JPH05286918A - Production of acrylonitrile dimer - Google Patents

Abstract

PURPOSE:To produce the subject straight chain dimer in high selectivity by dimerizing acrylonitrile in the presence of a ruthenium catalyst and a carboxylic acid without using a large amount of hydrogen while inhibiting generation of by-products not ready convertible to the raw compound. CONSTITUTION:When producing a straight chain dimer such as 1,4- dicyanobutene, 1,4-dicyanobutadiene and adiponitrile by dimerization of acrylonitrile, acrylonitrile as the raw material is introduced into a dimerization reactor while simultaneously introducing a carboxylic acid (e.g. acetic acid or propionic acid) and a ruthenium compound and the resultant mixture is reacted preferably at 100 to 180 deg.C. From the reaction product, the unreacted raw material, the unreacted carboxylic acid and propionitrile as the by-product are separated and the separated raw materials and the carboxylic acid are recycled into the dimerization process. The by-produced carboxylic acid beta-cyanoethyl ester is then separated from the dimer and subsequently subjected to an exchange reaction to obtain the carboxylic acid and acrylonitrile. The obtained carboxylic acid and acrylonitrile are recycled and supplied to the dimerization process.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a linear dimer of 1,4-dicyanobutene, 1,1, by dimerization of acrylonitrile.
A novel continuous production method for obtaining a dinitrile by a method for producing a dimer of acrylonitrile for producing 4-dicyanobutadiene and adiponitrile, which comprises: By converting the carboxylic acid β-cyanoethyl ester which is simultaneously produced in the dimerization reaction into acrylonitrile and carboxylic acid and circulating it to the dimerization reaction, the selectivity of the acrylonitrile dimer is increased, and it is possible to carry out industrially advantageously. It provides a simple process. The obtained dinitrile is an intermediate of hexamethylenediamine, which is a raw material of nylon-66, and an intermediate of rust preventive and vulcanization accelerator of rubber.

[0002]

2. Description of the Related Art Conventionally, a method for producing 1,4-dicyanobutenes and adiponitrile from acrylonitrile using a ruthenium catalyst is described in A. Misono, et a
1, Bull. Chem. Soc. Jpn. , 40 (1
967) 931 and is publicly known. This is a method of dimerizing acrylonitrile in the presence of hydrogen using a ruthenium catalyst. The reaction of this method discloses that the dimerization reaction of acrylonitrile does not occur at all when it is carried out without adding hydrogen, and the dimerization reaction of acrylonitrile proceeds only when the reaction is carried out in a hydrogen atmosphere.

However, in the above-mentioned reaction, when the reaction is carried out in a hydrogen atmosphere, the hydrogenation reaction of acrylonitrile occurs simultaneously with the dimerization of acrylonitrile, and a large amount of propionitrile is by-produced. Therefore, in order to improve the selectivity of this dimerization reaction, it is necessary to convert propionitrile to acrylonitrile by a dehydrogenation reaction, but this reaction also has low selectivity and catalytic activity, and therefore propionitrile The industrialization of the process of reconverting to acrylonitrile has the disadvantage that it is disadvantageous.

Japanese Patent Publication Nos. 44-24585 and 45-45
No. 4048 and Japanese Examined Patent Publication No. 54-12450 disclose that an improvement in the selectivity of the acrylonitrile linear dimer was recognized. In the production method, the selectivity of the acrylonitrile straight chain dimer is 55 to 67%, but since the reaction is carried out in the presence of hydrogen, propionitrile is 33 to 4%.
Since it was produced with a selectivity of 5% and a large amount of by-product of propionitrile was produced, it was not an industrially advantageous method for producing a linear dimer of acrylonitrile.

In Japanese Examined Patent Publication No. 54-12450, dimerization is carried out by using an inorganic ruthenium derivative, ruthenium carboxylate or ruthenium complex as a catalyst in the presence of hydrogen, and dimerization is carried out. From the group consisting of lead, zinc, cadmium, tin, iron and manganese. The dimerization reaction is promoted by coexisting a carboxylic acid metal salt of a selected element. Even in the method for producing acrylonitrile linear dimer according to this known technique, there is a problem in that the production of propionitrile cannot be avoided because hydrogen is used.

