Process for preparing solutions of anionic organic compounds

US6860906B2 · kind B2 · utility

Assignee

• Ciba Specialty Chemicals Corporation · US

Inventors

• Jacek Malisz · Weil am Rhein, DE
• Adolf Kaser · Bottmingen, CH
• Rainer Kaufel · Hartheim, DE
• Holger Lautenbach · Weil am Rhein, DE
• Elke Polley · Rheinfelden (Baden), DE
• Martina Hoffmann · Eschborn, DE

Key dates

• Filing date: May 21, 2001
• Grant date: Mar 1, 2005
• Expiry date: Sep 21, 2021

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S8/919
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Described is a process for preparing concentrated solutions or suspensions of anionic organic compounds which comprises a) acidifying an aqueous solution or suspension of an anionic organic compound containing salts and/or impurities to a pH of 4.5 or less, if the pH is above this value, so that b) the anionic organic compound is water-insoluble and precipitates in the form of the free acid, c) bringing the suspension to a salt content below 2% by weight, based on the total weight of the retentate, by means of ultrafiltration with a membrane having pore diameters of from 0.001 to 0.02 μm, and d) optionally washing out the salts with water having a pH below 4,5, e) optionally carrying out acid-free washing with water thereafter, and then f) concentrating, so that the amount of anionic organic compound is 5-50% by weight, and g) if desired, bringing the anionic organic compound into solution by adding an appropriate base.