JPH07118220A - Production of acrylonitrile dimer - Google Patents

Abstract

PURPOSE:To obtain a normal dimer of acrylonitfile in high selectivity by performing dimerization of acrylonitrile without using hydrogen and with the extreme reduction of the by-production of propionitrile and the beta-cyanoethyl ester of a carboxylic acid. CONSTITUTION:A normal dimer of acrylonitrile, i.e., 1,4-dicyanobutene, 1,4- dicyanobutadiene or adiponitrile is obtained by the dimerization of acrylonitrile. This process of the dimerization of acrylonitrile is carried out using a ruthenium compound as a catalyst in the presence of a specific carboxylic acid containing an oxygen, sulfur or nitrogen atom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing acrylonitrile linear dimer of 1,4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile by using a ruthenium catalyst in the dimerization of acrylonitrile. Acrylonitrile linear dimer 1,4-dicyanobutene, 1,4-dicyanobutadiene and adiponitrile are hexamethylenediamine, which is a raw material for nylon-6 and 6,
It is a compound useful as an intermediate such as a rust inhibitor and a rubber vulcanization accelerator.

[0002]

As a method for producing 1,4-dicyanobutene and adiponitrile from acrylonitrile using a ruthenium catalyst, for example, a method of carrying out a dimerization reaction of acrylonitrile in the presence of hydrogen is known (Bull.
Chem. Soc. Jpn., 41 (1968) 396). However, in this method, dimerization of acrylonitrile proceeds only when the reaction is carried out by adding hydrogen, and therefore, hydrogenation also occurs at the same time as dimerization of acrylonitrile and a large amount of propionitrile is by-produced. I have a problem. Further, in the methods disclosed in JP-B-44-24585, JP-B-45-4048 and JP-B-54-12450, since the reaction is carried out in the presence of hydrogen, the desired acrylonitrile straight chain is obtained. Although the selectivity of the dimer is improved to 55 to 67%, a large amount of propionitrile is by-produced at a selectivity of 33 to 45%.

Therefore, a method for dimerizing acrylonitrile in the absence of hydrogen has been investigated and examined.
Although the method is disclosed in Japanese Patent No. 14620, in this method, when the conversion rate of acrylonitrile is increased, the by-product of propionitrile is increased and the selectivity of the dimer is decreased, and the obtained dimer is obtained. The body is also a mixture of a straight chain dimer and a branched dimer, and there is a problem that the ratio of the target straight chain dimer is low.

[0004]

As described above, according to the known method for producing an acrylonitrile dimer, a large amount of a by-product such as propionitrile which cannot be easily regenerated to acrylonitrile is produced to form a dimer. Safety of equipment and operation by using hydrogen, which lowers the selectivity, forms a mixture of a linear dimer and a branched dimer, and lowers the selectivity of the desired linear dimer. There were problems such as the need for countermeasures. The object of the present invention, in the dimerization of acrylonitrile, by suppressing the by-production of propionitrile, it is possible to produce a linear dimer of acrylonitrile with a high selectivity production of industrially suitable acrylonitrile dimer To provide the law.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems in the known method for producing acrylonitrile dimer, and as a result, the presence of a specific carboxylic acid containing a hetero atom By dimerizing acrylonitrile in the absence of hydrogen, the by-product of propionitrile is significantly suppressed, and the by-product of carboxylic acid β-cyanoethyl ester accompanying the presence of carboxylic acid is also suppressed. The present invention has been accomplished by finding that a linear dimer of acrylonitrile can be obtained with high selectivity.

That is, the present invention relates to a linear dimer of 1,4-dicyanobutene, 1,4 by dimerization of acrylonitrile.
In a method for producing an acrylonitrile dimer for producing dicyanobutadiene and adiponitrile, a ruthenium compound is used as a catalyst, and (1) a carboxyl group or a carboxy group is added to a carbon atom forming a ring of a 5- to 12-membered cyclic compound. A cyclic carboxylic acid in which a methyl group is bonded and the atom forming the ring at the α-position of the carbon atom is substituted with an oxygen atom, a sulfur atom or a nitrogen atom, or (2) at the α-position or β-position of the carboxyl group The present invention relates to a method for producing an acrylonitrile dimer, which comprises dimerizing acrylonitrile in the presence of an acyclic carboxylic acid having a carbon atom bonded to a sulfur atom or a nitrogen atom.

