Synthesis of 4,6-dinitrobenzofurazan, a new electron-deficient aromatic

Abstract

Preparation of 4,6-dinitrobenzofurazan (6) has been investigated by a number of routes. Its synthesis from 4,6-dinitrobenzofuroxan (4,6-dinitrobenzofurazan 1-oxide) (1) by reduction with triphenyl- phosphine proceeds in similar overall yield to the known method of nitration of 5-nitrobenzofurazan (8) but in fewer steps. Nitration of 4-nitrobenzofurazan (7) was studied as an alternative route, and the difference in reactivity between (7) and (8) is discussed. The benzofurazan (6) readily forms hydroxy and methoxy Meisenheimer complexes which have been isolated as stable, but highly explosive, potassium salts.