2,3-Dichloro-4-hydroxy-benzoic acid and process for preparation thereof
US4092352A · kind A · utility
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Key dates
| Filing date | Oct 4, 1976 |
| Grant date | May 30, 1978 |
| Priority date | — |
| Expiry date | Oct 4, 1996 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C65/21
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A Reimer-Tiemann reaction of 2,3-dichlorophenol with carbon tetrachloride gives 2,3-dichloro-4-hydroxy-benzoic acid, a novel intermediate, which is then reacted with thiophene in the presence of phosphorus pentoxide or polyphosphoric acid to give 2,3-dichloro-4-(2-thienoyl)-phenol. This compound is then converted to the diuretic, ticrynafen, by known prior art reactions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.