Bischoloroformate preparation method with phosgene removal and monochloroformate conversion
AssigneeGeneral Electric Company
InventorsDaniel J. Brunelle, Thomas G. Shannon
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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.
Claims12
In a method for preparing aromatic bischloroformate compositions which comprises reacting a dihydroxyaromatic compound with phosgene in the presence of an aqueous alkali or alkaline earth metal base and at least one substantially inert and substantially water-insoluble organic liquid at a pH below about 8, the improvement which comprises raising the pH of the aqueous phase to a higher value in the range of about 7-12 after all solid dihydroxyaromatic compound has been consumed, and maintaining it in said range until a major proportion of the unreacted phosgene has been hydrolyzed.
In a method for preparing aromatic bischloroformate compositions which comprises reacting a dihydroxyaromatic compound with phosgene in the presence of an aqueous alkali or alkaline earth metal base and at least one substantially inert and substantially water-insoluble organic liquid at a pH bbelow about 8, the improvement which comprises raising the pH of the aqueous phase to a higher value in the range of about 9-11 after all solid dihydroxyaromatic compound has been consumed, and maintaining it in said range until a major proportion of the unreacted phosgene has been hydrolyzed.
Dependencies are inferred from the claim text.