JPS635020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the effective use of 1,2-dichloropropane.

More specifically, a method for producing allyl esters by reacting a mixture of decomposition products obtained by decomposing 1,2-dichloropropane, mainly consisting of allyl chloride and 1-chloropropenes, with carboxylic acids. Mainly 1-
This invention relates to the recovery of allyl chloride from unreacted materials consisting of chlorpropenes and allyl chloride.

1,2-dichloropropane is produced as a by-product during the production of allyl chloride by high-temperature chlorination of propylene and during the production of propylene oxide by chlorohydrination of propylene.
It is essential to suppress the by-product of 2-dichloropropane in order to improve the production unit of allyl chloride and propylene oxide.
Nevertheless, the amount of by-product 1,2-dichloropropane is considerable, and this by-product 1,2-
Effective use of dichloropropane has become an important issue in order to improve the basic unit of production in these manufacturing industries.

By the way, the main uses of 1,2-dichloropropane are inexpensive ones such as a solvent for 1,3-dichloropropene, which is a nematocide, and a solvent for asphalt for paving and oils and fats. However, 1,2-dichloropropane is a halogenated hydrocarbon, and its use as a solvent is restricted for safety reasons. Research has also been conducted to obtain allyl chloride by dehydrochlorinating 1,2-dichloropropane, but usually, when 1,2-dichloropropane is dehydrochlorinated, allyl chloride and 1-chloropropene (cis , trans) and 2-chloropropene are produced, and it is difficult to separate and purify them from each other. Moreover, in this method, a relatively large amount of allyl chloride is produced with a reaction rate of about 50 to 90% and a selectivity of about 40 to 70%. However, in order to isolate it from the mixture on an industrial scale, it is not a practical method because it requires more expense than the production of allyl chloride by directly chlorinating propylene. Therefore, attempts have been made to use these mixtures as industrial raw materials, but
For example, in the chlorohydrination reaction, not only allyl chloride but also chloropropenes are reacted, so the reaction product becomes a mixture, requiring expensive isolation and purification as in the case of decomposition products.

Under such circumstances, the present inventors have earnestly studied the effective use of 1,2-dichloropropane, first decompose 1,2-dichloropropane, and obtained mainly allyl chloride and chloropropene. proposed a method of converting only allyl chloride in the decomposition product into mainly allyl esters by reacting the decomposition product consisting of with various carboxylic acids (Japanese Patent Application No. 114,286/1986).

After that, we further considered a method for industrially effective use, and after reacting the decomposition product with carboxylic acids to produce allyl esters,
By recycling unreacted allyl chloride and chloropropenes, it is possible to almost completely convert allyl chloride in the decomposition product of 1,2-dichloropropane into allyl esters, and also to convert chlorpropenes into allyl esters. It has been found that it can be separated and obtained with high purity.

That is, in the method proposed above, 1,2-
In order to react with carboxylic acid to almost completely consume allyl chloride in the decomposition product of dichloropropane, use reaction equivalents of carboxylic acid and allyl chloride and select reaction conditions, or In contrast, methods such as using an excess amount of carboxylic acid must be used.

However, among these methods, the former method requires a long reaction time and the yield of allyl esters is significantly reduced due to polymerization of the produced allyl esters, and the latter method
Excessive carboxylic acid remains, resulting in a decrease in the basic unit of carboxylic acid, and depending on the carboxylic acid, there are problems such as the fact that it is extremely difficult to separate the unreacted carboxylic acid and the produced allyl esters.

The method of the present invention solves these problems (1) 1, 2
- A decomposition product of dichloropropane, mainly consisting of allyl chloride and chloropropenes (hereinafter simply referred to as the decomposition product), is reacted as a mixture with carboxylic acids to produce allyl esters. The unreacted product mainly containing allyl chloride and chloropropenes (hereinafter simply referred to as the first unreacted product) obtained in this process is reacted with an excess amount of carboxylic acid relative to the allyl chloride contained therein, A reaction mixture containing allyl ester produced by almost completely consuming chloride and unreacted carboxylic acid is obtained, and at the same time, highly pure chloropropenes are separated and obtained. Then (2) the reaction mixture is reacted with the decomposition product containing allyl chloride in an amount greater than the reaction equivalent to the unreacted carboxylic acid contained therein, thereby converting the unreacted carboxylic acid in the reaction mixture into allyl ester. Separate unreacted chloropropenes and allyl chloride (hereinafter simply referred to as the second unreacted product),
By recovering and recycling this second unreacted product to the reaction step (1) above, allyl chloride and chloropropene produced by decomposing 1,2-dichloropropane are converted into allyl esters. The latter problem was solved by isolating high-purity chloropropenes.

