Kinetics of the Reactions of Nitro-Activated Diphenyl Ethers with Substituted Anilines in Benzene.
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The kinetics and mechanisms of the reactions of nitro-activated diphenul ethers with substituted anilines in benzene have been investigated. The reactions except that of 2, 6-dinitro phenyl 2,4,6-trinitrophenyl ether are base catalysed. For some of the nucleophiles, the rates decreased with increasing temperature in the range 5 - 350C resulting in negative enthalpies of activation (~HN-4.1 to 20.0 kJmol-1). 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 involve one aniline molecules 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.