Secondary alpha-deuterium kinetic isotope effects: assumptions simplifying interpretations of mechanisms of solvolyses of secondary alkyl sulfonates.
For solvolyses of 2-propyl and cyclopentyl sulfonates, logarithms of alpha-deuterium kinetic isotope effects (alpha-KIE) correlate linearly with logarithms of nucleophilic solvent assistance (NSA); correlations have the same slopes, but different intercepts, consistent with both solvent and structural effects on alpha-KIEs for heterolysis, further supported by recent theoretical and experimental data. It is argued that alpha- and beta-KIEs cannot yet distinguish between mechanisms proceeding via one or more transition states of similar energies. Structural, solvent, and isotope effects can be rationalized by heterolysis accompanied by NSA.
Department of Chemistry, University of Wales, Swansea, Singleton Park, Swansea SA2 8PP, Wales, United Kingdom. cmsolvol@swansea.ac.uk
T William
TW
Bentley