JPH0667864B2 - Method for producing dihydroxynaphthalene - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing dihydroxynaphthalene,
More specifically, it relates to a method for acid-decomposing dihydroperoxide obtained by oxidation of diisopropylnaphthalene, and then separating dihydroxynaphthalene from an acid-decomposition reaction mixture to produce dihydroxynaphthalene with high purity and relatively high yield.

Technical background of the invention and its problems Diisopropylnaphthalene such as 2,6-diisopropylnaphthalene is oxidized to 2,6-diisopropylnaphthalene dihydroperoxide, which is acid-decomposed with an acidic catalyst to give 2,6-dihydroxynaphthalene. Can be obtained. This 2,6-dihydroxynaphthalene is industrially useful as a raw material for synthetic resins, synthetic fibers, pharmaceuticals, agricultural chemicals, dyes and the like.

By the way, U.S. Pat.No. 4,503,262 discloses that 2,6-diisopropylnaphthalene is dissolved in an organic solvent and oxidized with molecular oxygen in the presence of a heavy metal salt catalyst such as cobalt organic acid to give 2,6-diisopropylnaphthalene. In the method for producing dihydroperoxide, in particular, by using an aliphatic hydrocarbon solvent having 5 to 14 carbon atoms such as n-heptane as the organic solvent, the reaction rate, the yield and the purity of the desired dihydroperoxide are improved. It is described that it can be done.

However, conventionally, there is no known industrial method for obtaining dihydroxynaphthalene by oxidizing diisopropylnaphthalene with molecular oxygen to form dihydroperoxide, and subjecting this to acid decomposition in the presence of an acidic catalyst,
A method for producing β-isopropylnaphthalene hydroperoxide by oxidizing β-isopropylnaphthalene, which is a compound slightly related to diisopropylnaphthalene, with molecular oxygen in the presence of an aqueous base solution is disclosed in JP-A-51-34138 or UK. It is only described in Japanese Patent No. 654,035.

However, the oxidation reaction of diisopropylnaphthalene with molecular oxygen requires stricter oxidation conditions than, for example, the oxidation reaction of β-isopropylnaphthalene, and as a result, the production of naphthoquinones that inhibit the oxidation reaction also increases. It is difficult to directly apply the oxidation method of β-isopropylnaphthalene to diisopropylnaphthalene.

On the other hand, a method for producing hydroquinone or resorcin by oxidizing diisopropylbenzenes into diisopropylbenzene dihydroperoxides in the presence of an acidic catalyst is already well known. However, since diisopropylnaphthalene has different reactivity as compared with p-diisopropylbenzene or m-diisopropylbenzene, the optimum oxidation condition of diisopropylnaphthalene or the subsequent oxidation based on the prior art relating to the reaction of diisopropylbenzene is not used. At present, it is extremely difficult to predict the optimum acid decomposition conditions.

By the way, it is possible to industrially carry out a method for producing dihydroxynaphthalene, which comprises oxidizing diisopropylnaphthalene to form an oxidation reaction product, and then acid-decomposing it to form an acid-decomposition reaction mixture, and separating dihydroxynaphthalene from the mixture. There are several issues that must be resolved in order to achieve this.

For example, in the oxidation reaction, when highly oxidized until the reaction rate of diisopropylnaphthalene reaches 80% or more, the oxidation reaction mixture becomes liquid at a high temperature during the reaction, but when cooled to room temperature, diisopropylnaphthalene dihydroperoxide or Since the quantitative ratio of the solidified substance like other oxidation products is increased, in this case, the oxidation reaction mixture that has left the oxidation reactor and is cooled is solidified, and thus it is not easy to handle, and When the oxidation reaction is carried out in the presence of an aqueous base solution, it is not easy to remove the alkaline aqueous solution from the oxidation reaction mixture as it is. Therefore, in the process of industrially producing dihydroxynaphthalene by oxidizing diisopropylnaphthalene, even if the oxidation reaction mixture is cooled, a method for dissolving the oxidation reaction product and preventing solidification to facilitate handling is provided. Need to give. In order to solve such a problem, the applicant has added a water-insoluble dialkylketone such as methylisobutylketone to an oil phase and an aqueous phase to an oxidation reaction mixture containing dihydroperoxide obtained by oxidation of diisopropylnaphthalene. After the separation, the aqueous phase was removed, and acetone was added to the obtained oil phase to effect acid decomposition in the presence of an acid catalyst, and a method for producing dihydroxynaphthalene was proposed (Japanese Patent Application No. 61-81043).
issue).

