JPS621945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing diazocyano acid using a keto acid or its sodium salt as a starting material.

Conventionally, 4,4'-azobis(4-cyanovaleric acid)
Diazocyano acids such as (hereinafter sometimes simply abbreviated as ACVA) are used as fragrance intermediates and 1,3-
It is used as a (co)polymerization initiator for butadiene alone or for 1,3-butadiene and acrylonitrile.

The method for producing the diazocyano acid described above involves reacting a keto acid or its sodium salt, 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 produce diazocyano acid, and the solid diazocyano acid is collected by filtration from the resulting reaction mixture.

However, the above method has the following drawbacks.

When diazocyano acid is synthesized, 2 moles or more of sodium chloride is produced as a by-product per 1 mole of diazocyano acid, so diazocyano acid contains a large amount of sodium chloride. Diazocyanoic acid containing such a large amount of sodium chloride is
It is not preferred as an initiator for the (co)polymerization of 1,3-butadiene alone or of 1,3-butadiene and acrylonitrile.

If a purification step is provided to remove sodium chloride contained in diazocyanoic acid, the yield of diazocyanoic acid will be significantly reduced.

The inventors completed this invention as a result of intensive research aimed at providing a method for producing diazocyano acid that does not have the above-mentioned drawbacks.

That is, this invention makes a concentrated aqueous solution of a hydrazo compound by reacting a keto acid or its sodium salt, a cyanide such as sodium cyanide or hydrogen cyanide, and hydrazine in water, and 100 parts by volume per 100 parts by volume of the concentrated aqueous solution. 1 part or more of acetone to form an acetone-water solution of the hydrazo compound, add chlorine gas to the solution to oxidize the hydrazo compound to form diazocyano acid, and add acetone to the resulting reaction mixture if necessary. In addition, the ratio of acetone and water in the mixture is adjusted to a volume ratio of 85; 15 to 98; 2, and a supernatant acetone-aqueous solution containing diazocyano acid is separated from the mixture, and diazocyano acid is extracted from this solution. The present invention relates to a method for producing diazocyano acid, which comprises separating and obtaining diazocyano acid.

According to the method of the present invention, diazocyano acid with a low sodium chloride content can be produced in high yield.

Further, according to the method of the present invention, since the crystal particles of sodium chloride in the mixture of acetone and water containing a specific proportion of diazocyano acid and sodium chloride are large, sodium chloride can be removed from the mixture by a simple separation operation. It can be separated and removed, which is very advantageous in terms of the process.

In the method of this invention, a keto acid or its sodium salt, a cyanide compound such as hydrogen cyanide or sodium cyanide, and hydrazine are reacted in water to obtain a concentrated aqueous solution of a hydrazo compound.

Preferred examples of the keto acid or its sodium salt include levulinic acid and sodium levulinic acid.

Further, examples of the hydrazines include hydrazine hydrate, hydrazine sulfate, and the like.

In the method of this invention, a keto acid or a sodium salt of a keto acid (per mole) and a cyanide compound (per mole) are mixed in a small amount of water in the presence or absence of a mineral acid such as hydrochloric acid or an alkali such as sodium hydroxide.
It is preferable to react hydrazines (0.5 mol) with hydrazines (0.5 mol). In this method, the ratio between the total amount of water and the keto acid or sodium salt of the keto acid is
Preferably, the amount of the keto acid or the sodium salt of the keto acid is 10 to 120 parts by weight, particularly 30 to 80 parts by weight, based on 100 parts by weight of the total amount of water.

Furthermore, in the method of the present invention, after reacting each of the components in a relatively large amount of water, water may be removed by evaporation from this aqueous solution to obtain a concentrated aqueous solution of the reaction product.

The reaction of each component in water may be carried out by contacting a keto acid, sodium cyanide, and a hydrazine such as hydrazine sulfate in the presence of an alkali, or by contacting a keto acid with sodium cyanide in the presence of a mineral acid. The hydrazine hydrate may be added to the system and brought into contact with each other, preferably at a temperature of 20° C. or lower. The above reaction is preferably carried out at a temperature below 50°C, especially below 35°C.

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, R is an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 6.) In the method of this invention, the above-mentioned concentrated aqueous solution
An amount of 100 parts by volume or more per 100 parts by volume, preferably a volume ratio of acetone to water of 85; 15 to 98;
2, particularly preferably 90:10 to 95:5, to form an acetone-aqueous solution of the hydrazo compound.

When the ratio of acetone and water is outside the above range,
This is not preferred because it lowers the yield of diazocyano acid.

