Mechanism of the reaction of sulphides with N-chloroarenesulphonamides

Abstract

The kinetics of the reaction of R1R2S (R1 = Ra = alkyl or aryl) and ArS0,NCI-Naf were investigated in buffered water-ethanol solution. Analytical methods have been elaborated to follow the reaction which affords R W -SNS0,Ar and R1R2S0. From the reaction scheme proposed. kinetic equations are deduced and supported experimentally. In fast and slow (kd)) equilibrium reactions, respectively, ArSO,NCI-Na+ in water is transformed into ArS0,NHCI and ArSO,NCI, which are reactive electrophiles and which, in their turn, react with R1R2S, the first in a slow (kl') and the second in a relatively fast (k,) step to form reactive intermediates. The rate constants kd', kl ' , and k2 have been determined for different reactants and the observed substituent effects are correlated with the formation of an (RIRBSCI+ArSO,NQ-) ion-pair intermediate (Q = H or CI). Me, S is converted byPh2S by TsNCI, (kl' < k i ) , and MeSPh by both chlorinating agents (kl'k i ) . For the reactions of MeSPh with TsNCI, and TsNHCl k,/kl' is 3.5 x lo6. MeSPh is chlorinated by TsNCI, 1500 times faster than Ph&. For XC6H4SMe, electron-donating X groups increase the rate of reaction with both TsNHCl and TsNCI, (p -4.25 and -3.56, respectively). For YC6H4S02NHCI, electron-withdrawing Y groups produce an increase in reactivity toward MeSPh (p +I -76). From the ion-pair intermediate R1R2SNS0,Ar and R1R2S0 are formed, probably via a sulphurane intermediate, in fast, competitive SN reactions under different steric control. The formation of sulphoxides is more hindered by bulky R groups than that of sulphimides. Other productcontrolling factors are also discussed. MANN AND POPE found that sulphides react with salts alkaline medium, HOCl, ArS0,NCl-as reactants may be of N-chlorosulphonamides (e.g. with chloramine T) to neglected. Several authors have considered ArS0,NHCl yield sulphimides [equation (l)]. In media containing as the effective electr~ph:ile.~J~ Nevertheless, this water, sulphoxides are also produced [equation (2)]. species cannot be the only electrophile reacting with

A paradigm shift in rate determining step from single electron transfer between phenylsulfinylacetic acids and iron(III) polypyridyl complexes to nucleophilic attack of water to the produced sulfoxide radical cation: a non‐linear Hammett

“…[32] High ρ value is also observed in the oxidation reactions of organic sulfides by chloramine-T (ρ = À4.25), [33,34] N-chlorosaccharin (ρ = À3.33), [35] bromine (ρ = À3.2), [36] N-bromobenzamide (ρ = À3.18) [37] and PTAAs by N-chlorosaccharin (ρ = À3.12) [38] and ammonium meta vanadate (ρ = À3.64) [39] where electrophilic attack of the oxidizing species on the sulfur centre has been proposed as the rate-determining step.…”

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

“…Large negative reaction constants were exhibited by oxidations involving formation of halogeno-sulfonium cations, for example, by chloramine-T (−4.25) [30], bromine (−3.2) [31], and N-bromoacetamide (−3.75) [32]. In the oxidation by N -chloroacetamide (NCA) [33], the values of field (ρ I ) and resonance (ρ + R ) at 298 K are −1.3 and −1.7, respectively.…”

Mechanistic aspects for the oxidation of sunset yellow dye by chloramine-T in presence of perchloric acid and in sodium hydroxide medium catalyzed by Os(VIII): A spectrophotometric kinetic approach

“…Chloramine-T acts as an oxidizing agent in both acidic and alkaline media [17][18][19][20][21][22]. The redox potential of chloramine-T/sulfonamide system [23] is pH dependent (1.139, 0.778 and 0.614 V at pH 0.65, 7.0 and 9.7, respectively) and decreasing with increase in pH of the medium.…”

“…al. [17], Ruff and Kucsman [18], Bishop and Jennings [19], Hardy and Johnston [20], Pryde and Soper [21] and Higuchi et al [22]. Aqueous solution of chloramine-T (TsNClNa) behaves as a strong electrolyte [19] and depending on the pH, it furnishes different types of reactive species.…”