Bischoloroformate preparation method with phosgene removal and monochloroformate conversion
US4904810A · kind A · utility
31Cited by
1References
12Claims
0Family size
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Key dates
| Filing date | Jul 25, 1988 |
| Grant date | Feb 27, 1990 |
| Priority date | — |
| Expiry date | Jul 25, 2008 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C68/02
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Aqueous bischloroformates are prepared by the reaction of a dihydroxyaromatic compound (e.g., bisphenol A) with phosgene in a substantially inert organic liquid (e.g., methylene chloride) and in the presence of an aqueous alkali metal or alkaline earth metal base, at a pH below about 8. After all solid dihydroxyaromatic compound has been consumed, the pH is raised to a higher value in the range of about 7-12, preferably 9-11, and maintained in said range until a major proportion of the unreacted phosgene has been hydrolyzed. At the same time, any monochloroformate in the product may be converted to bischloroformate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.