Purification of 2-nitro-4-methylsulphonylbenzoic acid
US7285678B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 25, 2002 |
| Grant date | Oct 23, 2007 |
| Priority date | — |
| Expiry date | Feb 16, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C315/06
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.