KINETIC STUDIES ON THE INTERACTIONS OF SOME AROMATIC AMINES AND N-CHLOROANILIDES

Abstract

Reactions of N-Chloroacetanilide with various aromatic amines such as aniline, o-, m- and p-toluidines, p -chloro, g-bromo and p_ - carboxyanilines have been studied in 50-50 ethanol water (v/v). The reactions follow the following rate equation .* rate ~kr Qi-chloro compound] [anilineJ , being first order with respect to each reactant. The temperature effect on the reactions for the first four amines have been used to determine the Kinetic Parameters of the reactions.lt is found that these reactions follow isokinetic relationship, the isokinetic temperature being 321 K. All of these reactions follow Hammett relationship with a p value of -3.30 at 30°c. Results of solvent polarity effect indicate that the reactions occur via dipole-dipole interaction. Reaction rates are unaffect ed by the addition of radical traps and also of acetanilide. With a view to assess the effect of nuclear substituents in the aryl component of N-chloroanilides, the various substi tuents introduced are 4-CHj, 3-C^, 4-Br and 3-C1 along with K. The N-chloro compounds are subjected to reactions with two aromatic amines aniline and g_ - toluidine at five different temperatures ranging from 25° to 45°C The Kinetic Parameters for all these reactions have been evaluated. It is found that reactions of both the series follow isokinetic relationship as -iiiwell as the Hammett relationship. The isokinetic temperature found for reaction series with aniline is 524 K and that with p_- toluidine is 539 K. The reaction constant values for these reaction series are +3.75 and +3.56 respectively. In order to study the role of the various groups attach ed to the carbonyl group in the acyl moiety of the N-chloroar^ lides four different groups besides meti-^l are taken. These are ethyl, isopropyl, benzyl and phenyl. These N-chloroacylanilides have also been reacted with the same too aromatic amines in a similar way and the Kinetic Parameters for these reactions have also been evaluated. Both the reaction series are found to follow isokinetic relationship, the isokinetic temperatures being 564 K and 583 K for reactions with aniline and those with £ - toluidine respectively. Both the reaction series also follow Taft equation and the reaction constants are +1.98 and + 2.41 at 30 c for the two series respectively. The products of these reactions have been identified to be symmetrical azobenzene together with the corresponding anilides and chloride ion. These reactions have been explained in terms of a bimolecular interaction mechanism involving nucleophilic attack of the amino nitrogen on the electrophilic chlorine of the N-Cl bond.