JP3368931B2 - Method for producing carbonate ester - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for producing carbonates from carbon monoxide, oxygen and alcohols.
Carbonic acid ester is a very useful compound as a raw material for producing polycarbonate and isocyanate, and as a raw material for various organic synthesis.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Carbonic acid ester is produced from phosgene and alcohol, but since phosgene is extremely toxic and a compound containing corrosive halogen is produced as a by-product, a method for producing carbonic acid ester that does not use phosgene is desired. It was Therefore, a method for producing a carbonate ester from carbon monoxide, oxygen and alcohol using a catalyst has been proposed [2R
OH + CO + 1 / 2O ₂ → (RO) ₂ CO
+ H ₂ O]. For this catalyst, usually cuprous halide such as cuprous chloride, or palladium metal or a compound thereof is used. In the method using cuprous chloride as a catalyst (German Laid-Open Patent Publication No. 3045767), since the activity under low pressure conditions is not sufficient, in order to obtain sufficient activity, a high reaction pressure of 20 to 30 atm, This is not always an industrially satisfactory method that requires a particularly high carbon monoxide partial pressure. In addition, water and carbon dioxide, which is a by-product, change the catalyst, resulting in a decrease in activity and selectivity. Therefore, 10 to 20 for the reaction solution
A large amount of catalyst (wt%) is added to the reaction solution to maintain activity and selectivity (Ind. Eng. Chem. Prod. Res. Dev., 19,
396 (1980).). That is, it has a drawback that it becomes a highly corrosive and slurry-like reaction liquid containing a large amount of halogen. Further, a method using cupric chloride as a catalyst (Japanese Patent Publication No.
In 5-11129), the activity is inferior even when a large amount of catalyst is used, and many by-products such as methyl chloride, dimethyl ether, carbon dioxide gas are generated, and catalyst insolubilization and deactivation occur in the reaction for a long time. Had the drawback of. Further, a method using palladium as a catalyst (Japanese Patent Laid-Open No. 3-240756)
Then, there is a method of using palladium chloride or palladium carbon as a catalyst, but it has the drawback of being highly deactivated, accompanied by by-products of oxalic acid ester and carbon dioxide, and palladium is expensive, so practical application is difficult. is there. To reduce the activity of the catalyst due to water by-produced by the reaction, cuprous iodide +
It has been disclosed that carbonic acid ester is synthesized in the presence of water using 1,10-phenanthroline as a catalyst (JP-A-4-108765), but the reaction pressure is 45 atm or higher, and the reaction temperature is 130 ° C. Strict. Further, the catalyst is expensive and is not an industrially satisfactory method.

The present inventors have earnestly studied about a method for producing a carbonic acid ester by reacting carbon monoxide, oxygen and alcohol, and as a result, when a copper compound and an alkyl-substituted tertiary amine are used as a catalyst, The inventors have found that under a relatively low pressure and mild reaction conditions, the activity and selectivity are high, the catalyst is not deactivated, and the carbonate ester can be obtained extremely advantageously, and the present invention has been completed.

[0004]

That is, the present invention is
(1) A method for producing a carbonic acid ester from carbon monoxide, oxygen, and an alcohol, wherein only a copper compound and an alkyl-substituted tertiary amine are used as a catalyst, and (2) a method for producing a carbonic acid ester. The method according to (1), wherein the concentration of the copper compound in the reaction solution is 0.1 to 3 mol / liter. The method of the present invention will be described in detail below.

The catalysts used in the present invention are copper compounds and alkyl-substituted tertiary amines. As a copper compound,
Examples thereof include cupric chloride, cuprous chloride, cupric bromide, cuprous bromide, cuprous iodide, cupric nitrate, etc., but cupric chloride is particularly preferable. Copper compound is 0.1 to
The concentration range is 3 mol / L, and the concentration range of 1 to 3 mol / L is particularly preferable. Examples of the alkyl-substituted tertiary amine include aliphatic tertiary alkyl-substituted amines such as triethylamine, trimethylamine, diethylmethylamine, dimethylethylamine, and tripropylamine, and DABCO (diazabicyclo {2,2,2} octane) and the like. Alicyclic tertiary amines are preferably used. Further, a compound containing an alkyl-substituted tertiary amine group, or one obtained by immobilizing these alkyl-substituted tertiary amines on a suitable polymer such as a polymer or a carrier can also be used. The alkyl-substituted tertiary amine is used in a nitrogen atom / copper atom ratio of 0.01 to 2, preferably 0.1 to 0.8, based on the copper compound. The reaction system of this reaction may be a continuous system or a batch system, but a continuous system is more advantageous in producing a carbonate ester in terms of industrialization.

