Process for the preparation of diaryl carbonate
View Patent ↗The invention relates to a process for the preparation of a diaryl carbonate by transesterification of an aromatic alcohol with a dialkyl carbonate in the presence of a transesterification catalyst during a period of time [t a ], in which the aryl moiety is selected from unsubstituted phenyl and mono-, di- and trisubstituted phenyl groups, in which the alkyl moiety is selected from C 2 to C 4 linear and branched alkyl groups, in which the catalyst concentration is designated [c a ], expressed as gram catalyst per gram of aromatic alcohol and dialkyl carbonate, in which the period of time [t m ] and catalyst concentration [c m ] are determined to arrive at a pre-set approach to the equilibrium for the transesterification of the aromatic alcohol with dimethyl carbonate to methyl aryl carbonate and methanol, in which the product [c a ]*t a is at least 1.5*[c m ]*t m under otherwise the same reaction conditions.
1. A process for the preparation of a diaryl carbonate by transesterification of an aromatic alcohol with a dialkyl carbonate in the presence of a transesterification catalyst during a period of time [t a ],
in which the aryl moiety is selected from unsubstituted phenyl and mono-, di- and trisubstituted phenyl groups, in which the alkyl moiety is selected from C 2 to C 4 linear and branched alkyl groups,
in which the catalyst concentration is designated [c a ], expressed as gram catalyst per gram of aromatic alcohol and dialkyl carbonate,
in which the period of time [t m ] and catalyst concentration [c m ] are determined to arrive at a pre-set approach to the equilibrium for the transesterification of the aromatic alcohol with dimethyl carbonate to methyl aryl carbonate and methanol,
in which the product [c a ]*t a is at least 1.5*[c m ]*t m , under otherwise the same reaction conditions.
2. A process as claimed in claim 1 , in which the pre-set approach to the equilibrium for the transesterification of the aromatic alcohol with dimethyl carbonate to methyl aryl carbonate and methanol ranges from 70 to 100%.
3. A process as claimed in claim 1 , in which [c a ]*t a is the product of [c m ]*t m with such a factor that the reaction is run at least 50 percent of equilibrium.
4. A process as claimed in claim 1 , in which the catalyst concentration c a ranges from 0.001 to 2% wt, based on the total weight of the reactants.
5. A process as claimed in claim 1 , in which the period of time t a ranges from 2 minutes (120 s) to 50 hours (180*10 3 s).
6. A process as claimed in claim 1 , in which the product [c a ]*t a ranges from 0.1 to 100, preferably from 0.5 to 50, c a being expressed in g/g and t a in seconds.
7. A process as claimed in claim 1 , which is carried out as a continuous process.
8. A process as claimed in claim 1 , which is conducted in a reactive distillation mode.
9. A process as claimed in claim 1 , in which the aromatic alcohol is phenol.
10. A process as claimed in claim 1 , in which the C 2 to C 4 alkyl moiety is selected from the group consisting of ethyl and isopropyl.
11. A process as claimed in claim 1 , in which the reaction conditions include a pressure ranging from 0.01 to 100 bar and a reaction temperature ranging from 50 to 350° C.
12. A process as claimed in claim 1 , in which the product [c a ]*t a is 1.5 to 500 times [c m ]*t m , under otherwise the same reaction conditions.
13. A process as claimed in claim 12 , in which the product [c a ]*t a is at least 3*[c m ]*t m when the dialkyl carbonate is diethyl carbonate.
14. A process as claimed in claim 12 , in which the product [c a ]*t a is preferably at least 20*[c m ]*t m when the dialkyl carbonate is diisopropyl carbonate.