JPH0211592B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a method for converting 1,4-naphthoquinone into 2,3-
A novel method for producing epoxy-2,3-dihydro-1,4-naphthoquinone. A method for synthesizing 2,3-epoxy-2,3-dihydro-1,4-naphthoquinone (hereinafter abbreviated as NQ-oxide), which is important as an intermediate for organic compounds such as agricultural chemicals and 2-hydroxy-1,4-naphthoquinone. The following methods are known. (1) 1,4-naphthoquinone (hereinafter abbreviated as NQ)
A method of reacting NQ with calcium hypochlorite [T. Zinke, Chem. Ber, Vol. 25, p. 3599 (1892)] (2) A method of reacting NQ with an alkaline hydrogen peroxide solution in an alcohol solvent [Weitz,
Schobbert, Seibert, Chem.Ber., Volume 68, 1168
Page (1935); Fieser, Campbell, Fry, Gates,
J.Am.Chem.Soc., Vol. 61, p. 3216 (1939)] (3) A method in which NQ is suspended in water and reacted with an alkaline hydrogen peroxide solution using an inorganic base [Wada, Miyadera, Tsurumi (Special Publication 46 -17783)] (4) A method of suspending NQ in water and reacting it with an aqueous solution of sodium hypochlorite [Shrartsamn, CA, No. 78
Vol., 58119X (1978)] (5) A method in which NQ is suspended in water and reacted with an alkaline hydrogen peroxide solution using an organic base [Matsuura, Yamada, Sakai, Sato (Special Publication No. 56-54318)]. Methods (1) and (4) cause considerable side reactions,
The coloring of the liquid is also intense. Method (2) has a very low yield. Although methods (3) and (5) are improved in terms of yield and purity compared to the above-mentioned methods, several percent of unreacted NQ remains. Furthermore, since the reaction is carried out in an aqueous suspension state, the shape and purity of the NQ used affect the reaction rate, yield, and purity. Therefore, good quality
It has a drawback as an industrial production method in that NQ is required as a raw material. As a result of intensive research into an industrially advantageous production method for NQ-oxide that overcomes these drawbacks, the present inventors have discovered that the raw material NQ is dissolved in an inert organic solvent that is incompatible with water, such as methylene chloride. By reacting with an aqueous hypohalite solution such as sodium hypochlorite in the presence of a phase transfer catalyst such as tetrabutylammonium bromide under very mild conditions, the reaction proceeds smoothly and the purity can be maintained. The present invention was completed by discovering that good NQ-oxide can be produced in high yield. The method of the present invention is a method for producing NQ-oxide, which is characterized in that NQ is oxidized using an aqueous hypohalite solution in the presence of an inert organic solvent that is incompatible with water and a phase transfer catalyst. Exists. Since the NQ used in the present invention is dissolved in an organic solvent, it can be used in any form or with any purity. This method is more advantageous than conventional methods in that even when industrial grade NQ containing ~10% is used, highly pure NQ-oxide can be obtained in high yield. Various types of phase transfer catalysts can be used in the method of the present invention depending on the type of alkaline substance used. For example, quaternary ammonium salts such as tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium bromide, methyltrioctylammonium chloride or benzyltriethylammonium chloride; cyclic ethers such as crown ether;
Dimethylpolyethylene glycol; Cryptand; Quaternary phosphonium salts such as tetramethylphosphonium bromide and tetrabutylphosphonium bromide; General formula

Represented by [formula] Quaternary salt immobilized on a polymer; general formula