The present invention will be described in detail below. The ruthenium compound used as a catalyst is preferably an inorganic acid salt of ruthenium, an organic acid salt of ruthenium, or a coordination compound having ruthenium as a central atom, for example, ruthenium chloride, ruthenium bromide, ruthenium iodide, ruthenium sulfate. Inorganic acid salts of ruthenium such as ruthenium nitrate, ruthenium acetate, ruthenium propionate, ruthenium butanoate, ruthenium pentanoate, ruthenium hexanoate, ruthenium stearate, ruthenium naphthenate,
Ruthenium oxalate, ruthenium succinate, and other organic acid salts of ruthenium, or RuCl ₂ (dimethyl sulfoxide) ₄ , RuCl ₂ (acrylonitrile) ₄ , RuCl
₂ (triphenylphosphine) ₃ , RuCl ₂ (triphenylphosphine) ₄ , Ru (H ₂ O) (2-thiophenecarboxylate) ₂ (dimethylsulfoxide) _{3 and the} like are listed as coordination compounds having a central atom of ruthenium. You can These ruthenium compounds may be used alone or as a mixture of a plurality of compounds, and the amount thereof is usually 0.0001 to 10 mol% relative to acrylonitrile.
Is.

In the present invention, a base and / or a reducing agent may be used together with the ruthenium compound.
As the base, sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, inorganic salts such as sodium hydrogen carbonate, sodium acetate, organic acid salts such as sodium propionate, sodium methoxide, Examples thereof include metal alkoxides such as sodium ethoxide, methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, aniline, methylaniline, dimethylaniline, ethylaniline and diethylaniline, and ammonia. These bases may be used alone or as a mixture of a plurality of compounds, and the amount thereof is usually 0.05 to 30 times by mole with respect to the ruthenium compound,
The molar amount is preferably 0.1 to 20 times.

The reducing agent may be any reducing agent capable of reducing the ruthenium compound, and examples of the reducing agent include organic tin compounds, organic germanium compounds, organic silicon compounds, organic boron compounds, and organic aluminum compounds. Examples of the inorganic reducing agent include borohydride compounds, aluminum hydride compounds, metal hydrides, and simple metals. These reducing agents may be used alone or as a mixture of a plurality of compounds, and the amount thereof is usually 0.05 to 30 times by mole with respect to the ruthenium compound,
The molar amount is preferably 0.1 to 20 times.

A specific example of the reducing agent is trimethyl.
Stannane [HSn (CH₃)₃], Triethylstan
Nan (HSnEt₃), Tri-n-propylstannane
[HSn (n-Pr)₃], Tri-n-butyl stanna
[HSn (n-Bu)₃], Triphenylstannane
(HSnPh₃), Di-n-propylstannane [H ₂
Sn (n-Pr)₂], Di-n-butylstannane [H
₂Sn (n-Bu)₂], Diphenylstannane [H₂
SnPh₂] Organotin compounds such as trimethylgermane
[HGeMe₃], Triethylgermane [HGeE
t₃], Tri-n-propyl germane [HGe (n-P
r)₃] Organic germanium compounds, borohydride
Thorium (NaBH_Four), Lithium borohydride (Li
BH_Four) Etc., borohydride compounds, lithium hydride
Minium (LiAlH_Four) Aluminum hydride compounds such as
Products, metal hydrides such as sodium hydride (NaH), gold
Metallic elements such as sodium, magnesium, and zinc
The body.

As one of the carboxylic acids used in the present invention, a carboxyl group or a carboxymethyl group is bonded to a carbon atom forming a ring of a 5- to 12-membered cyclic compound,
Examples thereof include cyclic carboxylic acids in which the atom forming the α-position of the carbon atom is substituted with an oxygen atom, a sulfur atom or a nitrogen atom.

