JPS5851945B2 - Method for producing organic carbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing organic carbonates that produce fewer side reaction products than alcohols, carbon dioxide gas, alkali metal carbonates, and organic halogenides.

In detail, carbon dioxide gas is absorbed in advance into an organic halogenide or an inert organic solvent, and the raw materials are reacted in the organic halogenide or inert organic solvent that has absorbed the carbon dioxide to produce an organic carbonate. This is a method for producing organic carbonates in which carbon dioxide gas is separated from a reaction solution containing carbonate, and the separated carbon dioxide gas is used as carbon dioxide gas to be absorbed into an organic halogenide or an inert organic solvent.

It is known to synthesize organic carbonates by reacting alcohols, carbon dioxide gas, alkali metal carbonates, and organic halides in the presence of phase transfer catalysts such as amines and quaternary ammonium salts.

However, side reactions occur during the above reaction, and various problems must be solved in order to selectively produce the desired organic carbonate at low cost.

For example, the technical issue of minimizing side reaction products,
Technical issues regarding the effective use of carbon dioxide gas must be resolved as major issues.

The present inventors have been diligently conducting research on the synthesis of organic carbonates, and found that carbon dioxide gas is absorbed in advance into an organic halogenide or inert organic solvent, and that the carbon dioxide gas is separated from the reaction system and reused. The inventors have found that the above technical problem can be solved by doing so, and have completed and proposed the present invention.

That is, in the present invention, carbon dioxide gas is previously absorbed into an organic compound or an inert organic solvent, and the organic compound that has absorbed the carbon dioxide gas is
・Alcohols, carbon dioxide gas, alkali metal carbonates, and organic...logogenides are reacted in a halogenide or an inert organic solvent to produce an organic carbonate, and carbon dioxide gas is separated from the reaction solution containing the organic carbonate. The separated carbon dioxide gas is absorbed into an organic chloride or an inert organic solvent and used as carbon dioxide gas in the method for producing organic carbonate.

In the present invention, absorbing carbon dioxide gas in advance into an organic halogenide or an inert organic solvent plays an important role in suppressing side reaction products in the organic carbonate production reaction described later.

That is, the presence of carbon dioxide gas in the organic carbonate production reaction not only serves as a raw material component for the organic carbonate of the present invention, but also plays an important role in increasing the selectivity of the organic carbonate production.

Moreover, absorbing carbon dioxide gas in an organic compound or inert organic solvent in advance not only effectively recovers carbon dioxide gas, but also allows carbon dioxide gas to be uniformly dispersed in the reaction system, which will be described later. has an excellent effect on the production selectivity.

In the present invention, the timing and means of absorbing carbon dioxide into the organic halogenide or inert organic solvent are not particularly limited, and will be described in detail later, but the organic halogenide, alkali metal carbonate, alcohol, and carbon dioxide It is important to have carbon dioxide gas present prior to the reaction.

In the present invention, the organic halogenide or inert organic solvent that absorbs carbon dioxide gas is not particularly limited, and may be an organic halogenide used as a raw material for synthesis of organic carbonate or an inert organic solvent used in the reaction system described below. It is recommended to use

In general, as the organic chloride, it is preferable to use, for example, allyl chloride, methalyl chloride, benzyl chloride, etc., which serve as raw materials for the desired organic carbonate.

Further, as the organic solvent, a solvent is used that does not adversely affect the organic carbonate production reaction and is liquid under the absorption conditions of carbon dioxide gas absorption, which will be described later.

As the solvent, non-hydrogen polar solvents such as N-substituted amides such as dimethylformamide and nitriles such as acetonitrile are preferably used.

That is, the carbon dioxide absorption is carried out by adding fresh carbon dioxide to the carbon dioxide as necessary to absorb the carbon dioxide separated from the reaction solution, which will be described later, into the whole or a part of the organic halogenide or inert organic solvent used in the reaction. let

In general, the solubility of carbon dioxide in organic halogenides or inert organic solvents increases rapidly at low temperatures, so in order to increase the recovery rate of carbon dioxide, the temperature of organic halogenides or inert organic solvents should be low. However, in consideration of the material, the cooling device, and the manufacturing cost of the organic carbonate obtained, the range of -50°C to 20°C, preferably -30°C to 10°C is suitable.

The carbon dioxide gas absorption method may be carried out using a generally known gas absorption method.

For example, it is preferable to use a container equipped with a stirring device, a gas absorption tower, or the like.

The reaction in the present invention, that is, organic...logenide,
Techniques for synthesizing organic carbonates by reacting alkali metal carbonates, alcohols, and carbon dioxide gas are known.

