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.
The present invention relates to a process for the preparation of hydroxynaphthalenes of formula (I) ##STR1## wherein n represents a number from 1 to 6, X denotes C.sub.1 -C.sub.6 alkyl, halogen, carboxyl, carboxylic acid ester, nitro, chlorosulphonyl, arylsulphonyl, hydroxyl, alkoxy, acyloxy, or an amino or aminosulphonyl that is unsubstituted or N-substituted with alkyl or aryl, or two radicals X, together with the adjacent carbon atoms to which they are bonded, form a fused-on aromatic, cycloaliphatic, or heterocyclic ring, and m denotes a number from 0 to 6, wherein if m is greater than 1, then each X can have different or identical meanings, by reacting (1) a naphthalenesulphonic acid of formula (II) or a salt thereof ##STR2## wherein n and m have the above meanings and X.sub.1 has the same meaning as X or is SO.sub.3 H, with (2) alkali in the presence of (3) an alkylated urea derivative.
