Phenazines and Benzcinnolines

Abstract

A number of attempts have been made to devise general methods for the synthesis of phenazines^1,2,3; but in a series of researches carried out during 1945–46 we found that most of the well-known methods failed in the case of some di-alkoxyphenazines. On the other hand, comparatively good results were obtained using the little-known reaction of Waterman and Vivian⁴, which depends on the treatment of a 2-nitro-or 2:2′-dinitrodiphenylamine with an ‘Oxygen acceptor’ such as reduced iron, lead or charcoal at a high temperature. In simple cases the reaction presumably proceeds, as suggested by the original authors, through the elimination of oxygen and water, but in the case of the 2: 2′-dinitro derivatives the course of the condensation is more obscure.