Organic compounds -- part of the class 532-570 series – Organic compounds – Carbonate esters
Patent
1988-07-22
1991-04-30
Garner, Vivian
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbonate esters
528372, 558271, 558281, C07C 6802, C07C 6996
Patent
active
050119664
ABSTRACT:
Aromatic bischloroformates are prepared by the reaction of a dihydroxyaromatic compound such as bisphenol A with phosgene in the presence of water, base and an organic liquid such as methylene chloride. Initially, a mixture of the bisphenol, organic liquid and about 5-15% of the total base is prepared, and phosgene is passed into said mixture. The remainder of the base is added initially at a constant rate, and then only when the measured pH of the aqueous mixture is below a targeted value in the range of about 8-11 and in about 5-10% excess with respect to the phosgene then being introduced. This method minimizes hydrolysis of phosgene and formation of such by-products as monochloroformates and hydroxy-terminated polycarbonate oligomers.
REFERENCES:
patent: 4737573 (1988-04-01), Silva et al.
Fyvie Thomas J.
Silva James M.
Davis Jr. James C.
Garner Vivian
General Electric Company
Pittman William H.
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