For example, it is shown in Japanese Patent Application Laid-Open No. 5.4-41819, West German Patent Publication No. 2838701, and the like.

The method of synthesizing the organic carbonate, the type of raw materials, etc. in the present invention are not particularly limited, and may be selected from these known methods as necessary.

Examples of typical types of raw materials are as follows.

Organic...logenides are listed in West German Patent Publication No. 283870.
As shown in No. 1, allyl chloride, meta-allyl chloride, benzyl chloride, etc. are widely used, but in general, allyl chloride, meta-allyl chloride, benzyl chloride, etc. can be suitably used.

Further, alcohols are also exemplified in the above-mentioned West German Patent Publication, but polyhydric alcohols such as diethylene glycol and dipropylene glycol can generally be suitably used.

Further, as the alkali metal carbonate, soda ash light ash is preferably used, but other alkali metal carbonates can also be used by pulverizing them if necessary.

Furthermore, as the catalyst, amines such as triethylamine and quaternary ammonium salts such as tetraethylammonium chloride are generally suitably used.

The reaction proceeds easily when the four raw materials mentioned above are brought into contact at high temperature in the presence of a catalyst.

However, the reaction, as described in the above publication,
The first step is a reaction in which a carbonate monoalkali metal salt is produced from alcohol, carbon dioxide gas, and an alkali metal carbonate, and the second step is in which the carbonate monoalkali metal salt is reacted with an organic logenide in the presence of a catalyst to produce an organic carbonate. Since the reaction proceeds in a sequential manner, the reaction may be suitably carried out in two stages.

Further, since solids are involved in the reaction, it is preferable to proceed with the reaction in a slurry state in order to homogenize the reaction system and improve operation.

As a solvent for forming the slurry, an organic halogenide or an inert organic solvent, which is one component of the raw materials, may generally be used.

The method of carrying out the reaction in the present invention in two steps will be explained below. However, when obtaining organic carbonate from the four raw materials in one step, the reaction is almost the same as the second step reaction described below. It can be done under certain conditions.

In the first stage reaction, alcohol, carbon dioxide gas, and alkali metal carbonate are reacted in an organic halogenide or an inert organic solvent that has absorbed the carbon dioxide gas.

In the first stage reaction, organic compounds that have absorbed carbon dioxide gas
- It is preferable to stir and suspend an alkali metal carbonate in a halogenide or an inert organic solvent, and then gradually add an alcohol to the mixture, since aggregation of solids can be suppressed.

In addition, in order to suppress the formation of by-products, it is generally used as an alkali metal carbonate to suppress the formation of by-products.
It is preferable to use the above alkali metal positive carbonates.

Furthermore, the higher the concentration of carbon dioxide in the first stage reaction,
It is preferable to carry out the reaction under pressure of carbon dioxide gas because the reaction progresses quickly.

The carbon dioxide pressure depends on the reaction temperature, but is generally 2 kg.
/crilG or more, preferably 5 kP/iG or more, and more preferably 10 kg/citG.

The reaction temperature does not significantly affect the reaction and can be selected within a relatively wide range.

However, when an organic compound is present during the first stage reaction, there is a tendency for ether to be produced as a by-product, so it is desirable to lower the high temperature in order to prevent the by-product of ether.

Therefore, the reaction temperature in the first stage is generally -130 to -15
The most suitable temperature is 0°C, preferably in the range of -20 to 80°C.

The alkali metal carbonate used in the reaction may be supplied to the reactor during or prior to the reaction, but it is generally preferable to add it when carbon dioxide gas is absorbed into the organic halogenide or inert organic solvent. It is.

Next, in the second stage reaction, the reaction product obtained in the first stage reaction and an organic halogenide are reacted in the presence of carbon dioxide gas and a catalyst to obtain an organic carbonate.

The reaction is generally preferably carried out at elevated temperatures in order to increase the reaction rate.

However, the reaction temperature cannot be determined unconditionally because it varies depending on the raw materials, especially the type of organic halogenide.

Generally room temperature to 200°C, preferably 50°C to 150°C
It is preferable to select from the range of .

Further, when the organic halogenide has a chlorine atom at the allyl position or the benzyl position, the reactivity is good, so it is sufficient to select the reaction temperature from the range of 70°C to 120°C.

Further, in order to improve the reactivity and selectivity of organic carbonate, the reaction is preferably carried out under pressure of carbon dioxide gas as described above.

The partial pressure of carbon dioxide varies depending on the setting of the reaction temperature, so it is difficult to determine it unconditionally, but at the reaction temperature
ky/dG or more, preferably 10 su/cyrtG or more,
More preferably, it is 30 kg/critG or more.

