JPS5929657A - Preparation of beta-mercaptopropionitrile - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as a synthetic raw material of organic chemicals such as pharmaceuticals, agricultural chemicals, etc. from inexpensive low-toxic raw materials, in high yield, by reacting beta-chloropropionnitrile with a thiosulfuric acid salt, and hydrolyzing the product in the presence of an acid. CONSTITUTION:beta-Chloropropionitrile is made to react with a thiosulfuric acid salt in an aqueous medium such as water, alcohol, dioxane, etc. at a temperature between 60 deg.C and the boiling point of the solvent for 15min-5hr to obtain Bunte salt, which can be converted to the objective compound by hydrolyzing at a temperature between 60 deg.C and the boiling point of the solvent for 30min-8hr in the presence of an acid such as sulfuric acid, hydrochloric acid, etc. The molar ratio of beta-chloropropionitrile:thiosulfate is 1:(0.8-1.2), and that of beta-chloropropionitrile: acid is 1:(0.5-5.0). The thiosulfuric acid salt is e.g. sodium thiosulfate, magnesium thiosulfate, ammonium thiosulfate, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing β-mercaptopropionitrile. More specifically, the present invention relates to a method for producing β-mercaptopropionitrile using β-chloropropionitrile and thiosulfate, which are easily obtained from acrylonitrile, as raw materials.

β-Mercaptopropionitrile is a compound useful as a raw material for many organic synthetic products including medicines and agricultural chemicals.

Various methods are conventionally known for producing β-mercaptopropionitrile.

Typical production methods include the method of obtaining β-mercaptopropionitrile by alkaline hydrolysis of isothiuronium salt produced by the reaction of β-chloropropionitrile or acrylonitrile with thiourea CJ;
Org, Chem, 26 1443 (1961)
[see U.S. Pat. No. 3,211,777], or a method in which β-chloropropionitrile is reacted with carbon disulfide and sodium hydroxide in an inproper tool, and the resulting xanthate ester is thermally decomposed under reduced pressure [see U.S. Pat. No. 3,211,777] ], and a method of hydrolyzing a thioacetate obtained by the reaction of acrylonitrile and thioacetic acid [see US Pat. No. 2,630,448].

Although β-mercaptopropionitrile can be obtained relatively easily by these methods, the sulfur source compound used as an auxiliary raw material is carbon disulfide, which is highly toxic and difficult to handle, and thiourea or thiourea, which is expensive as an industrial raw material. It has drawbacks such as the use of acetic acid, and cannot necessarily be called an economical industrial production method.

On the other hand, as a production method using cheaper raw materials, an attempt has been proposed to directly obtain β-mercaptopropionitrile by reacting acrylonitrile with hydrogen sulfide. [U.S. Pat.
See Publication No. 369]. However, these reactions are carried out under pressure using a large excess (3 to 10 times molar) of hydrogen sulfide to avoid the formation of the by-product thiodipropionitrile, and the reactor is therefore highly corrosive. It is necessary to select a special material that can withstand the high pressure system of strong hydrogen sulfide.

This is extremely disadvantageous as an industrial manufacturing method.

Under these circumstances, the present inventors used β-chloropropionitrile, which can be produced inexpensively from acrylonitrile, which is mass-produced for textile raw materials, as the main raw material, and also used an inexpensive and less toxic sulfur source. As a result of intensive research to develop an economical industrial production method for β-mercaptopropionitrile, we found that β-mercaptopropionitrile was produced by using thiosulfate as a sulfur source.
- Bunt as a precursor of mercaptopropionitrile
The present invention has been accomplished by discovering that β-mercaptopropionitrile can be obtained in high yield by generating e-salt and then hydrolyzing it with acid.

That is, the present invention provides 13 unte as a precursor of β-mercaptopropionitrile by reacting β-chloropropionitrile with thiosulfate in an aqueous medium.
This is a method for producing β-mercaptopropionitrile, which is characterized by hydrolyzing Bun-te salt in the presence of an acid to form a salt.

