Process for the preparation of sulpho-free triphenyl-methane dyestuffs
US5013857A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 11, 1989 |
| Grant date | May 7, 1991 |
| Priority date | — |
| Expiry date | Dec 11, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B11/18
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Process for the preparation of sulpho-free triphenylmethane dyestuffs of the formula ##STR1## in which R.sup.1 -R.sup.3 denote hydrogen, C.sub.1 -C.sub.6 -alkyl, preferably methyl, or halogen, preferably chlorine, PA1 Y denotes hydrogen or NX.sup.5 X.sup.6, PA1 X.sup.1 -X.sup.6 denote hydrogen, C.sub.1 -C.sub.6 -alkyl, preferably methyl, ethyl, benzyl or phenyl and PA1 Z.sup.- denotes an anion by oxidation of their leuco products with manganese dioxide, characterized in that, after the oxidation is completed, manganese hydroxide or manganese carbonate and the carbinol base of the dyestuff are formed by the addition of hydroxide or carbonate, during or after which the carbinol base is taken up in a water-immiscible solvent, separated off from the manganese hydroxide or manganese carbonate and from the water phase, the solution is mixed with the acid HZ which may have been mixed with water, the solvent is either distilled off before the mixing or separated or distilled off after the mixing, and the dyestuff is isolated as a solution or in solid form after evaporation or crystallization.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.