According to the method for producing dihydroxynaphthalene as described above, the oxidation reaction mixture can be handled as a solution, which makes the handling very easy, and when the method in which the oxidation reaction is performed in the presence of a basic aqueous solution is used, the alkali The aqueous solution can be easily separated from the oxidation reaction mixture by oil phase separation,
In addition, since the amount of alkali mixed in the oil phase containing hydroperoxide can be minimized, dihydroperoxide can be efficiently acid-decomposed, so that the yield of dihydroxynaphthalene as a target product can be increased.

The present inventors have also found that there are the following problems to be solved in the above-mentioned method for producing dihydroxynaphthalene. That is, when trying to separate the target product dihydroxynaphthalene from the acid decomposition reaction mixture by a usual method, it is difficult to handle the mixture, and it is extremely difficult to separate dihydroxynaphthalene with a high recovery rate. there were. That is, for example, after an acid decomposition reaction mixture containing dihydroxynaphthalene is obtained, an alkaline aqueous solution is added to the acid decomposition reaction mixture to deactivate the acid catalyst, and then acetone is removed, and then the reaction mixture is mixed with an oil phase and an aqueous phase. When the water phase is removed by separation into water and the water-insoluble dialkiketone such as methylisobutylketone is removed from the obtained oil phase by distillation or the like to obtain dihydroxynaphthalene, the oil phase is separated from the water phase such as methylisobutylketone. It has been found that when the water-soluble dialkyketone is removed, the product, dihydroxynaphthalene, is obtained in a solidified state such as a lump, and the handling thereof becomes extremely complicated, which is a serious problem. Moreover, it was found that the dihydroxynaphthalene obtained by this method is not always satisfactory in terms of purity, and that the recovery rate of dihydroxynaphthalene is not necessarily high.

An object of the present invention is to solve the above problems and to provide a method for producing dihydroxynaphthalene from diisopropylnaphthalene with high yield and relatively high purity. It is intended to be provided.

SUMMARY OF THE INVENTION A method for producing dihydroxynaphthalene according to the present invention comprises acid-decomposing an oxidation reaction product containing diisopropylnaphthalene dihydroperoxide obtained by oxidizing diisopropylnaphthalene with molecular oxygen in the presence of a water-insoluble dialkyl ketone. , An acid decomposition reaction mixture containing dihydroxynaphthalene, acetone is distilled off from the acid decomposition reaction mixture, the water-insoluble dialkyl ketone is distilled off in the presence of benzenes, and dihydroxynaphthalene is recovered as a slurry of benzenes. The method is characterized in that dihydroxynaphthalene is isolated from the slurry.

According to the method for producing dihydroxynaphthalene according to the present invention, since the water-insoluble dialkyl ketone is added to the oxidation reaction mixture of diisopropylnaphthalene, the oxidation reaction product present in the oxidation reaction mixture is in the oxidation reaction mixture. Since solidification is prevented and benzenes are added to the acid decomposition reaction mixture to collect dihydroxynaphthalene as a slurry of benzenes, the target product dihydroxynaphthalene is in a solidified state like a lump. However, the reaction by-product is dissolved in benzenes and the target product dihydroxynaphthalene can be produced with a high recovery rate and a relatively high purity. .

DETAILED DESCRIPTION OF THE INVENTION The method for producing dihydroxynaphthalene according to the present invention will be described in more detail below.