According to JP-B-51-146420, acrylonitrile is added in an amount of 300-6 in the absence of hydrogen.
It discloses that at a reaction temperature of 00 ° C., it can be dimerized to C ₆ dinitrile using a ruthenium catalyst. However, even with this method, when the amount of by-product propionitrile is small, the conversion rate of acrylonitrile is low and it is about a few percent, and when the conversion rate of acrylonitrile is high, the by-product of propionitrile increases. , The selectivity to C6 dinitrile decreases. Moreover, the dinitrile produced has a problem that a mixture of a linear dimer and a branched dimer is produced and the selectivity of the intended linear dimer is low.

Therefore, the above-mentioned conventional method for producing a linear dimer of acrylonitrile has a problem that a large amount of by-products such as propionitrile which cannot be easily converted into an acrylonitrile raw material are produced, and the process is industrialized. , There was a disadvantage. An object of the present invention is to produce a linear dimer of acrylonitrile without producing a large amount of by-products such as propionitrile that cannot be easily converted into acrylonitrile in the production of acrylonitrile dimer. To provide the process.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for producing an acrylonitrile dimer for producing a linear dimer of 1,4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile by dimerization of acrylonitrile, Using a ruthenium compound as a catalyst without using a large amount of hydrogen, in the presence of a carboxylic acid, a dimerization reaction is performed without producing a large amount of propionitrile, and a carboxylic acid β- simultaneously produced in the dimerization reaction PROBLEM TO BE SOLVED: To provide a continuous production process of acrylonitrile dimer capable of effectively producing acrylonitrile dimer on an industrial scale by converting cyanoethyl ester into acrylonitrile and carboxylic acid and circulating the dimerization reaction. Is.

As a result of earnest studies on the above-mentioned problems, the present inventors have used a ruthenium compound as a catalyst in the dimerization reaction of acrylonitrile in the presence of carboxylic acid without using a large amount of hydrogen. It was found that the by-product of propionitrile can be greatly suppressed by carrying out the dimerization reaction. Further, carboxylic acid β-cyanoethyl ester by-produced in this reaction is an adduct of carboxylic acid and acrylonitrile, and it was found that it can be converted to acrylonitrile as a raw material with good selectivity, and the converted acrylonitrile and carboxylic acid are again dimerized. It became possible to circulate and supply to. Therefore, it was found that the selectivity of the acrylonitrile linear dimer can be significantly improved, and it was extremely advantageous for the production of the acrylonitrile linear dimer, and the invention relating to a novel industrial continuous process was completed. ..

The carboxylic acid β-cyanoethyl ester is
It is represented by the following general formula.

[Chemical 1] (In the formula, R is hydrogen or a saturated or unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group or an aromatic hydrocarbon group.)

[0011]

The present invention provides a method for producing an acrylonitrile dimer for producing a linear dimer of 1,4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile by dimerization of acrylonitrile, (A). A dimerization reaction step in which acrylonitrile is introduced into a dimerization reactor of acrylonitrile, and a carboxylic acid and a ruthenium compound are introduced to carry out a dimerization reaction to obtain a reaction product containing a dimer of acrylonitrile.

(B). The reaction product in the dimerization reaction step is guided, and unreacted acrylonitrile, unreacted carboxylic acid, product propionitrile, carboxylic acid β-cyanoethyl ester and acrylonitrile dimer are separated in the separation step and separated. The acrylonitrile and the carboxylic acid were recycled to the dimerization reaction step and supplied as a raw material, and the separated carboxylic acid β-cyanoethyl ester was supplied to the conversion step of the carboxylic acid β-cyanoethyl ester in the next step, Separation step for separating a dimer of acrylonitrile, which is the target product of reaction in the dimerization reaction

(C). A catalyst or a catalyst is added to the carboxylic acid β-cyanoethyl ester derived from the separation step, and the mixture is heated to perform a conversion reaction of the carboxylic acid β-cyanoethyl ester to obtain acrylonitrile and a carboxylic acid. The present invention relates to a method for producing an acrylonitrile dimer, characterized in that the acid comprises a conversion reaction step in which the acid is separated and circulated and supplied to each dimerization reaction step.

Conventionally known acrylonitrile dimerization methods were said to require a hydrogen atmosphere. In the present invention, however, hydrogen is not particularly required in the acrylonitrile dimerization method in the presence of a carboxylic acid as described above. The reaction is characteristic. In a reaction atmosphere where a large amount of hydrogen is used, when mixed with air, the explosive range is wide, so the reaction operation becomes complicated to operate safely, and the equipment becomes complicated because safety is required for airtightness. Not using a large amount of hydrogen industrially is very advantageous for simplifying the equipment and for safe operation.