Examples of the alcohol used in the present invention include aliphatic alcohols such as methanol and ethanol, aromatic alcohols such as phenol, unsaturated alcohols such as allyl alcohol, and polyhydric alcohols such as ethylene glycol, and preferably carbon. It is an alcohol having a number of 1 to 10. As the reaction solvent, alcohol as a raw material and / or carbonic acid ester as a product is used, but an appropriate solvent can also be used.

Carbon monoxide and oxygen, which are raw material gases, may be diluted with carbon dioxide, nitrogen, hydrogen and other inert gases for reaction. The reaction may be carried out at normal pressure, but is preferably carried out under pressure. Although the present catalyst system has a characteristic of exhibiting high activity under a relatively low reaction pressure, the activity can be further increased by increasing the reaction pressure. In the actual reaction, carbon monoxide partial pressure is in the range of 0.5 to 100 atm, preferably 3 to 10 atm, and oxygen partial pressure is in the range of 0.1 to 30 atm, preferably 0.3 to 10 atm. Reaction temperature is 50-1
It is in the range of 50 ° C, preferably 90 to 130 ° C.

[0008]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following examples in which methanol was used as the raw material alcohol, the activity of the catalyst was measured according to the following equation.
It is represented by the amount of dimethyl carbonate (hereinafter referred to as DMC) produced per liter of reaction time, that is, the space-time yield (mmol / L · h). Y = a * (1 / b) * (1 / c) Here, Y: space-time yield (mmol / L * h), a: DMC production amount (mmol), b: reaction liquid volume (L), c: Reaction time (h). In addition, the selectivity was calculated using the following formulas for the raw material carbon monoxide and methanol, respectively.

S (CO) = R (DMC) / {R (DMC) + R (CO ₂ )
} × 100 S (CH ₃ OH) = 2R (DMC) / {2R (DMC) + R (MC) + 2R
(DME) + 3R (DMM)} × 100 where S (CO): selectivity (%) for carbon monoxide of the raw material, S (CH ₃ OH): selectivity (%) for methanol of the raw material, R (DMC ): DMC production amount (mmol), R (CO ₂ ):
Carbon dioxide production (mmol), R (MC): Methyl chloride production (mmol), R (DMM): Dimethoxymethane (methylal)
Production amount (mmol), R (DME): Dimethyl ether production amount (mmo
l).

Example 1 Methanol 40 containing 66 mmol of cupric chloride and 22 mmol of triethylamine dissolved in a stainless steel autoclave (internal volume of about 400 ml) equipped with a Teflon inner cylinder and a stirrer.
After adding ml (31 g), carbon monoxide (3.6 atm), nitrogen (5.7 atm) and oxygen (0.7 atm) were added as partial pressures under normal pressure to bring the total pressure to 10 atm. The mixture was heated to 0 ° C. and reacted for 30 minutes.
After the reaction was completed, the liquid phase part and the gas phase part were analyzed by gas chromatography respectively, and as a result, dimethyl carbonate (hereinafter referred to as DMC
Abbreviated) was 720 mmol / L · h.
By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride. The selectivity was 98% with respect to the raw material carbon monoxide and 97% with respect to the raw material methanol. In addition, the liquid after the reaction did not contain any precipitate.

Example 2 The reaction was performed in the same manner as in Example 1 except that methanol containing about 7% by weight of water was used instead of the raw material methanol.
As a result, the space-time yield of DMC was 450 mmol / L · h. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride. Selectivity is 70% for the raw material carbon monoxide and 95 for the raw material methanol.
%Met. In addition, the liquid after the reaction did not contain any precipitate.

Example 3 The reaction was carried out in the same manner as in Example 1 except that 22 mmol of trimethylamine was used instead of 22 mmol of triethylamine. As a result, the space-time yield of DMC was 750 mmol / L · h.
Met. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride. The selectivity was 98% with respect to the raw material carbon monoxide and 97% with respect to the raw material methanol. In addition, the liquid after the reaction did not contain any precipitate.

Example 4 A reaction was carried out in the same manner as in Example 1 except that 22 mmol of DABCO (diazabicyclo {2,2,2} octane was used in place of 22 mmol of triethylamine.
The space-time yield of C was 650 mmol / L · h. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride. The selectivity was 98% with respect to the raw material carbon monoxide and 97% with respect to the raw material methanol.