In the present invention, first, diisopropylnaphthalene is oxidized to diisopropylnaphthalene dihydroperoxide, and this oxidation reaction is usually carried out by adding diisopropylnaphthalene to an aqueous base solution and mechanically mixing it into an emulsified state. It is carried out by blowing a gas containing oxygen.

In the present invention, an aqueous base solution does not necessarily have to be used in carrying out the oxidation, but in the following description, the case where the oxidation is carried out in the presence of the aqueous base solution will be described in detail.

In the present invention, specific examples of diisopropylnaphthalene include 2,6-diisopropylnaphthalene, 2,7-diisopropylnaphthalene, and 1,4-diisopropylnaphthalene. Of these, 2,6-diisopropylnaphthalene is preferred.

When the oxidation is carried out in the presence of an aqueous base solution, an alkali metal compound is preferably used as the base. Specific examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like. The concentration of these alkali metal compounds in the aqueous solution is preferably 20% by weight or less. The amount of the aqueous base solution used in the reaction mixture is usually
It preferably represents 5 to 80% by weight of the reaction mixture, particularly preferably 20 to 70% by weight. When the amount of the aqueous base solution used is less than 5% by weight of the reaction mixture, the oily unreacted diisopropylnaphthalene and its oxidation product and the reaction solution consisting of the aqueous base solution are not well dispersed and the emulsified state is insufficient. And adversely affect the oxidation reaction. On the other hand, the amount of base aqueous solution used is 80% by weight
If the amount is larger than the above range, the emulsified state of the reaction system deteriorates, which is not preferable. In addition, in the oxidation reaction,
The pH is usually maintained in the range of 7-14, preferably 11-14.

The diisopropylnaphthalene and its oxidation product and the aqueous base solution can be usually sufficiently emulsified by mechanical stirring, but if necessary, for example,
The stirring may be carried out in the presence of a conventionally known emulsifier such as stearic acid.

As the base, alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide and strontium hydroxide can also be used. Of these, calcium hydroxide is particularly preferable. These alkaline earth metal hydroxides may be used alone or in combination with the alkali metal compound.

As the molecular oxygen, oxygen gas may be used alone, but air is usually sufficient. The required amount of molecular oxygen is
Usually, it is in the range of 5 to 15 Nl / hour in terms of oxygen gas per 100 g of charged 2,6-diisopropylnaphthalene for the oxidation reaction, but it is not particularly limited.

The reaction temperature is usually 80 to 150 ° C., preferably 90 to 130 ° C., and the reaction time is usually 6 to 40 hours, varying depending on conditions such as reaction temperature. The reaction rate of diisopropylnaphthalene is preferably 80% or more in order to increase the production amount of dihydroperoxide. The reaction is
Usually, it is carried out under normal pressure, but if necessary, it may be carried out under pressure or under reduced pressure.

In the above oxidation reaction of diisopropylnaphthalene,
A reaction initiator is preferably used. For example, α,
α'-Azobis (cyclohexane-1-carbonitrile) can be used as a reaction initiator. By using a reaction initiator, the induction period of the reaction can be shortened. The amount used is usually 0.0 per 100 parts by weight of the charged reaction mixture containing the raw material diisopropylnaphthalene.
The range is from 05 to 1 part by weight.

By the oxidation reaction as explained above, for example, 2,6-
When diisopropylnaphthalene is oxidized, 2,6-
Diisopropyl naphthalene dihydroperoxide (hereinafter
In addition to DHP), as a by-product,
2- (2-hydroxy-2-propyl) -6- (2-hydroperoxy-2-propyl) naphthalene (HHP),
Carbinols such as 2,6-bis (2-hydroxy-2-propyl) naphthalene (DCA) and 2-isopropyl-6- (2-hydroxy-2-propyl) naphthalene (MCA) are produced, and 2-isopropyl-6- (2-
Hydroperoxy-2-propyl) naphthalene (MHP)
A monohydroperoxide such as

To determine the composition of the reaction product from the above oxidation reaction, after the reaction, the organic phase and the aqueous phase are separated, the aqueous phase is extracted with ether, etc., and the organic phase and the ether extract are analyzed by liquid chromatography. For example, unreacted diisopropylnaphthalene and oxidation reaction products DHP, HHP, DCA, MHP,
MCA etc. can be quantified.

