Reactions of Primary Amines and Alcohols with 4-Toluoyl Azide

Article abstract of DOI:10.1007/BF00810023

Primary amines 2 react with 4-toluoyl azide 1 in non-nucleophilic solvents in a clear second order reaction, which is strongly dependent on the size of the amine 2 and the solvent polarity (k₂: 15.51 (2a), 0.83 (2b) and 0.19 (2c) l/mol*min; ΔH(excit.) = 22.1 kJ/mol, ΔS(excit.) = -170.5 J/mol*K <2b in Acetonitril>).Drastic changes occur in the presence of nucleophilic solvents.With nucleophilic amines 2 added to these in the solutions a concurrent reaction with alcohols 4 yielding 4-toluoyl ester 5 is observed.This is especially dominating with the "smallest" alcohol methanol (4a) and/or effectively promoted by "bulky" amines (2b, 2c; up to 99percent 5a).Compared with the pure alcoholysis a huge acceleration of the ester formation, proportional to the concentration of the nucleophilic amine 2, is observed.The reaction mechanism is discussed with special emphasis on steric effects in the competition of nucleophiles for the aroyl azide 1. - Keywords.Aroyl azide; 4-Toluoyl azide; Alcoholysis; Aminolysis; "Nucleophilic catalysis"; Kinetics; Steric effects.