Method for purifying aminomethylenephosphonic acids for pharmaceutical use
US4937333A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 4, 1989 |
| Grant date | Jun 26, 1990 |
| Priority date | — |
| Expiry date | Aug 4, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07F9/3817
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
High purity ethylenediaminetetra(methylenephosphonic acid) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra(methylenephosphonic acid) are prepared by dissolving the aminomethylenephosphonic acid in an aqueous base, acidifying with a mineral acid at an elevated temperature to precipitate the crystals, maintaining the solution at an elevated temperature for a period of time sufficient to assure crystallization, cooling to a lower temperature and maintaining at that temperature for a time sufficient to precipitate the crystals and filtering the resulting crystals at that temperature, washing the crystals with water and recovering the desired high purity aminophosphonic acid. The ethylenediaminetetra(methylenephosphonic acid) is obtained in a purer state during its synthesis if the crystals are filtered hot without prior cooling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.