Example 5 The reaction was carried out in the same manner as in Example 1 except that 66 mmol of cupric bromide was used instead of 66 mmol of cupric chloride. as a result,
The space-time yield of DMC was 700 mmol / L · h. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl bromide. The selectivity was 97% with respect to the raw material carbon monoxide and 97% with respect to the raw material methanol. The liquid after the reaction did not contain any precipitate.

Example 6 In a stainless steel autoclave (internal volume of about 400 ml) equipped with a Teflon inner cylinder and a stirrer, cupric chloride 165 mmo
1, methanol 1 in which 55 mmol of triethylamine was dissolved
After adding 00 ml, carbon monoxide was flowed at 260 ml / min and air was passed at 100 ml / min, the total pressure was 10 atm, and the internal temperature was 110.
The reaction was carried out at 0 ° C for 6 hours. The raw materials and reaction gas were automatically sampled every hour and analyzed by gas chromatography. After the reaction was completed, the liquid phase portion was sampled and analyzed by gas chromatography. As a result, DMC was 35 g.
As a result, the average space-time yield was 590 mmol / L · h. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride. The selectivity is 90% for the raw material carbon monoxide and 9 for the raw material methanol.
It was 8%. In addition, only a very small amount of precipitate was observed in the liquid after the reaction.

Comparative Example 1 The reaction was performed in the same manner as in Example 6 except that 165 mmol of cupric chloride was used. DMC formed after 6 hours of reaction
Was 9.2 g, and the average space-time yield was 155 mmol / L · h. By-products were carbon dioxide, dimethoxymethane, methyl chloride and dimethyl ether. The selectivity through the whole reaction was 80% with respect to carbon monoxide as a raw material and 91% with respect to methanol as a raw material.

Comparative Example 2 The reaction was performed in the same manner as in Example 6 except that 165 mmol of cuprous chloride was used. DMC formed after 6 hours of reaction
Was 20 g, and the average space-time yield was 360 mmol / L · h. The by-products were carbon dioxide and a small amount of dimethoxymethane. The selectivity through the whole reaction was 90% with respect to the raw material carbon monoxide and 98% with respect to the raw material methanol. After the reaction, a large amount of a catalyst-derived precipitate (about 12 g) was generated in the reaction solution. As a result of analysis by an X-ray diffraction method, this precipitate was mainly Cu ₂ (OH) ₃ Cl {CuC
It consisted of a crystal of _{l 2 · 3Cu (OH) 2} }.

Example 7 The reaction liquid of Example 6 was taken out, and the reaction liquid and the catalyst were separated by an evaporator. Only a trace amount of triethylamine was detected in the distilled reaction solution. The resulting catalyst is 80
After drying at 30 ° C. for 30 minutes and dissolving in methanol only, the reaction was repeated for 6 hours in the same manner as in Example 6. As a result, 36 g of DMC was produced in the second reaction and 38 g in the third reaction. No decrease in activity or selectivity due to repeated use of the catalyst was observed. Moreover, only a very small amount of precipitate was always observed in the liquid after the reaction.

Comparative Example 3 The reaction solution and the precipitate of Comparative Example 2 were taken out, and the catalyst was separated by an evaporator. The obtained catalyst was dried at 80 ° C. for 30 minutes and then dispersed again in methanol. Most of the catalyst did not dissolve and was in a slurry form. The reaction was repeated for 6 hours as in Comparative Example 2. As a result, DMC was 1 in the second reaction.
7 g was produced, and 15 g was produced in the third cycle repeated in the same manner. The catalytic activity showed a tendency to decrease as the reaction was repeated. Further, the amount of precipitate contained in the reaction solution tended to increase with repetition.