That is, the method of the present invention involves decomposing 1,2-dichloropropane and reacting the resulting decomposition product containing mainly allyl chloride and chloropropenes with carboxylic acids to produce allyl esters. In the method, (1) unreacted products (hereinafter simply referred to as decomposition products) containing mainly allyl chloride and chloropropenes obtained when reacting the decomposition products (hereinafter simply referred to as decomposition products) with carboxylic acids to produce allyl esters; , simply referred to as the first unreacted product) with a reaction equivalent or more of carboxylic acid to the allyl chloride contained therein, and a reaction mixture containing the produced allyl esters and unreacted carboxylic acid, and chlorpropenes. (2) Next, the reaction mixture is reacted with a decomposition product containing allyl chloride in an amount greater than the reaction equivalent of the unreacted carboxylic acid contained therein, and the resulting allyl esters and (3) Separate this second unreacted material from the first unreacted material of (1) above (hereinafter simply referred to as the second unreacted material). This is a method for separating high-purity chloropropenes from a decomposition product of 1,2-dichloropropane and producing allyl esters.

The decomposition product of 1,2-dichloropropane used in the method of the present invention can be obtained by thermally decomposing 1,2-dichloropropane in the presence or absence of a catalyst or by reacting it with an alkali. Also,
Of course, those having the same composition as the decomposition products obtained in this way can also be used.

As the carboxylic acids that can be used in the method of the present invention, any aromatic carboxylic acid, an alkali metal salt thereof, or an aromatic carboxylic acid anhydride can be used. Specifically, phthalic acid, isophthalic acid, terephthalic acid, benzoic acid, naphthalene dicarboxylic acid,
Examples include aromatic carboxylic acids such as nitrophthalic acid, chlorobenzoic acid, cinnamic acid, and alkali metal salts thereof. Moreover, as the alkali metal salt of the above-mentioned carboxylic acid, sodium salt and potassium salt are preferable.

Furthermore, instead of alkali metal salts of carboxylic acids,
Carboxylic acid anhydrides and alkali metal carbonates can be used.

Hereinafter, one example of the method of the present invention will be explained in more detail with reference to FIG.

The flow sheet shown in FIG. 1 is for producing allyl ester from 1,2-dichloropropane.
Usually, the carboxylic acids and the catalyst are fed all at once from 1 to the reactor 7 equipped with a stirrer. Next, a reaction is carried out by continuously feeding a decomposition product obtained by decomposing 1,2-dichloropropane from 2 and consisting mainly of allyl chloride and chloropropenes. The reaction conditions at this time vary depending on the type of carboxylic acid, but the reaction pressure is 0 to 50 kg/cm ² G, preferably 0.
-10Kg/ ^cm2G , reaction temperature is 50-300°C, preferably 120-200°C.

Through this reaction, mainly allyl chloride in the 1,2-dichloropropane decomposition product reacts with carboxylic acids to selectively produce allyl esters. On the other hand, unreacted gases mainly containing chloropropenes and allyl chloride are removed from 4 continuously during the reaction or all at once after the completion of the reaction, and are stored in a recovery tank 9 via a cooler 8. On the other hand, the allyl esters as reaction products are transferred to a storage tank 10 through 6, where the produced inorganic salts are filtered, the catalyst and the like are recovered as necessary, and then the allyl esters are separated and purified by extraction, distillation, etc.

Although the allyl esters produced are obtained by the above method, the first unreacted product recovered still contains allyl chloride and chlorpropene which remain unreacted, and these are not recovered. It is extremely uneconomical to dispose of them and to collect them separately.

