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Updated: Jul 13, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
The rates of S(N)2 reactions and their relation to molecular and solvent properties
Luis G Arnaut1, Sebastião J Formosinho
1Chemistry Department, University of Coimbra, P-3049 Coimbra Codex, Portugal. lgarnaut@ci.uc.pt
Abstract:
The energy barriers of symmetrical methyl exchanges in the gas phase have been calculated with the reaction path of the intersecting/interacting-state model (ISM). Reactive bond lengths increase down a column of the Periodic Table and compensate for the decrease in the force constants, which explains the near constancy of the intrinsic barriers in the following series of nucleophiles: F(-) approximately Cl(-) approximately Br(-) approximately I(-). This compensation is absent along the rows of the Periodic Table and the trend in the reactivity is dominated by the increase in the electrophilicity index of the nucleophile in the series C
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