JPH1135517A - Method for producing 2-hydroxy-1,4-naphthoquinone - Google Patents

Abstract

(57) [Summary] [Object] To produce 2-hydroxy-1,4-naphthoquinone by an advantageous method. (1) Naphthoquinone dissolved in an inert organic solvent incompatible with water is oxidized with an aqueous solution of hypochlorite in the presence of a phase transfer catalyst to give 2,3-epoxy-2,3-dihydro. (1) A method for producing 1,4-naphthoquinone, (2) reacting with an alkaline compound dissolved in alcohol to form an alkali salt of 2-hydroxy-1,4-naphthoquinone, and (3) acidifying with a mineral acid. [Effect] The generation of impurities is suppressed, and 2-hydroxy-1,4-naphthoquinone having high purity can be obtained consistently and easily from naphthoquinone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a process for producing 1,4-naphthoquinone (hereinafter referred to as NQ) from 2-hydroxy-1,
The present invention relates to a method for producing 4-naphthoquinone (hereinafter referred to as 2-HNQ). 2-HNQ is a compound useful as an intermediate of a dye or pigment or an intermediate of medicine and agrochemicals.

[0002]

2. Description of the Related Art As a method for producing 2-HNQ or an alkali salt thereof, (1) a method of synthesizing triacetoxynaphthalene from NQ using acetic anhydride and boron trifluoride, and using this compound as an intermediate ( Justus Lie
bigs, Ann. Chem. , 311, 341 (19
00)) (2) 2,3-epoxy-2,3-dihydro-
1,4-naphthoquinone (hereinafter referred to as NQ-oxide)
Is obtained by reacting the compound with an alkali while substantially dispersing the compound in an alcohol to obtain an alkali salt of 2-HNQ (JP-B-46-2978).

[0003]

According to the method (1), 2-HNQ having relatively high purity can be obtained, but the raw material cost of boron trifluoride and acetic anhydride is high, the production process is long, and the wastewater treatment is difficult. Although it is problematic and suitable for the synthesis of reagents, it is industrially difficult. In the method (2), since the reaction is carried out in a substantially dispersed state, it is necessary to reduce the particle size of the NQ-oxide powder as a raw material in order to minimize the amount of NQ-oxide remaining without reacting. . Further, if water is mixed in alcohol or the like used as a medium, 2-HN
Since impurities such as a dimer of Q are generated, it is necessary to sufficiently remove water. Furthermore, if the reaction temperature is high, a dimer of 2-HNQ, which is an impurity, is formed, so that the reaction generally has to be performed at room temperature or lower, preferably at 15 ° C. or lower. Further, NQ-oxide as a raw material of this method is generally produced by epoxidizing NQ dispersed in an aqueous medium such as water with hydrogen peroxide or the like,
Following this epoxidation reaction, the present method cannot be omitted, and it is necessary to isolate NQ-oxide once in a solid form, dry, pulverize, etc., then disperse in alcohol and react with alkali. there were. As a method of obtaining NQ-oxide from NQ, a method of epoxidation using an aqueous hypohalite solution in the presence of an inert organic solvent incompatible with water and a phase transfer catalyst (Japanese Patent Publication No. 2-1159)
There is also 2), but as a raw material of the method of (2) for reaction in alcohol, it was necessary to once isolate NQ-oxide in a solid form.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily preparing a high-purity 2-HNQ from NQ without the necessity of isolating, drying and pulverizing the solution containing NQ-oxide obtained by epoxidation of NQ. Another object of the present invention is to provide a method which can be manufactured at low cost.

[0005]

The present inventors have studied to solve the above-mentioned problems, and as a result, (1) dissolved in an inert organic solvent which is not compatible with water in the presence of a phase transfer catalyst. A first reaction step of epoxidizing 1,4-naphthoquinone with an aqueous hypohalite solution to give 2,3-epoxy-2,3-dihydro-1,4-naphthoquinone;
(2) Alkaline obtained by dissolving 2,3-epoxy-2,3-dihydro-1,4-naphthoquinone dissolved in an inert organic solvent incompatible with water obtained in the first reaction step in an alcohol Reacting the compound with 2-hydroxy-1,
A second reaction step of forming an alkali salt of 4-naphthoquinone; and (3) the 2-hydroxy- obtained in the second reaction step.
A method for obtaining 2-hydroxy-1,4-naphthoquinone without performing isolation of an intermediate by filtration or the like by performing a third reaction step of acidifying an alkali salt of 1,4-naphthoquinone with a mineral acid. And completed the present invention. In addition, the slurry of the alkali salt of 2-HNQ obtained in the second reaction step may be separated by filtration or the like to obtain an alkali salt of 2-HNQ.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