Examples include quaternary salts obtained by modifying silica gel represented by the formula: However, considering toxicity, price, availability, and reactivity, quaternary ammonium salts are preferred, and moreover, tetrabutylammonium bromide, tetrabutylammonium chloride,
Alternatively, benzyltriethylammonium chloride is preferable in terms of catalytic effect and cost. The amount of the phase transfer catalyst to be used is generally 0.001 times or more by weight, and usually 0.1 times or less, preferably 0.005 to 0.05 times by weight, based on NQ. The inert organic solvent used in the method of the present invention is
Preferably, it dissolves NQ and is substantially incompatible with water. For example, aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane; aliphatic cyclic hydrocarbons such as cyclohexane; benzene,
Aromatic hydrocarbons such as toluene and xylene; ketones such as halogenated hydrocarbons such as methylene chloride, chloroform, 1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethylene, chlorobenzene, 0-dichlorobenzene, etc. can be mentioned. The amount of solvent used is generally determined under the reaction conditions.
The concentration may be at least a level that substantially dissolves NQ, and is usually selected from 1 to 30%. In the method of the present invention, an aqueous hypohalite solution is used as the NQ oxidizing agent. When hydrogen peroxide, which has been conventionally used as an oxidizing agent, is used, the reaction is difficult to proceed. Examples of the hypohalite include sodium or potassium salts of hypochlorous acid, hypobromous acid, etc., and sodium hypochlorite, which is inexpensive and easily available, is usually used. Sodium hypochlorite exists as a crystal, but it is usually commercially available as an aqueous solution, so industrially it is convenient to use the aqueous solution. Further, since the aqueous solution is usually alkaline, it may be used as is in the method of the present invention, but the strength of alkalinity can be adjusted by adding an alkaline substance as appropriate. Examples of alkaline substances include:
Examples include inorganic bases such as soda carbonate and sodium hydroxide, and organic bases such as trimethyl-benzyl ammonium hydroxide, but usually soda carbonate is used because it is inexpensive and easy to handle. The amount of these alkalis used is usually 0 to 0.5 times the amount of the hypohalite used. The amount of hypohalite aqueous solution used is usually 1.0 to 1.0 to NQ used as hypohalite.
It is 1.5 times the mole. The concentration of hypohalite is usually 5 to 20%. The temperature of the oxidation reaction is 10~70℃, preferably 20~
The temperature is 50°C, and the reaction time at that time is usually 0.1 to 4.0 hours. The method of the present invention is generally carried out as follows. Dissolve the raw material NQ in an organic solvent and add 10 to 20
% concentration of alkaline sodium hypochlorite aqueous solution and stir well at 20-50℃. after that,
Add a phase transfer catalyst and react at 30-35°C for 0.1-4.0 hours with good stirring. After the reaction, the organic layer is separated. To recover NQ-oxide from the organic layer, if there are few impurities in the raw material, the organic solvent can be distilled off under reduced pressure and NQ-oxide can be recovered as a residue. When the NQ content in the NQ-oxide is reduced, it is appropriate to concentrate the organic layer to a certain concentration, cool the concentrated solution, and collect the crystallized NQ-oxide by filtration. Next, the method of the present invention will be explained in detail using examples. In this specification, "%" means % by weight, and "part" means parts by weight, unless otherwise specified. Example 1 After dissolving 18 g of NQ with a purity of 94.6% in 100 ml of methylene chloride, 90% of 12% sodium hypochlorite was added to the solution.
g and stirred at 25-30℃ for 0.5 hour, then added 0.17 g of tetrabutylammonium chloride and stirred at 25-30℃ for 30 minutes.
The reaction was allowed to proceed at ~35° C. for 1 hour with stirring. After separating the methylene chloride layer and dehydrating it by adding Glauber's salt, the methylene chloride layer was removed under reduced pressure to form a white crystalline layer with a few black particles.
18.5 g of NQ-oxide was obtained. Analysis of the product by high performance liquid chromatography revealed that the purity was 95%, the amount of unreacted NQ was 3.9%, and the yield of NQ-oxide was 94 mol%. Example 2 The same procedure as in Example 1 was carried out except that tetrabutylammonium bromide was used instead of tetrabutylammonium chloride.
18 g of NQ-oxide was obtained. The purity of the product is 95
%, unreacted NQ was 3.5%, and the yield was 94 mol%. Comparative Example 1 In Example 1, methylene chloride and tetrabutylammonium chloride were not used, and the reaction was carried out at 45%
The same procedure as in Example 1 was carried out except that the temperature was 2 hours. The yield of NQ-oxide was 73.1 mol%, and the amount of unreacted NQ was 20%. Comparative Example 2 In Example 1, 150 ml of methylene chloride was used without using tetrabutylammonium chloride,
The reaction was carried out in the same manner as in Example 1 except that the reaction was carried out at 38°C for 2 hours. The yield of NQ-oxide was 43.6 mol%, and the amount of unreacted NQ was 51.6%. Comparative Example 3 In the method of Example 1, 35% hydrogen peroxide solution 14.1 was used instead of 12% sodium hypochlorite as the oxidizing agent.
The same procedure as in Example 1 was carried out except that 0.68 g of sodium carbonate and 30 g of water were used. The yield of NQ-oxide was 52.7%, and the amount of unreacted NQ was 40.6%. Example 3 After dissolving 16 g of NQ with a purity of 94.6% in 100 ml of orthoxylene, 12% sodium hypochlorite was added to the solution.
Add 90g and stir at 25-30℃ for 0.5 hours, then add 0.3g of tetrabutylammonium bromide.
The reaction was carried out at 45°C for 0.5 hour with stirring. Separate the ortho-xylene layer, remove it, add sodium sulfate to dehydrate it, and then concentrate the entire solution to about 30 ml under reduced pressure and cool it.
NQ-oxide is crystallized, filtered and dried, and the product is
12.4g was obtained. Analysis of the product by high performance liquid chromatography revealed that the purity was 97.5%, the amount of unreacted NQ was 1.2%, and the yield was 72.5 mol%. Example 4 In Example 3, 16.5 g of raw material NQ and ethylene chloride (Cl CH ₂ −CH ₂
The procedure was carried out in the same manner as in Example 3, except that 250 ml of NQ-oxide (purity: 98.5%) was obtained.
The yield was 77.9% and the NQ in the product was traceable. Example 5 In Example 1, 16.5 g of raw material NQ, 0.3 g of crown ether (18-Crown-6) instead of tetrabutylammonium chloride, and reaction at 35°C
The same procedure as in Example 1 was carried out except that the reaction was carried out for 2 hours, and 15.8 g of NQ-oxide (purity 93%) was obtained.
Yield is 85.5 mol%, unreacted NQ in product is 6.2%
It was hot.

Claims (1)

[Claims] 1. A method of oxidizing 1,4-naphthoquinone using an aqueous hypohalite solution in the presence of an inert organic solvent that is incompatible with water and a phase transfer catalyst. 3-epoxy-2,3-dihydro-
Method for producing 1,4-naphthoquinone. 2. The method according to claim 1, wherein the organic solvent is an aliphatic hydrocarbon, an aliphatic cyclic hydrocarbon, an aromatic hydrocarbon, or a halide thereof. 3. The method according to claim 1, wherein the phase transfer catalyst is a quaternary ammonium salt, a phosphonium salt, a crown ether, or a cryptand.