Bayer Aktiengesellschaft

Helmut Dittmer

Hubert Schonhagen

Heinrich Leister

Jurgen Schneider

Rolf Muders

Claus Krugermann

1-Amino-2-bromo-4-hydroxyanthraquinone is obtained in good yields and in an environmentally acceptable manner by bromination of 1-aminoanthraquinone in 2 to 5 times the quantity by weight of 80 to 98% strength sulphuric acid and using 1.1-1.5 mole of bromine under elevated pressure.

Process for the preparation of 1-amino-2-bromo-4-hydroxyanthraquinone

A process for separating off 1-amino-4-bromoanthraquinone-2-sulphonic acid from the reaction mixture formed by the bromination of 1-aminoanthraquinone-2-sulphonic acid in sulphuric acid, which process comprises adjusting the sulphuric acid concentration of the reaction mixture under the prevailing conditions of temperature and pressure to effect precipitation of 1-amino-4-bromoanthraquinone-2-sulphonic acid as the sulphate and thereafter separating the resultant sulphate precipitate from the reaction mixture.

Process for separating off 1-amino-4-bromoanthraquinone-2-sulphonic acid

A process for preparing 1-amino-4-bromoanthraquinone-2-sulphonic acid or an alkali metal salt thereof which comprises contacting 1-amino-anthraquinone at a temperature in the range of 90.degree. to 150.degree. C. with an SO.sub.3 -containing sulphuric acid (oleum) and thereafter treating the resultant sulphonated 1-amino-anthraquinone with at least 0.5 molar equivalent of bromine, relative to 1 mol of 1-amino-anthraquinone, at temperatures in the range from 60.degree. to 100.degree. C.

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Leverkusen, Germany

Helmut Dittmer