JPS6023663B2 - How to recover organic carbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating and recovering organic carbonates obtained by the reaction of organic halides, alkali metal carbonates, alcohols, and carbon dioxide gas.

That is, the present invention reacts an organic halide, an alkali metal carbonate, an alcohol, and a carbon dioxide gas to obtain an organic carbonate, and when recovering the organic carbonate from a slurry containing the organic carbonate, the by-product solid is separated. A method for separating organic carbonates, comprising: recovering a liquid phase containing an organic carbonate, washing the separated solid substance with an organic solvent, and extracting and recovering the organic carbonate occluded in the solid substance with an organic solvent. This is a collection method. Organic carbonates are produced by the phosgene method obtained by reacting raw materials such as diethylene glycol, allyl alcohol, phosgene, and alkalis, organic halides, alkali metal carbonates,
An alkali metal carbonate method obtained by reacting alcohols and carbon dioxide gas is known. In particular, the latter method does not require the use of highly toxic phosgene and can be said to be an industrially advantageous method, since it does not require the use of highly toxic phosgene and also has the advantage that asymmetric carbonates can be easily obtained. However, the method for synthesizing organic carbonates using the alkali metal carbonate method has not yet been industrialized. The present inventors have conducted extensive research into the synthesis of organic carbonates using the alkali metal carbonate method.

As a result, when organic carbonates are synthesized by reacting organic halides, alkali metal carbonates, alcohols, and carbon dioxide gas, solid substances based on the raw material alkali metal carbonates are produced as by-products, and the reaction system becomes sluic IJ. It has been found that during the theatrical separation of the solid material, a non-negligible amount of organic carbonate is occluded and lost in the solid material. Furthermore, as a result of intensive research into the method for separating the solids mentioned above, the present inventors have found that it is possible to separate the solids under anhydrous conditions when recovering the organic carbonate obtained by the synthesis method. This led to the completion of the present invention.
The present invention makes it possible to handle alkali metal halides, organic halides, etc. that cause corrosion of equipment materials under anhydrous conditions. Therefore, the present invention not only eliminates the problem of corrosion of equipment materials during the recovery of organic carbonate, but also simplifies the recovery of unreacted organic halides and organic solvents used during the reaction. This is an excellent industrial method. That is, the present invention provides organic halides, alkali metal carbonates,
When alcohol and carbon dioxide gas are reacted to obtain an organic carbonate and the organic carbonate is separated from the slurry containing the organic carbonate, solid matter is separated from the slurry containing the organic carbonate and a liquid phase containing the organic carbonate is recovered. In this method, the separated solid substance is washed with an organic solvent, and the organic carbonate occluded in the solid substance is extracted and recovered with the organic solvent.

Techniques for synthesizing organic carbonates by reacting organic halides, alkali metal carbonates, alcohols, and carbon dioxide gas are known. For example, it is shown in Japanese Patent Application Laid-Open No. 54-4181y, West German Patent Publication No. 2838701, etc.
The method of synthesizing the organic carbonate, the type of raw materials, etc. in the present invention are not particularly limited, and may be determined by selecting from these known methods as necessary. Examples of typical types of raw materials and reaction temperatures are as follows. Organic halides are widely used as shown in German Patent Publication No. 2838701, and generally allyl chloride, meta-allyl chloride, benzyl chloride, etc. can be suitably used. 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 after being crushed as necessary. Furthermore, as the catalyst, amines such as triethylamine and quaternary ammonium salts such as tetraethylammonium chloride are generally preferably used. Methods for reacting these raw materials are shown in the above-mentioned Japanese Patent Application Laid-Open No. 54-41819, West German Patent Publication No. 2838701, etc., but generally in the presence of a catalyst and in a carbon dioxide atmosphere at room temperature to 150 qo, preferably 70 qo. The reaction may be carried out at a temperature of ~120°C. In addition, when carrying out the organic carbonate synthesis reaction in two stages, alkali metal carbonates, alcohols, and carbon dioxide gas are reacted at a temperature of -30°C to 50q○, and the reactants and organic halides are reacted. It is preferable to carry out the reaction in the presence of a catalyst and in a carbon dioxide atmosphere at a temperature of 70 to 120°C. Said 1
Regardless of whether the reaction is carried out in one step or in two steps, solid matter caused by the alkali metal carbonate is generated in the reaction system.

