Polychloroaromatic compounds. Part V. Preparation and oxidation of pentachlorophenyl-substituted tertiary amines and reactions of n-butyl-lithium and other nucleophiles with various pentachlorophenyl derivatives

Abstract

Methods of preparing NN-disubstituted aminopentachlorobenzenes in good yield, by the reaction of hexachlorobenzene with secondary amines, have been studied. Oxidation of these compounds with peroxy-acids does not yield the expected N-oxides but gives mainly nitroso- and nitro-derivatives and several by-products. The course of this oxidative degradation, as inferred from the products, is discussed. Pentachloronitrosobenzene and pentachlorophenylhydroxylamine are more stable, than their nonchlorinated analogues.The action of n-butyl-lithium on the methoxy- and NN-dialkyl-aminobenzenes in ethers and in a hydrocarbon solvent gives mixtures of tetrachlorophenyl-lithium compounds, the isomeric ratio of which has been ascertained by n.m.r. spectroscopy. The tendency of the lithio-derivatives to generate polychloroarynes has been demonstrated by trapping these intermediates with furan. Nucleophilic substitution of pentachloronitrobenzene is shown to occur predominantly ortho to the nitro-group.