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:
Aug. 21, 1990
Filed:
Aug. 24, 1988
Applicant:
Inventors:
Edward J Griffith, Manchester, MO (US);
Liou-Liang Horng, Creve Coeur, MO (US);
Mark E Jason, Chesterfield, MO (US);
Assignee:
Monsanto Company, St. Louis, MO (US);
Primary Examiner:
Int. Cl.
CPC ...
C07C / ;
U.S. Cl.
CPC ...
562583 ;
Abstract
There is disclosed an improved process for preparing 1-hydroxy-3-oxa-1,2,4,5-pentane tetracarboxylic acid and 3,6-dioxa-1,2,4,5,7,8-octane hexacarboxylic acid wherein the unreacted starting acids are recovered in more desirable crystal habit. The acids are precipitated in salt form by lowering the pH of the reaction product to a range of from 4 to below 6 stepwise. The pH is lowered to above 6 in the first step and then relatively rapidly reduced to the desired level in the second step.