A process for producing dianthraquinone-N,N'-dihydrazine or its chlorination product, which comprises condensing 1-aminoanthraquinone at an elevated temperature in the presence of 1,3-dimethyl-2-imidazolidinone using an oxidizing agent and an alkaline condensing agent, and subjecting the resulting condensation product to a treatment known per se.
7,16-Dichlorodianthraquinone-N,N'-dihydroazine (I) ##STR1## is prepared by condensing 1-amino-3-chloroanthraquinone (II) in the presence of an alkaline condensing aid, of an oxidizing agent and of a urea derivative (III) ##STR2## (R: identical or different alkyl groups having 1 to 4 carbon atoms, which may be joined together to form a 5- or 6-membered ring that contains the urea group).
A process for preparing dianthraquinone-N,N'-dihydroazine (I) ##STR1## and its chlorination products (Ia) ##STR2## where n is 1 or 2, by condensation of 1-aminoanthraquinone (II) in the presence of an alkaline condensing aid, an oxidizing agent and a cyclic urea derivative at from 80.degree. to 150.degree. C. and subsequent purification and/or chlorination comprises using N,N'-dimethylpropyleneurea as the urea derivative.
