JPH0128032B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides 2,3-dicyano-1,4-dithia-, which has high purity and low naphthoquinone content, from an alkali metal salt of 1,4-naphthoquinone and 1,2-dicyano-1,2-dimercaptoethene.
A novel method for producing 9,10-anthraquinone. 2,3-dicyano-1,4-dithia-9,10-
Anthraquinone (hereinafter abbreviated as DDAQ) is used as a dithianone agent as a fungicide that is effective against a wide range of diseases such as leaf blight of rice and fruit trees and vegetables. The manufacturing method for DDAQ is to use 1,4-naphthoquinone (hereinafter abbreviated as NQ) and 1,2-dicyano-
Consisting of a process in which 1,2-dimercaptoethene (hereinafter abbreviated as DDM) is reacted with a dialkali metal salt in an aqueous medium while maintaining the pH value at 5, and the resulting product is oxidized in an aqueous medium. A method that does not use an organic solvent (Japanese Patent Publication No. 41-11730) is industrially effective. However, although the present inventors produced DDAQ based on the example of the present method, the purity and yield of the DDAQ obtained were low, and the NQ content in the obtained DDAQ was high, resulting in undesirable results. I couldn't help it. In fact, according to Japanese Patent Publication No. 51-38768, the purity is as follows: ``The product obtained in the manufacturing process contains 89% of the above-mentioned dithianone (same as DDAQ) and 11% of other by-products from the synthesis process.'' low. Furthermore, as indicated in the same publication, dithianone's raw material usually contains 0.5% or more of NQ, which causes damage to the skin and mucous membranes of those who use dithianone. Therefore, it is necessary to remove NQ from the dithianone raw material. According to the same publication, in order to remove NQ from the dithianone industrial raw material produced, general organic solvents such as benzene and toluene are used to remove the dithianone industrial raw material. Purification methods such as recrystallization, extraction, and adsorption methods are described. However, the solubility of DDAQ in organic solvents is extremely low, requiring the use of a large amount of solvent, and on top of that, the need for a purification process in addition to the manufacturing process is extremely costly and complicated from an industrial perspective. It is disadvantageous. The present inventors have compared the conventional NQ
It overcomes the above-mentioned drawbacks of producing DDAQ by reacting it with DDM in an aqueous medium, and achieves high purity and yield while reducing the NQ content in the obtained product, especially
We have been considering improving the manufacturing method to reduce the amount to 0.5% or less. We first reacted NQ with an alkali metal salt of DDM in an aqueous medium while controlling the pH to 5.1 to 5.8, especially about 5.3, and then treated with hydrogen peroxide, followed by the method described in Japanese Patent Publication No. 11730/1973. like,
When the obtained product containing dicyano-1,4-dithia-9,10-anthrahydroquinone (hereinafter abbreviated as DDAHQ) is oxidized in an aqueous medium, DDAQ
It was found that the purity and yield of However, this method yields high yields and high purity.
The suitable range of PH conditions is extremely narrow at 5.1 to 5.8, making it difficult to control industrially, and the resulting DDAQ
The NQ content inside was about 0.5%, which was not completely satisfactory. Therefore, in the above method, the product containing DDAHQ obtained by reacting NQ with an alkali metal salt of DDM and then treating with hydrogen peroxide is oxidized in the presence of a polar medium such as alcohol and an oxidizing agent such as iron chloride. When I did it below, it was included as an impurity.
NQ turns into a soluble separate compound, so that the NQ content in the obtained DDAQ is reduced to below about 0.1% and that the NQ and DDM The present invention was completed based on the discovery that there is no tendency for purity and yield to rapidly decrease due to changes in pH during reaction with alkali metal salts, and that the purity is actually higher than that of conventional methods. The present invention utilizes NQ suspended in an aqueous medium.
