Cassella Aktiengesellschaft

Wolf Weidemuller

Steffen Piesch

Artur Meyer

Friedrich Engelhardt

Ulrich Buhler

Herbert Wille

Friedrich Schophoff

Georg Daniek

Azo disperse dyestuffs are prepared by diazotization and coupling in an aqueous phase, the coupling being carried out in the presence of an ester of a lower aliphatic carboxylic acid.

Preparation of azo dyestuffs by diazotization and coupling in the

Carbazoleazomethines are prepared and sulfur dyestuffs are prepared by sulphurizing a carbazoleazomethine of the formula ##STR1## wherein R.sup.1 is hydrogen, hydroxyl, halogen, nitro, alkyl having 1 to 8 carbon atoms, alkoxy having 1 to 8 carbon atoms, dialkylamino having 1 to 4 carbon atoms per alkyl, alkanoyloxy having 1 to 8 carbon atoms, benzoyloxy, alkanoylamino having 1 to 8 carbon atoms or benzoylamino;

Sulphur dyestuffs of the carbazole series

The process for the preparation of a 3-(4-hydroxyanilino)carbazole of the formula ##STR1## wherein R is hydrogen, alkyl having 1 to 8 carbon atoms or halogenoalkyl having 1 to 8 carbon atoms, comprising reacting a 3-aminocarbazole of the formula ##STR2## with p-hydroquinone or p-aminophenol or a mixture of p-hydroquinone and p-aminophenol in at least stoichiometric amounts by heating to a temperature of 150.degree. to 300.degree. C. with exclusion of oxygen.

Process for the preparation of derivatives of

In the processs for isolating solid sulphur dyestuffs from crude sulphur dyestuff melts, the improvement comprises adding 10.sup.-4 to 1% by weight, relative to the amount of dyestuff, of an organic flocculating auxiliary to the crude dyestuff melt to produce a filterable dyestuff precipitate and then separating said precipitate.

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Frankfurt am Main, Germany

Wolf Weidemuller