Kinetics of hydrolysis of aromatic mono- and disulfonyl chlorides

Abstract

PRZEMYSLAW SANECKI and EDWARD ROKASZEWSKI. Can. J. Chem. 65, 2263 (1 987).A continuous polarographic method of recording instantaneous concentrations of -S02C1 groups in an aqueous acetic acid system containing CH3C02Na has been elaborated. Ten model monosulfonyl chlorides underwent hydrolysis according to pseudo-first order kinetics (20% H20, 80% V.V. CH3C02H, 0.5 mol x dm-3 CH3C02Na). Plots of hydrolysis for seven disulfonyl dichlorides with different number of -CH3 groups have been determined. Pseudo-first order rate constants for two consecutive reactions of hydrolysis (k, and k2) have been computed and the influence of -S02C1 and -SO; groups on the reactivity of the second group -S02CI has been discussed. The mechanism of nucleophilic substitution has also been discussed.PRZEMYSLAW SANECKI et EDWARD ROKASZEWSKI. Can. J. Chem. 65, 2263 (1987.On a dtveloppt une mtthode polarographique continue qui permet d'enregistrer instantantment la prtsence de groupements -S02C1 dans des systkmes aqueux d'acide acCtique contenant du CH3C02Na. Dix chlorures modkles de monosulfonyles ont subi une hydrolyse suivant une cinttique de pseudo-premier ordre (20% H20, 80% v/v de CH3C02H et 0,5 mol x dm-3 de CH3C02Na). On a determint les courbes d'hydrolyse de sept dichlomres de disulfonyles qui diffkrent par le nombre de groupements CH3. On a calcult les constantes de pseudo-premier ordre pour les deux reactions d'hydrolyse constcutives (k, et kZ) et on discute de l'influence des groupements -S02C1 et -SO; sur la rtactivitt du deuxikme groupement -S02C1. On discute aussi du mtcanisme de la substitution nucltophile.[Traduit par la revue] IntroductionThe solvolysis and hydrolysis of sulfonyl halogenides are subject of many papers (refs. 1-23 and references therein). The character of the investigations is closely linked with advances in knowledge on reaction mechanism as reported by Arrhenius, Bodenstein, Ingold, Winstein, Bronsted, and Hammett and co-workers. The titrimetric or conductometric methods were used in the determination of instantaneous concentrations of reagents or products, and spectral uv was used only in two cases.It has been found that monosulfonyl chlorides hydrolyze according to the SN2 mechanism (e.g. refs. 9, 10):

Sulfonyl Transfer Reactions − A Kinetic Study on the Solvolysis ofp-(Dimethylamino)benzenesulfonyl Chloride in Aqueous Acetic Acid

“…A rough value of the Hammett sensitivity ρ as estimated from a two ‐ point relationship is ca. −2.1, quite different from that reported for the associative mechanism (ρ = + 1.34) 4. The electronic demand of the reaction is rather suggestive of a dissociative, S N 1 process, which in the transition state involves the build‐up of positive charge on the sulfur atom.…”

“…Also the fact that rates are lowered by addition of perchloric acid ( k obs is reduced by a factor of 3.6 in the presence of 0.5 M HClO 4 )4 gives further support to the conclusion that a “regular” S N 2(S) mechanism is not followed, since in this case, reactivity should increase as a result of the increasing concentration of protonated substrate [cf. σ p (NH 3 + ) = 1.70; σ p (NH 2 ) = −0.57] 9…”

“…As far as other benzenesulfonyl chlorides possessing internal nucleophilic centres other than the hydroxy group are concerned, previously published studies on solvolysis of p ‐(dimethylamino)benzenesulfonyl chloride ( XI ) have suggested the plausibility of the occurrence of a dissociative mechanism 4. Indeed, it has been claimed that decomposition of XI in 80% aqueous acetic acid takes place by an S N 1 mechanism involving the cationic sulfene intermediate XII .…”

Kinetics of hydrolysis of aromatic bicycling disulfonyl dichlorides

“…This operation corrects only the correlation coefficient. Equation [2] together with [ 1 ] give an interstructural correlation [3]: [3] However, these correlations are not of a general character.…”