A water-insoluble dialkyl ketone is added to the above-mentioned oxidation reaction mixture to separate into an oil phase and an aqueous phase, and then separated into an oil phase. At this time, Japanese Patent Application No. 59-220549 relating to the applicant
No. 59-214275, the oxidation of diisopropylnaphthalene is carried out in the presence of a specific solvent such as a halogenated hydrocarbon or the presence of a secondary alkyl group-substituted aromatic hydrocarbon such as cumene. When the method of co-oxidation is adopted below, these solvents or the aromatic hydrocarbons are mixed in the oxidation reaction mixture after the completion of the oxidation, but these solvents are water-insoluble as necessary. Before adding the dialkyl ketone, an appropriate amount may be removed by distillation or the like.

Next, the water-insoluble dialkyl ketone is added to the oxidation reaction mixture as described above to separate the oil phase and the water phase, and then the oil phase is separated. Explaining this point, particularly in the oxidation reaction of diisopropylnaphthalene, when it is oxidized to a reaction rate of 80% or more as described above, the oxidation reaction mixture is liquid at the reaction temperature but cooled to room temperature. This increases the quantitative proportion of solidified oxidation products such as dihydroxynaphthalene. In this case,
Since the cooled oxidation reaction mixture has taken in the alkali aqueous solution and solidified, it is not easy to remove the alkali aqueous solution from the oxidation reaction mixture as it is. Therefore, in the process of industrially producing dihydroxynaphthalene by oxidizing diisopropylnaphthalene,
Even if the oxidation reaction mixture is cooled, it is necessary to perform a method of dissolving the oxidation reaction product and preventing solidification to facilitate handling, and in the present invention, the water-insoluble dialkyl ketone is added to the oxidation reaction mixture. Be done. Organic solvents other than the water-insoluble dialkyl ketone, for example, ketones other than the water-insoluble dialkyl ketone according to the present invention such as acetone and methyl ethyl ketone, alcohols such as methanol and ethanol, acetic acid, propion lower aliphatic carboxylic acid or benzene, When a hydrocarbon such as toluene or heptane is used, the oil / water separation operation is not so easy as compared with the case of using a water-insoluble dialkyl ketone, and the oil phase and the oil phase are not dissolved in terms of solubility of the oxidation reaction product. Is not good, and a large amount of alkali remains in the separated oil phase and is difficult to remove, which is not preferable for the next acid decomposition reaction. If the incompletely dealkalized oil phase is used as a raw material for acid decomposition, the yield of dihydroxynaphthalene produced by acid decomposition of diisopropylnaphthalene dihydroperoxide decreases. For this reason, the water-insoluble dialkyl ketone is used as the organic solvent added to the above-mentioned oxidation reaction mixture.

As the water-insoluble dialkyl ketone used in the present invention,
Specific examples include methyl propyl ketone having 5 to 10 carbon atoms, methyl isobutyl ketone, diisopropyl ketone, ethyl isobutyl ketone, propyl butyl ketone, diisobutyl ketone, and amyl butyl ketone. Among them, methyl isobutyl ketone is particularly preferable. preferable.

