Collect. Czech. Chem. Commun. 1999, 64, 1583-1593

Effects of the Nucleophile Structure on the Mechanisms of Reaction of 1-Chloro-2,4-dinitrobenzene with Aromatic Amines in Aprotic Solvents

Norma Sbarbati Nudelmana,*, Cecilia E. Silvana Alvarob, Monica Savinib, Viviana Nicotrab and Jeannette Yankelevichb

a Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina
b Departamento de Química, Facultad de Ingeniería, Universidad Nacional del Comahue, Neuquén, Argentina


The kinetics of reactions of 1-chloro-2,4-dinitrobenzene with aniline and several substituted aromatic amines, B, in toluene shows a quadratic dependence of the second-order rate constant, kA, on [B], which is preserved even in the presence of increasing amounts of dimethylaniline, while the reaction with N-methylaniline shows a linear dependence of kA vs [B]. All these results are interpreted by the "dimer nucleophile" mechanism, and confirmed by the effects of a non-nucleophilic hydrogen bond acceptor tertiary amine which show the relevance of the structure of the nucleophile and the role of mixed aggregates in defining the mechanisms of aromatic nucleophilic substitutions with amines in aprotic solvents.

Keywords: Aromatic nucleophilic substitutions; Aprotic solvents; Dimer nucleophile mechanism; Amine aggregation states; Nucleophile structure; Reaction mechanism; Reaction kinetics.