Therefore, the solid substance is present in the reaction system as a slurry containing organic carbonate. The composition of the slurry varies greatly depending on the ratio of raw materials added and cannot be specified. This is because the charging ratio of raw materials can be selected from a wide range. However, in order to maintain the fluidity of the reaction system, it is common to synthesize organic carbonates by using an excess of liquid raw materials to create a slurry, or by using a reaction solvent that does not have a negative effect on the reaction. be.

Furthermore, in order to improve the reactivity of raw materials and the selectivity of organic carbonates, it is common to use one or more alkali metal carbonates for every hydroxyl group of the alcohol.
Therefore, the alkali metal carbonate should be used in an amount of 1 or more per 1 hydroxyl group of the alcohol, and the organic halide should be used in a small excess of about 1 per 1 hydroxyl group of the alcohol, and a reaction solvent or organic halide should be used. It is preferable to use a large excess so that the organic halide also serves as a reaction solvent. In particular, when an organic halide with a low boiling point is used as a raw material, it is particularly suitable to use the organic halide in large amounts. As mentioned above, in the reaction system, in order to maintain the created solid material in a slurry state, a large excess of the raw material organic halide is used to double as a solvent, or an inert solvent such as dimethylformamide, etc. is used during the reaction. The reaction is carried out using acetonitrile, methylene chloride, etc.

In order to simplify the explanation of the present invention, the case in which an organic halide is used as the reaction solvent will be described below as a representative example, but the process can be carried out in almost the same way when using other solvents.

In the reaction system containing organic carbonate, there are alkali metal halides and alkali metal carbonates created by the reaction between alkali metal carbonates and organic halides, and alkali metal bicarbonates which are by-products from the reactions with alcohol and carbon dioxide gas. ; Unreacted alkali metal carbonates, etc. are included as intermediates.

Since the solid substance in the reaction system has almost no stickiness, it can be separated from the liquid phase by sieving. The concentration means for separating the solid substance of the reaction system from the liquid phase containing the organic carbonate is not particularly limited, and any known means may be used. For example, methods such as passing through paper or cloth, passing through suction or pressure using a Nutsche, passing through a filter press, and passing through centrifugation are preferably employed. The liquid phase containing the separated organic carbonate may be made into a product by separating the organic halide by means such as distillation and purifying the desired organic carbonate. On the other hand, the solid material separated according to the above speculation surprisingly occludes a large amount of organic carbonate.

Generally, in order to separate solid substances in the reaction system, water is added to dissolve the solid substances in the aqueous phase, and the organic halide phase is separated into an aqueous phase and an organic halide phase containing organic carbonate, and the organic halide phase is distilled. It is conceivable that organic carbonates and organic halides can be recovered by this method. However, when the above method is carried out industrially, organic halides are treated in the presence of water, which not only causes problems of corrosion of equipment materials, but also requires a large amount of water to completely separate the solids. do. In the present invention, the organic carbonate occluded in the solid substance is brought into contact with an organic solvent, and the organic carbonate is dissolved and extracted in the organic solvent. The organic solvent for extracting the organic carbonate (hereinafter also simply referred to as extraction solvent) is not particularly limited and can be used as long as it dissolves the organic carbonate and does not dissolve solid substances. However, in order to carry out the present invention most effectively, a compound that is used as a solvent in a reaction system in which organic halides, alkali metal carbonates, alcohols, and carbon dioxide gas are reacted is used. That is,
It is preferable to use an organic halide, which is also used as a raw material component, or a reaction solvent such as the above-mentioned dimethylformamide or acetonitrile. The means for extracting the organic carbonate occluded in the solid material is not particularly limited, and any known method may be employed. For example, there are methods such as suspending the solid material in an extraction solvent and separating it into sieves, and adding extraction solvent to the solid material and passing the extracted molten soot through a container filled with the solid material. Suitably adopted. Of course, in order to more completely recover the organic carbonate occluded in the solid material, the above extraction operation may be repeated. The extraction solvent may be used alone after being separated from the solid matter, or after being mixed with the liquid phase containing the organic carbonate from which the Oka-type matter has been separated from the reaction system, the extraction solvent and the organic carbonate may be separated by means such as distillation. .

