Process for the preparation of dyestuffs

US5502171A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Roderich Raue · Dover, US
• Alfred Brack · Odenthal, DE
• Karl-Heinrich Lange · Burscheid, DE

Key dates

• Filing date: May 16, 1995
• Grant date: Mar 26, 1996
• Expiry date: May 16, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B41/009
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Dyestuffs of the formula ##STR1## in which D is the radical of an aromatic or heterocyclic diazo component and PA1 Z is the radical of an aromatic or heterocyclic coupling component, are obtained in an ecologically advantageous manner by reacting an aromatic or heterocyclic diazo components of the formula EQU D--NH.sub.2 and a coupling component of the formula EQU H--Z.sub.1 with a nitrite, in the presence of CO.sub.2 at a pressure of 5-100 at. The process is suitable in particular for the preparation of concentrated dyestuff solutions, because expensive operations, such as, for example, pressure permeation and reverse osmosis, can be omitted.