JPH032859B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [] BACKGROUND TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing 3,3'-thiodipropionic acid. More specifically, the present invention relates to an improved process for producing 3,3'-thiodipropionic acid by reaction of acrylonitrile with sodium bisulfide or sodium sulfide and hydrolysis of the resulting nitrile intermediate. 3,3'-thiodipropionic acid and its derivatives are effective as stabilizers for synthetic resins, rubbers, oils and fats, etc., and their dialkyl esters are particularly effective as stabilizers for polypropylene, ethylene-propylene copolymers, etc. against heat and light. It is used as a curing agent. Prior Art Conventionally, 3,3'-thiodipropionic acid has been produced by a method using acrylic acid and hydrogen sulfide or sodium sulfide as raw materials. For example, special public relations
Publication No. 15170 describes a method of reacting acrylic acid and hydrogen sulfide using Triton B or caustic soda as a catalyst, and British Patent No. 571628 describes a method of reacting acrylic acid with sodium sulfide nonahydrate. are described, and all of these can be said to be simple manufacturing methods. However, the manufacturing method using acrylic acid as a raw material is
Although this method is simple, it is not economically advantageous in Japan because acrylic acid is expensive as an industrial raw material. As an alternative to the above method, the most suitable method is to use acrylonitrile, which is produced in large quantities as a raw material for acrylic fibers and is cheaper than acrylic acid, as a raw material. In the method using acrylonitrile as a raw material, a nitrile intermediate, i.e., 3,3'-thiodipropionitrile,
is known to be manufactured, for example, US Pat. No. 2,163,176, German Patent No. 2,104,911,
There are many reports such as Org.React, 5 , 111 (1952). 3, obtained using acrylonitrile as a raw material
Regarding the hydrolysis method of 3'-thiodipropionitrile using caustic soda, for example, there is a report by Matsuda et al., Journal of the Japan Petroleum Institute, Vol. 9, 38 (1966). In this method, 3,3'-thiodipropionitrile is produced using acrylonitrile and sodium sulfide as raw materials, and the nitrile compound is hydrolyzed by heating without isolating the 3,3'-thiodipropionitrile. It consists of obtaining dipropionic acid. Since the caustic soda necessary for the hydrolysis reaction is directly derived from sodium sulfide, the reaction is simple and economical, and this method is an excellent production method.
However, this method has a yield of 3,3'-thiodipropionic acid (based on acrylonitrile) of 70.1 to 76.1.
Since the yield is as low as %, there remains an economical problem as an industrial method. [] Summary of the Invention In view of the above circumstances, the inventors have proposed the 3,3′-
As a result of intensive research to develop an industrially advantageous method for producing thiodipropionic acid, we found that 3,3'-thiodipropionitrile or 3,3'-thiodipropionic acid can be produced by heating in an aqueous solution of caustic soda. Then, a part of it undergoes a reverse Michael reaction to produce 3-mercaptopropionic acid, acrylic acid, and polyacrylic acid as shown in the following formula, and as a result, 3,3'-thiodipropionic acid It was revealed that the yield of As a measure to prevent the above-mentioned reverse Michael reaction, the inventors added a catalytic amount of sulfur or sulfur-containing compounds or quinone compounds to the hydrolysis reaction system, thereby drastically reducing the reverse Michael reaction. It has been found that 3,3'-thiodipropionic acid can be obtained in high yield by reducing the amount of 3,3'-thiodipropionic acid. The present invention has been made based on these findings, and therefore, the method for producing 3,3'-thiodipropionic acid according to the present invention is a method for producing 3,3'-thiodipropionic acid obtained by reacting acrylonitrile with sodium hydrogen sulfide or sodium sulfide. The resulting 3,3'-thiodipropionitrile is reacted with a substantially stoichiometric amount of caustic soda and a catalytic amount of sulfur or sulfur-containing compounds or quinone compounds without isolating it from the reaction product. The sulfur or sulfur-containing compounds are hydrolyzed by heating in the presence of sulfur, sodium disulfide, sodium tetrasulfide, sodium polysulfide, thiophenol, tetramethylthiuram disulfide, 2-benzothiazoli disulfide, 2-(4-morpholinyldithio)
Benzothiazole, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, N-oxydiethylene-2-benzothiazolesulfenamide, N-cyclohexyl-2
-benzothiazole sulfenamide and 4,