"First reaction step" (epoxidation reaction) An inert organic solvent incompatible with water (hereinafter referred to as the present organic solvent) has a reactivity with NQ, NQ-oxide, an alkaline compound and a mineral acid. In addition, any one can be used as long as it dissolves an appropriate amount of NQ and NQ-oxide and is substantially incompatible with water. For example, n-
Aliphatic hydrocarbons such as hexane and n-octane, aliphatic cyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene, naphthalene, toluene, xylene (eg, meta-xylene or ortho-xylene), ethylbenzene, and methylnaphthalene Among them, NQ and aromatic hydrocarbons having relatively high solubility of NQ-oxide are preferred industrially.

Since NQ as a raw material is dissolved in the present organic solvent, any form can be used. In particular, when using NQ obtained by extracting a water-collected solution of a catalytic gas phase oxidation reaction product of naphthalene with an organic solvent represented by an aromatic hydrocarbon or the like, an organic solvent solution containing the NQ Without once isolating NQ from the solvent, etc.
It can be used as it is in an epoxidation reaction using a phase transfer catalyst.

As the phase transfer catalyst, various catalysts can be used depending on the kind of the alkaline compound used. For example, quaternary ammonium salts such as tetrabutylammonium bromide, tetrabutylammonium chloride and benzyltriethylammonium chloride; cyclic ethers such as crown ethers; dimethylpolyethylene glycol; cryptands; quaternary phosphonium salts such as tetramethylphosphonium bromide. No. The amount of the phase transfer catalyst to be used is generally 0.001 to 0.05 times by weight with respect to NQ as a raw material, preferably 0.1 to 0.05 times.
An appropriate amount is 003 to 0.01 times by weight.

As the epoxidizing agent for NQ used in the present invention, an aqueous solution of hypohalite is usually used. Examples of the hypohalite include, for example, sodium hypochlorite, sodium hypobromite, potassium hypochlorite, potassium hypobromite and the like. Is used. Although sodium hypochlorite can be obtained as a solid, an industrially commercially available aqueous solution of sodium hypochlorite may be used because of its easy handling. The amount of the hypohalite to be used is usually 1.0 to 1.5 mol times, preferably 1.1 to 1.35 mol times, more preferably 1.2 to 1 mol times with respect to NQ used. An appropriate amount is 0.3 mol times, but when a compound that reacts with hypohalite is contained, the amount used may be increased. Usually, the concentration of the aqueous solution of hypohalite is usually 5 to 15%.

In the first reaction step for obtaining NQ-oxide from NQ, a phase transfer catalyst is added to the above organic solvent in which NQ is dissolved, and an epoxidizing agent such as an aqueous solution of hypohalite is added dropwise. The reaction is carried out at 10 to 70 ° C, preferably 20 to 50 ° C, and usually advantageously at 30 to 40 ° C.

"Second reaction step" (isomerization reaction) In the reaction for obtaining an alkali salt of 2-HNQ from NQ-oxide, ie, in the isomerization reaction, the aqueous solution of hypohalite used in the epoxidation reaction was separated. It is desirable to do it later,
The organic solvent layer containing NQ-oxide and the aqueous layer obtained by the epoxidation reaction are allowed to stand by stopping stirring,
Can be easily separated.

In the present invention, the NQ-oxide isomerization reaction is generally carried out in an amount of 1.0 to 1.0 with respect to NQ-oxide.
It is preferable to carry out the reaction by adding the present organic solvent in which NQ-oxide is dissolved to an alcohol in which 1.5 mol times of the alkaline compound is dissolved. Conversely, adding an alcohol solution of an alkaline compound to the NQ-oxide solution side is not preferable because the yield and purity of the obtained 2-HNQ decrease. At the time of the isomerization reaction, the addition rate of the present organic solvent in which NQ-oxide is dissolved can be appropriately adjusted by stirring or removing heat of the reactor.

