Equilibria in complexes of N-heterocyclic molecules. Part 30. Reaction of 5-nitro-1,10-phenanthroline with aqueous bases

Abstract

In water and in dimethyl sulphoxide, hydroxide anion adds reversibly to position 6 of 5-nitro-1,10-phenanthroline to give an anion whose equilibrium constant of formation (in water) at 20 °C is 1.2 ± 0.1 dm³ mol^–1. When heated in aqueous media, this anion rearranges to the anion of the mono-oxime of 1,10-phenanthroline-5,6-quinone. A further reaction then affords ammonia in high yield and whose nitrogen atom is derived entirely from the nitro-group of the nitrophenanthroline, and 4,5-diazafluoren-9-one as the major organic product.