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. 23, 2007
Filed:
Mar. 25, 2002
Kambiz Javdani, Bucks, AL (US);
Gilbert Rodriguez, Bucks, AL (US);
James Peter Muxworthy, Huddersfield, GB;
Kambiz Javdani, Bucks, AL (US);
Gilbert Rodriguez, Bucks, AL (US);
James Peter Muxworthy, Huddersfield, GB;
Syngenta Limited, , GB;
Abstract
A method for removing impurities from 2-nitro-4-methylsulfonylbenzoic acid which comprises at least two of the following steps, in any order, (a) dissolving 2-nitro-4-methylsulfonylbenzoic acid in water at a pH of about 2 to 10, followed by filtration; (b) contacting an aqueous solution of 2-nitro-4-methylsulfonylbenizoic acid with activated carbon at a pH of about 2 to 10; (c) treating an aqueous solution of 2-nitro-4-methylsulfonylbenzoic acid with sufficient base to hydrolyze undesired nitro and dinitro substituted impurities; followed by maintaining the resulting aqueous solution comprising 2-nitro-4-methylsulfonylbenzoic acid at a temperature of up to about 95° C., and adjusting the pH of said solution to about a pH which is sufficient to effect crystallization of 2-nitro-4-methylsulfonylbenzoic acid upon cooling.