However, even if the partial pressure of carbon dioxide is made too high, the effect of the presence of carbon dioxide will be balanced, which may be disadvantageous from the viewpoint of economy and reaction operation.

Therefore, it is generally industrially preferable to select a weight of 100 kg/ff1G or less.

Although the reaction time cannot be determined unconditionally because it depends on the type of raw materials, reaction temperature, etc., the reaction is generally completed in about several hours.

In the case of a batch reaction, the completion of the reaction can also be determined from a decrease in the pressure inside the reactor due to a change in the solubility of carbon dioxide due to a change in the composition of the reactants.

Organic carbonate is produced in the reaction.

In the present invention, carbon dioxide gas is separated from the reaction system containing the organic carbonate, and the carbon dioxide gas is used as part or all of the carbon dioxide gas to be absorbed by the organic halogenide or inert organic solvent. .

The circulating use of carbon dioxide is based on the difference between the pressure at the end of the reaction and the pressure when carbon dioxide is absorbed into an organic chloride or an inert organic solvent, and the slurry containing organic carbonate obtained by the reaction and used when absorbing carbon dioxide. Organic...
It is preferable to use the difference in carbon dioxide solubility between the halogenide and the inert organic solvent.

In addition, as mentioned above, the recovery rate of carbon dioxide when reusing carbon dioxide is generally determined by the reaction system containing the organic carbonate obtained in the reaction and the carbon dioxide solubility of the organic halogenide or inert organic solvent used to absorb carbon dioxide. defined by the difference.

Generally, the solubility of carbon dioxide in liquids tends to increase rapidly as the temperature decreases, so the separation of carbon dioxide from the reaction system obtained in the above reaction is carried out at as high a temperature as possible.
It is preferable to carry out carbon dioxide absorption at as low a temperature as possible.

Further, in this case, there is an advantage that the sensible heat of the reaction system itself obtained in the above reaction can be utilized.

Furthermore, since the reaction system obtained in the above reaction is cooled by the heat of evaporation of carbon dioxide gas as the carbon dioxide gas is separated,
It is also a preferred embodiment to increase the recovery rate of carbon dioxide gas while applying heat from the outside.

On the other hand, the operation of separating carbon dioxide gas from the reaction system can also be used as part of the cooling process of the reaction system.

The method for separating the carbon dioxide gas is not particularly limited and any known method can be used, but a method using evaporation is generally preferably used.

However, when the reaction system obtained in the above reaction is a slurry and contains a large amount of low-boiling point substances, the carbon dioxide gas is It is preferable to separate with high purity.

For this reason, a method is preferably employed in which the separated carbon dioxide gas is cooled under high pressure, the partial pressure of the accompanying low-boiling substances is lowered, and then the carbon dioxide is flashed.

It is also a suitable method to separate and recover carbon dioxide gas from the reaction system with high purity by pressure distillation using a distillation column.

The separated carbon dioxide gas is effectively utilized by the reaction pressure to produce organic...
Circulate as a carbon dioxide source when absorbing carbon dioxide into halides or inert organic solvents.

Therefore, when employing the two-stage reaction method, it is most preferable to operate the circulation pressure at a level higher than the first-stage reaction pressure and lower than the second-stage reaction pressure.

Of course, the optimum pressure may be determined depending on the cost of the apparatus, the temperature of the refrigerant that can be used for coagulation and reflux of carbon dioxide gas, etc.

For example, it is preferable to use reaction pressure effectively without necessarily requiring a pressurizing device for separation and recovery of carbon dioxide gas and circulation use of recovered carbon dioxide gas.

The reaction for producing organic carbonate in the present invention is a batch method,
A semi-continuous method or a continuous method can be carried out as required.

Furthermore, depending on the reaction method, one container can be used for multiple operations, making it possible to simplify the equipment and improve the efficiency of the process.

For example, when performing a batch process, if there are multiple reactors, everything from the operation of absorbing carbon dioxide gas into an organic, halogenated compound or inert organic solvent using the reactors in a cascade system to the separation of carbon dioxide gas from the reaction system can be carried out. It can also be carried out in the same reactor.

In addition, when multiple reactors with different withstand pressures are connected in series and carbon dioxide absorption and reactions that do not require very high pressure are performed in two stages, the first stage reaction is performed in a reactor with a low withstand pressure.
Next, a method of carrying out the second stage reaction, separation of carbon dioxide, etc. in a high-pressure reactor is also suitably carried out.

It is also possible to carry out the invention continuously.

For example, each of the above operations can be carried out continuously by using a piston flow type reactor, a reactor in which a plurality of complete mixing vessels are connected in series and the number of short baths is reduced, or the like.