DDM with alkali metal salt in aqueous medium PH5.1~
5.8, followed by treatment with a dehydrogenating agent, and the resulting product containing DDAHQ is oxidized in the presence of a polar solvent and an oxidizing agent. The NQ used in the present invention is preferably a fine particle having a particle size of 32 mesh through, preferably 60 mesh through. The higher the purity of NQ, the better, but it may be an industrial product with a purity of about 90 to 97%. If the particle size is large, the reaction rate will be slow and side reactions will occur, which is not preferable. This NQ is suspended in an aqueous medium containing an acid such as acetic acid for pH adjustment, and then reacted with a solution of an alkali metal salt of DDM. In the present invention, the alkali metal salt of DDM is selected from lithium, sodium or potassium salts, and sodium salts are usually used. Although its manufacturing method is already known, it can be easily synthesized using carbon disulfide and sodium cyanide as raw materials. The alkali metal salt of DDM is used in an amount equal to or more than the mole of NQ, preferably 1.05 to 1.3 times the mole. In the present invention, the aqueous medium is a medium containing water as a main component, and even if other solvents, such as those used in the synthesis of DDM, are mixed in, this will not be a problem. In the present invention, the above reaction, that is, NQ and
The pH during the reaction with DDM is preferably in the range of 5.1 to 5.8 in order to obtain DDAQ with high purity and high yield. In the present invention, the reaction temperature is preferably 0 to 10°C, preferably 0 to 5°C. After the NQ and DDM alkali metal salts (usually dialkali metal salts) are reacted, a dehydrogenating agent is usually added. Examples of the dehydrogenating agent in this case include air, oxygen, hydrogen peroxide, nitric acid, or chlorine, and hydrogen peroxide is usually used. When treated with a dehydrogenating agent such as hydrogen peroxide
Products Containing DDAHQ Generally DDAQ and DDAHQ
quinhydrone is obtained as a blackish brown precipitate. The precipitate is separated and the product obtained is oxidized to DDAQ with an oxidizing agent. The product can then be used as a wet cake in the subsequent oxidation reaction. The oxidation reaction is carried out in the presence of a polar organic solvent and an oxidizing agent. Examples of the polar organic solvent include alcohols such as methanol, ethanol or propanol, carboxylic acids such as acetic acid, ketones such as acetone, and solvents that are stable to oxidizing agents such as dimethylformamide. As oxidizing agent, use is made of such oxidizing agents capable of oxidizing DDAHQ, such as ferric chloride or potassium dichromate. The oxidation reaction can be carried out usually at a temperature below the boiling point of the solvent, generally below 80°C, from 0 to 60°C, usually at room temperature.
The reaction can be carried out in a slurry state that can be operated without dissolution, and the amount of solvent is much smaller than in recrystallization methods, for example, about twice the amount of DDAQ or more.
The purpose of the present application can be achieved with ~20 times the amount. However, due to the solubility of DDAQ in the solvent,
In order to increase the amount of DDAQ obtained, it is better to reduce the amount of solvent. The invention generally operates as follows. A mixed solution of DDM disodium salt dimethyl sulfoxide (hereinafter abbreviated as DMSO) and water was kept at 0 to 5 °C and atomized with thorough stirring.
Add a mixed suspension of NQ, acetic acid and water to the specified pH.
hold and react. As the reaction progresses, the pH
increases, so add an acid, for example, an aqueous solution of acetic acid.
Adjust PH. In addition to acetic acid, carboxylic acids such as formic acid, benzoic acid, and phthalic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid can also be used as acids for pH adjustment. NQ gradually dissolves into a homogeneous aqueous solution, and then gradually becomes a heterogeneous system. 10-60 minutes after adding NQ, usually 15-40
After a few minutes, when hydrogen peroxide solution is added in an amount of 1 to 1.2 times the mole of NQ, a dark brown precipitate (quinhydrone, which is an intermolecular compound between DDAQ and its reduced form, DDAHQ) is precipitated. After 1 hour, the dark brown precipitate is separated and washed with water. The resulting wet cake is placed in a container with an organic solvent, such as an alcohol such as methanol, and a solution of ferric chloride dissolved in the same organic solvent is added with stirring. The mixture is stirred at room temperature for 0.5 to 3 hours, usually for 1 hour, and the resulting product is filtered, washed (washed with water and alcohol), and dried. Ferric chloride is used in an amount equal to or more than an equivalent molar amount, usually about 1.2 to 3 times the amount of NQ used as a raw material. Next, the present invention will be explained in detail with reference to Examples. Example 1-(1) (Example of reaction between NQ and DDM) 1.6 g (31.3 mmol) of sodium cyanide
2.5 g of carbon disulfide suspended in 7.8 g of DMSO
(32.8 mmol) is gradually added. Keep it at 30℃ for 1 hour and at 40℃ for 1.5 hours. Then add 20ml of water and bring to 50℃. After keeping at that temperature for 1.5 hours,
Cooling. The liberated sulfur is filtered off, and the reddish-brown liquid containing the disodium salt of DDM is placed in a 100 ml four-necked flask and kept at 0-2°C. While stirring well, add 2.33 g of NQ (14.6 mmol at 99.0% purity,
A suspension of 0.93 times the molar equivalent of DDM disodium salt) in a mixed solution of 20 ml of water and 1.0 g of acetic acid is added all at once. Stir well until the PH reaches a predetermined value (shown in Tables 1 and 2), and then maintain the PH using an acetic acid aqueous solution when the PH reaches the predetermined value.