Next, each step of the present invention will be described in detail below. Dimerization reaction step As the dimerization reaction step in the present invention, acrylonitrile, ruthenium compound, and carboxylic acid are continuously introduced into a dimerization reactor, and a predetermined reaction temperature and reaction pressure are set in an air atmosphere or an inert gas atmosphere. It is preferable to hold and carry out the dimerization reaction for a predetermined reaction time.

As the conditions for the dimerization reaction of acrylonitrile, the reaction temperature is preferably 70 to 220 ° C., particularly preferably 100 to 180 ° C. If the reaction temperature is too low, the reaction rate is slow and too high. If so, the deactivation of the catalyst becomes faster, which is not preferable. Reaction pressure is 50 mmHg
The reaction can be carried out under any pressure from under reduced pressure up to 100 kg / cm ² . The reaction time depends on the temperature,
Although it depends on the catalyst, it is preferably 0.1 to 10 hours.

Although it is not necessary to use a solvent, a solvent such as nitrile, ether, hydrocarbon, amide, halogenated hydrocarbon and ester can also be used in order to carry out a mild reaction. Although it may be in the presence of air, it is preferable to use an inert gas such as nitrogen, carbon dioxide, or argon gas in order to avoid an explosion atmosphere for safety.

The ruthenium compound as a catalyst used in the invention is an inorganic ruthenium derivative, ruthenium carboxylate or a coordination compound having ruthenium as a central atom, such as ruthenium chloride, ruthenium bromide, ruthenium iodide, Ruthenium sulfate, inorganic ruthenium derivatives such as ruthenium nitrate, ruthenium acetate, ruthenium propionate, ruthenium butanoate, ruthenium pentanoate, ruthenium hexanoate, ruthenium stearate, ruthenium naphthenate, ruthenium oxalate,
Ruthenium carboxylate such as ruthenium succinate, Ru
Coordination compounds having ruthenium as the central atom such as Cl ₂ (acrylonitrile) ₃ , RuCl ₂ (triphenylphosphine) ₃ , and RuCl ₂ (triphenylphosphine) 4 can be used. These ruthenium compounds may be used alone or as a mixture of a plurality of compounds.

In the present invention, a base and / or a reducing agent may be used in combination with the above ruthenium compound. As the base used, sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, sodium acetate, sodium propionate, sodium methoxide, sodium ethoxide, ammonia, methyl Examples thereof include amine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, aniline, methylaniline, dimethylaniline, ethylaniline and dimethylaniline.

Preferred examples of the reducing agent include trimethylstannane, triethylstannane, tri-n-propylstannane, tri-n-butylstannane, triphenylstannane, di-n-propylstannane and di-. -N-
Butylstannane, diphenylstannane, trimethylgermane, triethylgermane, tri-n-propylgermane, sodium hydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, metallic sodium, metallic magnesium, metallic zinc, etc. Can be mentioned.

The amount of the ruthenium compound used as a catalyst in the present invention is 0.001 to 1 with respect to acrylonitrile.
Preference is given to using 0 mol%. When a base and / or a reducing agent is used in combination, the addition amount of the base is
If the amount is small, the effect of addition is small, and if the amount is large, the amount of dimer produced is reduced due to loss of acrylonitrile. It is preferable that the amount be a molar ratio. The reducing agent is suitably used in a proportion of 0.05 to 30 times mol, preferably 0.1 to 20 times mol, of the ruthenium compound used.

As the organic acid used in the present invention,
Suitable are organic carboxylic acids having 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms, optimally acetic acid, propionic acid, methylpropionic acid, dimethylpropionic acid,
Butanoic acid, methylbutanoic acid, ethylbutanoic acid, dimethylbutanoic acid, pentanoic acid, hexanoic acid and the like are preferably used. These carboxylic acids may be added alone, or a plurality of compounds may be mixed and used. The above carboxylic acid is 0.0 based on the acrylonitrile used.
It is preferable to use it in a ratio of 1 to 100 times mol, preferably 0.05 to 10 times mol. If the amount of carboxylic acid used is too small, the dimer formation rate will be slow, and if it is too large, the acrylonitrile concentration will decrease and the dimer formation rate will be slow, which is not preferable. The reaction may be a continuous reaction method of a tubular reaction system or a tank reaction system, or a batch reaction method.

Unreacted Substance Separation Step The reaction product obtained in the dimerization reaction step is an acrylonitrile dimer of the desired product, unreacted acrylonitrile and unreacted carboxylic acid, propionitrile, carboxylic acid β-cyanoethyl ester. And because it contains low polymer,
The reaction product obtained in the dimerization reaction step is derived and separated in the unreacted material separation step to separate unreacted acrylonitrile and unreacted carboxylic acid and propionitrile from the reaction product. The unreacted acrylonitrile and carboxylic acid separated in this step are circulated and fed again to the dimerization reaction step as raw materials.

