Kinetics Of The Reactions Of Nitro-Activated Diphenyl Ethers With Substituted Anilines In Benzene

ABSTRACT

The kinetics and mechanisms of the reactions of nitro-activated diphenyl ethers with substituted anilines in benzene have been investigated. The reactions except that of 2', 6'- dinitro phenyi 2, 4, 6- trinitrophenyl ether are base catalysed. For some of the nucleophiles, the rates decreased with increasing temperature in the range 5 - 35 °C resulting in negative enthalpies of activation (AH" -4.1 to -20.0 kJmol. This can be rationalised in terms of a step-wise mechanism involving (at least) a pre-equilibrium. The catalysis of the mono-nitro substituted diphenyl ethers involves two aniline molecules and proceeds by temperature – Independent rates while that of the dinitro substituted ones involves one aniline molecule and proceeds by temperature - dependent rates In the above temperature range. The results are interpreted in terms of a cyclic mechanism assisted in special cases by steric factors.