Process for the preparation of triphenylemethane coloring agents

US5808116A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Arpad Acs · Schwalbach, DE
• Hans-Josef Remsperger · Flörsheim, DE
• Jurgen Berger · Mutlangen, DE

Key dates

• Filing date: Dec 11, 1995
• Grant date: Sep 15, 1998
• Expiry date: Dec 11, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B11/20
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Triaminotriphenylmethane pigments are prepared by PA1 a) first reacting an iron, boron or aluminum trihalide complex compound of a 4,4',4"-trihalotriphenylmethane halide with a salt of an aromatic aminosulfonic acid in a molar ratio of 0.6:1 to 1.4:1 at a temperature between 130.degree. and 180.degree. C., under hydrogen halide partial pressure of at least 1 bar and in the presence of a polar, water-insoluble organic solvent, subsequently PA1 b) reacting the reaction suspension obtained according to a) with at least 5 molar equivalents of an aromatic amine subsequently PA1 c) either bringing the amine melt obtained according to b), in the absence of a water-soluble solvent, to a pH of between 1 and 6 by addition of a mineral acid or first bringing it to a pH of at least 9 with an alkali metal hydroxide solution in the presence of a viscosity-lowering additive, carrying out a phase separation, adding a water-insoluble organic solvent to the organic phase and then bringing this to a pH of between 1 and 6 by addition of a mineral acid. The pigments obtained can be processed into high-quality printing inks.