Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-06-14
2002-10-01
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06458914
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns a method for manufacturing dialkyl carbonate. More specifically, it concerns a method for efficiently manufacturing dialkyl carbonate from CO, O
2
, and alcohol.
BACKGROUND OF THE INVENTION
In recent years, aromatic polycarbonates have come to be widely used in numerous fields as engineering plastics showing outstanding mechanical properties such as impact resistance, as well as outstanding heat resistance, transparency, etc.
The so-called phosgene method, in which aromatic dihydroxide compounds such as bisphenol are reacted with phosgene by the interfacial polycondensation method, has been widely used as a method for manufacturing these aromatic polycarbonates. However, the phosgene method currently in industrial use has been reported to show many drawbacks, such as the fact that highly toxic phosgene must be used, the fact that there are problems with processing the large amounts of sodium hydroxide produced as a byproduct, and health and pollution problems resulting from the methylene chloride ordinarily used as a reaction solvent.
The process of transesterification (melting method) of aromatic dihydroxy compounds and carbonic acid diesters using alkali metal compounds such as sodium hydroxide as catalysts is known as a method for manufacturing aromatic polycarbonates other than the phosgene method. This method has attracted widespread attention due to its advantage of allowing manufacturing using inexpensive aromatic polycarbonates and the fact that it is desirable from an environmental hygiene standpoint as it does not require the use of toxic compounds such as phosgene and methylene chloride.
In manufacturing polycarbonate using such melt methods, diaryl carbonates such as diphenyl carbonate are used as carbonic acid diesters. This diaryl carbonate, as disclosed in Japanese Unexamined Patent Application Publication No. H9-194430, is manufactured by transesterification of dialkyl carbonate and a hydroxyl-group-containing aromatic hydrocarbon such as phenol. The dialkyl carbonate used as a raw material for this diaryl carbonate is manufactured from carbon monoxide, oxygen, and alcohol using a catalyst composed of a cuprous halide such as cuprous chloride.
For example, when methanol is used as an alcohol, dimethyl carbonate is manufactured by the following reaction:
2 CH
3
OH+CO+1/2O
2
→(CH
3
O)
2
CO+H
2
O
Concerning the cuprous chloride used as a catalyst in this case, in a primary reaction, cupric methoxychloride is formed by the reaction:
2CuCl+2CH
3
OH+1/2O
2
→2Cu(OCH
3
)Cl+H
2
O
and it is thought that regeneration occurs in the following secondary reaction:
2Cu(OCH
3
)Cl+CO→(CH
3
O)
2
CO+2CuCl.
Moreover, the method of adding a hydroacid halide to the reaction system in order to increase the catalytic activity of the cuprous halide used as the catalyst has been presented (cf. Japanese Unexamined Patent Application No. H5-194327).
However, in the above method in which a cuprous halide is used as a catalyst, as the conversion rate of the aforementioned cupric alkoxy chloride formed is low, the yield of the dialkyl carbonate obtained may not be sufficient, and the catalyst used may cause clogging of the reaction vessel and tubing, impairing manufacturing efficiency.
SUMMARY OF THE INVENTION
Against this backdrop, the inventors of the present invention conducted thorough studies on methods for efficiently manufacturing dialkyl carbonate, and they discovered that by using a combination of specified copper compounds and other metal compounds as a catalyst, it is possible to produce dialkyl carbonate in a high yield while maintaining high catalytic activity during the reaction without clogging of the reaction vessel, tubing, etc., by the catalyst, thus perfecting the present invention.
The present invention was developed based on the above prior art in order to provide a method for efficiently manufacturing dialkyl carbonate from CO, O
2
, and alcohol.
The method for manufacturing dialkyl carbonate of the present invention uses one of catalysts 1-5 below as a catalyst in the manufacture of dialkyl carbonate using carbon monoxide, oxygen, and alcohol as starting materials.
