Patent GB-857430-A (GB)
Title: Process for the production of polycarbonates
Filed: 1958-07-04
Abstract: In the manufacture of polycarbonates of nuclearly chlorinated or brominated di-(monohydroxyaryl)- alkanes or cycloalkanes, improved physical properties of the polycarbonates are obtained by treating the halogenated dihydric phenols prior to the polycarbonate forming reaction, with a basic agent in order to split off aliphatically-bound halogen.  The polycarbonate may be made (a) by reacting the halogenated dihydric phenols with an ester forming derivature of carbonic acid e.g. a diester of carbonic acid, phosgene a bis-chlorocarbonate of the halogenoted dihydric phenol or another dihydric phenol, or a dialkyl, dicycloalkyl or diaryl dicarbonate of the halogenated dihydric phenol or another dihydroxy compound; (b) by reacting a bischlorocarbonate of the halogenated dihydric phenol with a dihydroxy compound; or (c) by heating a dialkyl, dicycloalkyl or diaryl dicarbonate of the halogenated dihydric phenol alone. Other dihydroxy compounds may be combined with the halogenated dihydric phenol e.g. di(monohydroxyaryl)- alkanes or cycloalkanes; monoculear dihydric-phenols of the benzene, napthalene, diphenyol or anthracene series; alkylene, oxyalkylene, thioalkylene, cycloaliphatic or aromatic glycols; or hydroxylbenzyl alcohols.  The molecular weight of the polycarbonate may be controlled by including a monofunctional compound in the reaction mixture (e.g a monohydric phenol or an aromatic amine).  The polycarbonates are useful for the production of fibres, films, mouldings, lacquers and coatings.  Examples describe the making of polycarbonates by reacting (1) 2, 2-(4, 41-dihydroxy-3,31, 5, 51-tetrachlorodiphenyl)- propane and phosgene; (2) 2, 2- (4, 41-dihydroxy -3, 31-dichlorodiphenyl)- propane and phosgene; (3) 1, 1- (4, 41-dihydroxy -3, 31, 5 51- tetrachlorodiphenyl)-cyclohexane and phosgene; (4) 2, 2-(4, 41-dihydroxy-3, 31, 5, 51-tetrachlorodiphenyl)-propane, 4, 41-dihydroxy-3, 31, 5, 51-tetrachlorodiphenyl -methane and phosgene; (5) 4, 41-dihydroxy-3, 31, 5, 51- tetrachlorodiphenyl methane, 2,2-(4, 41-dihydroxydiphenyl)-propane and phosgene; (6) 2, 2-(4, 41-dihydroxy-3, 31, 5, 51-tetra bromodiphenyl)-propane and phosgene; (7) 2, 2-(4, 41-dihydroxy-3, 31, 5, 51-tetrabromodiphenyl)-propane, 2, 2-(4, 41-dihydroxy-diphenyl)- propane and phosgene; (8) 2, 2-(4, 41-dihydroxy- 3, 31, 5, 51-tetrachlorodiphenyl)-propane and di -(2, 6-dichlorophenyl)-carbonate; (9) 2, 21-(4, 41-dihydroxy3-31, 5, 51-tetrachlorophenyl)- propane bis-chlorocarbonate and 2, 2-(4, 41- dihydroxydiphenyl)- propane.  Some of the polycarbonates are soluble in benzene, toluene, dioxane, pyridine, tetrahydrofurane, methylene chloride, chloroform, dimethyl formamide and cresol.  Specifications 772,627, 808,485, 808,486, 808,487 and 808,489 are referred to.ALSO:Nuclearly chlorinated or bromated di- (monohydroxyaryl)-alkanes or cycloalkanes are rendered free from any aliphatically-bound halogen by treating them with a basic agent, e.g. ammonia; alkali metal or alkaline earth metal hydroxides, carbonate formates or acetates; or organic bases such as diethylamine, triethylamine, pyridine, dimethylaniline or triethyl benzyl ammonium hydroxides.  Thus the halogenated phenol may be (a) heated with aqueous sodium hydroxide solution containing a small amount of triethylamine and then precipitated with dilute hydrochloric acid, washed, dried and recrystallised from toluene; (h) heated with aqueous sodium carbonate solution, p  filtered, washed, dried and distilled; (c) distilled after the addition of calcium acetate; or (d) boiled three times with aqueous sodium carbonate solution. Specified halogenated phenol are 4, 41-dihydroxy-3, 31-dichlorodiphenyl methane, 4, 41-dihydroxy-3, 31, 5, 51-tetrabromodiphenyl methane, 2, 2-(4, 41-dihydroxy-3, 31-dichoro diphenyl)-propane, 2, 2-(4, 41-dihydroxy-3, 31, 5, 51-tetrachlorodiphenyl)-propane, 2, 2 (4, 41-dihydroxy-3, 31, 5, 51-tetrabromodiphenyl)-propane and 1, 1-(4, 41-dihydroxy-3, 31, 5, 51-tetrachlorodiphenyl) cyclohexane.  The halogenated phenols are converted into thermo plastic polycarbonates (see Group IV(a)). Specifications 772,627, 808,485, 808,486, 808,487 and 808,489 are referred to.