In-situ treatment of pyridine 2,3-dicarboxylic acid esters with an oxidizing agent
US7795439B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 25, 2004 |
| Grant date | Sep 14, 2010 |
| Priority date | — |
| Expiry date | May 29, 2026 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D213/803
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A method for the in-situ treatment of a pyridine-2,3-dicarboxylic acid ester with an oxidizing agent, such as hydrogen peroxide, to improve product quality is provided. The method for the in-situ removal of impurities from a saponified solution of pyridine-2,3-dicarboxylic acid ester comprises the steps of providing a solution of pyridine-2,3-dicarboxylic acid ester, saponifying the solution with a base to form the corresponding pyridine-2,3-dicarboxylic acid salt, reacting the solution with an oxidizing agent in an amount effective to remove impurities, acidifying the solution with an acid to convert the pyridine-2,3-dicarboxylic acid into the corresponding pyridine-2,3-dicarboxylic acid, and collecting a purified solution comprising pyridine-2,3-dicarboxylic acid. Further provided is a method for the preparation of herbicidal 2-(2-imidazolin-2-yl)nicotinic acids, esters, and salts by using a pyridine-2,3-dicarboxylic acid salt prepared by the above method as an intermediate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.