The above-mentioned cyclic compound is a cyclic compound in which atoms other than the above-mentioned heteroatoms are composed of only carbon atoms, but it is a cyclic compound containing heteroatoms such as O, S, N in addition to the above-mentioned heteroatoms. Alternatively, a substituent such as an alkyl group, an aryl group, an acyl group, an alkoxyl group, or a halogen may be bonded. Further, it may be a monocyclic compound or a condensed cyclic compound, but a 5- or 6-membered monocyclic compound is preferable.

The cyclic compound may be a saturated cyclic compound or an unsaturated cyclic compound. In the case of an unsaturated cyclic compound, the unsaturated bond (double bond) is a carbon atom forming a ring. A carboxyl group or a carboxymethyl group is bonded, and the atom forming the α-position ring of the carbon atom is an oxygen atom,
One or more of them may be present at any position of the cyclic compound as long as it does not prevent substitution with a hetero atom of a sulfur atom or a nitrogen atom.

Examples of the above-mentioned cyclic carboxylic acid include:
As a cyclic carboxylic acid in which a carboxyl group is bound to a carbon atom forming a ring of a 5-membered cyclic compound and an atom forming a ring at the α-position of the carbon atom is substituted with an oxygen atom, 2
-2-furancarboxylic acids such as furancarboxylic acid, 3-methyl-2-furancarboxylic acid, 4-methyl-2-furancarboxylic acid, and tetrahydro-2-furancarboxylic acid,
As a cyclic carboxylic acid in which a carboxymethyl group is bonded to a carbon atom forming a ring of a 5-membered cyclic compound and an atom forming a ring at the α-position of the carbon atom is substituted with an oxygen atom, 2- Furanacetic acid, 3-methyl-2-furanacetic acid, 4
And 2-furan acetic acid such as methyl-2-furan acetic acid and tetrahydro-2-furan acetic acid. Particularly preferable among these cyclic carboxylic acids are 2-furancarboxylic acids such as 2-furancarboxylic acid, 3-methyl-2-furancarboxylic acid, and 4-methyl-2-furancarboxylic acid.

A cyclic carboxylic acid in which a carboxyl group is bound to a carbon atom forming a ring of a 5-membered cyclic compound and an atom forming a ring at the α-position of the carbon atom is substituted with a sulfur atom is , 2-thiophenecarboxylic acid, 3-methyl-
2-thiophenecarboxylic acids such as 2-thiophenecarboxylic acid and 5-methyl-2-thiophenecarboxylic acid, a carboxymethyl group is bonded to a carbon atom forming a ring of a 5-membered cyclic compound, and α of the carbon atom The cyclic carboxylic acid in which the atom forming the ring at position is substituted with a sulfur atom is 2
-Thiophene acetic acid, 3-methyl-2-thiophene acetic acid,
2-thiopheneacetic acid such as 4-methyl-2-thiopheneacetic acid may be mentioned. Particularly preferable among these cyclic carboxylic acids are 2-thiophenecarboxylic acids such as 2-thiophenecarboxylic acid, 3-methyl-2-thiophenecarboxylic acid and 5-methyl-2-thiophenecarboxylic acid.

A cyclic carboxylic acid in which a carboxyl group is bound to a carbon atom forming a ring of a 5-membered cyclic compound and an atom forming a ring at the α-position of the carbon atom is substituted with a nitrogen atom is , N-acetylproline, N-propionylproline, N-benzoylproline and the like N-acylproline, N-carbomethoxyproline, N-carboethoxyproline, N-carbopropoxyproline, N-carbobenzyloxyproline and the like N. -2-pyrrolidinecarboxylic acid (proline) such as carboalkoxyproline
And a carboxyl group bonded to a carbon atom forming a ring of a 6-membered cyclic compound, and an atom forming a ring at the α-position of the carbon atom is substituted with a nitrogen atom. Are N-acetyl-2-piperidinecarboxylic acid, N-propionyl-2-piperidinecarboxylic acid, N
-N-acyl-2-piperidinecarboxylic acid such as benzoyl-2-piperidinecarboxylic acid, N-carbomethoxy-2-piperidinecarboxylic acid, N-carbethoxy-2
-Piperidinecarboxylic acid, N-carbopropoxy-2-
Piperidinecarboxylic acid, N-carbobenzyloxy-2
-N-carboalkoxy-2 such as piperidinecarboxylic acid
And 2-piperidinecarboxylic acid (pipecolic acid) such as piperidinecarboxylic acid. Particularly preferred among these cyclic carboxylic acids are N-acetylproline, N-propionylproline, N-benzoylproline, N-carbomethoxyproline, N-carboethoxyproline, N-carbopropoxyproline, N-carboproline. It is 2-pyrrolidinecarboxylic acid (proline) such as benzyloxyproline.

