Preparation of 4,5-diamino-1-(2′-hydroxyethyl)-pyrazole and acid addition salts thereof
US6452019B1 · kind B1 · utility
11Cited by
5References
6Claims
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Key dates
| Filing date | Feb 22, 2002 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Feb 22, 2022 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D231/38
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Disclosed is an improved process for the preparation of 4,5-diamino-1-(2′-hydroxyethyl)pyrazole and acid addition salts thereof such as the addition salt from sulfuric acid. The process comprises a novel combination of steps beginning with an alkyl(alkoxymethylene)cyanoacetate and 2-hydroxyethylhydrazine and the formation of intermediate compounds 5-amino-4-alkoxycarbonyl-1-(2′-hydroxyethyl)pyrazole (I), 5-amino-4-carboxyl-1-(2′-hydroxyethyl)pyrazole (II), 5-amino-1-(2′-hydroxyethyl)pyrazole (III), 5-amino-1-(2′-hydroxyethyl)4-nitrosopyrazole (IV).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.