In the method of the present invention, chlorine gas is preferably added to the solution in an amount of 0.5 mol or more, particularly 0.5 to 1 mol, and further 0.5 to 0.6 mol per mol of levulinic acid or its sodium salt used to oxidize the hydrazo compound. to produce diazocyanoic acid.
The oxidation reaction is preferably carried out at a temperature below 30°C, particularly below 10°C.

Preferred examples of the diazocyano acids include 4,4'-azobis(4-cyanovaleric acid).

In the above method, a method known per se is employed for adding chlorine gas.

In the method of this invention, if necessary, acetone is added to the reaction mixture containing diazocyano acid obtained as described above to adjust the ratio of acetone to water in the mixture by volume to 85; 15 to 98; 2. , preferably 90; 10 to 95; get.

In the method of the present invention, when diazocyano acid is produced by the above-mentioned oxidation reaction, sodium chloride is produced as a by-product in an amount of twice or more mole or more relative to the diazocyano acid. In the method of this invention, 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 diazocyanoic acid 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. , the pH of the solution should be 3-5, especially 4-5.
It is preferable to adjust it to

When the acetone-aqueous solution containing diazocyano acid is separated and obtained, if the ratio of acetone and water in the mixture is outside the above range, the amount of sodium chloride in the separated solution containing diazocyano acid will be significantly large. This is not preferable since the diazocyano acid finally obtained contains large amounts of chlorine and sodium.

In order to separate and obtain the supernatant acetone-aqueous solution containing diazocyano acid from the above mixture, the mixture may be filtered to obtain the acetone-aqueous solution of diazocyano acid as a filtrate, and the supernatant of the mixture may be obtained in decane. It may also be obtained by station. 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 the diazocyano acid, and the remaining solid may be separated and obtained by adding a small amount of water and washing with water. Diazocyanoic acid can be separated and obtained, preferably by evaporating acetone, adding water to the residue, and collecting the diazocyanoic acid by filtration. Add 100 to 1500 parts by weight, especially 100 parts by weight, to the residue after evaporating acetone to 100 parts by weight of diazocyanoic acid.
Add ~1000 parts by weight of water, preferably after homogeneous mixing, at a temperature below 30 °C, particularly preferably 10 °C
It is preferable to separate and obtain the solid diazocyano acid at the following temperature. If necessary, a small amount of water contained in the diazocyano acid crystals may be removed by drying under reduced pressure.

According to the method of this invention, diazocyano acid having a Na content of 500 ppm or less can be produced.

The diazocyano acid produced by the method of the present invention can be used as an initiator for homopolymerization of 1,3-butadiene or copolymerization of 1,3-butadiene and acrylonitrile.

Examples and comparative examples are shown below.

Example 1 0.963 Kg (8.3 mol) of levulinic acid was placed in a reaction vessel equipped with a stirrer, gas inlet pipe, gas vent, and dropping pipe.
0.42 g of water was taken and cooled to 5°C. Concentrated hydrochloric acid here
0.058Kg, after adding water 0.08, NaCNO.420Kg
(8.5 mol) dissolved in 0.83 of water was added dropwise so that the reaction temperature did not exceed 10°C, and then the reaction was carried out at 10°C or lower for 15 minutes. At this time, the generated cyanohydrin precipitated and the reaction system took on a soft cream-like appearance. Here NH ₂ NH ₂・H ₂ OO.208Kg (4.15mol)
was added dropwise and heated to become a liquid at 30°C, and the reaction continued at 35°C for 3 hours. Next, cool to 5℃, add acetone 12, and then add 0.315Kg (4.5mol) of _Cl2 gas.
was added and allowed to react at a temperature not exceeding 10°C. After the reaction, the temperature was returned to 20°C, and when stirring was stopped, the mixture was clearly separated into a slightly yellow liquid part and a white precipitate part. The liquid part is acidic with hydrochloric acid, so after adjusting the pH to 4 by adding NaHCO ₃ , the white precipitate was removed by filtration, and a large amount of acetone was distilled off using an aspirator while keeping the liquid part at 20°C.
ACVA was precipitated. Add 2 parts of water, stir and wash at 5℃, collect ACVA by suction filtration, dry under reduced pressure at 20℃ until constant weight, and obtain pure white.
ACVA0.835Kg was obtained. This is one peak determined by liquid chromatography, and the elemental analysis results are ACVA.
Calculated value of (C ₁₂ H ₁₆ N ₄ O ₄ ) C: 51.43%, H: 5.75
%, N; 19.99%, the actual value is C; 51.52%,
H: 5.68%, N: 19.85%. Also, ACVA
The NaCl content in it was 62 ppm.

