The Nucleophilic Substitution Reactions of 5- and 7-Chloro-4,6-dinitrobenzofurazan 1-Oxide by Aromatic Amines.

Abstract

7-Chloro-4,6-dinitrobenzofurazan 1-oxide is a powerful electrophile which reacts with a variety of primary and secondary aromatic amines, even those with deactivating substituents , to give arylamino - benzofurazan oxides under mild conditions. Tertiary aromatic amines react through carbon to give aminoarylbenzofurazan oxides. During, or as a consequence of, the substitution reactions, tautomerism occurs to give in all but one example an equilibrium mixture of 5- and 7-substituted 4,6-dinitrobenzofurazan oxides in which the latter predominates. Thus 5-chloro-4,6-dinitrobenzofurazan 1-oxide and 7- chloro-4,6-dinitrobenzofurazan 1-oxide both react with aniline to yield the same isomeric mixture of products: 4,6-dinitro-7- phenylaminobenzofurazan oxide (predominantly 1-oxide) (major) and 4,6- dinitro-5-phenylaminobenzofurazan 1-oxide (minor). The 5- and 7- phenylamino 4,6-dinitrobenzofurazans were prepared to assist in structural assignment of the N-oxides.