In the method of the present invention, in the above method, 1,
After reacting the decomposition product of 2-dichloropropane with carboxylic acids, the reaction is carried out as follows using the first unreacted material containing allyl chloride and chloropropenes stored in the recovery tank 9. .

That is, the first unreacted material contains a considerable amount of allyl chloride that can be converted into allyl ester.

Therefore, as described above, the carboxylic acids, catalyst, etc. are fed all at once. The first unreacted material containing chloropropenes and allyl chloride stored in the recovery tank 9 is fed into this continuously or all at once. The amount of carboxylic acids supplied to the reactor in this reaction and the amount of recovered unreacted material is such that the amount of carboxylic acids is equal to or more than the reaction equivalent amount of allyl chloride contained in the unreacted material.
While reacting under the same conditions as described above, the unreacted gas, which is mainly chloropropenes, is extracted from 3 continuously or all at once after the reaction is completed, and the chlorpropenes are isolated. If necessary, it may be removed using a suction pump or the like.

Through this reaction, allyl chloride in the unreacted material reacts with carboxylic acids to give a reaction mixture containing allyl esters and unreacted carboxylic acids, while chloropropenes containing almost no allyl chloride are obtained.

Furthermore, the decomposition product of 1,2 dichloropropane is fed continuously or all at once into the reaction mixture in the reactor 7, and the reaction is carried out under the same reaction conditions as described above. Unreacted substances containing allyl chloride and chloropropenes are extracted from 4, passed through a cooler 8, and stored in a recovery tank 9.

The second unreacted product stored in this manner contains a considerable amount of unreacted allyl chloride together with chloropropenes, and is recycled in place of the first unreacted product.

In the method of the present invention, the decomposition products obtained by decomposing 1,2-dichloropropane, mainly consisting of allyl chloride and chloropropenes, are reacted as a mixture with carboxylic acids to selectively allyl chloride. Although it can be converted into esters, by recycling the unreacted material containing several tens of percent allyl chloride, it is possible to utilize it almost completely, and the recovery rate of allyl chloride can be significantly improved. I can do it. Chlorpropenes can also be isolated, and chlorpropenes of purity that can be used industrially can be obtained. Therefore, according to the method of the present invention, 1 and 2
-Dichloropropane can be used industrially advantageously.

Further, in the method of the present invention, the reaction rate and yield of allyl chloride in the 1,2-dichloropropane decomposition product are comparable to those of pure allyl chloride.

The present invention will be explained below using examples.

Example (1) Thermal decomposition of 1,2-dichloropropane An electric heater was wound around the center 70 cm of a quartz tube with an inner diameter of 25 mm and a length of 110 cm, and the internal temperature was set at 480°C. 1,2-dichloropropane was charged at 350 g/hr from one end of this quartz tube and thermally decomposed inside the tube.
The decomposition products coming out in gas form from the other end were condensed in a condenser cooled with ice water to obtain decomposition products at a rate of 230 g/hr. The composition of this decomposition product is allyl chloride
47.2% by weight, 47.7% by weight of 1-chloropropene (cis and trans combined), 0.1% by weight of benzene, and 5.0% by weight of unreacted 1,2 dichloropropane.

(2) Production of allyl ester Next, 148 g (1 mol) of phthalic anhydride, 116 g (1.1 mol) of anhydrous sodium carbonate, 5 g of triethylamine, 0.9 g of water, and 0.5 g of hydroquinone were placed in an autoclave with an internal volume of 1, and then the autoclave was heated. After replacing the inside with nitrogen, heat to 140℃ while stirring.
The temperature rose to Next, 357 g of the thermal decomposition product of 1,2-dichloropropane (allyl chloride content)
(168.4 g, 2.2 mol) was gradually charged over 4 hours.
Thereafter, the reaction was continued for another 2 hours. The reaction temperature is
The temperature was maintained at 140° C. and the reaction pressure was 10 Kg/cm ² G. Carbon dioxide gas and unreacted allyl chloride and chlorpropene were gradually removed from the autoclave and discharged to the outside of the system through a dry ice trap. The composition of unreacted substances in the dry ice trap at this time was 19.8% by weight of allyl chloride, 1% by weight of allyl chloride,
-Chlorpropene (cis and trans combined) 80.2
It was in weight%.