As the separation unit operation in the unreacted material separation step, a distillation operation is suitable, and unreacted acrylonitrile and carboxylic acid and propionitrile by a side reaction are
Target product acrylonitrile dimer, carboxylic acid β-
Comparing the vapor pressure with cyanoethyl ester and low polymer, propionitrile due to side reaction with unreacted acrylonitrile and carboxylic acid clearly forms a light-boiling component, so the reaction product obtained in the dimerization reaction step Then, unreacted acrylonitrile and carboxylic acid as light boiling components are separated by distillation from propionitrile by a side reaction, and the separated unreacted acrylonitrile and carboxylic acid are recycled to the raw materials and reused. The by-product propionitrile separated as a light boiling component is taken out of the system and discarded.

On the other hand, the acrylonitrile dimer, the carboxylic acid β-cyanoethyl ester, and the low-polymerization product, which are the desired products, are preferably separated as high-boiling components from the residue obtained by substantially removing the light-boiling components. It is desirable to select a perforated plate column, a packed column, a plate column or a bubble column as the rectification column for the distillation operation to be separated. As the distillation operation, continuous distillation is preferable, but batch distillation may also be used.

The process for separating the high-boiling components is essentially composed of the following two separation processes. That is, the carboxylic acid β-cyanoethyl ester is separated, and the product separation step to be supplied to the conversion step of the next step and the high boiling point of the residue excluding the carboxylic acid β-cyanoethyl ester are separated from the target product acrylonitrile dimer. A dimer separation step.

The high-boiling fraction obtained in the above-mentioned unreacted matter separation step contains the target product acrylonitrile dimer (linear dimer 1,4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile). ), Carboxylic acid β-
Since it contains a cyanoethyl ester, a low polymer and a ruthenium catalyst used in the dimerization reaction step, it is desirable to carry out the separation operation in a distillation unit operation in order to separate each component. When the components are separated by distillation, the above components form a polymer at a high temperature. Therefore, it is preferable to prevent the formation of the polymer by performing a separation under reduced pressure that allows separation at a low temperature.

Product Separation Step In the case of vacuum distillation, the carboxylic acid β-cyanoethyl ester is separated as the first component from the high-boiling components of the above components from the vapor-liquid equilibrium, so that the carboxylic acid β-cyanoethyl ester is substantially separated. Separated and fed to the conversion reaction step.

Dimer Separation Step Next, since the high boiling point obtained from the bottom of the column contains the acrylonitrile dimer of the target product, the low polymerization product and the ruthenium catalyst used in the dimerization reaction step, Vacuum distillation is carried out in a high boiling fraction distillation column, but batch distillation is preferred because multi-component acrylonitrile dimers are separated. The target product acrylonitrile dimer is obtained from the top of the column.

The distillation residue from which the target product acrylonitrile dimer has been substantially sufficiently removed in the high boiling fraction distillation column is taken out from the bottom of the column. The residue from the bottom of the column contains by-produced low-polymerization products and the ruthenium catalyst used in the dimerization reaction step. Therefore, it is desirable to perform ruthenium catalyst recovery step to recover ruthenium.

Conversion reaction step The carboxylic acid β-cyanoethyl ester separated in the unreacted material separation step is introduced into this step, the conversion reaction is carried out by the following reaction to obtain acrylonitrile and carboxylic acid, and the dimerization reaction step Supply as a raw material. In the conversion reaction step, acrylonitrile and carboxylic acid are produced by heating carboxylic acid β-cyanoethyl ester without catalyst or in the presence of catalyst.

The conversion reaction of carboxylic acid β-cyanoethyl ester can be generally represented by the following reaction formula.

[Chemical 2] (In the formula, R is hydrogen or a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group or an aromatic hydrocarbon group.) That is, it is a sub-side in the dimerization reaction of the present invention. This is a very useful method for simultaneously producing acrylonitrile and a carboxylic acid with high selectivity by heating the resulting carboxylic acid β-cyanoethyl ester in the absence of a catalyst or in the presence of a catalyst.