The quinone compound is at least one selected from the group consisting of 4'-dithiomorpholine, and the quinone compound is at least one selected from the group consisting of benzoquinone oxime, p,p'-dibenzoylbenzoquinone oxime, hydroquinone, and hydroquinone monomethyl ether. It is characterized by certain things. [] Detailed Description of the Invention 1 Reaction of Acrylonitrile with Sodium Hydrogen Sulfide or Sodium Sulfide This reaction itself is known from the above-mentioned document by Matsuda et al., and the present invention does not use this known method unless it conflicts with the purpose. Therefore, this cyanoethylation reaction may be carried out. Note that details of implementation of the present invention will be described later. In the present invention, the catalytic hydrolysis according to the present invention is carried out without isolating the nitrile intermediate from this known cyanoethylation reaction product. Here, "without isolation from the reaction product" means that the nitrile is not recovered from the reaction product by distillation, extraction, or other means. Therefore, it is within the scope of the present invention to remove or separate some of the components other than the nitrile intermediate. The nitrile intermediate produced by this reaction is hydrolyzed by caustic soda derived from sodium sulfide to the corresponding 3,3'-thiodipropionic acid, but in the present invention, this caustic soda is substantially Ensure that it is present in stoichiometric amounts. Here, stoichiometric means that the Na/AN molar ratio is 1:1 (AN is acrylonitrile)
In addition, Na in this case includes sodium hydrosulfide or sodium sulfide. Therefore, when using sodium sulfide as a raw material, it is theoretically unnecessary to add caustic soda, and when using sodium hydrogen sulfide as a raw material, an equimolar amount of caustic soda is theoretically required. In addition, when sodium hydrosulfide is used as a raw material, an additional amount of caustic soda may be added after the cyanoethylation step is completed. 2 Catalyst The compound used as a reverse Michael reaction inhibitor is sulfur or a sulfur-containing compound or a quinone compound. Although it is not necessarily clear how these compounds inhibit the reverse Michael reaction during hydrolysis of the nitrile intermediate, these compounds will be referred to as catalysts in the present invention. Furthermore, the amount used will also be referred to as the catalytic amount even if it is a relatively large amount as described below. Among these compounds, sulfur-containing compounds are divided into inorganic compounds and organic compounds.Inorganic compounds include sodium disulfide, sodium tetrasulfide, and polysulfide, while organic compounds include thiophenol and tetrasulfide. Methylthiuram disulfide, 2-benzothiazolyl disulfide, 2-(4-morpholinyldithio)benzothiazole, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, N-cyclohexyl-2- Examples of the quinone compounds include benzoquinone oxime, p,p'-dibenzoylbenzoquinone oxime, hydroquinone, and hydroquinone monomer ether. In the present invention, these types of compounds can also be used by appropriately mixing them. There are no particular restrictions on the amount of these compounds used, but the weight ratio of these compounds to the raw material acrylonitrile is approximately 1.
It is good to set it to about 5%, preferably about 2 to 4%. 3. Specific details of the reaction In carrying out the method of the present invention, in order to increase the yield of 3,3'-thiodipropionic acid, first, the most suitable method for producing 3,3'-thiodipropionitrile in the pre-reaction is selected. It is important to obtain a stable yield under the conditions. 1 Cyanoethylation reaction - Synthesis of nitrile intermediate The ratio of acrylonitrile and sodium hydrogen sulfide + caustic soda or sodium sulfide and water used in the reaction for producing 3,3'-thiodipropionitrile is expressed as a molar ratio.
Na/S/ _H2O /AN=1.1~1.3/0.53~0.57/5
~10/1 range, preferably 1.2/0.56/7 ~
A range of 8/1 is good. The reaction temperature is preferably in the range of 20 to 50°C, preferably in the range of 30 to 40°C. If the reaction temperature is lower than 20°C, the produced 3,3'-thiodipropionitrile may crystallize, and sodium sulfide nonahydrate precipitates, which is undesirable since it inhibits the reaction. On the other hand, above 50℃, 3,
Hydrolysis of 3'-thiodipropionitrile is likely to occur and heat is generated, which is undesirable. The reaction is preferably carried out by adding acrylonitrile to an aqueous solution of sodium sulfide or sodium hydrogen sulfide + caustic soda. The reaction time is 3 times including the addition time of acrylonitrile.