EXAMPLES In order to explain the present invention more specifically, the present invention will be explained below using Examples, but the present invention is not limited to these Examples.

In the examples, allyl chloride was dehydrated with anhydrous calcium chloride and then subjected to simple distillation before use.

Diethylene glycol was dehydrated with anhydrous magnesium sulfate and then used by simple distillation.

Furthermore, as triethylamine, a special grade reagent was used as it was.

The yield in the examples is a value based on the diethylene glycol used, and was determined by gas chromatography using tetralin, which was dissolved in diethylene glycol at a fixed ratio and added to the reaction system, as an internal standard.

Reference example 1 Autoclave with a capacity of 500 m1 equipped with a magnetic stirrer (
Nitto Autoclave Co., Ltd.) and soda ash light ash (Tokuyama Soda Co., Ltd.) 58.3f? , allyl chloride 11
4.1' and 3.2 i of triethylamine were charged, and the mixture was replaced with carbon dioxide gas taken out from a liquefied carbon dioxide gas cylinder, and then pressurized to 30 kg/c1fLG at room temperature (24°C) to absorb carbon dioxide gas into allyl chloride.

While stirring the autoclave at a speed of 1000 rpm, 26.5 f of diethylene glycol was continuously added dropwise to the autoclave at room temperature over 30 minutes, and stirring was continued for 30 minutes even after the dropwise addition was completed.

During this time, the autoclave internal pressure was maintained at 30 Yu/craG.

The autoclave internal pressure was purged and the autoclave was opened.

The reaction system was in a slurry state, and a small amount of the liquid phase was sampled and analyzed by gas chromatography.

The liquid phase contained only allyl chloride and triethylamine, and diethylene glycol, a raw material, and reaction products were not observed.

The autoclave was sealed again, replaced with carbon dioxide gas, and heated for 30 minutes.
After pressurizing to kg/cvtG, the temperature was raised to 100°C using an electric heater, and reaction was carried out for 4 hours.

The pressure during the reaction was 65-70 9/cIILG.

The autoclave was opened after cooling.

The reaction system was in a slurry state, and the liquid phase was analyzed by gas chromatography.

The yield of diethylene glycol bis(allyl carbonate) was 86%.

Example 1 Two autoclaves having the same specifications as Reference Example 1 were charged with 58.3f of soda ash, 114.8p of allyl chloride, and 3.2i of triethylamine.

One autoclave was under the same conditions as in Reference Example 1, after which carbon dioxide gas was supplied and then 26.59 g of diethylene glycol was charged, and the reaction was continued at elevated temperature without opening the autoclave.

(Hereafter referred to as autoclave A.

) After replacing the inside of the other autoclave with carbon dioxide gas, it was cooled to -30°C by pouring it into a refrigerant.

(Hereafter referred to as autoclave B.) After the reaction, autoclave A is removed from the electric heater and connected to autoclave B, and the carbon dioxide gas in autoclave A is transferred to autoclave B.
It was gradually absorbed into allyl chloride inside.

During this time, the temperature of autoclave B was maintained at -30°C.

After 30 minutes, the pressure in both autoclaves became 6 kg/iG and remained almost constant.

After closing autoclave B, the temperature was returned to room temperature (25°C), and the internal pressure became 21 kg/cr?tG.

Then, the autoclave B has an internal pressure of 30 kg/cTLG.
Carbon dioxide gas was replenished from a liquefied carbon dioxide cylinder until .

Then diethylene glycol 26.5? was continuously added dropwise over 30 minutes, and then the reaction was carried out in the same manner as in autoclave A.

The yield of diethylene glycol bis(allyl carbonate) in autoclave B was 87%.

Comparative Example 1 In Reference Example 1, soda ash light ash, allyl chloride, triethylamine, and diethylene glycol were charged at room temperature without replacing carbon dioxide gas.

The autoclave was closed and the temperature was raised to 100° C. while stirring.

At this time, the autoclave had a ratio of 9/CrItQ of about 3.5 due to the air present inside and the vapor pressure of allyl chloride.

After 4 hours of reaction, the autoclave was cooled and opened.

Analysis of the liquid phase of the autoclave by gas chromatography revealed that the yield of diethylene glycol bis(allyl carbonate) was 3.8%.

Comparative example 2 The operation was carried out in substantially the same manner as in Example 1 except for the following conditions.

That is, autoclave B was charged with diethylene glycol from the beginning.

The autoclave B is cooled to 30°C, but the autoclave A
When autoclaves B and A were connected and carbon dioxide gas was transferred from autoclave A to autoclave B while stirring, stirring soon became impossible.

