VARYING RESONANCE DEMANDS IN SUBSTITUENT EFFECTS. ACETOLYSIS OF NEOPHYL p-BROMOBENZENESULFONATES

Article abstract of DOI:10.1016/S0040-4020(01)89958-0

Rates of acetolysis of 2-aryl-2-methylpropyl p-bromobenzenesulfonates were determined for an extended series of substituents.The substituent effect can be described accurately in terms of our LArSR relationship (Yukawa-Tsuno Equation), giving an r value of 0.57.The correlation result can be reasonably accounted for on the basis of the accepted mechanism of this reaction, involving a rate-determining aryl-assisted transition state.The present study leads to the conclusion that this unique r value should be related to the resonance demand characteristic of the aryl-assisted ionization process of this reaction.The simple application of the Brown ρ?⁺ equation or its extended treatment and the interpretation based thereon are criticized.