The other carboxylic acid used in the present invention is an acyclic carboxylic acid having a sulfur atom or a nitrogen atom as a hetero atom bonded to the carbon atom at the α-position or β-position of the carboxyl group. To be As the acyclic carboxylic acid, one substituent selected from -SR ¹ group and -NR ² R ³ group is bonded to the α-position carbon atom of the carboxyl group of the aliphatic carboxylic acid having 2 to 6 carbon atoms. The acyclic α-substituted carboxylic acids, and the aliphatic carboxylic acid having 2 to 6 carbon atoms has —SR ¹ group and —NR ^{2 at} the β-position carbon atom of the carboxyl group.
Acyclic β-substituted carboxylic acids to which one substituent selected from R ³ group is bonded (provided that R ¹ ,
R ² and R ³ are hydrogen or an alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, an allyl group having 6 to 15 carbon atoms, an acyl group having 2 to 15 carbon atoms, and an alkyl group having 2 to 15 carbon atoms. Indicates a carboalkoxyl group).

At the carbon atom at the α-position of the carboxyl group of the aliphatic carboxylic acid having 2 to 6 carbon atoms, the aforementioned --SR ¹ group, --NR
Examples of the acyclic α-substituted carboxylic acids having one substituent selected from ² R ³ groups include methylthioacetic acid, ethylthioacetic acid, α-methylthiopropionic acid,
Acyclic α-alkylthio-aliphatic carboxylic acids such as α-ethylthiopropionic acid, N-acetylglycine, N-
Propionylglycine, N-benzoylglycine, N-
Acyclic N-acyl-aliphatic-α-, such as acetylalanine, N-propionylalanine, N-benzoylalanine
Acyclic N-carboalkoxyl-, such as amino acids, N-carbomethoxyglycine, N-carboethoxyglycine, N-carbobenzyloxyglycine, N-carbomethoxyalanine, N-carboethoxyalanine, N-carbobenzyloxyalanine Aliphatic-alpha-amino acids are mentioned.

At the β-position carbon atom of the carboxyl group of the aliphatic carboxylic acid having 2 to 6 carbon atoms, the above-mentioned --SR ¹ group, --NR
Examples of the acyclic β-substituted aliphatic carboxylic acid having one substituent selected from ² R ³ groups include, for example, β-
Acyclic β-alkylthio-aliphatic carboxylic acids such as methylthiopropionic acid and β-ethylthiopropionic acid, N
Acyclic N-, such as -acetyl-β-alanine, N-propionyl-β-alanine, N-benzoyl-β-alanine
Acyl-aliphatic-β-amino acids, N-carbomethoxy-β-alanine, N-carbethoxy-β-alanine,
Acyclic N such as N-carbobenzyloxy-β-alanine
-Carboalkoxyl-aliphatic-β-amino acids. Among these acyclic carboxylic acids, particularly preferred are acyclic N-acetylglycine, N-propionylglycine, N-benzoylglycine, N-acetylalanine, N-propionylalanine, N-benzoylalanine and the like. -Acyl-aliphatic- [alpha] -amino acids are mentioned.

When the carboxylic acid is present in a large amount, the production amount of carboxylic acid β-cyanoethyl ester increases and the target dimer selectivity decreases, so that the amount of carboxylic acid is usually 0.0001 to 0.001 to acrylonitrile. It is suitable to use it in a molar ratio of 5 times, preferably 0.001 to 2 times. The above carboxylic acids may be used alone or as a mixture of a plurality of compounds.