After another 30 minutes, the internal pressure was 5.0 kg/ctyYG.

Thereafter, autoclaves A and B were connected, autoclave B was closed, and the temperature was raised to room temperature (25°C).

At this time, the internal pressure of autoclave B was 17 to 9/ffl.
It became.

The temperature continued to rise further, and when the temperature reached 100° C. after 30 minutes, stirring was possible again.

After 4 hours, the autoclave was cooled and the contents were taken out.

As a result, the yield of diethylene glycol bis(allyl carbonate) was 76%.

Example 2 Two autoclaves of the same specifications as Reference Example 1 were each charged with 58.5 kg of soda ash. , l, dimethylformamide 100111
I prepared 1.

One autoclave was replaced with carbon dioxide gas from a liquefied carbon dioxide cylinder, and then heated at 30 kg/cyy at room temperature (24°C).
Pressure was applied to tG to absorb carbon dioxide gas into dimethylformamide.

Diethylene glycol 26% was added to the autoclave at room temperature while stirring at a speed of 100 rpm. ! l to 30
The solution was continuously added dropwise in portions, and stirring was continued for 30 minutes even after the addition was completed.

During this time, the autoclave internal pressure was 30kg/cr? I kept it on LG.

Then allyl chloride 45.9P, triethylamine 3.2? was charged, the temperature was raised to 100°C, and the reaction was carried out for 4 hours.

The pressure during the reaction was 63 to 70 kg/criG.

(Hereafter referred to as autoclave A.

) After replacing the inside of the other autoclave with carbon dioxide gas, it was cooled to 30° C. by charging it with a refrigerant.

(Hereafter referred to as autoclave B.

) After the reaction, autoclave A was removed from the electric heater and connected to autoclave B, and carbon dioxide gas in autoclave A was gradually absorbed into dimethylformamide in autoclave B.

During this time, the temperature of autoclave B was maintained at -30°C.

After 30 minutes, the pressure inside both autoclaves was 5 to 9/crIL.
G, and it became almost constant.

While maintaining the temperature at -30°C, autoclave B was supplied with carbon dioxide gas from a liquefied carbon dioxide gas cylinder until the internal pressure reached 8 kg/iG, and diethylene glycol 26.1' was continuously added dropwise over 30 minutes.

After dropping the diethylene glycol, stirring was continued for 30 minutes.

Allyl chloride 45.9P,) ethylane 3.2
'i? was charged, the temperature was raised to 100°C, and the reaction was carried out for 4 hours.

The pressure during the reaction was 65 to 73 kg/iG.

The yield of diethylene glycol bis(allyl carbonate) was 72% in autoclave A and 74% in autoclave B.
Met.

Example 3 A first-stage reactor in which a carbon dioxide gas absorption can for absorbing carbon dioxide gas into allyl chloride, a first-stage reactor in which diethylene glycol, carbon dioxide gas, and soda ash (light ash) are reacted, and a reaction system obtained in the first-stage reactor A second-stage reactor for heating and reacting is connected to a carbon dioxide evaporator for separating carbon dioxide from the reaction system obtained in the second-stage reactor, and the carbon dioxide evaporator and carbon dioxide absorption can are cooled. They were connected via a container.

In addition, the carbon dioxide gas absorption can contains allyl chloride 920r and soda ash 466'? was supplied as a slurry, diethylene glycol 2121, triethylamine 25.61 and tetralin 8.51 were supplied to the first stage reactor, and carbon dioxide gas was supplied to the second stage reactor so that the internal pressure was 70 to 9/cit G. supplied.

In addition, the temperature of the carbon dioxide absorption canister is -20℃, and the temperature of the second stage reactor is 120℃.
The temperature of the condenser was set at -20°C.

The pressure in the carbon dioxide evaporator was 10 ky/=c, and the pressure in the carbon dioxide absorber was 9 kg/iG.

The reaction slurry extracted from the carbon dioxide evaporator was decomposed with water, and the separated organic layer was analyzed by gas chromatography.

As a result, the yield of diethylene glycol bis(allyl carbonate) was 82%.

Claims (1)

[Claims] 1 Carbon dioxide gas is absorbed in an organic halogenide or inert organic solvent in advance, and alcohols, carbon dioxide gas, alkali metal carbonates, and organic halides are dissolved in the organic halide or inert organic solvent that has absorbed the carbon dioxide gas. reacting a compound to produce an organic carbonate, separating carbon dioxide gas from the reaction solution containing the organic carbonate, and using the separated carbon dioxide gas as a carbon dioxide gas to be absorbed into an organic compound or an inert organic solvent. A method for producing organic carbonate, characterized by: