Bayer Aktiengesellschaft

Gerhard Berg

Klaus Wunderlich

Walter Hohmann

Karl-Julius Reubke

A process for the preparation of 1-amino-4-bromoanthraquinone-2-sulfonic acid or an alkali metal salt thereof by converting 1-aminoanthraquinone (which can be obtained by reduction of 1-nitroanthraquinone with sodium sulfide and/or sodium bisulfide or reaction of the 1-nitroanthraquinone with ammonia) by contacting the same with oleum at a temperature in the range of 90.degree. to 150.degree. C. optionally in the presence of an alkali metal sulfate and thereafter treating the so-sulfonated composition with bromine at a temperature in the range of from 60.degree. to 100.degree. C. 1-amino-4-bromoanthraquinone-2-sulfonic acid or an alkali metal salt thereof can be precipitated from the reaction mixture either by adjusting the sulfuric acid concentration thereof to 60 to 85 percent by weight or by stirring the reaction mixture into water, which optionally contains an alkali metal sulfate.

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Leverkusen, Germany

Gerhard Berg