The reaction of the present invention is expressed by the following general formula.

CI CHz CH2CN + Mvh Ss On→
Mvh03SICHxC'&CN +M171>CIM
vh 03 S2 CH2CH2CN 10Hz 0rH
8CHZ CH2CN 10MVhH8O4 [However, 2M
is an alkali metal, alkaline earth metal or ammonium ion, and n is the valence or ionic valence of M and is 1 or 2. ] The main raw material β-chloropropioni-3-tolyl used in the present invention may be selected from any source. β
- When chloropropionitrile is obtained by the addition reaction of hydrogen chloride to acrylonitrile, hydrogen chloride gas is introduced into the acrylonitrile in the presence or absence of a solvent through a ball filter or the like while keeping the temperature below room temperature. It can be synthesized almost quantitatively.

In addition, the thiosulfates used in the present invention include alkali metal thiosulfates such as sodium thiosulfate and potassium thiosulfate, alkaline earth metal salts of thiosulfates such as magnesium thiosulfate and calcium thiosulfate, and ammonium thiosulfate. may be used alone or as a mixture of two or more. There is no restriction on the presence or absence of water of crystallization of thiosulfate.

Among these thiosulfates, sodium thiosulfate pentahydrate (commonly known as "hypo") is industrially produced in large quantities at low cost.
) is most preferred for industrial production methods.

Next, two general embodiments of the present invention will be described.

4-1) Production of 13unte salt The production of Bunte salt by the reaction of β-chloropropionitrile and thiosulfate is carried out in an aqueous medium using approximately equimolar amounts of both.

β-chloropropionitrile: thiosulfate = 1:0.8
-1.2 (molar ratio) You may use either raw material in excess.

As the aqueous medium, for example, water or a mixed solution such as water-alcohol, water-dioxane, water-tetrahydrofuran, or water-dinethyl sulfoxide is used.
Industrially, the reaction in water or a water-alcohol mixture is advantageous.

The concentrations of β-chloropropionitrile and thiosulfate in the aqueous medium were 5. It is preferable that the amount is approximately 50% by weight, but in this case, it is not necessarily necessary to mix uniformly.

The reaction temperature is usually in the range of 60°C to the boiling point of the reaction solution,
Further, a reaction time of about 15 minutes to 5 hours is sufficient.

After the reaction, the Bunte salt obtained may be separated from the inorganic salts by solvent extraction or the like and then subjected to the next hydrolysis, 9 but usually, the hydrolysis is carried out by subsequently adding an acid. When 13unte salt is isolated, thermal extraction with alcohols or the like can be used.

2) Hydrolysis The acids used for hydrolysis of 13unte salt include hydrochloric acid,
There are mineral acids such as sulfuric acid and phosphoric acid, organic carboxylic acids such as formic acid and oxalic acid, organic sulfonic acids such as P-toluenesulfonic acid, and solid acids such as strongly acidic ion exchange resins. Considering the separation process, etc., mineral acids such as sulfuric acid and hydrochloric acid are preferred from an industrial perspective.

The amount of acid used is based on β-chloropropionitrile.

β-Chloroprohionitrile: acid =1:0.5-3.0 (molar ratio) Preferably.

β-chloropropionitrile: acid =1:1. O~2.5 (molar ratio) selected within the range.

The acid concentration is preferably in the range of 10 to 40% by weight.

The temperature of the hydrolysis reaction is usually in the range from 60°C to the boiling point of the reaction solution, and the reaction time υ1 is sufficient to be about 30 minutes to 8 hours.

Here, for example, by carrying out the reaction at a reaction temperature of 85°C or higher for 5 hours or more, the obtained β-mercaptopropionitrile can be further hydrolyzed to β-mercaptopropionic acid, so if the 9 conditions are appropriately selected, Integrated production of β-mercaptopropionic acid from β-chloropropionitrile is possible.

