JP2003238487A - Method for producing carbonic ester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for continuously producing a carbonic ester. <P>SOLUTION: The method for producing the carbonic ester comprises carrying out a transesterification between a carbonic ester such as dimethyl carbonate or diethyl carbonate and a hydroxy compound such as 2-methoxyethanol or 2-methoxypropanol in the presence of, as a catalyst, a catalytic compound lower in boiling point than the raw material carbonic ester, the raw material hydroxy compound and the final carbonic ester, such as trimethylamine or dimethylethylamine. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a carbonic acid ester. The product carbonic acid ester is a compound useful as a solvent and an additive, particularly as a solvent component and an additive of a non-aqueous electrolyte for a lithium secondary battery.

[0002]

2. Description of the Related Art As a method for producing carbonic acid ester, a method of reacting phosgene or chlorocarbonic acid ester with a hydroxy compound, a method of transesterification of carbonic acid ester, and the like are known. Furthermore, JP-A-63-233
No. 954, JP-A-6-166660 and JP-A-7-10811 disclose a method of shifting the equilibrium by removing a hydroxy compound, which is a by-product of the transesterification reaction, out of the system, and a method of transesterification reaction solution. A method is described in which, after obtaining a target carbonic acid ester by distillation, the remaining components are used in a transesterification reaction.

[0003]

Distillation is generally used to separate the carbonic acid ester produced by such a method. However, when the catalyst remains, the ester exchange reaction of the esterification reaction may occur during the distillation. Since the equilibrium has moved and the target substance cannot be obtained satisfactorily, it was necessary to remove the catalyst in advance. When a homogeneous catalyst is used as a catalyst, complicated steps such as neutralization and washing with water are required to remove the catalyst. Therefore, recently, it has been attempted to remove the catalyst by a method such as filtration using a heterogeneous catalyst. However, heterogeneous catalysts generally have the disadvantage of being less active than homogeneous catalysts.

An object of the present invention is to provide a method capable of efficiently carrying out a transesterification reaction to produce a carbonate ester more economically than conventional methods.

[0005]

The inventors of the present invention have made extensive studies in view of such circumstances, and as a result, as the catalyst, use a compound having a boiling point lower than any of the starting carbonic acid ester, the starting hydroxy compound, and the produced carbonic acid ester. Then, it was found that the catalyst can be removed together with the distillation for separating the product without separately providing the catalyst removing step, and the carbonic acid ester can be economically produced. .

That is, the gist of the present invention is to produce a carbonic acid ester by transesterifying a carbonic acid ester and a hydroxy compound to produce a carbonic acid ester.
A method for producing a carbonic acid ester, which comprises using a catalyst compound having a lower boiling point than both the raw material hydroxy compound and the carbonic acid ester produced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. In the present invention, a carbonic acid ester and a hydroxy compound are transesterified in the presence of a specific catalyst to produce a carbonic acid ester. The carbonic acid ester of the raw material is not particularly limited, and either a symmetrical carbonic acid ester or an asymmetrical carbonic acid ester can be used, but since the symmetrical carbonic acid ester is generally easier to obtain, the symmetrical carbonic acid ester is usually used as the raw material carbonic acid ester. use. Specific examples of the symmetrical carbonic acid ester include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-n-butyl carbonate,
Examples thereof include dialkyl carbonates such as di-n-pentyl carbonate and di-n-hexyl carbonate, and diaryl carbonates such as diphenyl carbonate. Of these, dimethyl carbonate and diethyl carbonate are preferable, and dimethyl carbonate is particularly preferable.

The hydroxy compound as a raw material is not particularly limited, and an alcohol having no substituent (unsubstituted alkanol), an alcohol having a substituent (substituted alkanol)
Any of these can be used. Specific examples of the unsubstituted alkanol include methanol, ethanol, n-
Propyl alcohol, n-butyl alcohol, n-pentyl alcohol, n-hexyl alcohol, n-octyl alcohol and the like can be mentioned.