The catalyst used in the conversion reaction of carboxylic acid β-cyanoethyl ester is a ruthenium compound, a copper compound, a silver compound, a cobalt compound, a mercury compound, a lead compound and a nickel compound. These metals are formic acid, acetic acid, Propionic acid, butanoic acid, pentanoic acid, hexanoic acid, stearic acid, naphthenic acid, oxalic acid, succinic acid,
Adipic acid, benzoic acid, and other organic carboxylates having 1 to 20 carbon atoms, halides, sulfates, inorganic salts, such as nitrates, acetylacetonate, and tertiary phosphine complexes, etc. Coordination with these metals as the central atom Compound, methoxide,
Alkoxides such as ethoxide, oxides, hydroxides,
These are simple substances of these metals. These catalysts may be used alone or as a mixture of a plurality of compounds.

The reaction method in this step is carried out by heating without catalyst or in the presence of a catalyst to produce acrylonitrile and carboxylic acid from carboxylic acid β-cyanoethyl ester. When the catalyst is added, the addition amount is suitably 10 mol% or less, preferably 5 mol% or less. If the added amount is large, the catalyst efficiency is not good.

The reaction temperature is preferably 40 to 300 ° C, preferably 60 to 250 ° C. The reaction pressure is
The reaction can be performed under any pressure from a reduced pressure of 50 mmHg to a pressure of 100 kg / cm ² . The reaction time of this step depends on the type of catalyst, the amount of catalyst used, the reaction temperature,
Varies depending on pressure and stirring conditions, but preferably 0.0
The reaction time is 1 to 50 hours, but a reaction time of 0.01 to 10 hours is preferable from the viewpoint of economical productivity.

In this step, a solvent may be used,
Also, it may not be used. Although it is not particularly necessary to use, for example, aromatic hydrocarbon, aliphatic or alicyclic hydrocarbon,
Ethers, nitriles and the like can be used as the reaction solvent.

The reaction can be carried out in a closed system, but it is preferable that the acrylonitrile and carboxylic acid produced are separated and reacted. The produced acrylonitrile and carboxylic acid are circulated and reused as raw materials for the dimerization reaction. In this case, the residue contains the low-polymerization product and the catalyst (when using a catalyst) as a by-product,
It is desirable to recover the catalyst by treating it in the catalyst recovery step.

When the carboxylic acid β-cyanoethyl ester is reacted under the above reaction conditions to carry out the reaction while separating the produced acrylonitrile and the carboxylic acid, a reactive distillation apparatus is used as the reaction apparatus for simultaneously carrying out the reaction and the separation. preferable. The reactive distillation apparatus should be installed with a reaction section at the bottom to allow a sufficient reaction residence time, and the reaction mode should be self-flowing in a tubular reaction system or a tank reaction system so that the reaction section can be sufficiently heated. The reaction method is also preferable, and the batch reaction method is also preferable.

Acrylonitrile and carboxylic acid are separated from the reaction product, and the separated acrylonitrile and carboxylic acid are recycled to the raw material for the dimerization reaction and reused.
The rectification part of the reactive distillation apparatus is a perforated plate column, a packed column, a plate column,
It is desirable to select a bubble tower. The residue from which acrylonitrile and carboxylic acid were separated in the rectification section was taken out intermittently from the bottom of the column, and the batch type reactive distillation apparatus was used for substantial reaction to further reduce the amount of by-produced low-boiling substances in the high-boiling fraction. Since it contains the polymer and the catalyst used in the reaction step (when a catalyst is used), it is desirable to perform the treatment in the catalyst recovery step to recover the catalyst.

Next, the manufacturing method of the present invention will be described with reference to FIG. FIG. 1 is a manufacturing process showing an embodiment of the present invention and does not limit the present invention. Acrylonitrile as a raw material, carboxylic acid, and a ruthenium catalyst are mixed at a predetermined ratio and supplied from a line 7. At this time, the acrylonitrile and the carboxylic acid separated and recovered from the pipe 11 derived from the unreacted material separation process, the pipe 16 derived from the conversion reaction process and the pipe 21 derived from the batch separation process are also mixed and reacted in the line 8. The raw materials are prepared so that the mixing ratio of the liquid is adjusted. The prepared raw material liquid is introduced into the dimerization reaction step 1 to carry out the dimerization reaction.