3) After the completion of the recovery reaction, β-mercaptopropionitrile can be separated and purified from the reaction mixture by extraction with an organic solvent and distillation of the extract. Any extraction solvent may be used as long as it dissolves β-mercaptopropio 7-nitrile and is immiscible with water, particularly benzene, toluene, dichloromethane, and 1,2-dichloroethane.

1 , 1 , ] −) +J Chlorethane, chloroform, ether, etc. are used.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Production example [Production of β-chloropropionitrile] Stirrer,
108.7 f of acrylonitrile was charged into a reactor equipped with a cooling condenser, a thermometer, and a gas inlet tube, and after cooling with water to 5°C, 74.3 tons of hydrogen chloride was introduced from the gas inlet tube over about 7 hours. . During the introduction of hydrogen chloride gas, the liquid temperature in the reactor was maintained at 2 to 6°C. After the introduction of hydrogen chloride, the reaction mixture was aged for 2 hours at room temperature and then distilled under reduced pressure.
β-chloropropionitrile with iTg, yield of 93E%, and purity of 98% was obtained.

Example 1 8-1) Formation of Bunte's Salt In a reactor equipped with a thermometer, a stirrer, two dropping funnels, and a cooling condenser, 250.8 F sodium thiosulfate pentahydrate and 20 of water were charged and dissolved with stirring. Add β-chloro 7'o bionitrile 91 shown in the above production example to this solution.
．． A solution of 6F in 2001 ethanol was added through the dropping funnel and reacted under reflux for 5 hours.

Next, the solvent was distilled off under reduced pressure, and the mixture was extracted with heat using 600 tons of slightly water-containing ethanol. The obtained pale cream-colored solid was further reconsolidated from ethanol to obtain 153F (yield: 81%) of Bun-te salt in the form of white crystals.

The elemental analysis values of the product were as shown in Table 1.

Table 1 2) Hydrolysis Bunte salt thus obtained 481 total 4811
After dissolving 752 in a mixture of water and 36% hydrochloric acid and reacting at 90°C for 1 hour, a portion of the reaction solution was separated and analyzed by gas chromatography. As a result, the reaction yield was 15.6F. The production of β-mercaptopropionitrile at a rate of 72% was observed.

Furthermore, 9 reaction liquids were extracted with 100-1,2-dichloroethane, and this extract was distilled to yield 14.2f.
β-mercaptopropionitrile (boiling point 67-b, purity 99%) was obtained.

Reference Example 1 Bun t e salt 48F synthesized in 1) of Example 1 was dissolved in a mixed solution of 160 f of water and 125 t of 36-thihydrochloric acid and reacted at 90°C for 8 hours, after which a portion of the reaction solution was separated. The results were obtained by gas chromatography analysis.

The production of β-mercaptopropionic acid of 19.3 F (reaction yield 73%) and β-mercaptopropionitrile of 0.3 F (reaction yield 1.3%) was observed.

Example 2 In a reactor similar to Example 1, 22.9 ml of
of β-chloropropionitrile, 62.71 parts of sodium thiosulfate pentahydrate, and 1001 parts of water were charged and reacted at 90°C for 1 hour.

Next, 98 thiosulfuric acid was added dropwise through the 9-dropping funnel.
Subsequently, the reaction was continued at 90°C for 30 minutes.

The results of gas chromatography analysis of the obtained reaction solution were as shown in Table 2.

Table 2 Example 3 The reaction was carried out in exactly the same manner as in Example 2 except that the hydrolysis reaction time was changed to 1 hour, and the results shown in Table 3 were obtained.

11- Table 3 Examples 4 to 6 The reaction was carried out in the same manner as in Example 2 except that the type and amount of thiosulfate used were changed, and the results shown in Table 4 were obtained.

Table 4 Patent applicant: Nitto Chemical Industry Co., Ltd. Representative: Masahiko Namba 12-

Claims (1)

[Claims] The Bunte salt is produced as a precursor to β-mercaptopropionitrile by reacting β-chloropropionitrile with thiosulfate in an aqueous medium, and the Bunte salt is then hydrolyzed in the presence of acid. A method for producing β-mercaptopropionitrile.