The above-mentioned substituted alkanol is not particularly limited, but when a hydroxy compound having an ether group in the molecule is used, various solvents and additives as a carbonic acid ester produced, particularly a solvent component of a non-aqueous electrolyte solution for a lithium secondary battery and It is preferable because a compound useful as an additive can be obtained.
Specific examples of the hydroxy compound having an ether group in such a molecule include 2-methoxyethanol, 2-methoxypropanol, 3-methoxypropanol and 1-.
Methyl-2-methoxyethanol, 2-methoxybutanol, 3-methoxybutanol, 4-methoxybutanol, 1- (methoxymethyl) propanol, 1-methyl-2-methoxypropanol, 2-ethoxyethanol, 2-ethoxypropanol, 3 -Ethoxypropanol, 1-methyl-2-ethoxyethanol, 2-ethoxybutanol, 3-ethoxybutanol, 4-ethoxybutanol, 1- (ethoxymethyl) propanol,
1-methyl-2-ethoxypropanol, 2-butoxyethanol, 2-butoxypropanol, 3-butoxypropanol, 1-methyl-2-butoxyethanol,
2-butoxybutanol, 3-butoxybutanol, 4
-Butoxybutanol, 1- (butoxymethyl) propanol, 1-methyl-2-butoxypropanol, o-
Methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2- (2-methoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethanol, 2
-(2-Butoxyethoxy) ethanol, 2- (2-methoxyethoxy) propanol, 2- (2-ethoxyethoxy) propanol, 2- (2-butoxyethoxy)
Propanol, 3- (2-methoxyethoxy) propanol, 3- (2-ethoxyethoxy) propanol, 3
-(2-butoxyethoxy) propanol, 4- (2-
Methoxyethoxy) butanol, 4- (2-ethoxyethoxy) butanol, 4- (2-butoxyethoxy) butanol, 2- (2-methoxybutoxy) ethanol,
2- (2-ethoxybutoxy) ethanol, 2- (2-
Butoxybutoxy) ethanol, 2- (2-methoxybutoxy) propanol, 2- (2-ethoxybutoxy)
Propanol, 2- (2-butoxybutoxy) propanol, 3- (2-methoxybutoxy) propanol, 3
-(2-Ethoxybutoxy) propanol, 3- (2-
Butoxybutoxy) propanol, 4- (2-methoxybutoxy) butanol, 4- (2-ethoxybutoxy)
Butanol, 4- (2-butoxybutoxy) butanol, 2- (2- (2-methoxyethoxy) ethoxy) ethanol, 2- (2- (2-ethoxyethoxy) ethoxy) ethanol, 2- (2- (2- Butoxyethoxy)
Ethoxy) ethanol, 2- (2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethanol, 2-
(2- (2- (2-ethoxyethoxy) ethoxy) ethoxy) ethanol, 2- (2- (2- (2-butoxyethoxy) ethoxy) ethoxy) ethanol, 2- (2-
(2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethoxy) ethanol, 2- (2- (2- (2-
Examples thereof include alkoxy alcohols such as (2-ethoxyethoxy) ethoxy) ethoxy) ethoxy) ethanol, and alcohols having a cyclic ether group such as tetrahydrofurfuryl alcohol and tetrahydropyranylmethyl alcohol.

Of these, hydroxy compounds having one ether group in the molecule are preferred, and 2-methoxyethanol, 3-methoxypropanol, 4-methoxybutanol, 2-ethoxyethanol, 3-ethoxypropanol, 4- Alkoxy alcohols such as ethoxybutanol, 2-butoxyethanol, 3-butoxypropanol and 4-butoxybutanol and alcohols having a cyclic ether group such as tetrahydrofurfuryl alcohol and tetrahydropyranylmethyl alcohol are particularly preferable.

Among the catalyst compounds known as transesterification catalysts, catalyst compounds having a boiling point lower than that of the starting carbonic acid ester, the starting hydroxy compound and the produced carbonic acid ester are used. Therefore, the selection of the catalyst compound depends on the kinds of the raw material carbonic acid ester, the raw material hydroxy compound and the produced carbonic acid ester, but the boiling point is usually 30.
0 ° C or lower, preferably 150 ° C or lower, more preferably 9
A catalyst compound at 0 ° C or lower can be used. The catalyst compound is preferably a tertiary amine or a tertiary phosphine, particularly preferably a tertiary amine.

