Ciba-Geigy Corporation

Ciba-Geigy Ag

Ciba-Geiby Corporation

Rudolf Blattner

Holger Hahn

A process for the preparation of triphendioxazines of oxidising cyclisation of 2,5-diarylamino-1,4-benzoquinones with oleum and further optional oxidising agents and/or catalysts, which process comprises charging a reactor simultaneously with the 2,5 diarylamino-1,4-benzoquinone and oleum.

Process for the preparation of triphendioxazines

A novel process for the preparation of anthraquinoid intermediates and vat dyes by alkali fusion of suitable precursors in the presence of alcohol. The process comprises starting from benzanthrone, pyrazolanthrone or anthraquinone derivatives and carrying out the reaction in a machine with kneading action and in the presence of an alkali metal hydroxide and an aliphatic alcohol with a boiling point below 120.degree. C., at elevated temperature, to effect dimerization or cyclization, the weight ratio of alkali metal hydroxide to benzanthrone, pyrazolanthrone or anthraquinone derivative being &lt;1:1. The process makes it possible to prepare in good quality anthraquinoid intermediate which can be further processed to dyes, as well as vat dyes which are suitable for dyeing or printing cellulosic material.

Process for the preparation of anthraquinoid intermediates and vat dyes

In the preparation of anthraquinone imides by condensing a vattable anthraquinone compound which contains at least one primary amino group with an aromatic halogen compound, in an organic solvent and at elevated temperature, it is advantageous first to heat the organic solvent to the reaction temperature and then, at this temperature, to add the educts to the solvent.

Process for the preparation of anthraquinone imides

The invention relates to an improvement of the process for the preparation of 1,4-diaminoanthraquinones by oxidation of the corresponding 2,3-dihydro-1,4-diaminoanthraquinones with nitrobenzene, which improvement is brought about by carrying out the reaction under reduced pressure.

Process for the preparation of 1,4-diaminoanthraquinones

There is disclosed a process for isolating 2-naphthylamine-3,6,8-trisulfonic acid in the form of the alkali or ammonium salt from the sulfonation mixture resulting from the sulfonation of the corresponding naphthylaminemonosulfonic or -disulfonic acid in oleum, which process comprises starting from a sulfonation mixture which contains the naphthylaminetrisulfonic acid in the form of the monopotassium or monoammonium salt, charging said mixture into water or dilute sulfuric acid such that the concentration of the sulfuric acid in the dilute solution or suspension of the sulfonation mixture is 30 to 77% by weight, simultaneously allowing the temperature to rise to 90.degree. to 125.degree. C., subsequently slowly cooling said solution or suspension to a temperature below 40.degree. C., during said cooling adding at least 0.1% by weight, based on naphthylaminetrisulfonic acid, of a dispersant, and isolating the precipitated monopotassium or monoammonium salt of 2-naphthylamine-3,6,8-trisulfonic acid. The naphthylaminetrisulfonic acid isolated in this manner in the form of the monopotassium or monoammonium salt from the sulfonation mixture can be used direct for the manufacture of textile dyes.

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Rheinfelden, Germany

Rudolf Blattner