Example 2 0.963 kg (8.3 mol) of leplic acid and water were placed in a reaction vessel equipped with a stirrer gas inlet tube, a gas vent, and a dropping tube.
0.42 was taken and cooled to 5°C. Concentrated hydrochloric acid here
0.058Kg, after adding water 0.08, NaCNO.420Kg
(8.5 mol) dissolved in 0.83 of water was added dropwise so that the reaction temperature did not exceed 10℃, and then
The reaction was carried out for 15 minutes as follows. The cyanohydrin produced at this time precipitated, and the reaction system took on a soft cream-like appearance. Here NH ₂ NH ₂・H ₂ OO.208Kg (4.15mol)
was added dropwise and heated to become a liquid at 30°C. After reacting at 35°C for 3 hours, water was distilled off under reduced pressure at this temperature until the water content in the system reached 0.63. Next, cool to 5℃,
Add acetone 12, then _Cl2 gas 0.315Kg
(4.5 mol) was added, and the reaction was carried out at a temperature not exceeding 10°C. After the reaction, the mixture was heated to 20°C, and when stirring was stopped, it was clearly separated into a slightly yellow liquid part and a white precipitate part. The liquid part is acidic with hydrochloric acid, so after adjusting the pH to 4 by adding NaHCO ₃ , the white precipitate was removed by filtration, and the acetone was distilled off using an aspirator while keeping the liquid part at 20°C. A large amount of ACVA was precipitated. . 2.7 kg of water was added thereto, the temperature was raised to 5°C, and after stirring and washing, ACVA was collected by suction filtration and dried under reduced pressure at 20°C until a constant weight was obtained, yielding 835 kg of pure white ACVAO. This is one peak by liquid chromatography,
The elemental analysis results are ACVA (C ₁₂ H ₁₆ N ₄ O ₄ ) calculated values C: 51.43%, H: 5.75%, N: 19.99%,
Actual values are C: 51.35%, H: 5.79%, N: 20.21%
It was hot. Moreover, the NaCl content in ACVA was 28 ppm.

Comparative Example 1 0.963 kg (8.3 mol) of levulinic acid and water were placed in a reactor equipped with a stirrer, gas inlet pipe, gas vent, and dropping pipe.
1.0 was taken and cooled to 5°C. Concentrated hydrochloric acid here 0.058
Kg, after adding water 0.3, NaCNO.420Kg
(8.6 mol) dissolved in 1.6 mol of water was added dropwise so that the reaction temperature did not exceed 10°C, and then at 10°C.
The reaction was allowed to proceed for 15 minutes. At this time, unlike in Example 1, no product precipitation was observed. Here NH ₂ NH ₂・
After dropping 0.208 kg (4.15 mol) of H ₂ O, the mixture was reacted at 35° C. for 3 hours. Next, cool to 5℃, add 3.3 kg of acetone, then add 0.31 Kg (4.4 mol) of _Cl2 gas,
The reaction was carried out in such a way that the temperature did not exceed ℃. When acetone was distilled off under reduced pressure at 20°C from the reaction solution in which some of the produced ACVA was precipitated, a large amount of ACVA was precipitated. 3 with suction filtration
Crude ACVA was obtained over time. It was further washed with 0.7 kg of water, filtered and dried under reduced pressure to obtain ACVA of 0.69 kg. This ACVA contained 2000 ppm NaCl.

Claims (1)

[Claims] 1. A keto acid or its sodium salt, a cyanide such as sodium cyanide or hydrogen cyanide, and a hydrazine are reacted in water to form a concentrated aqueous solution of a hydrazo compound, based on 100 parts by volume of the concentrated aqueous solution. Acetone in an amount of 100 parts by volume or more is added to obtain an acetone-water solution of the hydrazo compound, and chlorine gas is added to the solution to oxidize the hydrazo compound to form diazocyano acid, and the resulting reaction mixture contains, if necessary, Acetone is added to adjust the ratio of acetone and water in the mixture to a volume ratio of 85; 15 to 98; 2, and a supernatant, an acetone-water solution containing diazocyano acid, is separated from the mixture. A method for producing diazocyano acid, which comprises separating and obtaining diazocyano acid. 2. The method for producing diazocyano acid according to claim 1, wherein the ratio of acetone to water in the acetone-aqueous solution of the hydrazo compound is 85:15 to 98:2 by volume. 3. The method for producing diazocyano acid according to claim 1, characterized in that acetone is evaporated from an acetone-aqueous solution containing diazocyano acid, and diazocyano acid is separated and obtained from the remainder.