JPH10101635A - New production of azo ester compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method for producing an azoiminoether hydrochloride by which the azoiminoether hydrochloride useful as a synthesis intermediate, etc., for a polymerization initiator, etc., is produced with an easy control of the reaction, in high purity and yield by suspending a specific azonitrile compound in alcohols, introducing a prescribed amount of hydrogen chloride and reacting the compound. SOLUTION: This azoiminoether hydrochloride is obtained by suspending an azonitrile compound of formula I [R<1> to R<4> are each a (substituted) alkyl or a (substituted) phenyl; R<1> and R<2> , or R<3> and R<4> can form an alkylene] in alcohols of the formula R<5> OH (R<5> is a lower alkyl), introducing and reacting hydrogen chloride by keeping the content of the hydrogen chloride not to excess the saturating content in the alcohols but to maintain not less than 30% W/W to provide the objective azoiminoether hydrochloride of formula II. The azoester compound of formula III is preferably produced by hydrating the azoiminoether hydrochloride of formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing an azoimino ether hydrochloride which is an important intermediate of an azoguanyl compound or an azo ester compound useful as a polymerization initiator in the production of a polymer compound, and a method for producing the azo imino ether hydrochloride. The present invention relates to a method for producing an azoester compound using a salt.

[0002]

2. Description of the Related Art As a method for producing azoimino ether hydrochloride, there is known a method of reacting a corresponding azonitrile compound with alcohols and hydrogen chloride in a non-aqueous reaction system (US Pat. No. 2,599,299). here,
The reaction is carried out by introducing hydrogen chloride so as to be saturated with respect to the alcohols used. But with this method,
The reaction progresses rapidly, and even on a small experimental scale, it is extremely difficult to control the reaction by cooling, etc., and large-scale production is not possible with large-scale production on an industrial scale by scale-up. Condition.

In order to solve this problem, a method of introducing hydrogen chloride into a mixed solvent of a solvent having low solubility of hydrogen chloride and an alcohol (Japanese Patent Publication No. 58-223).
No. 0) or a method of sequentially adding azobisnitrile to an alcohol solution containing an acid (Japanese Patent Laid-Open No. 64-26).
No. 545). However, these methods still have problems.

That is, in the former method, it is difficult to completely remove a solvent having low solubility in hydrogen chloride such as toluene from the reaction system after completion of the reaction. In the case of producing a compound or the like, the azoester compound is dissolved in the remaining toluene or the like, so that an operation for removing the azoester compound is required, and there is a problem that the isolation and recovery operation becomes complicated.

In the latter case, it is necessary to add the azobisnitrile to the reaction system sequentially in the form of powder or in the form of a solution or slurry using alcohols or other solvents. It is not practical to add the solid in the reaction system sequentially to the reaction system because the workability is poor and there is a risk that the worker is always exposed to hydrogen chloride in the system.
Also, since azobisnitrile is hardly soluble in alcohols and other general solvents, even if it is added in a slurry form, the crystals are clogged in the charging device, and the crystals cannot be added at a constant rate and the reaction is sufficiently performed. There is a problem that it cannot be controlled.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and does not use a solvent having low solubility in hydrogen chloride such as toluene, so that the reaction can be easily controlled and the operation can be easily performed. It is an object of the present invention to provide a method for producing an azoimino ether hydrochloride and an azo ester compound having good properties and low danger.

[0007]

The present invention provides (1) a compound represented by the general formula [1]:

[0008]

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(Wherein, R ¹ , R ² , R ³ and R ⁴ each independently represent an alkyl group which may have a substituent or a phenyl group which may have a substituent. , R ¹ and R ² and / or R ³ and R ⁴ may form an alkylene chain) with R ⁵ —OH (R ⁵
Represents a lower alkyl group. ), And hydrogen chloride is added thereto so that the concentration thereof is maintained at a value that is less than saturation with respect to the alcohols in the reaction system and does not fall below 30% W / W. General formula [2], characterized in that the reaction is carried out by introduction.

