Process for the manufacture of anthraquinone compounds

A process for the manufacture of quaternized anthraquinone or anthraquinone of the formula I ##STR33## wherein each of R.sub.1 and R.sub.2 independently represents hydrogen, alkyl or cycloalkyl, R.sub.3 represents hydrogen or alkyl, R.sub.4 represents alkylene or cycloalkylene, R.sub.5 and R.sub.6 represents alkyl, aryl or aralkyl, R.sub.7 represents alkyl, aralkyl, aryl or cycloalkyl, and An represents an anion which comprises the steps of, (1) reacting in an aprotic solvent at temperatures of 80.degree. to 150.degree. C., an .alpha.-nitro-anthraquinone (A) of the formula II ##STR34## with an amine of the formula ##STR35## to give 1-amino-anthraquinone (B), wherein R.sub.1 and R.sub.2 have the meaning given above, (2) halogenating said compound (B) by diluting the reaction mixture with a protic solvent and introducing a bromine/methanol mixture at -20.degree. to +70.degree. C. to give 1-amino-4-bromo-anthraquinone (C), (3) condensing said compound (C) after neutralization with a diamine of the formula ##STR36## or with an amine of the formula HN-R.sub.3 R.sub.7 at 60.degree. to 100.degree. C. in presence of a heavy metal salt to give 1,4-diamino-anthraquinone (D), wherein R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 have the meaning given above, and (4) optionally subsequently quaternizing said compound (D) to give the corresponding quaternized anthraquinone, and carrying out the reaction steps (1) to (4) or (1) to (3) in one single operation without isolation of the intermediates (B), (C) and (D) or (B) and (C).