Specific examples of the tertiary amine include trimethylamine, dimethylethylamine, dimethylpropylamine, dimethylisopropylamine, dimethylbutylamine, triethylamine, diethylmethylamine, diethylpropylamine, diethylisopropylamine, diethylpropylamine, triethylamine. Propylamine,
Tributylamine, N-methylpyrrolidine, N-methylpyrrole, N-methylpiperidine, N-methylmorpholine, N-methylimidazole, N, N, N ′, N′-tetramethylmethylenediamine, N, N, N ′, Examples thereof include N'-tetramethylethylenediamine, and triethylamine, dimethylisopropylamine and diethylmethylamine are preferable.

Specific examples of the tertiary phosphine include trimethylphosphine, triethylphosphine and tripropylphosphine. The amount of the catalyst compound used is usually 0.00001 or more, preferably 0.0001 or more, and usually 0.2 or less, preferably 0.1 or less in terms of molar ratio to the raw material carbonate ester (catalyst compound / raw material carbonate ester). Is.

Since the equilibrium of the transesterification reaction depends on the molar ratio of the raw material carbonic acid ester and the hydroxy compound, the molar ratio of the raw material carbonic acid ester and the hydroxy compound (raw material carbonic acid ester / hydroxy compound) is usually 0.
1 or more, preferably 0.25 or more, more preferably 0.
It is 4 or more, and is usually 50 or less, preferably 4 or less, more preferably 2.5 or less.

The transesterification reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen, and the reaction temperature is usually -5.
0 ° C or higher, preferably 0 ° C or higher, and usually 200
C. or lower, preferably 150.degree. C. or lower. The reaction pressure is usually 1 to 10 atm, preferably 1 to 2 atm. Under such conditions, it is preferable to react for 5 minutes to 5 days, particularly 10 minutes to 10 hours.

In the transesterification reaction, the hydroxy compound derived from the raw material carbonic acid ester, which is a by-product, may be removed from the reaction system to shift the reaction equilibrium in a desired direction. In particular, when the boiling point of the by-product hydroxy compound is lower than the boiling point of the catalyst compound, it is preferable to remove it during the reaction. As a method for removing the by-produced hydroxy compound, a gas phase containing the hydroxy compound is discharged to the outside of the system, or an inert gas such as nitrogen gas is blown into the system to allow the hydroxy compound to accompany it to the outside of the system. The method of discharging may be mentioned. When the gas phase containing a hydroxy compound is discharged to the outside of the system, it is preferable to use an azeotropic agent such as an aliphatic hydrocarbon, an aromatic hydrocarbon, an ether or a ketone in order to accelerate the evaporation of the hydroxy compound. For example,
To promote the evaporation of methanol generated from dimethyl carbonate, hexane, cyclohexane, benzene, etc. may be present in the reaction system.

The product solution of the transesterification reaction is distilled and
The starting carbonic acid ester, the hydroxy compound, the asymmetric carbonic acid ester, and the produced carbonic acid ester including the symmetrical carbonic acid ester are separated into respective components to obtain the desired carbonic acid ester.
At this time, since the catalyst compound is first distilled out and separated,
Distillation can be performed without causing an equilibrium transfer reaction that accompanies distillation of each component.

Fractions other than the target product, for example, starting carbonic acid ester, hydroxy compound, and other components than the target carbonic acid ester and catalyst compound may be recycled to the transesterification reaction system for reuse.

[0019]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. The analysis was performed by gas chromatography (apparatus: Shimadzu Corporation, GC14B; column: GL).
Manufactured by Science, TC5HT; conditions: hold at 40 ° C. for 5 minutes,
The temperature was raised to 250 ° C. at 10 ° C./min and held for 3 minutes; both injection and detector (FID) were performed at 250 ° C.). Internal standard substance (n-decane)
Was quantified with a calibration curve. Fractions from the distillation were analyzed using area percentage.

