Process for the manufacture of dianthraquinonyl-N,N'-dihydroazine

A one-batch process for the manufacture of dianthraquinonyl-N,N'-dihydroazine, which comprises reacting 1-nitroanthraquinone in a mixture of (a) water or a mixture of water and at least one alcohol and (b) an alkali metal hydroxide or a mixture of alkali metal hydroxides at a temperature of between room temperature and the boiling temperature of the reaction mixture with hydrazine, hydrazine hydrate, methyl hydrazine, ethyl hydrazine, phenyl hydrazine, hydrazinium chloride, hydrazinium dichloride, hydrazinium sulfate, hydrazinium bromide, benzenesulfonyl hydrazine, hydroxylamine, hydroxylamine hydrochloride, hydroxylammonium sulfate or hydroxylamine sulfonic acid, subsequently removing any alcoholic constituents present from the reaction mixture, adding to the reaction mixture dimethyl sulfoxide or dimethyl sulfoxide and a further amount of alkali metal hydroxide, and bringing the reaction to completion at a temperature between 80.degree. and 140.degree. C.