Reactions of oximate alpha-nucleophiles with esters: evidence from solvation effects for substantial decoupling of desolvation and bond formation.
This communication is concerned with deviations from linearity in Brønsted-type nucleophilicity plots as indicators of changes in transition-state structures, in particular as related to solvational effects. Increasing dimethyl sulfoxide (DMSO) content of DMSO-water mixtures removes the leveling off observed in Brønsted type plots of the reaction of p-nitrophenylacetate (PNPA) with oximate alpha-nucleophiles. This is interpreted as due to virtually complete decoupling between desolvation of the oxyanion nucleophile and bond formation in the rate-determining transition state (solvational imbalance).
Buncel
Erwin
E
SIRCOB, University of Versailles, 45, Avenue des Etats-Unis, 78035 Versailles Cedex, France. terrier@chimie.uvsq.fr
Cannes
Céline
C
Chatrousse
Alain-Pierre
AP
Terrier
François
F
D002801:Cholinesterase Reactivators / Q000737:chemistry; D007700:Kinetics; D010091:Oximes / Q000737:chemistry*; D010648:Phenylacetates / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry
D002801:Cholinesterase Reactivators; D010091:Oximes; D010648:Phenylacetates; D014867:Water; C118008:4-nitrophenylacetic acid