How does structure determine organic reactivity? Partitioning of carbocations between addition of nucleophiles and deprotonation

Abstract

Publisher Summary This chapter reviews the results of the studies of the kinetics and products of stepwise nucleophilic substitution and elimination reactions of alkyl derivatives, focuses on factors that control the rate constant ratio k s / k p for the partitioning of carbocations, and provides an understanding of how the absolute rate constants k s and k p that constitute this ratio, change with changing carbocation structure. The analyses presented in the chapter are possible because of some recent experimental results that include: determinations of absolute rate constants with values up to k s = 10 10 s -1 for the reaction of carbocations with water and other nucleophilic solvents, determination of the large values of the rate constant ratio k s / k p from the low yields of alkene product, kinetic studies of stepwise hydration reactions of alkenes, and recent characterization of carbocations that partition to form an alkene. The chapter also discusses the explanations for the large changes in the rate constant ratio for the partitioning of carbocations between reaction with BrOnsted and Lewis bases that result from small changes in carbocation structure.