The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 17, 2000
Filed:
Apr. 02, 1999
Applicant:
Inventors:
Assignee:
DSM N.V., Heerlen, NL;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C07D / ;
U.S. Cl.
CPC ...
546321 ;
Abstract
Process for recovering a pyridine-2,3-dicarboxylic acid from a process stream in the preparation process of the pyridine-2,3-dicarboxylic acid in which the process stream is subjected to nanofiltration at a pH higher than 4.5 and the pyridine-2,3-dicarboxylic acid-containing concentrate is utilised. Preferably, the pH is chosen to be between 7 and 9 and the concentration factor in nanofiltration greater than 3. In a suitable embodiment the process stream is formed by the mother liquor obtained in the preparation of pyridine-2,3-dicarboxylic acid by oxidising a suitable quinoline or the corresponding 2,3-lutidine and separating the solid material.