title: Unraveling structure-reactivity relationships in SNV reactions: kinetics of the reactions of methoxybenzylidenemalononitrile, 2-(methylthiobenzylidene)-1,3-indandione, 2-(benzylthiobenzylidene)-1,3-indandione, and methyl beta-methylthio-alpha-nitrocinnamate with OH- and thiolate ions in aqueous DMSO.
abstract: The kinetics of the title reactions were determined in 50% DMSO-50% water (v/v) at 20 degrees C; n-BuS-, HOCH2CH2S-, and MeO2CCH2S- were used as thiolate ions. The reactions with the thiolate ions gave rise to two separate kinetic processes. The first refers to rapid, reversible attachment of RS- to the substrate leading to a tetrahedral intermediate (k1RS), k(-1)RS, the second to the conversion of the intermediate to products (k2RS). In most cases all of the rate constants (k1RS, k(-1)RS and k2RS could be determined. In combination with results from previous studies, a detailed discussion regarding the effects of activating substituents and leaving groups on rate and equilibrium constants as well as on intrinsic rate constants is presented. The reaction with OH- only allowed a determination of k1OH for nucleophilic attack on the substrate; in this case the tetrahedral intermediate remains at steady-state levels under all conditions.
authors.affiliation: Contribution from the Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA.
authors.forename: C F
authors.initials: CF
authors.lastname: Bernasconi
authors.forename: R J
authors.initials: RJ
authors.lastname: Ketner
authors.forename: M L
authors.initials: ML
authors.lastname: Ragains
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: Z
authors.initials: Z
authors.lastname: Rappoport