Catalyst 1: A catalyst prepared by mixing (i) a cupric halide and (ii-1) an alkoxide compound of a metal from groups III through VIII of the periodic table.
Catalyst 2: A catalyst prepared by mixing (i) a cupric halide, (ii-2) a metal halide compound from groups III through VIII of the periodic table, (ii-3) at least one compound selected from the group composed of an alkali metal alkoxide, an alkaline earth metal alkoxide, a quaternary ammonium alkoxide having Formula (1) below, and a quaternary phosphonium alkoxide having Formula (2) below, with it being possible to use a substance containing the following:
R
1
R
2
R
3
R
4
NOR
5
(1)
R
1
R
2
R
3
R
4
POR
5
(2)
(where R
1
-R
4
may be the same or different and denote hydrogen atoms or hydrocarbon groups having 1-20 carbon atoms, and R
5
denotes a hydrocarbon group having 1-20 carbon atoms.)
Catalyst 3: A catalyst prepared by mixing (I) a copper halide and (II) an alkaline earth metal halide.
Catalyst 4: A catalyst prepared by mixing (a) a copper compound not containing halogen atoms and (b) a halide acid.
Catalyst 5: A catalyst prepared by mixing (A) a copper compound not containing halogen atoms and (B) an alkoxide compound capable of being reacted with the aforementioned (A) copper compound to produce a copper alkoxide.
The alcohol used in the manufacturing method for dialkyl carbonate of the present invention should preferably be methanol.
DETAILED DESCRIPTION OF THE INVENTION
The following is a detailed description of the method for manufacturing dialkyl carbonate of the present invention.
We will first explain the starting materials and catalysts used in the method for manufacturing dialkyl carbonate of the present invention.
STARTING MATERIALS AND CATALYSTS
In the present invention, carbon monoxide (CO), oxygen (O
2
), and alcohol are used as starting materials.
There are no particular restrictions on the alcohol used as a starting material, with examples including methanol, ethanol, propanol, butanol, isopropanol, isobutanol, and hexanol. Among these, methanol should preferably be used.
Catalysts 1-5 below may be used as the catalyst of the present invention.
Catalyst 1: A catalyst composed of (i) a cupric halide and (ii) an alkoxide compound of a metal from groups III through VIII of the periodic table.
Catalyst 2: A catalyst composed of (i) a cupric halide, (ii-2) a metal halide compound from groups III through VIII of the periodic table, (ii-3) at least one compound selected from the group composed of an alkali metal alkoxide, an alkaline earth metal alkoxide, a quaternary ammonium alkoxide having Formula (1) below, and a quaternary phosphonium alkoxide having Formula (2) below, with it being possible to use a substance containing the following:
R
1
R
2
R
3
R
4
NOR
5
(1)
R
1
R
2
R
3
R
4
POR
5
(2)
(where R
1
-R
4
may be the same or different and denote hydrogen atoms or hydrocarbon groups having 1-20 carbon atoms, and R
5
denotes a hydrocarbon group having 1-20 carbon atoms.)
Catalyst 3: A catalyst composed of (I) a copper halide and (II) an alkaline earth metal halide.
Catalyst 4: A catalyst composed of (a) a copper compound not containing halogen atoms and (b) a halide acid.
Catalyst 5: A catalyst composed of (A) a copper compound not containing halogen atoms and (B) an alkoxide compound capable of being reacted with the aforementioned (A) copper compound to produce a copper alkoxide.
The various catalysts are explained below.
Catalysts 1 and 2
Examples of (i) the cupric halide used in catalyst 1 include cupric chloride, cupric fluoride, cupric bromide, and cupric iodide. These may also be used in mixtures of two or more. Among these substances, cupric chloride is preferred.
An example of (ii-1) the alkoxide compound of a metal from groups III through VIII of the periodic table is the alkoxi
Kimura Takato
Shimoda Tomoaki
Tanaka Masahide
Boykin Terressa M.
General Electric Company
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