JPH0329063B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a method for producing 4,4'-azobis(4-cyanovaleric acid) (hereinafter sometimes simply abbreviated as ACVA) using levulinic acid or its sodium salt as a starting material. Regarding.

ACVA is used as a (co)polymerization initiator for acrylamide and 1,3-butadiene or for 1,3-butadiene and acrylonitrile.

ACVA is produced by reacting levulinic acid or its sodium salt with a cyanide compound such as sodium cyanide or hydrogen cyanide and a hydrazine such as hydrazine hydrate or hydrazine sulfate in water to generate a hydrazo compound. A method is known in which chlorine gas is added to the resulting solution to oxidize the hydrazo compound to generate ACVA, and the solid ACVA is collected by filtration from the resulting reaction mixture. However, this conventionally known method has a synthesis yield of 66% or less.

That is, when synthesizing a hydrazo compound as an intermediate for ACVA synthesis, the reaction route differs depending on the reaction order of the reaction reagents, and there is a route via ketazine or cyanohydrin.

The production method of ACVA via ketazine is as follows:
Sodium levulinate and hydrazine in water
After reacting at 100°C for 6 hours to produce ketazine, it was cooled, a large excess of hydrogen cyanide was added, and the mixture was heated at 20°C.
After reacting for 16 hours, excess hydrogen cyanide was distilled off,
A method of synthesizing ACVA by adding chlorine is known (US Pat. No. 2,520,338).

However, when levulinic acid and hydrazine are directly reacted at high temperatures as in the above example, 6-methylpyridazinone is produced almost quantitatively and ketazine is not obtained. Add caustic soda to levulinic acid to form sodium levulinic acid and prevent the reaction to form a cyclized product.
It produces ketazine. Although the ketazine production reaction is carried out at high temperatures and hydrazotization is carried out using a large excess of hydrogen cyanide, the synthesis yield is low at 66% at most.

As a result of intensive research into a method for obtaining ACVA in high yield, the inventors discovered that a mixture of cyanide compounds such as sodium cyanide and hydrogen cyanide and hydrazines and levulinic acid were combined under conditions where the amount of water was limited to a specific range. The inventors discovered that a hydrazo compound can be rapidly produced in high yield by carrying out a catalytic reaction with a sodium salt thereof, and as a result of further research, they completed this invention.

That is, the present invention provides a mixture of hydrazines and a cyanide compound such as sodium cyanide or hydrogen cyanide, and levulinic acid or its sodium salt in the presence of 25 to 200 parts by weight of water per 100 parts by weight of levulinic acid or its sodium salt. contact with sodium salt,
A hydrazo compound is produced by the reaction, and acetone and/or
Alternatively, the present invention relates to a method for producing 4,4'-azobis(4-cyanovaleric acid), which comprises adding chlorine gas to a solution containing water to oxidize a hydrazo compound.

According to the method of this invention, ACVA can be produced in high yield.

In the method of this invention, the amount of water during the reaction is important. The amount of water is 25 to 200 parts by weight, preferably 30 to 100 parts by weight, per 100 parts by weight of levulinic acid or its sodium salt. The smaller the amount within the above range, the more preferable. If the amount of water is less than the above-mentioned lower limit, stirring and mixing of the reaction system will become difficult, which is not preferable, and if the amount of water is more than the above-mentioned upper limit, the yield of ACVA will decrease, which is not preferable.

Furthermore, in the method of the present invention, a mixture of a cyanide compound such as sodium cyanide or hydrogen cyanide and hydrazines is contacted and reacted with levulinic acid or its sodium salt in the presence of the specified amount of water to produce hydrazine. It is necessary to generate a compound.

When reacting a mixture of a cyanide compound and hydrazines in advance with levulinic acid or its sodium salt as described above, it is possible to react via both the cyanohydrin route and the ketazine route described above. The above method has the advantage that even if the amount of water in the reaction system is reduced, the reaction system is less likely to solidify compared to the case of the cyanohydrin route or the ketazine route alone.
Furthermore, in this invention, the advantage that the reaction system is difficult to solidify even if the amount of water is reduced is that ketazine and cyanohydrin are produced in a mixed manner;
This is thought to be because the generated ketazine and cyanohydrin react with each other successively and change into a hydrazo compound that is easily soluble in water. When the hydrazo compound producing reaction is carried out at a relatively high temperature, the reaction can be carried out uniformly during the reaction even if the amount of water in the reaction system is considerably reduced. Therefore, the stirring operation during the reaction is easy and ACVA can be obtained in high yield.

Examples of the hydrazines include hydrazine hydrate, hydrazine sulfate, and the like.

The mixture of the cyanide compound and hydrazine can be obtained, for example, by mixing a small amount of water, the cyanide compound, and the hydrazine.