After the reaction, the reaction product of the dimerization reaction is introduced into the unreacted substance separation step 2 through the conduit 9, the acrylonitrile and the carboxylic acid are separated from the reaction product by the distillation unit operation, and the dimerization reaction step is performed through the conduit 11. To be used in circulation. In addition, the by-product of the reaction, propionitrile,
It is separated as a light-boiling component by a distillation unit operation, taken out of the system by the conduit 10 and discarded. The target product acrylonitrile dimer, carboxylic acid β-cyanoethyl ester, and low-polymerization product obtained as high-boiling components are led out through a conduit 12, and in the product separation step 3 and the dimer separation step 6, a high-boiling point product is obtained. The fraction is separated into each component. First, product separation step 3
Then, the carboxylic acid β-cyanoethyl ester is first separated as a high-boiling component by a distillation unit operation, and is discharged through the conduit 13.

In the dimer separation step 6, the product separation step 3
The target product acrylonitrile dimer is separated from the high-boiling fraction obtained by the conduit 18 from the bottom of the distillation column. Since the high boiling point obtained by the conduit 18 contains the acrylonitrile dimer of the target product, the low-polymerized by-product and the ruthenium catalyst, the acrylonitrile dimer is separated from the top of the column by vacuum distillation, and the conduit 19 Thus, an acrylonitrile dimer as a target product can be obtained. Further, since the high boiling point from the bottom of the column contains a low-polymerized product by-produced and a ruthenium catalyst, it is desirable to recover ruthenium by taking it out through the conduit 20 and treating it in the ruthenium catalyst recovery step.

The carboxylic acid β-cyanoethyl ester separated by the conduit 13 is directly introduced into the conversion reaction step 4 in the case of the non-catalytic conversion reaction, but when the catalyst is used, the required amount of the catalyst is supplied from the conduit 14 It is mixed and introduced into the conversion reaction step 4. In the conversion reaction step 4, carboxylic acid β-cyanoethyl ester is converted to obtain acrylonitrile and carboxylic acid.

The acrylonitrile and the carboxylic acid obtained by the conversion reaction are led out through the conduit 16 and recycled to the dimerization reaction step. The reaction concentrated solution is intermittently taken out through the conduit 15 from the bottom of the conversion reaction operation, and the reaction is substantially performed in the batch separation step 5, and the obtained acrylonitrile and carboxylic acid are intermittently discharged through the conduit 21. Mix into conduit 16. Since the residue taken out from the bottom of the column through the conduit 17 contains the low-polymerized by-product and the catalyst used in the reaction step (when a catalyst is used), it is treated in the catalyst recovery step to recover the catalyst. ..

[0045]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. Example 1 In the attached FIG. 1, ruthenium acetate was introduced into the dimerization reaction step 1 as a catalyst for the following raw material composition and dimerization reaction through a conduit 8 to carry out the reaction. Acrylonitrile 1500
Parts, 500 parts of acetic acid, and 13 parts of ruthenium acetate are supplied to the dimerization reaction step 1 from the conduit 8 per hour, and the dimerization reaction is carried out under stirring in a nitrogen atmosphere at a reaction temperature of 150 ° C. and a reaction gauge pressure of 5 kg / cm. ^{2 with a} reaction residence time of 6 hours. The composition of the reaction solution after 6 hours of reaction was analyzed by gas chromatography. As a result, 1200 parts of unreacted acrylonitrile, 1,4-dicyanobutene,
It contained 156 parts of a linear dimer of 1,4-dicyanobutadiene and adiponitrile, 9 parts of propionitrile, 249 parts of β-cyanoethyl acetate, 368 parts of acetic acid and 18 parts of a low polymer.

The results of the dimerization reaction were as follows: conversion of acrylonitrile was 20%, selectivity of linear dimer was 52%, β
The selectivity for cyanoethyl acetate was 39% and the selectivity for propionitrile was 3%. The formula for calculating the selectivity is
It is represented by the following equations 1, 2, and 3.

[0047]

[Equation 1]

[0048]

[Equation 2]

[0049]

[Equation 3]

The above dimerization reaction product is introduced from the conduit 9 into the unreacted product separation step 2 and unreacted acrylonitrile 1200 is introduced.
Parts, 368 parts of unreacted acetic acid and 9 parts of by-product propionitrile were separated by distillation over time. As the distillation conditions, the following atmospheric distillation conditions were used. The bottom temperature of the distillation column was set at 83 to 125 ° C. to substantially separate the following components. Acrylonitrile 78 ° C./760 mmHg Propionitrile 97 ° C./760 mmHg Acetic acid 118 ° C./760 mmHg Acrylonitrile and acetic acid were separated from the reaction product by a distillation unit operation, and circulated and used in a dimerization reaction step through a conduit 11. The by-product of the reaction, propionitrile, was separated as a light-boiling component by the above-mentioned distillation unit operation and taken out of the system through the conduit 10.