After the reaction was completed, the pressure inside the autoclave was gradually lowered to normal pressure and cooled to room temperature. Then, the contents were taken out from the autoclave, the formed inorganic substances were filtered, the filtered residue was washed with ether, and the filtrate and ether washings were combined. After washing this ether solution with water to remove water-soluble components,
The ether solution was dried over anhydrous sodium sulfate, the ether was distilled off under reduced pressure, and diallyl phthalate was extracted.
227 g (0.92 mol) was obtained.

(3) Reaction of unreacted substances and carboxylic acid 148 g (1 mol) of phthalic anhydride, 116 g (1.1 mol) of anhydrous sodium carbonate, 5 g of triethylamine, water
After putting 0.9 g of hydroquinone and 0.5 g of hydroquinone into an autoclave having an internal volume of 1, the inside of the autoclave was purged with nitrogen, and the temperature was raised to 140°C while stirring. Next, 193 g of recovered allyl chloride obtained in (2) (allyl chloride content: 38.3 g, 0.5 mol) was gradually charged over 4 hours. Thereafter, the reaction was continued for another 2 hours. The reaction temperature was maintained at 140℃, and the pressure was 10Kg/cm ² G.
The carbon dioxide gas and unreacted chloropropenes generated were gradually removed from the autoclave and discharged to the outside of the system through a dry ice trap. In the dry ice trap at this time, 1-chloropropene containing 0.3% by weight of unreacted allyl chloride was obtained.

(4) Reaction between the reaction mixture and the thermal decomposition product After the reaction, the pressure inside the autoclave was gradually lowered to normal pressure and the reaction mixture containing diallyl phthalate and unreacted phthalic anhydride was added to the reaction mixture obtained in (1). 1,2-
324 g of dichloropropane thermal decomposition product (allyl chloride content: 153 g, 2.0 mol) was gradually charged over 4 hours. Thereafter, the reaction was continued for an additional 2 hours. The reaction temperature is
Carbon dioxide gas, unreacted allyl chloride, and chlorpropene were gradually removed from the autoclave while maintaining the temperature at 140° C. and a pressure of 10 Kg/cm ² G, and discharged to the outside of the system through a dry ice trap. The composition of unreacted substances in the dry ice trap was 20.0% by weight of allyl chloride and 80.0% by weight of 1-chloropropene (cis and trans combined).

After the reaction was completed, the pressure inside the autoclave was gradually lowered to normal pressure, and the autoclave was cooled to room temperature. Then, purified in the same manner as in (2) to obtain 236g of diallyl phthalate.
(0.96 mol) was obtained.

(5) Reuse of unreacted materials The unreacted materials recovered in the dry ice trap were used in the same reaction as in (3) above, and similar results were obtained.

[Brief explanation of the drawing]

FIG. 1 illustrates a flow sheet of the method of the present invention. In FIG. 1, 7 is a reactor with a stirrer, 8 is a cooler, 9 is a collection tank, and 10 is a product storage tank.

Claims (1)

[Claims] 1. A method for producing allyl esters by decomposing 1,2-dichloropropane and reacting the resulting decomposition product containing mainly allyl chloride and chloropropenes with carboxylic acids. (1) Unreacted products (hereinafter simply referred to as decomposition products) mainly containing allyl chloride and chloropropanes obtained when the decomposition products (hereinafter simply referred to as decomposition products) are reacted with carboxylic acids to produce allyl esters; (simply referred to as the first unreacted product) with carboxylic acids in an amount equal to or more than the reaction equivalent of the allyl chloride contained therein, and a reaction mixture containing the generated allyl esters and unreacted carboxylic acids and chlorpropenes. (2) Next, the reaction mixture is reacted with a decomposition product containing allyl chloride in an amount greater than the reaction equivalent of the unreacted carboxylic acids contained therein to separate the produced allyl esters and allyl chloride. (3) Separate this second unreacted material from the unreacted material containing chloride and chloropropenes (hereinafter simply referred to as the second unreacted material), and use this second unreacted material as the first unreacted material in (1) above. A method for producing allyl esters characterized by cyclic use.