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1. (WO2001032786) PROCESS FOR THE PREPARATION OF SOLUTIONS OF ANIONIC ORGANIC COMPOUNDS

Pub. No.:    WO/2001/032786    International Application No.:    PCT/EP2000/010415
Publication Date: Fri May 11 01:59:59 CEST 2001 International Filing Date: Tue Oct 24 01:59:59 CEST 2000
IPC: C09B 67/26
C09B 67/54
Applicants: CIBA SPECIALTY CHEMICALS HOLDING INC.
MALISZ, Jacek
KÄSER, Adolf
KAUFEL, Rainer
LAUTENBACH, Holger
POLLEY, Elke
HOFFMANN, Martina
Inventors: MALISZ, Jacek
KÄSER, Adolf
KAUFEL, Rainer
LAUTENBACH, Holger
POLLEY, Elke
HOFFMANN, Martina
Title: PROCESS FOR THE PREPARATION OF SOLUTIONS OF ANIONIC ORGANIC COMPOUNDS
Abstract:
A process for the preparation of concentrated solutions or suspensions of anionic organic compounds is described, which process comprises a) acidifying an aqueous solution or dispersion of an anionic organic compound that comprises salts and/or impurities, to a pH of 4.5 or less, if the pH is above that value, so that b) the anionic organic compound becomes insoluble in water and precipitates out in the form of the free acid, c) bringing the suspension, by means of micro- or ultra-filtration, to a salt content of less than 2 % by weight, based on the total weight of the retained material, with d) optional washing out of the salts with water at a pH of less than 4.5, e) then optionally washing with water until acid-free, then f) increasing the concentration so that the content of anionic organic compound is from 5 to 50 % by weight, and g) optionally dissolving the anionic organic compound by addition of a suitable base.