[0010]

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(Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as described above), and (2) the method of (1) According to the method, the general formula [2]

[0012]

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(Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as described above), characterized by producing an azoimino ether hydrochloride, and then hydrolyzing it. General formula [3]

[0014]

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(Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as described above).

That is, the present inventors have conducted various studies on the concentration of hydrogen chloride (relative to the alcohol used) required for the reaction for producing azoimino ether hydrochloride in order to solve the above problems. As a result, the concentration of hydrogen chloride was 30% W / W with respect to alcohols existing in the reaction system.
If it is less than 3, the reaction is not completed. When the concentration of hydrogen chloride is 30% W / W or more, the reaction is completed. However, as the concentration approaches the saturated state, the reaction becomes violent and the control of the reaction becomes difficult. Furthermore, when hydrogen chloride is excessively introduced, it goes without saying that the reaction proceeds rapidly, and the working environment is significantly deteriorated by the excessive hydrogen chloride. That is, in order to safely proceed and complete the iminoetherification reaction while controlling the reaction, from the start of the reaction to the end of the reaction, the reaction system is made of hydrogen chloride in consideration of the alcohol used in the reaction. The inventors have found that the concentration should be introduced so as to be less than the saturation with respect to the alcohols present in the system and not less than 30% W / W, thereby completing the present invention.

In the general formulas [1] and [2], R ¹ ,
The alkyl group represented by R ² , R ³ and R ⁴ may be linear, branched or cyclic, and includes, for example, an alkyl group having 1 to 6 carbon atoms. Represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group,
n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, 2-methylbutyl group, 1-methylbutyl group, neopentyl group, 1-ethylpropyl group, n-hexyl group, Examples include an isohexyl group, a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group. Further, any substituent may be used as long as it is inert to the reaction, and examples thereof include a phenyl group, a tolyl group, and a xylyl group. Examples of the phenyl group which may have a substituent include a phenyl group, a tolyl group, and a xylyl group. The alkylene chain may be linear or branched, and may be, for example, n
-A linear alkylene group having preferably 3 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, such as a propylene group, an n-butylene group, and an n-pentylene group, and preferably a carbon atom such as an isobutylene group or a 2-ethylpropylene group. Numerical Formulas 4 to 10 and more preferably 4 to 6 branched alkylene groups are exemplified.

The lower alkyl group represented by R ⁵ in the alcohol represented by R ⁵ —OH may be linear or branched, but preferably has 1 to 5 carbon atoms.
6 lower alkyl groups, more preferably a methyl group, an ethyl group, and a propyl group, and further preferably a methyl group. Since these alcohols are a reactant and also act as a reaction solvent, it is not necessary to use another reaction solvent. In consideration of the reaction solvent, it is necessary to use the alcohol in an amount of about 1 to 2 times the weight of the azonitrile compound.

In the method of the present invention, first, an azonitrile compound is suspended in an alcohol, and then hydrogen chloride is introduced into the suspension. The method for introducing hydrogen chloride is such that the concentration of hydrogen chloride in the reaction system from the start of the reaction to the end of the reaction is less than the saturation with respect to the alcohols present and does not fall below 30% W / W. At the beginning of the reaction, or the concentration of hydrogen chloride at that time is less than 30% W / W of saturation with respect to alcohols in the reaction system.
The reaction may be carried out by first adding an amount such that the amount does not fall below, and as the reaction proceeds, the introduction of hydrogen chloride may be repeated as appropriate so that the concentration of hydrogen chloride is less than saturation and does not fall below 30% W / W. . That is, regardless of the method of introduction, the concentration of hydrogen chloride with respect to alcohols in the reaction system is always less than 30% W / W from the start of the reaction to the end of the reaction.
Is preferably 30% W / W or more, but may be maintained at a concentration closer to 30% W / W.

The temperature at the time of introducing hydrogen chloride into the reaction system is usually 0 ° C. to 30 ° C., preferably 0 ° C. to 20 ° C. The reaction temperature after the introduction is usually 0 ° C. to 40 ° C. Preferably it is 10 to 30 degreeC.