The separated extraction solvent can be recycled for washing the solid material. Further, when the extraction solvent is the same as the reaction solvent of the reaction system as described above, it can be recycled to the reaction system. Furthermore, when the extraction solvent is an organic halide, it can be reused as a raw material. On the other hand, the solid material after the extraction operation can be discarded as is, or if the solid material contains an alkaline component, it can be used as an acid neutralizer.

In addition to containing some organic matter, the solid substance also consists of alkali metal halides, bicarbonates, and carbonates.The solid substance is used as a raw material for the production of alkali carbonate by the sorbet method, and is used to produce organic carbonate. It can also be regenerated as alkali metal carbonate, which is a raw material for synthesis. As is clear from the above description, the present invention does not use any water to clean the solid matter by-produced in the reaction system, so there is no problem of corrosion of equipment materials.

Moreover, since the extraction solvent can be easily separated from the organic carbonate produced in the reaction system, it can be used repeatedly as an extraction solvent. In order to carry out the present invention more specifically, the present invention will be described below using comparative examples and examples, but the present invention is not limited to these examples.

In the examples, organic halides were dehydrated with anhydrous calcium chloride and then subjected to simple distillation, alcohols were dehydrated with anhydrous magnesium sulfate and then subjected to simple distillation, and special grade reagents were used as catalysts as they were.

The compositions of the reaction liquid phase and the extract were expressed as area percentages (hereinafter simply expressed as GC%) determined by gas chromatography.

Reference example: An autoclave with a capacity of 500 ml and equipped with an electromagnetic fly grinder (
Nitto Autocube Co., Ltd.), soda ash light ash (Tokuyama Soda Co., Ltd.) 58.3 hours, allyl chloride 114.
On August 8th, 3.2 nights of triethylamine was charged, and the system was replaced with carbon dioxide gas.

Thereafter, carbon dioxide gas was pressurized to 30k9'G. The autoclave was heated to room temperature (
Diethylene glycol 26.5 ml at 24°C)
It was continuously added dropwise over a period of time. During this time, the carbon dioxide pressure was 3
It was maintained at 0 kg/ground G. Thirty minutes after the completion of the dropwise addition of the ethylene glycol, the temperature was raised to 100 qo using an electric heater, and the mixture was reacted for 4 hours. The pressure during the reaction was 65 to 70 k9'. After the reaction, the autoclave was cooled to room temperature, the internal pressure was purged, and then the autoclave was opened to discharge the reaction slurry. Comparative Example The reaction slurry obtained in the reference example and 800 cc of tap water were placed in a separating funnel to dissolve the solids.

After adding 800 cc of water to the separated and floating organic layer and mixing well, it was left to stand for one day. The precipitated organic layer was separated and subjected to simple distillation. As a result, 60.4 ml of allyl chloride was recovered as a distillate. Initially, about 20 cc of crab exudate was cloudy due to water content. The distillation residue was 91.7g of diethylene glycol bis(allyl carbonate) in 62.1 hours. C.
%Met. Example 1 The reaction slurry obtained in Reference Example was suctioned and separated using an aspirator using a qualitative paper having a diameter of 11 mm (Toyo Sarugami Co., Ltd.: Qualitative Paper No. 2).

