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. 27, 1992
Filed:
Oct. 24, 1991
Applicant:
Inventor:
Jon C Thunberg, Milford, NH (US);
Assignee:
W. R. Grace & Co.-Conn., New York, NY (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
C07C / ;
U.S. Cl.
CPC ...
562554 ;
Abstract
N-methyliminodiacetic acid is separated from mixtures of N-methyliminodiacetic acid and sodium sulfate formed by acidification of solutions of its disodium salt with sulfuric acid. Thus the disodium salt is acidified with sulfuric acid to a ph of about 2 and concentrated by evaporating water so as to crystallize sodium sulfate. The sodium sulfate is separated, and the resulting mother liquor is cooled to precipitate N-methyliminodiacetic acid, which is then separated.