Reactivity–selectivity relationship and kinetic solvent isotope effects in nucleophilic substitution reactions

Abstract

Selectivity plots, log(K_x1/K_x2)vs. σ_y, have been obtained for various nucleophilic substitution reactions: (i) with anilines (N) in methanol (S), k_N/k_S, using literature data for YC₆H₄CH₂Cl, YC₆H₄COCl, YC₆H₄SO₂Cl, YC₆H₄COCH₂Br, YC₆H₄CH(CH₃)Cl and YC₆H₄CH[C(CH₃)₃]OSO₂C₆H₄NO₂; and (ii) with kinetic solvent isotope effects (KSIE) in water and methanol, k_SOH/k_SOD, determined in this work for the same compounds (except for the latter two). The two selectivity plots are shown to be equivalent in applying mechanistic criteria based on four reactivity–selectivity regions identified by the, slopes of the selectivity plots. Δρ_y. Straightforward applications were possible in most cases except for the aminolysis of phenacyl bromides and 1-phenylethyl chlorides. For these two, detailed analyses of kinetic results were required, in addition to the reactivity-selectivity considerations, before deciding the reaction mechanism.