The test was completed in about 1 minute, and the droplets stopped falling. Diethylene glycol bis(allyl carbonate) 32. $
．． C. A flow rate of 109.4% was obtained. The liquor was subjected to simple distillation to recover 48.3 ml of allyl chloride. The distillation residue was washed with 100cc of water and dehydrated with anhydrous sodium sulfate to obtain a purity of 91.4G. C. 49.1% of crude diethylene glycol bis(allyl carbonate) was obtained. 50 cc of allyl chloride was added to the collected solid material, and the mixture was thoroughly stirred and filtered with suction. This operation was repeated four times. The content of diethylene glycol bis(allyl carbonate) in the extracted and recovered liquid was 12.54.
0 1.4 0. $. C. %Met. Combine all extracted extracts and distill in the same manner as the reaction slurry.
Allyl chloride 176%, purity 92. $. C. % crude diethylene glycol bis(allyl carbonate) 15
．． I got one night. Example 2 The reaction of Reference Example was carried out using a combination of the allyl chloride recovered from the reaction slurry monkey liquid and the extraction recovery liquid in Example 1 as a raw material.

The reaction slurry was prepared in the same manner as in Example 1 and diethylene glycol bis(allyl carbonate) 34. leather. C.
A solution of 106.4% was obtained. In addition, extraction was repeated three times from the separated solids in the same manner as in Example 1 to obtain 144 volumes of recovered extract liquid. Diethylene glycol bis(
Allyl carbonate) content is 8.20. C. %Met. Example 3 120 minutes of the extracted and recovered liquid obtained in Example 2 was used in place of allyl chloride in Reference Example, and a reaction was carried out in the same manner as in Reference Example to obtain a reaction slurry.

Thereafter, the reaction slurry was treated in the same manner as in Example 1 to obtain a reactant solution and three extracts, which were combined and subjected to simple distillation. As a result, 162% of allyl chloride was recovered, and the purity was 91% from the distillation residue. powder. C. % crude diethylene glycol bis(allyl carbonate) 7
I got 7 nights. Example 4 Allyl chloride 45.9 yen and acetonitrile 100 yen instead of allyl chloride 114.8 yen in the reference example
A reaction was carried out in the same manner as in Reference Example using cc.

Thereafter, the reaction slurry was separated in the same manner as in Example 1, and diethylene glycol bis(allyl carbonate) 28.7
G. C. A solution of 127% was obtained. 5. Simple distillation of the oak liquor to obtain A-IJ chloride.5. Illusion. C. %, acetonitrile 93
．． 7G. C. A distillate of 64% was obtained. The purity from the distillation residue is 90. Momme. C. 52.3% of crude diethylene glycol bis(allyl carbonate) was obtained. After adding 50 cc of acetonitrile to the garden molds that had been delivered and thoroughly rinsing them, suction sarugashi was performed. This operation was repeated four times. The contents of diethylene glycol bis(allyl carbonate) in the resulting extracted recovery liquid were 10.4 and 3.8, respectively.
1.2, 0.4G. C. %Met. Example 5 A reaction was carried out in the same manner as in the Reference Example using 45.9 ml of allyl chloride and 100 cc of a combined solution of the three extractions of Example 4 instead of the 114.8 ml of allyl chloride used in the reference example.

Claims (1)

[Claims] 1. Obtaining an organic carbonate by reacting an organic halide, an alkali metal carbonate, an alcohol, and a carbon dioxide gas,
When recovering the organic carbonate from the slurry containing the organic carbonate, solid matter is separated from the slurry containing the organic carbonate, a liquid phase containing the organic carbonate is recovered, and the separated solid matter is washed with an organic solvent. 1. A method for separating and recovering organic carbonate, which comprises extracting and recovering organic carbonate occluded in a solid substance using an organic solvent. 2. The method according to claim 1, wherein the organic solvent is an organic halide. 3 Claims that include extracting the organic carbonate occluded in a solid substance into an organic solvent, separating the organic solvent by distillation, and reusing part or all of the organic solvent as a reaction solvent or a solvent for washing the solid substance. The method described in 1.