110874-70-9Relevant articles and documents
Reactions of Charged Substrates. 8. The Nucleophilic Substitution Reactions of (4-Methoxybenzyl)dimethylsulfonium Chloride
Buckley, Neu,Oppenheimer, Norman J.
, p. 540 - 551 (1997)
Displacement reactions on the title compound (1) occur only for nucleophiles with intermediate hardness. Nucleophiles that react display a range of mechanisms. 1 reacts with the neutral nucleophile pyridine-d5 through a mixed SN1/SN2 mechanism; salt added to control ionic strength affects the rate for the unimolecular process, but has no effect on the bimolecular rate constant. The mechanism of displacement by N3- and SO32- depends on the presence or absence of exogenous salt. At constant ionic strength, the mechanism is mixed SN1/SN2 over most of the range of [Nu]. With nucleophile only present, plots of kobsd vs [Nu] exhibit severe breaks that are not the result of salt effects. Analysis of rate constants and product ratios suggests that at low [Nu] reaction occurs simultaneously through concerted Hughes-Ingold SN2 and preassociation-concerted mechanisms. At high [Nu], displacement occurs only through the preassociation-concerted mechanism. Comparison of these results with data for gas-phase dissociation of benzyl dimethylsulfoniums and with solution results for benzyl pyridiniums suggests that the intrinsic stability of the intermediate does not necessarily determine the mechanism.
