May 7  2009  5  US 2009/0117314 Al  4-yl phenyl carbonate  di(biphenyl-4-yl)carbonate  4-(1- naphthyl)phenyl phenyl carbonate  4-(2-naphthyl)phenyl  phenyl carbonate  di[ 4-(1-naphthyl)phenyl]carbonate  di-[ 4- (2-naphthyl)phenyl]carbonate  4-phenoxyphenyl phenyl car› bonate  di( 4-phenoxypheny I )carbonate  3-pentadecy lpheny I  phenyl carbonate  di(3-pentadecylphenyl)carbonate  4-tri› tylphenyl phenyl carbonate  di( 4-tritylphenyl)carbonate   methyl salicyl phenyl carbonate  di(methylsalicyl)carbonate   ethylsalicyl phenyl carbonate   di( ethylsalicyl)carbonate   n-propylsalicyl phenyl carbonate  di(n-propylsalicyl)carbon› ate  isopropylsalicyl phenyl carbonate  di(isopropylsalicyl)  carbonate  n-butylsalicyl phenyl carbonate  di(n-butylsalicyl)  carbonate  isobutylsalicyl phenyl carbonate  di(isobutylsali› cyl)carbonate  tert-butylsalicyl phenyl carbonate  di(tert-bu› tylsalicyl)  carbonate   di(phenylsaticyl)carbonate  and  di(benzy lsalicy I )carbonate.  [0075]  Particularly preferred diary! compounds are diphe› nyl carbonate  4-tert-butylphenyl phenyl carbonate  di( 4-tert› butylphenyl)carbonate   biphenyl-4-yl phenyl  carbonate   di(biphenyl-4-yl)carbonate  4-(1-methyl-1-phenylethyl)phe› nyl phenyl carbonate  di[4-(1-methyl-1-phenylethyl)phenyl]  carbonate and di(methylsalicyl)carbonate.  [0076]  Diphenyl carbonate is very particularly preferred.  [0077]  It  is possible to use both one diary! carbonate and  different diary! carbonates.  [0078]  The diary! carbonates may also be used with  residual contents of the monohydroxyaryl compounds from  which they were prepared. The residual contents of the mono› hydroxyaryl compounds may be up to 20% by weight  pref› erably up to 10% by weight  particularly preferably up to 5%  by weight and very particularly preferably up to 2% by  weight.  [0079]  Based on the dihydroxyaryl compound(s)  in gen› eral 1.02 to 1.30 mo! of the diary! carbonate(s)  preferably  1.04 to 1.25 mo!  particularly preferably 1.045 to 1.22 mo!   very particularly preferably 1.05 to 1.20 mo!  per mole of  dihydroxyaryl compound are used.  It  is also possible to use  mixtures of the abovementioned diary! carbonates  the molar  amounts per mole of dihydroxyaryl compound which are  mentioned above then being based on the total amount of the  mixture of the diary! carbonates.  [0080]  For controlling or changing the terminal groups  one  or more monohydroxyaryl compound(s) which were not used  for the preparation of the diary! carbonate(s) used can addi› tionally be employed. These may be those monohydroxyaryl  compounds of the general formula (III)  [0083]  Such  monohydroxyaryl  compounds  are   for  example  1-  2- or 3-methylphenol  2 4-dimethylphenol  4-ethylphenol  4-n-propylphenol  4-isopropylphenol  4-n› butylphenol  4-isobutylphenol  4-tert-butylphenol  4-n-pen› tylphenol  4-n-hexylphenol  4-isooctylphenol  4-n-nonylphe› nol  3-pentadecylphenol  4-cyclohexylphenol  4-(1-methyl› l-phenylethyl)phenol  4-phenylphenol  4-phenoxyphenol   4-(1-naphthyl)phenol  4-(2-naphthyl)phenol  4-tritylphenol   methyl salicylate  ethyl saticylate  n-propyl saticylate  isopro› pyl salicylate  n-butyl salicylate  isobutyl salicylate  tert-butyl  salicylate  phenyl salicylate and benzyl salicylate.  [0084]  4-tert-Butylphenol  4-isooctylphenol and 3-penta› decylphenol are preferred.  [0085]  The monohydroxyaryl compound(s) should be cho› sen so that the melting point thereof is above that of the  monohydroxyaryl compound which was used for the prepa› ration of the diary! carbonate used. The monohydroxyaryl  compound may be added at any time in the course of the  reaction.  It  is preferably added at the beginning of the reac› tion. The proportion of free monohydroxyaryl compound  may be 0.2 to 20 mo!%  preferably 0.4 to 10 mo!%  based on  the dihydroxyaryl compound.  [0086]  It  is also possible to change the terminal groups of  the resulting polycarbonates by addition of at least one addi› tional diary! carbonate  the base monohydroxyaryl com› pound of which has a higher boiling point than the base  monohydroxyaryl compound of the diary! carbonate mainly  used. Here too  the additional diary! carbonate may be added  at any time in the course of the reaction.  It  is preferably added  at the beginning of the reaction. The proportion of the diary!  carbonate having the higher-boiling base monohydroxyaryl  compound  based on the total amount of diary! carbonate  used  may be 1 to 40 mo! %  preferably 1 to 20 mo! % and  particularly preferably 1 to 10 mo! %.  [0087]  Catalysts which may be used in the melt transesteri› fication method for the preparation of polycarbonates are the  basic catalysts known in the literature  such as  for example   alkali metal and alkaline earth metal hydroxides and oxides  and/or onium salts  such as  for example  ammonium or phos› phonium salts. Preferably onium salts  particularly preferably  phosphonium salts  are used in the synthesis. Such phospho› nium salts are  for example those of the general formula (IV)  (IV)  (III)  in which  in which  [0088]  R  7 - $^{10 }$represent identical or different optionally sub› stituted C$_{1 }$-C$_{10}$-alkyl-  CcC$_{14}$-aryl-  C$_{7}$ -C$_{15}$-arylalkyl or  C$_{5}$ -C$_{6}$-cycloalkyl radicals  preferably methyl or C$_{6}$-C$_{14}$- aryl  particularly preferably methyl or phenyl  and  [0089]  x- represents an anion selected from the group con› sisting of hydroxide  sulphate  hydrogen sulphate  bicar› bonate  carbonate  halide  preferably chloride  and alkylate  or arylate of the formula-OR 11  in which R$^{11 }$represents  an optionally substitutedCcC$_{14}$-aryl-  C$_{7}$-C$_{15}$-arylalkyl or  C$_{5}$ -Cccycloalkylrest  C$_{1 }$-C$_{20}$-alkyl  preferably phenyl.  [0081]  RA  represents linear or branched C$_{1 }$-C$_{34}$-alkyl   C$_{7}$-C$_{34}$-alkylaryl  CcC$_{34}$-aryl or  --COO-RD  RD  repre› senting hydrogen   linear or branched C$_{1 }$-C$_{34}$-alkyl   C$_{7}$ -C$_{34}$-alkylaryl or CcC$_{34}$-aryl  and  [0082]  RB   R  c  independently of one another  are identical  or different and represent hydrogen  linear or branched  C$_{1 }$-C$_{34}$-alkyl  C$_{7}$-C$_{34}$-alkylaryl or CcC$_{34}$-aryl. 