Reaction of nitric acid and its esters with organic bases

Abstract

A study of solutions of benzylamine in the solvent carbon tetrachloride has shown that an interaction between these compounds readily occurs leading to the formation of chloroform, ammonia, benzylamine benzylidene, sym-dibenzyl urea and benzylammonium chloride. These products have been isolated from such binary mixtures and a mechanism consistent with their formation is proposed. Considerable difficulties were met with in the analysis of the products, formed in reactions of tertiary amines with alkyl nitrate esters. By employing a wide variety of techniques it has been possible to separate and identify a number of related compounds formed from the interaction of n-propyl nitrate with tri-n-propylamine at elevated temperatures. A detailed kinetic study investigation of the nitration of N-methyl-N-nitrosoaniline by anhydrous nitric acid in carbon tetrachloride solution has been undertaken. The reaction was found to be first order with respect to this aromatic substrate and third order with respect to nitric acid. Catalysis of the nitration was observed by trifluoro-acetic acid and retardation by dimethylformamide and acetonitrile. An interpretation of the latter effect has been made in terms of hydrogen bonding with nitric acid.Using an isotopically labelled nitroso group in the aromatic substrate has permitted differentiation between the four possible reaction pathways - the essential stages of which are (i) direct nitration, (ii) intramolecular nitrosation, (iii) intramolecular nitramine rearrangement and (iv) intermolecular nitrosation. The intermolecular nitrosation route (iv) was found to operate and to give a small deuterium kinetic isotope effect.