Process for the manufacture of liquid dyestuff preparations with a low salt content

摘要

Production of low-salt, liquid dye preparations comprises: (i) diazotising an aromatic amine; (ii) double coupling the obtained diazo compound with I-acid-urea (i.e. N,N-bisÄ1-hydroxy-3-sulpho- 6-naphthylÜurea) in presence of an inorganic base but in absence of an organic base; and (iii) de-salting and optionally concentrating the product by pressure permeation to give an inorganic salt content of less than 1 wt.% based on the total preparation. Preferably the dyes are of formula (I) (where A = preferably a group of formula (II)).