Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted-Benzenesulfonates and Y-Substituted-Phenyl 4-Nitrobenzenesulfonates with Azide Ion: Regioselectivity and Reaction Mechanism

摘要: The second-order rate constants for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (4a–4f) and Y-substituted-phenyl-4-nitrobenzenesulfonates (5a–5f) with ion have been measured spectrophotometrically. 4a–4f proceed through SO CO bond fission pathways competitively. Fraction the decreases rapidly as substituent X in benzenesulfonyl moiety changes from an electron-withdrawing group to electron-donating group. Hammett plots are linear ρX = 1.87 0.56 fission, respectively. fact that is further away reaction site than one reason smaller ρX value. nature mechanism (i.e., a stepwise which expulsion leaving occurs after rate-determining step) also responsible value obtained fission. Bronsted-type plot 5a–5f βlg = −0.63, typical reported previously concerted mechanism. Effects substituents Y on regioselectivity discussed detail.