Reactions of primary amines and alcohols with 4-toluoyl azide

摘要

Primary amines2R:n-butyl(2a), cyclohexyl (2b), 3-pentyl (2c) react with 4-toluoyl azide1in non-nucleophilic solvents in a clear second order reaction, which is strongly dependent on the size of the amine2and the solvent polarity (k2Acetonitril; 25 °C: 15.51 (2a), 0.83 (2b) and 0.19 (2c) 1/mol·min; ΔH#=22.1 kJ/mol, ΔS#=−170.5 J/mol·K 2bin Acetonitril). Drastic changes occur in the presence of nucleophilic solvents. With nucleophilic amines2added to these in the solutions a concurrent reaction with alcohols4R: methyl (4a), ethyl (4b),n-butyl (4c) yielding 4-toluoyl ester5is observed. This is especially dominating with the “smallest” alcohol methanol (4a) and/or effectively promoted by “bulky” amines (2b, 2c; up to 995a). Compared with the pure alcoholysis a huge acceleration of the ester formation, proportional to the cencentration of the nucleophilic amine2, is observed. The reaction mechanism is discussed with special emphasis on steric effects in the competition of nucleophiles for th