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

Abstract

Measured activation parameters, as well as the effect on rate of adding inert electrolytes, are consistent with solvolysis of p‐(dimethylamino)benzenesulfonyl chloride XI occurring through a concerted, asynchronous bimolecular mechanism, in which bond breaking takes place far ahead of bond formation in the transition state.

Kinetics and mechanism of the C-S coupling reactions of aryl Grignard reagents with aryl arenesulfonates

“…A number of investigations have been already reported using linear free energy relationships to distinguish between concerted S N 2(S) and stepwise S N a mechanisms for the nucleophilic substitution of aryl arenesulfonates at sulfur atom [32][33][34][35]. The generally accepted mechanism is a concerted synchronous S N 2(S) mechanism in which nucleophilic attack to sulfur and leaving group departure occurs in a single step [32][33][34].…”

“…Sulfonyl transfer reactions of arenesulfonic acid derivatives bearing phenoxides or halides as leaving group are expected to take place by three different mechanisms (Scheme 3): [31] (i) addition-elimination S N a mechanism involves a pentavalent complex [31][32][33][34]; (ii) stepwise S N 1(S) mechanism is expected to proceed via an incipient sulfonylium cation [35]; (iii) concerted S N 2(S) mechanism proceeds via a transition state in which bond formation and bond breaking occurs synchronously [31][32][33][34]. Sulfonyl group transfer is associative in mechanisms (i) and (iii) and dissociative in mechanism (ii).…”

“…In fact, to elucidate the transition state structure in the rate determining step, substituent constants should be carefully chosen not only for the substituents on the nucleophile [33,34], but also for the substituents on the arenesulfonyl group [33][34][35] and on the leaving group [32][33][34].…”

“…were reported for charge delocalization. Comprehensive studies on the hydrolysis of arenesulfonates also provided convincing evidence that sulfonyl transfer in an associative process leads to large negative values ∆H ≠ with low values of ∆H ≠ [35]. The relatively low value of ∆H ≠ and the large negative value of ∆S ≠ found for the reaction of phenyl magnesium bromide 1a with phenyl tosylate 2 suggest that the reaction might follow an associative process in the formation of transition state as expected.…”

“…To the best of our knowledge, there is no reported work on the kinetics and mechanism of the reaction of Grignard reagents with sulfonates at sulfur center, although numerous studies have been reported on the kinetics and mechanism of the reactions of nitrogen and oxygen nucleophiles with sulfonates [31][32][33][34][35][36]. In this paper, we report our results in the kinetics and mechanism of the C-S coupling of Grignard reagent derived aryl carbanions with phenyl tosylate.…”