The temperature of the reaction between the above mixture and levulinic acid or its sodium salt is preferably 0 to 50°C, more preferably 5 to 40°C. If it is lower than 0°C, the reaction system will solidify and stirring will become difficult, and if it is higher than 50°C, side reactions will easily occur and the yield of ACVA will decrease. Reaction time is more than 10 minutes, especially more than 1 hour.
Preferably within 20 hours. 1-5 from an industrial standpoint
time is preferable. Generally, the reaction time is determined in relation to the reaction temperature. The reaction system has a pH of 4 to 10, especially 5 to 10.
9 is preferred. Especially high (preferably 90
% or more) In order to obtain an ACVA yield, in the case of levulinic acid, 30 to 100 parts by weight of levulinic acid should be used.
levulinic acid and 2 to 20 parts by weight per 100 parts by weight of levulinic acid at a reaction temperature of 5 to 40°C.
adding a mixture with Conc Hcl to said mixture;
The reaction may proceed in the form of a concentrated homogeneous solution (or slurry), and Ccnc Hcl may be added to the reaction system in an amount that does not cause the pH of the system to fall within the range of 5 to 9. If the reaction is carried out at the above temperature for about 1 to 10 hours (this time or more is acceptable), the ACVA yield will be high (preferably 90%
% or more). When sodium levulinate is used, it is preferred to use hydrogen cyanide.

In the method of the present invention, a concentrated aqueous solution of a hydrazo compound represented by the following formula, which is a reaction product, can be obtained by the method described above.

(In the formula, M is H or Na.) In the method of the present invention, the concentrated aqueous solution contains acetone and/or water, preferably in an amount of 100 parts by volume or more per 100 parts by volume of the concentrated aqueous solution. , preferably the ratio of acetone to water is 85:15 by volume.
Acetone is added in an amount of ˜98:2, particularly preferably 90:10 to 95:5 to form an aqueous solution of the hydrazo compound, preferably an acetone-water solution.

When the ratio of acetone and water is greater than 98:2, the solubility of ACVA decreases significantly and a large amount of acetone-water mixed solvent is required, and when it is less than 85:15, the solubility of the by-product sodium chloride increases. , the content of sodium chloride contained in the acetone-water solution containing ACVA becomes high.

In the method of the present invention, preferably 0.4 mol or more, particularly 0.5 mol or more, and further 0.5 to 0.6 mol of chlorine gas is added to the solution per 1 mol of levulinic acid or its sodium salt used to oxidize the hydrazo compound. to generate ACVA. The oxidation reaction is preferably carried out at a temperature below 30°C, particularly below 10°C. A method known per se is used for adding chlorine gas.

In the method of this invention, if necessary, acetone is added to the reaction mixture containing ACVA obtained as described above to adjust the ratio of acetone to water in the mixture to 85:15 to 98:2 by volume. Preferably 90:
The temperature of the mixture is preferably adjusted to 10 to 95:5, preferably 0 to 60°C, particularly 15 to 60°C, and the supernatant liquid, an acetone-water solution containing ACVA, is separated from the mixture.

In the method of the present invention, when ACVA is produced by the above-mentioned oxidation reaction, sodium chloride is by-produced in an amount twice or more moles relative to ACVA.
In the method of the present invention, preferably by adjusting the ratio of acetone and water in the mixture to the above-mentioned specific range, sodium chloride produced as a by-product crystallizes and precipitates in the mixture;
Only a very small amount of sodium chloride is dissolved in the acetone-water solution in which ACVA is dissolved. In the method of this invention, when the ratio of acetone to water in the acetone-aqueous solution of the hydrazo compound is already 85:15 to 98:2 by volume, acetone may or may not be further added. .

In addition, when hydrochloric acid is contained in the reaction mixture in the method of this invention, an alkali such as sodium hydroxide or a weakly alkaline compound such as sodium carbonate or sodium hydrogen carbonate is added to neutralize the hydrochloric acid. It is preferable to adjust the pH of the solution to 3-5, particularly 4-5.

When the acetone-water solution containing ACVA is separated and obtained, if the ratio of acetone to water in the mixture is less than 85:15, the amount of sodium chloride in the separated solution containing diazocyano acid will increase significantly. The final ACVA contains a large amount of chlorine and sodium, and if the ratio is greater than 98:2, a large amount of acetone is required to dissolve the ACVA, which is not preferable.

In order to separate and obtain the supernatant acetone-aqueous solution containing ACVA from the mixture, the mixture may be filtered to obtain the acetone-aqueous solution of ACVA as a filtrate, and the supernatant of the mixture may be decanted. It may be obtained by In the method described above, the sodium chloride crystals are separated and removed.