It is best to set it to 5 hours. The 3,3'-thiodipropionitrile obtained under the above reaction conditions appears as a pale yellow oil and is separated on top of the alkaline aqueous solution. A part of the generated 3,3'-thiodipropionitrile is hydrolyzed and converted into an amide form and a carboxylic acid form, which are converted into 3,3'-thiodipropionitrile.
The yield calculated as 3'-thiodipropionitrile is 97
~98% (AN basis). 2 Hydrolysis Reaction The next hydrolysis reaction consists of adding a reverse Michael inhibitor and heating without isolating the 3,3'-thiodipropionitrile produced. The hydrolysis temperature is 112-115℃ (reflux), and the reaction time is 2-115℃ (reflux).
It takes about 6 hours. When heated under these conditions, ammonia and a small amount of hydrogen sulfide are released from the system, and hydrolysis is completed. After the reaction is complete,
When the temperature of the reaction solution reaches 70 to 80°C, hydrochloric acid or dilute sulfuric acid is added to acidify the generated 3,3'-thiodipropionic acid-Na salt. At this time, the cloudy substance produced in the reaction solution is removed by heating using a ceramic filter or diatomaceous earth. The obtained mother liquor is sufficiently cooled to 5°C, and the precipitated 3,3'-thiodipropionic acid is separated using a centrifuge to obtain crude wet crystals. These wet crystals contain 4 to 6% salt by weight, so add 1 to 3 times the weight of water to the wet crystals, dissolve by heating to 80°C, and cool to 5°C again. By crystallizing and separating white crystals using a centrifuge, purified 3,3'-thiodipropionic acid can be obtained. Incidentally, the recrystallized filtrate can be reused as the next reaction solvent for 3,3'-thiodipropionitrile.
The obtained wet crystals of 3,3'-thiodipropionic acid were
By drying with hot air at 60-80°C for 2-3 hours, 3,3'-thiodipropionic acid (melting point 130-131°C) with a water content of 0.1% by weight or less can be obtained in high yield. The 3,3'-thiodipropionic acid thus produced satisfies all standard values for hue, melting point, neutralization value, sulfate radicals, sulfides, etc. Note that the 3,3'-thiodipropionic acid-Na salt produced by hydrolysis can be recovered in the form of a salt instead of being acidified and recovered as a free acid as described above. Such embodiments are also within the scope of this invention. 4 Examples In the following experimental examples, "parts" means "parts by weight." Example 1 In a 1-liter reaction tank equipped with a stirrer, a thermometer, a dropping tank, and a condenser, 84.4 parts of sodium hydrogen sulfide with a purity of 73.0% by weight (the remainder is water), 172.9 parts of water, and 48 parts of water were added.
108.3 parts by weight of caustic soda was added, stirred and dissolved, and the liquid temperature was maintained at 35°C. A dropping tank was charged with 106.5 parts of acrylonitrile, and the acrylonitrile was added dropwise over 3 hours while stirring the inside of the reaction tank well.
During the dropwise addition of acrylonitrile, the cyanoethylation reaction was a slightly exothermic reaction, so the reaction temperature was maintained at 35° C. while occasionally cooling the reaction vessel, and after the completion of the dropwise addition, the aging reaction was carried out at the same temperature for 2 hours. After the aging reaction, 0.4 part of sulfur powder was added to the reaction solution and heated gradually. Hydrolysis started rapidly when the temperature exceeded 70℃, and the reaction temperature reached 90-100℃.