Regarding the amount of the water-insoluble dialkyl ketone to be added, 0.2 to 5 parts by weight, preferably 0.5 to 3 parts by weight of the water-insoluble dialkyl ketone is usually added to 1 part by weight of the oxidation reaction mixture. The oxidation reaction mixture containing the water-insoluble dialkyl ketone is usually kept in the temperature range of 30 to 90 ° C. to separate into an aqueous phase and an oil phase, and then an oil phase containing dihydroxynaphthalene is separated. In this case, the alkali used during the oxidation reaction is removed in the aqueous phase. The oil phase is
It can be washed with water as needed. By adding a water-insoluble dialkyl ketone to the oxidation reaction mixture in this way, the oxidation reaction product can be dissolved and prevented from solidifying to facilitate handling, and the amount of alkali mixed in the oil phase after separation can be increased. Can be significantly reduced as compared with the case where the water-insoluble dialkyl ketone is not used. The alkali concentration in the oil phase can be determined by an atomic absorption method or a neutralization titration method.

In the present invention, when the diisopropylnaphthalene is oxidized without using a basic aqueous solution, the oil-water separation of the above-mentioned oxidation reaction mixture can be omitted.

In the present invention, the oxidation reaction product containing diisopropylnaphthalene dihydroperoxide obtained as described above is acid-decomposed in the presence of the aforementioned water-insoluble dialkyl ketone to obtain an acid-decomposition reaction mixture containing dihydroxynaphthalene.

In the present invention, it is preferable to add acetone to the oil phase containing the oxidation reaction product and then perform acid decomposition, because the yield of dihydroxynaphthalene is improved.

Acetone is usually added per 1 part by weight of the separated oil phase,
It is preferably added in an amount of 0.2 to 2 parts by weight, preferably 0.5 to 1 part by weight.

An acid catalyst is used in the acid decomposition reaction. Specific examples of the catalyst include inorganic acids such as sulfuric acid, hydrochloric acid and phosphoric acid, solid acid ion exchange resins, solid acids such as silica gel and silica alumina, chloroacetic acid and methane sulfone. Acids, organic acids such as benzenesulfonic acid and toluenesulfonic acid, and heteropolyacids such as phosphotungstic acid and phosphomolybdic acid are preferably used. The amount of acidic catalyst used depends on the type and reaction conditions, but is usually 0 based on the total reaction mixture.
It is preferably in the range of 05 to 10% by weight. This acid decomposition reaction is carried out in the range of 0 to 100 ° C, preferably 20 to 80 ° C.

Further, in the present invention, in some cases dihydroxynaphthalene is obtained by oxidation of diisopropylnaphthalene and hydrogen peroxide is allowed to coexist in this reaction system at the same time, among the carbinols which are by-products obtained in the oxidation reaction, HHP and A method of oxidizing DCA and dihydroperoxides and simultaneously acid-decomposing this dihydroperoxide with an acidic catalyst can also be adopted. In this case, dihydroxynaphthalene can be obtained in a high yield, which is preferable.

As the hydrogen peroxide, in addition to hydrogen peroxide or an aqueous solution of hydrogen peroxide, a substance that generates hydrogen peroxide under reaction conditions, for example, sodium peroxide or an aqueous solution of hydrogen peroxide can be used. In particular, in the acid decomposition reaction, hydrogen peroxide is used in a proportion of 0.9 to 2 mol, preferably 1.0 to 1.5 mol, per mol of the alcoholic hydroxyl group of the carbinols, so that the desired yield of dihydroxynaphthalene can be increased. You can get at a rate. Further, by using hydrogen peroxide under such conditions, the production of by-products due to the condensation of carbinols can be significantly controlled at the same time.

In the present invention, acetone is distilled off from the acid decomposition reaction mixture containing the dihydroxynaphthalene thus obtained, and the water-insoluble dialkyl ketone is distilled off and dihydroxynaphthalene is recovered as a slurry of benzenes, and the slurry is obtained. From which dihydroxynaphthalene is isolated. The method will be described in detail below.