Example 1 In a 500 ml four-necked flask equipped with a distillation head (5 stages), 180 g (2.0 mol) of dimethyl carbonate and 2-
152 g (2.0 mol) of methoxyethanol, 8.1 g (80 mmol) of triethylamine and 18 g of hexane were charged, and the mixture was heated under reflux and 161 g (24 g) of hexane.
4 ml) to the reaction kettle at a rate of 1 ml / min,
An azeotropic mixture of hexane and methanol was distilled off from the top of the column. During this time, the temperature of the reaction solution was maintained at 74 ° C. After the addition of hexane was completed, gradually add 1 liter of liquid to further the reaction.
Heated to 32 ° C. The conversion rate of dimethyl carbonate is 80%,
The conversion of 2-methoxyethanol is 98%, the yield of methyl carbonate (2-methoxyethyl) is 46%, and bis (2
The yield of -methoxyethyl) was 28%. The reaction solution was distilled in a 5-stage distillation column at a pressure of atmospheric pressure to 22 mmHg to first distill off triethylamine, and then distill off dimethyl carbonate, 2-methoxyethanol and methyl carbonate (2-methoxyethyl). The yield of methyl carbonate (2-methoxyethyl) was 109 g (yield 38%), and the recovered amount of triethylamine was 8.1 g. Bis (2-methoxyethyl) carbonate was obtained as a bottom residue in an amount of 100 g (yield 28%).

Comparative Example 1 Dimethyl carbonate 162 was added to a four-necked flask having a capacity of 500 ml.
g (1.8 mol), 2-methoxyethanol 137 g
(1.8 mol) and sodium methoxide 9.7 mg
(0.18 mmol) was charged, and the mixture was heated at 87 ° C. and reacted for 3 hours. The conversion rate of dimethyl carbonate is 42%, 2-
The conversion of methoxyethanol is 48%, methyl carbonate (2
The yield of -methoxyethyl) was 33%, and the yield of bis (2-methoxyethyl) carbonate was 5%. The reaction solution was distilled under reduced pressure in a 5-stage distillation column at a pressure of 7 to 18 mmHg, but the equilibrium moved during the distillation because the catalyst was not removed,
6 g of methyl carbonate (2-methoxyethyl) (2% yield)
I could only get it. Bis (2-methoxyethyl) carbonate remaining in the kettle increased to 111 g (yield 35%).

Reference Example 1 144 g (1.6 g) of dimethyl carbonate was placed in the same apparatus as in Example 1.
Mol), 122 g (1.6 mol) of 2-methoxyethanol, 8.6 mg (0.16 mmol) of sodium methoxide and 143 g of hexane were charged, while distilling an azeotropic mixture of hexane and methanol from the top of the column, 66-
The mixture was heated at 101 ° C. and reacted for 5.5 hours. The reaction solution is cooled to room temperature, and a strongly acidic ion exchange resin (manufactured by Mitsubishi Chemical, S
K1B) The catalyst was removed by passing through a 4.0 ml column. The conversion rate of dimethyl carbonate was 79%, the conversion rate of 2-methoxyethanol was 94%, the yield of methyl carbonate (2-methoxyethyl) was 42%, and the yield of bis (2-methoxyethyl) carbonate was 25%. there were. The reaction liquid was distilled under reduced pressure at a pressure of 12 mmHg in a 5-stage distillation column. Methyl carbonate (2-
The yield of methoxyethyl) was 79 g (37% yield). 72 g (yield 25%) of bis (2-methoxyethyl) carbonate was obtained as a bottom residue.

[0023]

According to the present invention, carbonate ester can be obtained economically.

Continued front page    F-term (reference) 4G069 AA06 AA10 BA21A BA21B                       BE14A BE14B CB61 DA02                       GA20                 4H006 AA02 AC48 BA51 BA85 BD36                       BD52 BP10 KA57                 4H039 CA66 CD90

Claims (7)

[Claims] 1. When a carbonate ester is produced by transesterifying a carbonate ester and a hydroxy compound, a catalyst compound having a lower boiling point than any of the raw carbonate ester, the raw hydroxy compound and the produced carbonate ester is used as a catalyst. A method for producing a carbonic acid ester, comprising: 2. The method for producing a carbonate ester according to claim 1, wherein the catalyst compound is removed by distillation after the transesterification reaction. 3. The method for producing a carbonate ester according to claim 2, wherein the removed catalyst compound is reused in a transesterification reaction. 4. The method for producing a carbonic acid ester according to claim 1, wherein the catalyst compound is a tertiary amine. 5. The method for producing a carbonate ester according to claim 1, wherein the starting carbonate ester is a dialkyl carbonate. 6. The hydroxy compound is an alcohol,
The method for producing the carbonic acid ester according to claim 1. 7. The starting carbonic acid ester is a dialkyl carbonate and the hydroxy compound is an alkoxy alcohol.
The method for producing a carbonic acid ester according to claim 6.