US 7,814,626 B2  8  7  (III)  (IV)  wherein  RA  represents linear or branched C$_{1 }$-C$_{34}$-alkyl, C$_{7}$-C$_{34}$- alkylaryl, CcC$_{34}$-aryl or  --COO-RD,  wherein  RD  repre› sents hydrogen, linear or branched C$_{1 }$-C$_{34}$-alkyl, C$_{7}$-C$_{34}$ - alkylaryl or CcC$_{34}$-aryl, and  RB  and Re independently of one another are identical or  different and represent hydrogen, linear or branched C$_{1 }$-C$_{34}$- alkylaryl, C$_{7}$ -C$_{34}$-alkylaryl or CcC$_{34}$-aryl.  Suchmonohydroxyaryl compounds are, for example, 1-, 2- or 3-methylphenol, 2,4-dimethylphenol, 4-ethylphenol, 4-n› propylphenol, 4-isopropylphenol, 4-n-butylphenol, 4-isobu› tylphenol, 4-tert-butylphenol, 4-n-pentylphenol, 4-n-hexy› lphenol,  4-isooctylphenol,  4-n-nonylphenol,  3-pentadecylphenol,  4-cyclohexylphenol,  4-(1-methyl-1- phenylethyl)-phenol,  4-phenylphenol,  4-phenoxyphenol,  4-(1-naphthyl)-phenol, 4-(2-naphthyl)phenol, 4-tritylphenol,  methyl salicylate, ethyl salicylate, n-propyl salicylate, n-butyl  salicylate, isobutyl salicylate, tert-butyl salicylate, phenyl  salicylate and benzyl salicylate.  4-tert-Butylphenol,  4-isooctylphenol  and  3-pentade› cylphenol are preferred.  The monohydroxyaryl compound(s) are to be so chosen  that their boiling point is above that of the monohydroxyaryl  compound employed in the preparation of the diary! carbon› ate that is used. The monohydroxyaryl compound can be  added at any point in time during the reaction.  It  is preferably  added at the beginning of the reaction. The amount of free  monohydroxyaryl compound can be from 0.2 to 20 mo! %,  preferably from 0.4 to 10 mo!%, based on the dihydroxyaryl  compound.  It  is additionally possible to change the end groups of the  resulting polycarbonates also by addition of at least one addi- tional diary! carbonate whose base monohydroxyaryl com› pound has a higher boiling point than that of the base mono› hydroxyaryl compound of the diary! carbonate mainly used.  Here too, the additional diary! carbonate can be added at any  point in time during the reaction.  It  is preferably added at the  beginning of the reaction. The amount of the diary! carbonate  having the higher boiling base monohydroxyaryl compound  in the total amount of diary! carbonate used can be from 1 to  40 mo! %, preferably from 1 to 20 mo! % and particularly  preferably from 1 to 10 mo! %.  The basic catalysts known in the literature, such as, for  example, alkali and alkaline earth hydroxides and oxides  and/or onium salts, such as, for example, ammonium or phos- phonium salts, can be used as catalysts in the melt transes- terification process for the preparation of polycarbonates.  Preference is given to the use of onium salts, particularly  preferably phosphonium salts, in the synthesis. Such phos- phonium salts are, for example, those of the general formula  (IV)  The addition of the catalysts is preferably carried out in  solution in order to avoid harmful overconcentrations during  metering. The solvents are preferably compounds that are  inherent in the system and the process, such as, for example,  the dihydroxyaryl compounds, diary! carbonates or option- ally monohydroxyaryl compounds that are employed. Mono- It  is her possible to add before the polycondensation, in  addition to the catalysts and catalyst amounts already men› tioned hereinbefore, supplementary amounts of onium cata› lysts. In the case where the above-mentioned catalyst is  already an onium catalyst, the onium catalyst added in  supplementary amounts before the polycondensation can be  the same onium catalyst mentioned above or a different  onium catalyst.  The alkaline-reacting salts of alkali metals and alkaline  earth metals can be mixed in during the preparation of the  oligocarbonates, that is to say at the beginning of the synthe› sis, or in a later process step, in order to suppress undesirable  secondary reactions. The total amount of catalyst can also be  added to the process in several steps.  Within the scope of the present invention, ppb and parts per  million ("ppm") are to be understood as meaning parts by  weight, unless indicated otherwise.  If alkali or alkaline earth metal ions are supplied in the form  of their salts, the amount of alkali or alkaline earth ions,  determined, for example, by atom absorption spectroscopy, is  from 1 to 500 part per billion ("ppb"), preferably from 5 to  300 ppb and most preferably from 5 to 200 ppb, based on  polycarbonate to be formed. In preferred forms of the process  according to the invention, however, no alkali salts are used.  These can be, for example, alkaline-reacting salts of alkali  metals and alkaline earth metals, such as hydroxides, option› ally substituted C$_{1 }$-C$_{10}$-alkoxides and C$_{6}$-C$_{14}$-aryl oxides of  lithium, sodium and potassium, preferably hydroxides,  optionally substituted C$_{1 }$-C$_{10}$-alkoxides or C$_{6}$-C$_{14}$-aryl  oxides of sodium. Preference is given to sodium hydroxide,  sodium phenolate or the disodium salt of 2,2-bis-( 4-hydrox› ypheny !)-propane.  Co-catalysts can optionally also be used in order to  increase the rate of the polycondensation.  The catalysts are preferably used in amounts of from 1 o-s  to 10-$^{3 }$mo!, particularly preferably in amounts of from 1 o- 7  to 10- $^{4 }$mo!, based on one mole of dihydroxyaryl compound.  Particularly preferred catalysts are tetraphenylphospho› nium chloride, tetraphenylphosphonium hydroxide and tet› raphenylphosphonium phenolate, tetraphenylphosphonium  phenolate being very particularly preferred.  X- represents an anion selected from the group hydrox- ide, sulfate, hydrogen sulfate, hydrogen carbonate, carbonate,  halide, preferably chloride, and alkylate or arylate of the  formula ---OR 11 , wherein R $^{11 }$represents an optionally sub› stituted CcC$_{14}$-aryl, C$_{7}$-C$_{15}$-arylalkyl or C$_{5}$ -Cccycloalkyl  radical, C$_{1 }$-C$_{20}$-alkyl, preferably phenyl.  R 7 - $^{10 }$represent identical or different optionally substituted  C$_{1 }$-C$_{10}$-alkyl, CcC$_{14}$-aryl, C$_{7}$-C$_{15}$-arylalkyl or C$_{5}$-Cccy› cloalkyl radicals, preferably methyl or C$_{6}$-C$_{14}$-aryl, particu› larly preferably methyl or phenyl, and  wherein 