Vigorous release of ammonia gas was observed. In order to control rapid hydrolysis, the reaction tank was slightly cooled so that the reaction temperature did not exceed 100°C. When the rapid hydrolysis subsided in about 30 minutes, the reaction solution was heated and the reaction was carried out at 115-117°C (reflux) for 4 hours. The released ammonia gas was collected in dilute sulfuric acid. When the reaction tank was cooled and the reaction liquid reached 70 to 80°C, 26% by weight sulfuric acid was added from the dropping tank to perform acid precipitation, and the end point was PH = 1.8 of the reaction liquid. The hydrogen sulfide gas released by this acid precipitation was collected with a caustic soda aqueous solution. The reaction solution after acid precipitation became slightly cloudy, and this cloudy substance was separated and removed through a ceramic filter while keeping the temperature at 80℃ (Normally, decolorization is not necessary, but if necessary, the mother liquor can be decolorized by passing it through an activated carbon bath. do). When the acid precipitation mother liquor thus obtained was cooled to 5° C. with thorough stirring, a large amount of white crystals were precipitated. The crystals were thoroughly shaken off using a centrifuge to obtain 215.5 g of wet crystals. Add 165 parts of water to the obtained wet crystals, heat to 80°C with stirring to completely dissolve the crystals, then cool to 5°C to perform recrystallization, and centrifuge the crystallized crystals. When separated in a vessel, 184.2 parts of wet crystals and 196.0 parts of liquid (containing 7.2 parts of 3,3'-thiodipropionic acid and 15.0 parts of Glauber's salt) were obtained. The obtained wet crystals were dried in a hot air drying chamber at 80°C for 3 hours to obtain 156.6 parts (yield 88.0% (AN standard)) of purified 3,3'-thiodipropionic acid (melting point 129-131°C). It was done. The recrystallization liquid was used as raw material water in the following Example 2. Example 2 Using the same apparatus as in Example 1, 180 parts of the recrystallization solution of Example 1 and 73% by weight of sodium hydrogen sulfide were added to the reaction tank.
84.4 parts and 108.3 parts of 48% by weight caustic soda,
The temperature was maintained at 35°C with stirring. A dropping tank was charged with 106.5 parts of acrylonitrile, and the acrylonitrile was added dropwise over 3 hours while stirring the inside of the reaction tank well.
Since some heat was generated during the dropwise addition of acrylonitrile, the reaction temperature was maintained at 35° C. while occasionally cooling the reaction vessel, and after the completion of the dropwise addition, an aging reaction was carried out at the same temperature for 2 hours. After the aging reaction, stop stirring and separate the upper layer of 3,3'-thiodipropionitrile into two layers.
It was placed in a drip tank. Add 0.4 part of sodium tetrasulfide to the lower alkaline water layer, heat while stirring,
When the temperature reached 90°C, 3,3'-thiodipropionitrile was added dropwise from the dropping tank over a period of about 1 hour. The reaction solution generated heat, but not violently, and NH ₃ gas was gradually released. The reaction temperature was maintained at approximately 100°C. After dropping 3,3′-thiodipropionitrile,
The mixture was further heated to carry out a hydrolysis reaction at 115-117°C (reflux) for 4 hours. The sulfuric acid precipitation method and the method for recrystallizing 3,3'-thiodipropionic acid were carried out in accordance with the methods of Example 1. Purified 3,3'-thiodipropionic acid (melting point
129.5-131°C) was obtained (163.8 parts of yield 92.0% (AN standard)). Examples 3 to 7 and Comparative Examples 1 to 2 Examples and comparative examples after Example 3 are shown in Table 1 below.
summarized in. 【table】

Claims (1)

[Claims] 1. 3,3'-thiodipropionitrile obtained by the reaction of acrylonitrile with sodium bisulfide or sodium sulfide in substantially stoichiometric amounts without isolating it from the reaction product. It consists of hydrolyzing by heating in the presence of caustic soda and a catalytic amount of sulfur or sulfur-containing compounds or quinone compounds, and the sulfur or sulfur-containing compounds are sulfur, sodium disulfide, sodium tetrasulfide, polysulfide. Soda, thiophenol, tetramethylthiuram disulfide, 2-benzothiazolyl disulfide,
2-(4-morpholinyldithio)benzothiazole, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, N-oxydiethylene-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide At least one selected from the group consisting of phenamide and 4,4'-dithiomorpholine, and the quinone compound is selected from the group consisting of benzoquinone oxime, p,p'-dibenzoylbenzoquinone oxime, hydroquinone and hydroquinone monomethyl ether. A method for producing 3,3'-thiodipropionic acid, characterized in that at least one type of 3,3'-thiodipropionic acid is used.