[0013] The temperature of the isomerization reaction can be arbitrarily selected, but if it is too low, the reaction rate is disadvantageous. On the contrary, if it is too high, a dimer of 2-HNQ which is an impurity is formed and 2
Since the purity of -HNQ decreases, it can be usually selected in the range of 5 to 50C, preferably in the range of 20 to 40C. By the reaction, NQ-oxide is converted into an alkali salt of 2-HNQ and precipitates to form a slurry.
The alkali salt of Q can be filtered as it is to obtain an alkali salt of 2-HNQ.

In the present invention, a strong alkaline compound is usually used as the alkaline compound. As the strongly alkaline compound, caustic alkalis such as sodium hydroxide and potassium hydroxide are used, but compounds which dissolve in alcohol under the reaction conditions and act as alkalis, for example, alcoholates such as sodium methylate and sodium ethylate may also be used. Good. The amount of the alkaline compound used is assuming that the generated 2-HNQ is a monobasic acid,
1 equivalent or more based on 1 mole of the raw material, for example, 1 mole or more for a monovalent base such as sodium hydroxide, generally 1.0
The molar ratio is usually 1.5 to 1.5 times, usually 1.1 to 1.3 times.

As the alcohol, any alcohol can be used as long as it dissolves an alkaline compound. Generally, lower aliphatic alcohols are preferable, and methanol or ethanol, which is industrially particularly inexpensive, is preferable. The concentration of the alkaline compound dissolved in the alcohol can be arbitrarily selected depending on the reaction conditions such as the solubility and the temperature, but is generally 5 to 30% by weight.

In the present invention, the objective 2-
Alcohol may be mixed with water as long as the yield and purity of HNQ can be reduced. Moisture in alcohol is 40 wt% or less, preferably 30 wt%
If it is below, since the yield and purity of 2-HNQ do not substantially decrease, an alcohol solution of the above-mentioned alkaline compound can be obtained by mixing an aqueous solution of the alkaline compound and alcohol for easy handling.

"Third reaction step" (acidification reaction) The slurry of the alkali salt of 2-HNQ obtained in the second reaction step is further acidified with a mineral acid to form 2-HNQ. By separation by filtration or the like, high purity 2-H
NQ can be obtained. Examples of the acid used include mineral acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and among them, sulfuric acid is preferred in terms of handling.

[0018]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following description unless it exceeds the gist.

"Example 1""First reaction step" In a 1-liter separable flask equipped with a bottom stopper valve equipped with a reflux condenser and a stirrer, purity was 97%.
% Of NQ was dissolved in 380 g of ortho-xylene (NQ concentration: 6.5 wt%), 0.27 g of tetrabutylammonium bromide as a phase transfer catalyst was added, and the internal temperature was kept at 40 ° C .; % Aqueous sodium hypochlorite solution was added over 60 minutes. After the addition of the aqueous solution of sodium hypochlorite, stirring was stopped and the aqueous layer and the organic layer were allowed to stand and separated. The aqueous layer was removed, 25 g of washing water was added to the organic layer, and the mixture was stirred for 10 minutes, and then separated by standing to remove the aqueous layer.

"Second reaction step" 7.38 g of sodium hydroxide (1.1 times the number of moles of NQ) in a 1 liter separable flask equipped with a reflux condenser and a stirrer under a nitrogen stream. Was dissolved in 97.1 g of methanol having a water content of 26%. A 40 ° C. orthoxylene solution in which the NQ-oxide obtained in the first reaction step was dissolved was added over 60 minutes so that the temperature in the flask was maintained at 40 ° C., and the reaction was further performed at the same temperature for 60 minutes. I let it.

"Third reaction step" 195 g of water was added to the slurry of 2-HNQ sodium salt obtained in the second reaction step.
Was added, and 10.5 g of 95% sulfuric acid was gradually added to obtain a slurry of released 2-HNQ. 2-HNQ
The slurry was cooled to 20 ° C., filtered, washed with water, and dried under reduced pressure to obtain 2-HNQ. 2-HNQ obtained
Is 99% and the yield of 2-HNQ is 85.6 m
ol%.

Example 2 "First Reaction Step" In a 1-liter separable flask equipped with a bottom stopper valve equipped with a reflux condenser and a stirrer, a purity of 99% was used.
% NQ (26.8 g) was dissolved in 381 g of ortho-xylene (NQ concentration: 6.5 wt%), and 0.27 g of tetrabutylammonium bromide, a phase transfer catalyst, was added to the solution. % Aqueous sodium hypochlorite solution was added over 60 minutes. After the addition of the aqueous solution of sodium hypochlorite, stirring was stopped and the aqueous layer and the organic layer were allowed to stand and separated. The aqueous layer was removed, 25 g of washing water was added to the organic layer, and the mixture was stirred for 10 minutes, and then separated by standing to remove the aqueous layer.