In the product separation step 3 and the dimer separation step 6 in which the high boiling content of the distillation residue of the unreacted material separation step 2 is led out through the conduit 12, the high boiling content is separated into each component. First, in the product separation step 3, β-cyanoethyl acetate having a high vapor pressure in a high boiling point was first separated by a distillation unit operation.
As the distillation conditions, the following vacuum distillation conditions were used. The bottom temperature of the distillation column was set to 125 ° C. to substantially separate the following components. 1 part of 249 parts of β-cyanoethyl acetate
Separation was carried out at 10 ° C./25 mmHg. Next, the high-boiling residue was introduced into the dimer separation step 6 through the conduit 18 and separated by distillation under the following distillation conditions. 1,4-dicyanobutene, 1,4-
156 parts of a linear dimer of dicyanobutadiene and adiponitrile was separated from the top of a vacuum distillation column at 165 to 185 ° C / 30 mmHg. The residue from the bottom of the column contains a low-polymerized by-product and the ruthenium catalyst used in the reaction step, and thus was treated in the ruthenium catalyst recovery step.

In the product separation step 3, 249 parts of the separated β-cyanoethyl acetate was led out through the conduit 13, 0.9 part of ruthenium acetate was added through the conduit 14 and introduced into the conversion reaction step 4 to carry out the reaction. The conversion reaction conditions are as follows: after the conversion reaction at a reaction temperature of 170 ° C. and a reaction residence time of 2.0 hours,
114 parts of acrylonitrile and 130 parts of acetic acid were obtained and were recycled to the dimerization reaction step through the conduit 16. The reaction concentrated liquid is intermittently taken out from the bottom of the conversion reaction operation through the conduit 15, and further, the reaction is substantially performed in the batch separation step 5, the distillate is recovered through the conduit 21, and the bottom is supplied through the conduit 17. Since the residue taken out contains the low-polymerized product by-produced and the catalyst used in the reaction step (when a catalyst is used),
The catalyst is recovered in the catalyst recovery step.

Regarding the conversion reaction results of β-cyanoethyl acetate, the conversion was 100% and the selectivity of acrylonitrile was 98%. The reaction result calculation formula is Formula 4,
It is represented by 5.

[0054]

[Equation 4]

[0055]

[Equation 5]

The formulas for calculating the results of all reactions are shown in Formulas 6 and 7. The conversion rate is 12.
It was 4%, and the selectivity of the linear dimer was 83.9%.

[0057]

[Equation 6]

[0058]

[Equation 7]

Example 2 In the attached FIG. 1, the reaction was carried out by introducing ruthenium propionate as a catalyst for the following dimerization reaction from the conduit 8 into the dimerization reaction step 1. Acrylonitrile 1
500 parts, 500 parts of propionic acid, and 15 parts of ruthenium propionate are supplied to the dimerization reaction step 1 from the conduit 8 per hour, and the dimerization reaction is carried out under a nitrogen atmosphere with stirring at a reaction temperature of 150 ° C. and a reaction gauge pressure. The reaction residence time was 6 hours at 5 kg / cm ² . The composition of the reaction solution after 6 hours of reaction was analyzed by gas chromatography. as a result,
1,200 parts of unreacted acrylonitrile, 1,
174 parts of a linear dimer of 4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile, 9 parts of propionitrile, 237 parts of β-cyanoethylpropionate,
It contained 362 parts of propionic acid and 18 parts of low polymer.

The results of the dimerization reaction were as follows: conversion of acrylonitrile was 20%, selectivity of linear dimer was 58%, β
The selectivity for cyanoethylpropionate was 33% and the selectivity for propionitrile was 3%. The formula for calculating the selectivity is represented by the following formulas 1, 2, and 3.

The above dimerization reaction product is introduced from the conduit 9 into the unreacted product separation step 2 and unreacted acrylonitrile 1200 is introduced.
Parts, 362 parts of unreacted propionic acid, and 9 parts of by-product propionitrile were separated by distillation over time. As the distillation conditions, the following atmospheric distillation conditions were used. The bottom temperature of the distillation column was controlled at 83 to 148 ° C. to substantially separate the following components. Acrylonitrile 78 ° C./760 mmHg Propionitrile 97 ° C./760 mmHg Propionic acid 141 ° C./760 mmHg Acrylonitrile and propionic acid were separated from the reaction product by a distillation unit operation, and circulated and used in a dimerization reaction step through a conduit 11. The by-product of the reaction, propionitrile, was separated as a light-boiling component by the above-mentioned distillation unit operation and taken out of the system through the conduit 10.