Example 8 The pressure during the reaction was set to 20 atm, and the flow rate of carbon monoxide was set to 39.
The reaction was performed in the same manner as in Example 6 except that the flow rate of air was 0 ml / min and the flow rate of air was 150 ml / min. The DMC produced after 4 hours of reaction was 50 g, with an average space-time yield of 126
It was 0 mmol / L · h. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride.
The selectivity was 90% with respect to the raw material carbon monoxide and 97% with respect to the raw material methanol. In addition, only a very small amount of precipitate was observed in the liquid after the reaction. After the reaction, the water concentration in the reaction solution was about 10% by weight (calculation excluding the catalyst component). Comparative Example 4 The reaction was carried out in the same manner as in Example 1 except that 66 mmol of cupric chloride and 22 mmol of pyridine were used as the catalyst. After the reaction for 30 minutes, the reaction solution was analyzed and as a result, the space-time yield of DMC was 160 mmol / L · h. Example 9 As a catalyst, 165 mmol of cupric chloride and 55 mmol of triethylamine were used, and 100 ml of raw material methanol was added with water.
The reaction was carried out under the same conditions as in Example 6 (total pressure: 10 atm, internal temperature: 110 ° C., reaction time: 6 hours) except that 0 g (220 mmol) was added. As a result, 21 g of DMC was obtained, and the average space-time yield was 350 mmol / L · h. After the reaction, the water concentration in the reaction solution was about 10% by weight (calculated excluding the catalyst component). Comparative Example 5 165 mmol of cuprous chloride alone was used as a catalyst, and 4.0 g (220 mmol) of water was added to 100 ml of methanol as a raw material, under the same conditions as in Example 6 (total pressure: 10 atm, internal temperature: 110).
The reaction was carried out at a temperature of 6 hours. As a result, D
12.5 g of MC was obtained, and the average space-time yield was 210 mmol.
It was / L · h. From the results of Example 9 and Comparative Example 5,
It can be seen that the catalyst of the present invention stably produces DMC with higher activity than the conventional catalyst even in the presence of water. Comparative Example 6 The reaction was carried out under the same reaction conditions as in Example 8 except that only cuprous chloride was used as the catalyst. The DMC produced after the reaction for 4 hours was 32 g, and the average space-time yield was 8
It was 10 mmol / L · h. By-products were small amounts of carbon dioxide and traces of dimethoxymethane, methyl chloride. The selectivity was about 90% with respect to carbon monoxide as a raw material and 98% with respect to methanol as a raw material. The reaction solution contained a large amount of precipitate derived from the catalyst. The water concentration is
It was about 6% by weight (calculated excluding the catalyst component). From the results of Example 8 and Comparative Example 6, the catalyst of the present invention showed higher DM activity than the conventional catalyst even under higher pressure reaction conditions.
It can be seen that C is generated.

From the results of Examples 1 to 9 and Comparative Examples 1 to 6 as described above, the catalyst of the present invention is a carbonate ester under the industrially advantageous relatively low pressure reaction conditions of about 10 to several tens of atmospheres. Shows sufficiently high activity and selectivity for In addition, this catalyst system is characterized by high durability of the catalyst against water produced as a by-product. That is, the catalyst of the present invention maintains high activity in the carbonic acid ester synthesis even when an alcohol containing about 5 to 10% of water is used as a raw material. After the reaction, the catalyst recovered by removing the unreacted raw material alcohol, the produced carbonic acid ester, and water by a simple operation such as evaporation is dissolved in the alcohol again, and the catalyst performance is improved even if the reaction is repeated. It also has the characteristic of not decreasing. Furthermore, when an amine such as triethylamine or trimethylamine is used as the alkyl-substituted tertiary amine of the present invention, the reaction liquid does not form a slurry because it contains almost no precipitate, and a complicated auxiliary device such as a slurry pump is used in the plant. It has an important advantage in industrialization that no equipment is required. Further, the tertiary amine is said to generate a quaternary amine by the reaction of a carbonic acid ester, but in the present carbonic acid ester synthesis reaction, it was added as a catalyst at least under the conditions described in this Example. No reaction between the tertiary amine and the carbonate formed was observed. Therefore, in the coexistence of the present catalyst, such side reaction does not occur, which is advantageous.

[0022]

According to the method of the present invention, when a copper compound and an alkyl-substituted tertiary amine are used as a catalyst in a method for producing a carbonic acid ester from carbon monoxide, oxygen and alcohol, a relatively low pressure is used. Both activity and selectivity are high even under mild reaction conditions, and there is no deactivation due to by-product water due to the reaction, so that a carbonate ester can be industrially extremely advantageously produced.

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 68/00 C07C 69/96

Claims (2)

(57) [Claims] 1. A method for producing a carbonic acid ester from carbon monoxide, oxygen and an alcohol, which comprises using only a copper compound and an alkyl-substituted tertiary amine as a catalyst. 2. The method according to claim 1, wherein the concentration of the copper compound used as the catalyst in the reaction solution is 0.1 to 3 mol / liter.