Nucleophilic Substitution at Sulphonyl Sulphur. Part 2. Hydrolysis and Alcoholysis of Aromatic Sulphonyl Chlorides

Article abstract of DOI:10.1039/P29810000438

Kinetics of hydrolysis, methanolysis and ethanolysis of furan-2 and -3-, thiophen-2- and -3-, and benzene-sulphonyl chlorides have been measured.Fair correlations with Taft ?* values for heterocycles are found; more satisfactory trends are observed by applying the two-parameter (polar and steric) Taft-Pavelich equation, particularly for the hydrolysis reaction including data for aliphatic sulphonyl chlorides.In this case the negative δ value, which is related to the steric parameter, is consistent with steric acceleration due to relief of strain in the transition state.Alcoholysis rates of substituted thiophen-2-sulphonyl chlorides (5-CH3, 5-Cl, 4-NO2, and 5-NO2) have been also measured in order to compare the substituent effects with those already observed for hydrolysis.The data are in accord with previous findings, that an S_N2 type mechanism takes place which is shifted toward an S_N1 process (looser transition state) or an S_AN process (tighter transition state) in the hydrolysis and alcoholysis reactions, respectively.

Full text of DOI:10.1039/P29810000438

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