Abstract: A process for making bisphenol monochloroformate polycarbonate oligomers is provided by continuously introducing phosgene into a bisphenol mixture under agitated interfacial conditions. The pH of the phosgenation mixture falls below a predetermined value, thereby effecting the introduction of an aqueous alkali hydroxide consistent with the use of particular base introduction control systems. In accordance with the use of such control systems, the pH of the mixture can be stabilized, and the phosgenation and base introduction terminated when the pH of the mixture suddenly dips at least about 1 pH unit, or a sudden increase in the flow rate of aqueous alkali metal hydroxide is noted after a plateau in the rate of base introduction.

Abstract: Oligomeric carbonate bischloroformates are prepared with low phosgene usage by phosgenating a dihydroxyaromatic compound in an interfacial reaction in the presence of small amounts of trialkylamine, preferably, triethylamine. In this invention, the molar ratio of phosgene to dihydroxyaromatic compound, hydrolysis of phosgene, formation of such byproducts as monochloroformates and hydroxyl-terminated polycarbonate oligomers, and batch time are minimized and consumption of the dihydroxylaromatic compound is substantially complete.

Abstract: A method is provided for detecting the endpoint of an interfacial aromatic polycarbonate polymerization reaction. The method involves illuminating a sample of the polymerization reaction mixture with a light source and monitoring the extent of apparent light scattering of the sample throughout the course of the polycondensation reaction until at the endpoint, a predetermined threshold extent of apparent light scattering is achieved.

Abstract: A method for making cyclic polycarbonate oligomers is provided by converting oligomeric monochloroformate carbonates to the cyclic state. Improvements in materials usage, process control, and product characteristics are obtained.

Abstract: Aromatic polycarbonates are prepared by initially phosgenating a mixture of bisphenol and aqueous alkali metal hydroxide under interfacial reaction conditions to form an oligomeric bisphenol monochloroformate followed by the further introduction of phosgene and base and thereafter the elimination of reacted phosgene and the incorporation of endcapping phenol and tertiary organic amine and additional alkali metal hydroxide into the mixture. Reduced phosgene usage, the substantial elimination of emulsion formation, increased pH measurement accuracy and avoidance of production of diarylcarbonates are substantially provided.

Abstract: Aromatic bischloroformate compositions are interfacially converted to polycarbonates in a single step which includes capping with a monohydroxyaromatic compound. The reaction is conducted by adding an interfacial polycarbonate formation catalyst such as triethylamine and incrementally adding a base such as aqueous sodium hydroxide solution, without pH control, until the reaction mixture is non-emulsified. The amount of base to be added without pH control may be determined by titration. Further base is then added as necessary to provide a pH in the range of about 10-13.

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.

Abstract: A method is provided for making reaction products of phosgene and dihydric phenol under interfacial reaction conditions. The dihydric phenol such as BPA is introduced into the reactor in the form of a stable suspension which reduces phosgene hydrolysis, minimizes phosgene escape and effects improved BPA metering into the reactor.

Abstract: Polyphenylene oxides are prepared by the catalytic reaction of oxygen with a monohydroxyaromatic compound such as 2,6-xylenol in a continuous-flow tubular reactor containing multiple agitated zones. In the case of a copper catalyst system, it is often preferred to pre-mix the non-gaseous constituents of the reaction mixture in an inert atmosphere, and also to use a reactor with various agitator and zone dimensions in various regions.