In the method of the present invention, for example, acetone and water may be removed by evaporation from the acetone-aqueous solution containing ACVA, and ACVA may be separated by adding a small amount of water to the remaining solid and washing with water. ,
Preferably, the acetone is evaporated and water is added to the remainder.
ACVA can be separated and obtained by filtering and collecting ACVA. Add 100 to 1500 parts by weight, especially 100 to 1000 parts by weight of water per 100 parts by weight of ACVA to the residue after evaporation of acetone, mix preferably uniformly, and then heat at a temperature of 30°C or lower, particularly preferably 100°C. ACVA, which is solid at temperatures below ℃
It is preferable to obtain it separately. If necessary, a small amount of water contained in the ACVA crystals may be removed by drying under reduced pressure.

According to the preferred method of the present invention, ACVA with a low Na content can be produced.

ACVA produced by the method of this invention is
Homopolymerization of 1,3-butadiene or 1,3-
It can be used as a copolymerization initiator for butadiene and acrylonitrile. Acetone of ACVA after removing NaCl crystals obtained during the manufacturing process
Aqueous solutions can also be used as catalyst solutions.

Examples and comparative examples are shown below.

Example 1 25.25 g of NaCN in a 14-necked flask equipped with a stirrer, gas inlet tube, gas vent, and dropping tube.
(0.53mo), _H2O15ml , _{NH2NH2 ・ H2O12.52g}
(0.25 mo) was taken and stirred at 25°C. Some NaCN remained as undissolved particles. A solution prepared by adding 3.5 g of ConcHcl to 58.0 g (0.5 mo) of levulinic acid was added dropwise to this while maintaining the reaction temperature at 25 to 28°C. The system appears as a pale yellow, slightly viscous slurry, and is composed of NaCN.
The undissolved particles disappeared during the drop. Connc here
7 g of Hcl was added, heated to 35°C, and reacted at this temperature for 3 hours. The system remained a slurry. Cool this to 5℃ and add 540ml of acetone.
40ml _H2O was added. Next, 21.3 g of Cl ₂ gas (0.3 mo
) was injected.

After the reaction, the temperature was returned to 20°C, and when stirring was stopped, the mixture was clearly separated into a slightly yellow transparent part and a white precipitate part. After removing the white precipitate by filtration and distilling off the acetone using an aspirator while keeping the liquid part at 20°C, a large amount of
ACVA was precipitated. Add 200ml of H ₂ O to this and 5℃
After stirring and washing, ACVA was collected by suction filtration.
Dry under reduced pressure at 20℃ until constant weight to obtain pure white
63.57 g of ACVA was obtained. This is for levulinic acid
The yield was 90.7%.

As for the elemental analysis results, the calculated values of ACVA (C ₁₂ H ₁₆ N ₄ O ₄ ) are C: 51.43%, H: 5.75%, N: 19.99%, whereas the actual values are C: 51.29%, H: 5.58%, N. :
It was 20.05%.

Moreover, the Na content in this ACVA was 180 ppm.

Example 2 25.25 g of NaCN in a 14-necked flask equipped with a stirrer, gas inlet tube, gas vent, and dropping tube.
(0.53mo), _H2O15ml , _{NH2NH2 ・ H2O12.52g}
(0.25 mo) was taken and stirred at 25°C. Some NaCN remained as undissolved particles. A solution prepared by adding 3.5 g of ConcHcl to 58.0 g (0.5 mo) of levulinic acid was added dropwise to this while maintaining the reaction temperature at 25 to 28°C. The system appears as a pale yellow, slightly viscous slurry, and is composed of NaCN.
The undissolved particles disappeared during the drop. The mixture was heated to 35°C and reacted at this temperature for 3 hours. The system remained a slurry. Cool this to 5℃ and add acetone.
540 ml and 40 ml of _H2O were added. Then the reaction temperature is
21.3g of Cl ₂ gas while cooling so as not to exceed 10℃
(0.3mo) was injected.

After the reaction, the temperature was returned to 20°C, and when stirring was stopped, the mixture was clearly separated into a slightly yellow transparent part and a white precipitate part. After removing the white precipitate by filtration and distilling off the acetone using an aspirator while keeping the liquid part at 20°C, a large amount of
ACVA was precipitated. Add 200ml of H ₂ O to this and 5℃
After stirring and washing, ACVA was collected by suction filtration.
Dry under reduced pressure at 20℃ until constant weight to obtain pure white
63.85 g of ACVA was obtained. This is for levulinic acid
The yield was 91.1% (Na content 21.0 ppm).

