Solvolysis of sulphonyl halides. VII. Hydrolysis of some aromatic sulphonyl chlorides in aqueous dioxan

Abstract

The rates of reaction and the parameters of activation have been determined for the hydrolysis of 4-nitro-, 3-nitro-, 4-bromo-, 4-methoxy-, 4-methyl-and unsubstituted benzenesulphonyl chlorides m aqueous dioxan containing mole fractions of water between 0 . 9 and 1.00. Further evidence is also found for Vizgert's hypothesis that 2,4,6-trimethylbenzenesulphonyl chlorlde hydrolyses by the SN1 mechanism. I n all other cases the inversion of the effects of substituents which occurs as the water content of the solvent is decreased, the passage of the rate through a maximum incertaincases, and the failure of theHammett free energy correlationcan beaccounted for in terms of 8,2 type mechanisms for hydrolysis in which both bond-making and bond-breaking processes are of importance but are differently biased by the various substituents.

Solvent network at the transition state in the solvolysis of hindered sulfonyl compounds

“…In recent years, the problem became more complicated with the study of sterically hindered arenesulfonyl compounds in which the attack on the S atom is apparently inhibited by the presence of ortho ‐alkyl groups . On the other hand, hindered structures based on derivatives of benzene sulfonyl chloride have shown a significant increase in reactivity, the so‐called positive steric effect, which is in disagreement with the classical interpretation of the electronic effect of substituents on the rate of S N 2 processes . Based on the described observations, and others already available in the literature, deviations of the TS structure are expected for a number of hindered substrates …”

Kinetics of hydrolysis of aromatic mono- and disulfonyl chlorides

“…(R)Ar-SO2C1 + H 2 0 -+ (R)Ar-S03H + HCl At a constant concentration of the nucleophilic agent such as H 2 0 (2,8,12,14,16,17), OH-(8, 22), CH3CO; (12, 19,22), the reaction is described by a pseudo-first order kinetic equation.…”

Isotope Effects in the Solvolysis of Sterically Hindered Arenesulfonyl Chlorides

“…Despite the existence of a large corpus of research on solvolytic processes near sulfonyl centers , details on the mechanism of this nucleophilic substitution remain unclear. A number of authors have proposed S N 2 or borderline S N 1–S N 2 mechanisms for this process . However, sterically hindered derivatives of aromatic sulfonic acids that contain o ‐alkyl groups show kinetic features that pose questions on the classical view of the bimolecular substitution mechanism .…”

“…A number of authors have proposed S N 2 or borderline S N 1–S N 2 mechanisms for this process . However, sterically hindered derivatives of aromatic sulfonic acids that contain o ‐alkyl groups show kinetic features that pose questions on the classical view of the bimolecular substitution mechanism .…”

“…o ‐Alkyl derivatives of benzenesulfonyl chlorides show increased reactivity in solvolysis processes . In this respect, as shown in Scheme , the feasibility of uni‐ and bimolecular mechanisms , structural modifications of the S N 2‐type transition state (TS) involving a second molecule of nucleophile (S N 3‐mechanism) , the stabilization of the bimolecular TS by intramolecular interactions, hyperconjugation effects, or stereochemical rearrangements during the nucleophilic attack have been discussed.…”