AGGREGATION EFFECTS IN THE REACTIONS OF 2,4-DINITROCHLOROBENZENE WITHANILINE IN APROTIC-SOLVENTS

The kinetics of the reaction of 2,4-dinitrochlorobenzene with aniline have been studied in toluene and in toluene-methanol binary solvents a nd compared with the reactions in benzene and chloroform. The reaction s in aprotic solvents exhibit a rate dependence that is third-order in amine consistent with aggregates of the aniline acting as the nucleop hile. Molecular complexes between the aniline and the substrate were a lso detected spectrophotometrically. Additionally an inhibitory effect of toluene complexes was observed, which is similar to the previously reported effect of benzene in the reaction of the same substrate with n-butylamine. The reaction in the presence of pyridine shows an amine . dependence which indicates formation of 'mixed aggregates' between a niline and pyridine. All the above results, as well ai recently report ed studies of other reactions different from SNAr, are fully interpret ed within the 'dimer nucleophile' mechanism.