Organic compounds -- part of the class 532-570 series – Organic compounds – Carbonate esters
Reexamination Certificate
2002-09-03
2003-07-22
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbonate esters
C502S311000
Reexamination Certificate
active
06596896
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aromatic carbonate production process. More specifically, it relates to a process for producing an aromatic carbonate by reacting an aromatic monohydroxy compound with carbon monoxide and molecular oxygen in the presence of a specific catalyst.
PRIOR ART
Aromatic carbonates typified by diphenyl carbonate are very useful compounds as a raw material for polycarbonates. Heretofore, the aromatic carbonates have been produced by reacting an aromatic monohydroxy compound with phosgene. However, this process involves many problems to be solved as an industrial production process because phosgene has high toxicity and a large amount of an inorganic salt is by-produced. Then, some processes for producing an aromatic carbonate without using phosgene are proposed. That is, the following processes are proposed to produce an aromatic carbonate by reacting an aromatic monohydroxy compound with carbon monoxide and molecular oxygen. For example, JP-B 56-38144 (the term “JP-B” as used,herein means an “examined Japanese patent publication”) discloses a process in which a phenol is reacted with carbon monoxide in the presence of a compound containing the group IIIA, IVA, VA, VIA, IB, IIB, IVB, VB, VIB, VIIB or VIIIB metal of the periodic table, a base and a palladium catalyst, JP-A 2-104564 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses a process which uses a palladium compound, manganese compound, tetraalkylammonium salt and quinone, JP-A 8-92168 teaches a process which uses a palladium compound, alkali metal halide and activated carbon, JP-A 8-99935 teaches a process which uses a palladium compound, lead compound, quaternary ammonium halide and copper compound, and JP-A 8-281114 proposes a process in which a reaction is carried out in the presence of a supporting catalyst containing a platinum group metal compound and a metal compound which serves as a co-catalyst carried on a known carrier, a quaternary ammonium or phosphonium salt and a base.
Further, Catalysis Letters 54 (1998) reports at pp. 29-31 that Ce(OAc)
3
.H
2
O provides a high aromatic carbonate production yield of 76% out of inorganic redox co-catalysts in a process for carrying out a reaction in the presence of a catalytic system consisting of a palladium catalyst, organic redox co-catalyst, base and desiccant.
As described above, the catalytic system of the prior art for producing an aromatic carbonate by reacting an aromatic hydroxyl compound with carbon monoxide and molecular oxygen consists of a platinum group compound such as an expensive palladium compound, an inorganic redox agent such as a manganese, cobalt or cerium metal compound and a co-catalyst such as a quaternary ammonium salt as essential components, and an expensive base and ligand or additives such as hydroquinone and quinone are used. Since the reaction system is complicated, it is difficult to separate an aromatic carbonate which is the reaction product from catalytic components and to purify it due to insufficient reaction selectivity. In addition, the yield is insufficient, the total pressure is relatively high to improve the rate of reaction, and an explosive mixed gas may be formed through operation. Therefore, much attention must be paid to the composition of the obtained product, thereby posing a safety problem.
Since an expensive precious metal such as palladium, a redox agent and a relatively large amount of a quaternary ammonium salt are used in the above process, not only the activity and selectivity of the catalytic system but also the recyclability of the catalytic system are extremely important factors to carry out the process industrially and economically. For this purpose, an attempt has been made to make heterogeneous a part or most part of a palladium catalyst by carrying palladium on a heterogeneous carrier such as activated carbon so as to improve recyclability (JP-A8-92168). According to researches conducted by the present inventors, the catalyst strongly adsorbs part of the reaction product, thereby impairing the persistence of the reaction. Therefore, it has been found that the regeneration of the catalyst is complicated and it is not preferred to use the regenerated catalyst in an industrial process. The above JP-A 8-281114 proposes a process in which a metal oxide containing a metal oxide having functions as a redox agent is used as a carrier or part of a carrier. However, researches conducted by the present inventor have revealed that the catalyst is unsatisfactory in terms of reaction yield and selectivity, the carrying power of a precious metal compound such as a palladium compound may be insufficient and the palladium metal and the redox agent dissolve in a reaction solution. As a result, it has been found that this process is not preferred as an economical process.
Thus, a catalytic system which makes it possible to produce an aromatic carbonate simply and efficiently by reacting an aromatic hydroxy compound with carbon monoxide and molecular oxygen has not been found yet.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a catalytic system which shows high activity and selectivity so that an aromatic carbonate can be produced economically and efficiently by reacting an aromatic monohydroxy compound with carbon monoxide and molecular oxygen and a process for producing an aromatic carbonate in the presence of the above catalytic system. Problems to be solved by the Invention
The present inventor has conducted intensive studies to find a catalytic system having the above function and has discovered that an aromatic carbonate can be obtained efficiently and industrially advantageously when an aromatic monohydroxy compound is reacted with carbon monoxide and molecular oxygen in the present of a specific catalytic system. Thus, the present invention has been accomplished based on this discovery.
According to the present invention, there is provided a process for producing an aromatic carbonate by reacting an aromatic monohydroxy compound with carbon monoxide and molecular oxygen, wherein the reaction is carried out under dehydration condition and in the presence of catalysts consisting of (a) palladium or a palladium compound (component (a)), (b) a redox catalyst (component (b)), (c) a heteropoly-acid or salt thereof (component (c)) and (d) a quaternary ammonium salt or quaternary phosphonium salt (component (d)).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Illustrative examples of the aromatic monohydroxy compound which can be used in the reaction of the present invention include phenol, cresol, xylenol, substituted phenols such as trimethylphenol, tetramethylphenol, ethylphenol, propylphenol, methoxyphenol, ethoxyphenol, chlorophenol and bromophenol, isomers thereof, naphthol and substituted naphthols such as methylnaphthol, chloronaphthol and bromonaphthol, and isomers thereof. Out of these, phenol is particularly preferred.
Carbon monoxide and molecular oxygen which are gas components used in the reaction of the present invention may be used in a diluted state with another gas which does not exert a bad influence upon the reaction, such as nitrogen, argon or carbon dioxide. Air may be used as the molecular oxygen.
The catalytic system used in the reaction of the present invention comprises at least the following components (a), (b), (c) and (d):
(a) palladium or a palladium compound (component (a)),
(b) a redox catalyst (component (b)),
(c) a heteropoly-acid or salt thereof (component (c)), and
(d) a quaternary ammonium salt or quaternary phosphonium salt (component (d)).
In the above catalytic system of the present invention, the component (a) is metallic palladium or a palladium compound. Examples of the component (a) include carried metallic palladium such as palladium black, palladium-on-carbon, palladium-on-alumina and palladium-on-silica; inorganic salts of palladium such as palladium chloride, palladium bromide, palladium iodide, palladium sulfate and palladium nitrate; organic sa
Ban Tetsuo
Fujiwara Yuzo
Jia Chengguo
Muramoto Masaharu
Yamaji Teizo
McKane Joseph K.
Shiao Robert
Sughrue & Mion, PLLC
Teijin Limited
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