collected.…”

“…For this, a number of different chromium (VI) derivatives like tetraethylammonium chlorochromate (Swami et al, 2010), tetrabutylammonium bromochromate (Ghammamy et al, 2007), tetraheptylammonium bromochromate (Ghammamy et al, 2009), tetrahexylammonium fluorochromate (Koohestani et al, 2008), tetramethylammonium fluorochromate (Sadeghy and Ghammami, 2005), tetraethylammonium chlorochromate (Mansoor and Shafi, 2011a,b), benzimidazolium fluorochromate (Mansoor, 2010;Mansoor et al, 2011), tributylammonium chlorochromate (Mansoor and Shafi, 2010a,b), tetraethyl ammonium bromochromate (Mansoor and Shafi, 2011a,b), triethylammonium chlorochromate (Mansoor and Shafi, 2010a,b), imidazolium dichromate (Mansoor and Shafi, 2009), benzimidazolium dichromate (Kumar et al, 2011) and imidazolium fluorochromate (Mansoor and Shafi, 2012) have been developed to improve the selectivity of oxidation of organic compounds. The kinetics and mechanism of oxidation of thio acids by various oxidants have been reported (Asopa et al, 1990;Rathore et al, 1994;Khurana et al, 1998;Gangwani et al, 2000;Bhatt et al, 2001;Malini et al, 2008). However, the kinetics of oxidation of thio acids by TriPAFC, a Cr(VI) reagent has not yet been studied.…”

“…As the activated complex is formed, the reactants lose their freedom to move independently. Further, as the charge separation takes place in the transition state, the charged ends get solvated by solvent molecules (Malini et al, 2008). This results in immobilization of large number of solvent molecules.…”

Kinetics and Mechanism of Oxidation of Methyl Phenyl Sulphide by Imidazolium Fluorochromate

“…The synthesis of sulphoxides were reported for first time by Marcker in 1865 and since then a number of methods were developed for conversion of sulphides to sulphoxides. Oxidation of organic sulphides by several oxidants such as N-halo compounds [2][3][4] , peroxo compounds 5 and chromium compounds 6 have been reported.…”