"Second reaction step" 7.38 g of sodium hydroxide (1.1 times the number of moles of NQ) in a 1 liter separable flask equipped with a reflux condenser and a stirrer under a nitrogen stream. Was dissolved in 97.1 g of methanol having a water content of 26%. A 40 ° C. orthoxylene solution in which the NQ-oxide obtained in the first reaction step was dissolved was added over 60 minutes so that the temperature in the flask was maintained at 40 ° C., and the reaction was further performed at the same temperature for 60 minutes. I let it.

"Third reaction step" 195 g of water was added to the slurry of sodium salt of 2-HNQ obtained in the second reaction step.
Was added, and 10.5 g of 95% sulfuric acid was gradually added to obtain a slurry of released 2-HNQ. 2-HNQ
The slurry was cooled to 20 ° C., filtered, washed with water, and dried under reduced pressure to obtain 2-HNQ. 2-HNQ obtained
Is 99.1% and the yield of 2-HNQ is 87.
It was 5 mol%.

Comparative Example 1 400 g of a methanol solution in which 26.6 g of NQ having a purity of 99% was dispersed was maintained at 15 ° C. in a 1-liter separable flask equipped with a bottom stopper valve equipped with a reflux condenser and a stirrer. 24.2 g of a 35% hydrogen peroxide aqueous solution containing 1.3 g of sodium carbonate was added to 24
Added over 0 minutes. After addition of aqueous hydrogen peroxide, the mixture was filtered and dried to isolate NQ-oxide.

In a 1-liter separable flask equipped with a reflux condenser and a stirrer under a nitrogen stream, 7.3 g of sodium hydroxide (1.1 times the molar number of NQ) was dissolved in 400 g of methanol. . The NQ-oxide isolated therein was added over 120 minutes while maintaining the temperature at 15 ° C,
A slurry of the sodium salt of 2-HNQ was obtained.

The sodium salt of 2-HNQ was isolated by filtration from the obtained slurry, and the obtained wet was added to 300 g of water to form a water slurry, and 10.4 g of 95% sulfuric acid was gradually added to liberate the slurry. A slurry of 2-HNQ was obtained. After the 2-HNQ slurry was cooled to 20 ° C., it was filtered, washed with water, and dried under reduced pressure to obtain 2-HNQ. The purity of the obtained 2-HNQ was 93.5%,
The yield of Q was 77.0 mol%.

[0028]

According to the present invention, 2-HNQ can be produced consistently from NQ dissolved in the present organic solvent without isolating NQ-oxide and the like as a solid on the way. Is simple and 2-HNQ with high purity can be obtained.

Claims (6)

[Claims] (1) In the presence of a phase transfer catalyst, 1,4-naphthoquinone dissolved in an inert organic solvent incompatible with water is epoxidized with an aqueous hypohalite solution to give 2,2 3-epoxy-2,3-dihydro-1,4-naphthoquinone in the first reaction step, and (2) dissolved in an inert organic solvent incompatible with water obtained in the first reaction step. A second reaction step of reacting 2,3-epoxy-2,3-dihydro-1,4-naphthoquinone with an alkaline compound dissolved in alcohol to form an alkali salt of 2-hydroxy-1,4-naphthoquinone; (3) A method for producing 2-hydroxy-1,4 naphthoquinone, comprising a third step of acidifying the alkali salt of 2-hydroxy-1,4-naphthoquinone obtained in the second reaction step with a mineral acid. 2. An inert organic solvent incompatible with water is an organic solvent selected from an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent and an aliphatic cyclic hydrocarbon solvent. 2. The production method according to 1. 3. A phase transfer catalyst comprising: a quaternary ammonium salt;
The method according to claim 1, which is a phosphonium salt, a crown ether or a cryptand. 4. The method according to claim 1, wherein the alcohol is a lower aliphatic alcohol. 5. The method according to claim 4, wherein the lower aliphatic alcohol is methanol or ethanol. 6. The method according to claim 1, wherein the alkaline compound is sodium hydroxide or potassium hydroxide.