PURIFICATION OF 2-NITRO-4-METHYLSULPHONYLBENZOIC ACID

Title:

PURIFICATION OF 2-NITRO-4-METHYLSULPHONYLBENZOIC ACID

Document Type and Number:

WIPO Patent Application WO2002076934

Kind Code:

A3

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- methylsulfonylbenzoic 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 DEG 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.

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Inventors:

JAVDANI KAMBIZ (US)
RODRIGUEZ GILBERT (US)
MUXWORTHY JAMES PETER (GB)

Application Number:

PCT/GB2002/001433

Publication Date:

February 20, 2003

Filing Date:

March 25, 2002

Export Citation:

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Assignee:

SYNGENTA LTD (GB)
JAVDANI KAMBIZ (US)
RODRIGUEZ GILBERT (US)
MUXWORTHY JAMES PETER (GB)

International Classes:

C07C315/04; C07C315/06; C07C317/00; C07C317/24; C07C317/44; (IPC1-7): C07C317/44; C07C315/06

Domestic Patent References:

WO1990006301A1

1990-06-14

Foreign References:

US5006158A	1991-04-09
US5424481A	1995-06-13

Other References: