US Patent 7985824 Method of making polycarbonate

A method of making a polycarbonate is described. The method comprises reacting an activated diaryl carbonate and a dihydroxy compound at a reaction temperature in a reactor to form a reaction mixture wherein the reactor comprises a heated cover and an open space between the cover and the reaction mixture. The dihydroxy compound comprises a vapor pressure greater than or equal to 0.01 kiloPascals at the reaction temperature and the temperature of the open space in the reactor, the temperature of the cover, or the temperature of the open space and the cover is greater than or equal to the melt temperature of the monomer having the highest melt temperature.