In the present invention, in order to carry out the reaction mildly, as a reaction solvent, nitriles such as acetonitrile and propionitrile, sulfoxides such as dimethyl sulfoxide and tetramethylene sulfoxide, and ethers such as diethyl ether and diisopropyl ether are used. -Terones, hydrocarbons such as hexane and toluene, acetamide, N, N-
It is also possible to use amides such as dimethylformamide, halogenated hydrocarbons such as methylene chloride and chloroform, esters such as methyl acetate and ethyl acetate, alcohols such as methanol and ethanol, and solvents such as water. .

As a reaction method, for example, acrylonitrile, a ruthenium compound and a carboxylic acid are charged in a reaction vessel in the above proportions, heated to a predetermined temperature with stirring, and then reacted at a predetermined pressure for a predetermined time. It is preferable. At this time, the reaction temperature is usually 70 to 220 ° C., preferably 10 in consideration of the dimer formation rate and the deactivation of the catalyst.
At 0 to 180 ° C., the reaction pressure is usually in the range of reduced pressure of 50 mmHg to increased pressure of 100 kg / cm ² . The reaction time varies depending on the temperature, pressure, and amount of catalyst, but is preferably 0.01 to 30 hours. After the reaction, the formed acrylonitrile linear dimer is easily separated and purified by distillation or the like.

[0023]

EXAMPLES Next, the present invention will be specifically described with reference to examples. The conversion rate and selectivity shown in each example were obtained by the following equations.

[0024]

[Equation 1]

[0025]

[Equation 2]

[0026]

[Equation 3]

[0027]

[Equation 4]

Example 1 15.0 g (283 mmol) of acrylonitrile was placed in a 100 ml stainless steel autoclave equipped with a stirrer, and then RuCl ₂ (dimethyl sulfoxide) ₄ was added.
37.1 mg (0.0766 mmol), sodium propionate 22.0 mg (0.229 mmol) and 2
-858 mg (7.66 mmol) of furancarboxylic acid was added. After substituting the space of the autoclave with nitrogen, the temperature was raised to 150 ° C with stirring, and the reaction temperature was 150 ° C.
The reaction was carried out at a reaction pressure of 5 kg / cm ² for 6 hours.

After the reaction was completed, the autoclave was cooled,
When the reaction solution was analyzed by gas chromatography, it was found that 12.1 g of unreacted acrylonitrile (22
8 mmol) and 2.22 g of 1,4-dicyanobutene (2
0.9 mmol), 1,4-dicyanobutadiene 0.2
0 g (1.9 mmol), adiponitrile 0.085 g
(0.79 mmol), propionitrile 0.088 g
(1.6 mmol) and 0.54 g (3.3 mmol) of 2-furancarboxylic acid β-cyanoethyl ester were included.

From these results, the conversion rate of acrylonitrile was 19%, and the linear dimer (1,4-dicyanobutene,
The total selectivity of 1,4-dicyanobutadiene and adiponitrile) is 86%, and the selectivity of propionitrile is 3%.
%, The selectivity of 2-furancarboxylic acid β-cyanoethyl ester was 6%.

Examples 2 to 7 Carboxylic acids shown in Table 1 in Example 1 (7.6)
6 mmol) was used, and the reaction was performed in the same manner as in Example 1 to analyze the product. The results are shown in Table 1.

[0032]

[Table 1]

[0033]

EFFECT OF THE INVENTION The present invention solves the problem of by-production of propionitrile and acrylonitrile-branched dimer in the known method for producing acrylonitrile dimer, and further by-product of carboxylic acid β-cyanoethyl ester. , Acrylonitrile linear dimer can be produced with high selectivity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Shimakawa 5 1978, Kozugushi, Ube City, Yamaguchi Prefecture 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, wherein a ruthenium compound is used as a catalyst. (1) A carboxyl group or a carboxymethyl group is bonded to a carbon atom forming a ring of a 5- to 12-membered cyclic compound, and an atom forming a ring at the α-position of the carbon atom is an oxygen atom, a sulfur atom or In the presence of a cyclic carboxylic acid substituted with a nitrogen atom, or (2) an acyclic carboxylic acid having a sulfur atom or a nitrogen atom bonded to the α- or β-position carbon atom of the carboxyl group, acrylonitrile A method for producing an acrylonitrile dimer, which comprises quantifying.