Example 3 25.25 g of NaCN in a 14-necked flask equipped with a stirrer, gas inlet tube, gas vent, and dropping tube.
(0.53mo) _{, H2O50ml} , _NH2H2・_H2O12.52g
(0.25 mo) was taken and stirred at 5°C. Some NaCN remained as undissolved particles. A solution prepared by adding 3.5 g of Conc Hcl to 58.0 g (0.5 mo) of levulinic acid was added dropwise to this while maintaining the reaction temperature at 25 to 28°C.
The system appears as a pale yellow, slightly viscous slurry.
The undissolved particles of NaCN disappeared during the dropping. here
7 g of Conc Hcl was added, heated to 35°C, and reacted at this temperature for 3 hours. The system remained a slurry. Cool this to 5℃, add 540ml of acetone,
40ml _H2O was added. Next, 21.3 g of Cl ₂ gas was added while cooling so that the reaction temperature did not exceed 10°C.
(0.3mo) was injected.

After the reaction, the temperature was returned to 20°C, and when stirring was stopped, the mixture was clearly separated into a slightly yellow transparent part and a white precipitate part. After removing the white precipitate by filtration and distilling off the acetone using an aspirator while keeping the liquid part at 20°C, a large amount of
ACVA was precipitated. Add 200ml of H ₂ O to this and 5℃
After stirring and washing, ACVA was collected by suction filtration.
Dry under reduced pressure at 20℃ until constant weight to obtain pure white
58.87 g of ACVA was obtained. This is for levulinic acid
The yield was 84.0% (Na content 230 ppm).

Comparative Example 1 58.0 g of levulinic acid in a 4-necked flask equipped with a stirrer, gas inlet tube, gas vent, and dropping tube.
(0.5 mo) Conc Hcl 3.5 g and H ₂ O 130 ml were added.
Here, while keeping the reaction temperature at 5℃,
An aqueous solution of 25.25 g (0.53 mo) of NaCN dissolved in 50 ml of H ₂ O was added dropwise. The reaction solution was colorless and transparent. Here NH ₂ NH ₂・H ₂ O12.52g (0.25mo)
was added, warmed to 35°C, and stirred for 3 hours.
After cooling to 5℃, add 1000ml of acetone and _Cl2 gas.
21.3 g (0.3 mo) was added to maintain the liquid temperature at 5-10°C. After the reaction, the temperature was returned to 20°C, and the mixture was post-treated and dried in the same manner as in Example 1 to obtain 45.5 g of ACVA. The yield was 65% based on levulinic acid.

Comparative Example 2 In a four-necked flask equipped with a stirrer, gas inlet tube, gas vent, and dropping tube, 58.0 g of levulinic acid was added.
(0.5 mo), 3.5 g of Conc HCl, and 5 ml of _H2O were added. While keeping the reaction temperature at 5℃,
An aqueous solution of 25.25 g (0.53 mo) of NaCN dissolved in 50 ml of H ₂ O was added dropwise. Solidification occurred rapidly at the end of the dropwise addition, making temperature control impossible and stirring impossible. Here, concHCl7g, NH ₂ NH ₂・
12.52 g (025 mo) of H ₂ O was added and warmed to 35°C. Stirring became possible after the temperature exceeded 20°C, and at 33°C the slurry-like state turned into a slightly yellow transparent liquid. After reacting at 35℃ for 3 hours, cool to 5℃ and add 540ml of acetone.
was added, and 21.3 g (0.3 mo) of Cl ₂ gas was added to keep the liquid temperature below 10°C. After the reaction, the temperature was returned to 20°C, post-treated and dried in the same manner as in Example 1 to obtain 56.6 g of ACVA.

Comparative Example 3 The same procedure as in Example 1 was carried out up to the point where a concentrated aqueous solution of a hydrazo compound was obtained. After cooling this to 5℃
After adding 200 ml of H ₂ O, 21.3 g (0.3 mo) of Cl ₂ gas was blown into the reaction mixture while cooling it so that the reaction temperature did not exceed 10°C. ACVA precipitated in large quantities as a white slurry. This white slurry was suction filtered and dried under reduced pressure to obtain 61.2 g of ACVA. This ACVA
There was 30,000 ppm of Na in it. This ACVA was washed again with 600 ml of H ₂ O and dried, but the Na content was still 1500 ppm.

Claims (1)

[Claims] 1. (a) a mixture of a cyanide compound and hydrazine; (b) levulinic acid or its sodium salt; and (c) 25 to 200 parts by weight per 100 parts by weight of levulinic acid or its sodium salt. A hydrazo compound is produced by contacting and reacting in the presence of water, and chlorine gas is added to a solution in which acetone and/or water is added to the resulting concentrated aqueous solution of the hydrazo compound to oxidize the hydrazo compound. The volume ratio of acetone and water in the reaction mixture obtained by oxidation is 85:15 ~
A supernatant acetone-aqueous solution is separated from the mixture by adjusting the ratio to 98:2, and 4,4'-azobis(4-cyanovaleric acid) is separated and obtained from this acetone-aqueous solution. A method for producing azobis (4-cyanovaleric acid).