Aromatic polycarbonates have been widely used in many fields, as engineering plastics excellent in thermal resistance, impact resistance, transparency, and the like.
As a method for producing aromatic polycarbonate, for examples, the following methods are known.
(i) A method of causing interfacial polycondensation of bisphenol A with phosgene in the presence of an alkaline catalyst (phosgene process).
(ii) A method of causing melt-polycondensation of bisphenol A with diphenyl carbonate (ester exchange process) (Patent Document 1).
In the method (i), the reaction proceeds at a low temperature, so colorless transparent polycarbonate can be obtained. However, this method has problems that toxic phosgene is used; inorganic salts such as sodium chloride produced as a by-product by the reaction should be removed by washing; due to the use of a solvent such as methylene chloride, complicated processes such as polymer purification and recovery of the solvent are required after the reaction; and the like.
On the other hand, the method (ii) has advantages that phosgene is not used; inorganic salts are not by-produced by the reaction; a solvent does not need to be used and hence it is easy to separate polycarbonate from the reaction system; and the like.
As a method for producing diphenyl carbonate, the following methods are known, similarly to the method for producing aromatic polycarbonate.
(iii) A method of reacting phenol with phosgene (phosgene process).
(iv) A method of reacting phenol with a carbonate compound (dialkyl carbonate or cyclic carbonate) (ester exchange process).
As the method for producing diphenyl carbonate, the method (iv) not using phosgene is preferable in view of the reduction in environmental load and of safety.
As a method for producing a carbonate compound, the following methods are known.
(v) A method for producing cyclic carbonate by reacting carbon dioxide gas with alkene oxide in the presence of a catalyst (Patent Document 2).
(vi) A method for producing dialkyl carbonate or cyclic carbonate by reacting phosgene with an alcohol (Patent Document 3).
(vii) A method for producing dialkyl carbonate by causing an ester exchange reaction between cyclic carbonate or dimethyl carbonate and alcohol in the presence of a catalyst for an ester exchange reaction (Non-Patent Document 1).
(viii) A method for producing dialkyl carbonate by reacting methyl chloroformate with an alcohol (Patent Document 3).
However, the method (v) has a problem that this method can only produce a cyclic carbonate and cannot individually produce various types of carbonate compounds.
The method (vi) has problems that the production facilities are corroded by by-produced hydrogen chloride, phosgene has a high level of toxicity, and the like.
The method (vii) has problems that since it is an equilibrium reaction, a large excess amount of alcohol should be used to increase the yield of a target substance, it is difficult to separate and remove a by-produced asymmetrical carbonate compound (intermediate), and the like.
The method (viii) has a problem that the production facilities are corroded by by-produced hydrogen chloride.
As a method for producing a carbonate compound that solves the above problems, the following method has been proposed.
(ix) A method for producing a carbonate compound and chloroform by reacting hexachloroacetone with an alcohol in the presence of a catalyst (Patent Documents 4 to 6).
USPTO Backgrounds
USPTO Backgrounds