After the reaction, the azoimino ether hydrochloride may be isolated by post-treatment according to a conventional method. If the azoimino ether hydrochloride thus obtained is reacted with ammonia or amines according to a conventional method after or without isolation, various amidines can be obtained in high yield and high quality (contain almost no residual solvent). ), And the azoimino ether hydrochloride is subjected to hydrolysis treatment after isolation or without isolation as a reaction solution, so that the corresponding azoester compound can be easily and with high yield. Can be obtained at a rate. The amount of water used for the hydrolysis may be such that all the ammonium chloride precipitated as a by-product is dissolved. Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0022]

【Example】

Example 1 2,2′-azobis (2-methylpropionitrile) 12
0 g was suspended in 200 g of methanol, and 120 g of hydrogen chloride (hydrogen chloride concentration 37.5% W / W, hydrogen chloride concentration at the end of the reaction 30% W / W) was introduced at 18 ° C under ice cooling. 25-30
After stirring at 6 ° C. for 6 hours, 2,2′-azobis (1
-Imino-1-methoxy-2-methylpropane) dihydrochloride was confirmed to be formed. Then, add 1
After cooling to 5 ° C. and standing overnight, the mixture was poured into 420 g of water to carry out hydrolysis, and the aqueous layer was separated and removed to give dimethyl 2,2′-.
140 g of a yellow liquid of azobis (2-propionate) was obtained. (83% yield)

Example 2 2,2'-azobis (2-methylpropionitrile) 12
0 g was suspended in 200 g of methanol, and 98 g of hydrogen chloride (hydrogen chloride concentration 33% W / W) was introduced at 18 ° C. under ice cooling.
After stirring at 25-30 ° C. for 3 hours, hydrogen chloride 22 g
Was introduced again (the concentration of hydrogen chloride at the end of the reaction was 30% W / W), and the mixture was stirred for 4 hours. 2,2′-azobis (1-imino-
After confirming that 1-methoxy-2-methylpropane) dihydrochloride has been formed, the reaction solution was cooled to 15 ° C. and allowed to stand overnight, and then poured into 420 g of water to perform hydrolysis. Separation and removal gave 135 g of dimethyl 2,2'-azobis (2-propionate) as a yellow liquid. (80% yield)

Example 3 2,2'-azobis (2-methylpropionitrile) 12
0 g was suspended in 200 g of methanol, and 98 g of hydrogen chloride (hydrogen chloride concentration 33% W / W) was introduced at 18 ° C. under ice cooling.
After stirring at 25-30 ° C for 1.5 hours, 11 g of hydrogen chloride was added.
Was introduced again. After further stirring at 25 to 30 ° C. for 1.5 hours, 11 g of hydrogen chloride was introduced (the concentration of hydrogen chloride at the end of the reaction was 30%), and stirring was performed for 4 hours. 2,2′-azobis (1-imino-1-methoxy-2-methylpropane) 2
After confirming that the hydrochloride had been formed, the reaction solution was cooled to 15 ° C. and allowed to stand overnight, then poured into 420 g of water to carry out hydrolysis, and the aqueous layer was separated to remove dimethyl 2,2′- 133 g of a yellow liquid of azobis (2-methylpropionate) was obtained. (79% yield)

Comparative Example 1 2,2'-azobis (2-methylpropionitrile) 12
0 g was suspended in 200 g of methanol, and 180 g of hydrogen chloride (saturated concentration) was introduced at 18 ° C. under ice cooling. During the reaction, the reaction progressed rapidly, and cooling was performed using a large amount of ice water in order to suppress heat generation. However, the temperature could not be controlled, the internal temperature rose to 40 ° C. or more, and a large amount of hydrogen chloride was volatilized. After the introduction of hydrogen chloride, the mixture was stirred and reacted for 6 hours. Then, the reaction solution was poured into 420 g of water to carry out hydrolysis, the aqueous layer was removed, and dimethyl 2,2 ′ was obtained.
-Yellow liquid 1 of azobis (2-methylpropionate)
Although 20 g was obtained, 8% of the raw material 2,2'-azobis (2-methylpropionitrile) was present in this yellow liquid.