In the product separation step 3 and the dimer separation step 6 in which the high-boiling fraction of the distillation residue of the above-mentioned separation step 2 was led out through the conduit 12, the high-boiling fraction was separated into each component. First, in the product separation step 3, β-cyanoethylpropionate having a high vapor pressure in a high boiling component was first separated by a distillation unit operation. As the distillation conditions, the following vacuum distillation conditions were used. The bottom temperature of the distillation column was set to 125 ° C. to substantially separate the following components. 1 part of 237 parts of β-cyanoethyl propionate
It separated at 14 degreeC / 25 mmHg. Next, the high-boiling residue was introduced into the dimer separation step 6 through the conduit 18 and separated by distillation under the following distillation conditions. 1,4-dicyanobutene, 1,4-
174 parts of a linear dimer of dicyanobutadiene and adiponitrile was separated from the top of a vacuum distillation column at 165 to 185 ° C / 30 mmHg. The high boiling point from the bottom of the column contains a low-polymerized by-product and the ruthenium catalyst used in the reaction step, and thus was treated in the ruthenium catalyst recovery step.

In the product separation step 3, 237 parts of the separated β-cyanoethylpropionate was discharged through the conduit 13, 4 parts of copper acetate and 2 parts of metallic copper were added to the β-cyanoethylpropionate through the conduit 14, The reaction was carried out by introducing it into the conversion reaction step 4. The reaction conditions are that the reaction temperature is 170
After the conversion reaction at a temperature of 2.0 ° C. for a reaction residence time of 2.0 hours, 96 parts of acrylonitrile and 134 parts of propionic acid were obtained.
It was recycled to the dimerization reaction step. The reaction concentrate is
It is intermittently taken out from the bottom of the conversion reaction operation through the conduit 15, and then the reaction is substantially carried out in the batch separation step 5. The distillate is recovered through the conduit 21, and from the bottom of the tower, the residue is taken out through the conduit 17. Contains a by-produced low-polymerization product and the catalyst used in the reaction step (when a catalyst is used), and therefore is treated in the catalyst recovery step to recover the catalyst.

Regarding the conversion reaction results of β-cyanoethylpropionate, the conversion was 100% and the acrylonitrile selectivity was 97%. The formula for calculating the reaction results is represented by Formulas 4 and 5.

The formulas for calculating the results of all reactions are represented by Formulas 6 and 7. The conversion rate was 13.6% and the selectivity of the linear dimer was 85%.

[Brief description of drawings]

FIG. 1 is a process drawing of an example of producing acrylonitrile dimer.

[Explanation of symbols]

 1 Dimerization reaction step 2 Unreacted material separation step 3 Product separation step 4 Conversion reaction step 5 Batch separation step 6 Dimer separation step 7-21 Pipes for introducing / deriving liquid between each step

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Kashiwagi 5 1978, Kozugushi, Ube City, Yamaguchi Prefecture Ube 5 Ube Kosan Co., Ltd. Ube Laboratory

Claims (1)

[Claims] 1. A method for producing an acrylonitrile dimer for producing a linear dimer of 1,4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile by dimerization of acrylonitrile, comprising: (a). A dimerization reaction step in which acrylonitrile is allowed to flow into an acrylonitrile dimerization reactor, a carboxylic acid and a ruthenium compound are introduced, and a dimerization reaction is performed to obtain a reaction product containing an acrylonitrile dimer (b). The reaction product in the dimerization reaction step is guided, and unreacted acrylonitrile, unreacted carboxylic acid, product propionitrile, carboxylic acid β-cyanoethyl ester and acrylonitrile dimer are separated in the separation step and separated. The acrylonitrile and carboxylic acid thus prepared are recirculated to the dimerization reaction step and supplied as raw materials,
The separated carboxylic acid β-cyanoethyl ester is supplied to a conversion reaction process of the carboxylic acid β-cyanoethyl ester in the next step, and a separation process for separating a dimer of acrylonitrile which is a reaction target produced in the dimerization reaction ( c). A catalyst or a catalyst is added to the carboxylic acid β-cyanoethyl ester derived from the separation step, and the mixture is heated to carry out a conversion reaction of the carboxylic acid β-cyanoethyl ester to obtain acrylonitrile and a carboxylic acid. A method for producing an acrylonitrile dimer, characterized in that the acid comprises a conversion reaction step in which the acid is circulated and supplied to each dimerization reaction step.