30 minutes later, 1.5g of hydrogen peroxide (35%) in about 5 minutes
(15.4 mmol) and 10 ml of water are gradually added. Since the pH increases, maintain it at the specified pH with an acetic acid aqueous solution. After 1 hour, the reaction temperature was increased from 0 to 2℃ to 10 to 15℃.
Gradually raise to ℃. After the reaction, the blackish brown precipitate (quinhydrone forms of DDAHQ and DDAQ) is separated, and the resulting wet cake is thoroughly washed with water. Example 1-(2) (Oxidation treatment experiment of the present invention) In Example 1-(1), the wet cake (quinhydrone body) obtained by performing the experiment at various pH was treated with ferric chloride (hexahydrate). 7.0g (26.0mmol) in methanol 50ml
The mixture was suspended in a solution dissolved in and stirred well at room temperature for 1 hour. The resulting pale brown precipitate was filtered, thoroughly washed with water, and then dried. The obtained product was analyzed by high performance liquid chromatography. The results are shown in Table 1.

[Table] Comparative example (Oxidation treatment experiment in aqueous medium) In Example 1-(1), the wet cake obtained by carrying out the experiment at various PHs was mixed with 7.0 g of ferric chloride (hexahydrate).
(26.0 mmol) was suspended in an aqueous solution of 50
Stir well for 2 hours at °C. The light brown precipitate obtained is filtered off, thoroughly washed with water, and then dried. The obtained product was analyzed by high performance liquid chromatography. The results are shown in Table 2.

[Table] Example 2 In Example 1-(1), the wet cake obtained at PH5.3 was mixed with 7.0 g of ferric chloride (hexahydrate).
(26.0 mmol) in 25 ml of methanol was suspended and stirred well at room temperature for 1 hour. The light brown precipitate obtained is filtered off, thoroughly washed with water, and then dried. The amount of product obtained was 4.04g.
The product was analyzed by high performance liquid chromatography. The purity of DDAQ was 99.2%, the NQ content was traceable, and the yield was 93.1 mol. Example 4 The same procedure as in Example 3 was carried out using ethanol instead of methanol, and the purity of DDAQ was 98.5.
%, NQ content was 0.08%, and yield was 90.5 mol%. Note that the same procedure could be carried out using dimethylformamide.

Claims (1)

[Scope of Claims] 1. 1,4-naphthoquinone suspended in an aqueous medium and an alkali metal salt of 1,2-dicyano-1,2-dimercaptoethene at pH 5.1 to 5.8 in an aqueous medium.
and then treated with a dehydrogenating agent, and the resulting product containing 2,3-dicyano-1,4-dithia-9,10-anthrahydroquinone is oxidized in the presence of a polar solvent and an oxidizing agent. Features 2,
A method for producing 3-dicyano-1,4-dithia-9,10-anthraquinone. 2. The method according to claim 1, wherein the polar solvent is alcohol, dimethylformamide, carboxylic acid, or acetone. 3. The method according to claim 1, wherein the alcohol is methanol or ethanol. 4. The method according to claim 1, wherein the oxidizing agent is ferric chloride.