Comparative Example 2 2,2'-azobis (2-methylpropionitrile) 12
0 g was suspended in 200 g of methanol, and 105 g of hydrogen chloride (hydrogen chloride concentration 34.4% W / W, hydrogen chloride concentration at the end of the reaction 25%) was introduced at 18 ° C under ice cooling. After stirring at 25 to 30 ° C. for 6 hours, it was confirmed that 2,2′-azobis (1-imino-1-methoxy-2-methylpropane) dihydrochloride had been formed. Then, the mixture was cooled to 15 ° C. and allowed to stand overnight, and then poured into 420 g of water for hydrolysis. The aqueous layer was separated and removed, and dimethyl 2,2′-azobis (2
As a result, 5% of unreacted 2,2′-azobis (2-methylpropionitrile) remained in the obtained yellow liquid.

[0027]

The present invention has the following effects. (1) Conventionally, the concentration of hydrogen chloride with respect to alcohols was saturated, but in the present invention, the concentration of hydrogen chloride in the reaction system at the time of the reaction is adjusted so as to be less than saturation and not less than 30% W / W. By adjusting the concentration to preferably 30% W / W or more but closer to 30% W / W, the reaction proceeds and completes smoothly, and the reaction can be easily controlled. (2) The concentration of hydrogen chloride is 30% with respect to alcohols.
By adjusting the concentration closer to W / W, the amount of hydrogen chloride used was greatly reduced, the working environment was remarkably improved, and the use of other solvents such as toluene became unnecessary. (3) In the present invention, since the azonitrile compound as a raw material is suspended in alcohols and hydrogen chloride is introduced therein, it is observed when the azonitrile compound is added to the reaction system in a solid or slurry form. Clogging due to crystals in the charging device does not occur. (4) Since the reaction system does not contain a solvent having low solubility of hydrogen chloride such as toluene, after completion of the iminoetherification reaction, the reaction solution is directly subjected to hydrolysis treatment to isolate and recover the azoester compound. In this case, complicated operations can be avoided. Since many excellent effects as described above can be expected, it can be said that the present invention is a method for producing an azoimino ether hydrochloride and an azo ester compound which is extremely useful industrially.

Claims (5)

[Claims] 1. A compound of the general formula [1] ^{(Wherein, R 1, R 2, R} 3 and R ⁴ are, each independently represents which may have a may have a substituent alkyl group or a substituted phenyl group, R ¹ And R ² and / or R ³ and R ⁴ form an alkylene chain), and an alcohol represented by R ⁵ —OH (R ⁵ represents a lower alkyl group). The reaction is carried out by introducing hydrogen chloride into the suspension so that the concentration thereof is maintained at a value which is less than saturation with respect to the alcohols in the reaction system and does not fall below 30% W / W. General formula [2] characterized by the following: (In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as described above.)
A method for producing an azoimino ether hydrochloride represented by the formula: 2. The concentration of hydrogen chloride in the reaction system from the start of the reaction to the end of the reaction is maintained at a value which is less than saturation and does not fall below 30% W / W with respect to the alcohols present. The method according to claim 1, wherein the concentration of hydrogen chloride is adjusted at the beginning of the reaction so as to be performed. 3. At the start of the reaction, hydrogen chloride is present so that its concentration in the reaction system is less than saturation with respect to the alcohols present and does not fall below 30% W / W. The method according to claim 1, wherein hydrogen chloride is introduced as necessary to maintain the concentration at a value less than saturation and not less than 30% W / W. 4. The method according to claim 1, wherein the compound of the general formula [2] (In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as described above.)
Wherein azoimino ether hydrochloride represented by the formula is produced and then hydrolyzed. (In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same as described above.)
A method for producing an azoester compound represented by the formula: 5. The process according to claim 4, wherein the reaction solution of the iminoetherification reaction is subjected to a hydrolysis treatment as it is.