When acetone is distilled off from the acid decomposition reaction mixture, the acid catalyst in the acid decomposition reaction mixture is usually removed prior to the distillation. When the above solid acid is used as the acid catalyst, the catalyst can be removed by filtration. Further, when a soluble catalyst such as sulfuric acid is used as the acid catalyst, a base such as sodium hydroxide or sodium carbonate is usually added in the form of an aqueous solution to neutralize the acid catalyst to make it insoluble in the oil phase containing dihydroxynaphthalene. It is possible to use a method in which acetone is removed by extracting the salt into the aqueous phase and distilling the oil-water mixture by a normal atmospheric pressure or reduced pressure distillation method.
The acetone removed at this time is a reaction product and is externally added to the reaction system. Next, the acid decomposition reaction mixture is separated into an oil phase and an aqueous phase, and the oil phase is taken out. The separated aqueous phase contains, for example, a neutralized acid catalyst, and this aqueous phase is usually discarded.
If desired, further addition of water and subsequent separation of the aqueous layer can also be carried out in order to complete the removal of the neutralized acid catalyst.

Then, the separated oil phase is distilled to remove the water-insoluble dialkyl ketone contained therein, and the dihydroxynaphthalene is recovered as a dispersed slurry in benzenes.

It is not always necessary to completely remove the water-insoluble dialkyl ketone by distillation, and a small amount of the water-insoluble dialkyl ketone may be present in the oil phase. Distillation of the ketone is usually carried out under normal pressure to 20 mmHg,
The column bottom temperature is preferably 50 to 120 ° C.

As a method of distilling off the water-insoluble dialkyl ketone and collecting the dihydroxynaphthalene as a slurry of benzenes, the following method can be exemplified.

(A) A method in which benzenes are added while distilling the water-insoluble dialkyl ketone from the oil phase by distillation to precipitate 2,6-dihydroxynaphthalene to obtain a slurry of benzenes.

(B) A method in which benzenes are added to the oil phase, and then the water-insoluble dialkyl ketone is distilled off from the obtained mixture to precipitate dihydroxynaphthalene to obtain a slurry of benzenes.

By distilling away the water-insoluble dialkyl ketone from the oil phase containing dihydroxynaphthalene and adding benzenes to the oil phase, dihydroxynaphthalene can be recovered as a slurry of benzenes.

In the present invention, by precipitating dihydroxynaphthalene and recovering it as a slurry of benzenes, if a large amount of water-insoluble dialkyl ketone is present in the oil phase, the recovery rate of dihydroxynaphthalene will decrease, The purity of the obtained dihydroxynaphthalene also decreases. Therefore, when dihydroxynaphthalene is precipitated from the oil phase, the weight ratio (I / II) of the water-insoluble dialkyl ketone (I) to the benzenes (II) in the oil phase is
It is desirable to carry out the operation of precipitating dihydroxynaphthalene from the oil phase under the conditions of 0.15, preferably 0.1 and more preferably 0.075 or less.

Examples of benzenes added to the oil phase include benzene, toluene, xylene, trimethylbenzenes, cumene, cymene, diisopropylbenzenes, etc. Among them, cumene is particularly preferable.

In the present invention, the use ratio of benzenes is usually 50 to 1000 parts by weight, preferably 100 to 100 parts by weight, per 100 parts by weight of the acid decomposition product mixture containing dihydroxynaphthalene (excluding water-insoluble dialkyl ketone). Used in an amount of 300 parts by weight.

In the present invention, the following method can be used as a method for isolating dihydroxynaphthalene from the slurry of solid dihydroxynaphthalene obtained by the above method and benzenes.

A method may be employed in which the slurry is once heated to an appropriate temperature to dissolve the solid content, and then cooled to around room temperature to crystallize dihydroxynaphthalene, which is then separated by filtration. Alternatively, a method of cooling the obtained slurry as it is to an appropriate temperature and separating it by filtration can be used. According to this method, dihydroxynaphthalene from which isopropylnaphthol, which is a by-product of the reaction, has been removed, can be separated and recovered. In the present invention, specifically as such a dihydroxynaphthalene, 2,
Examples thereof include 6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene and 1,4-dihydroxynaphthalene.

Effects of the Invention According to the method for producing dihydroxynaphthalene according to the present invention, since the water-insoluble dialkyl ketone is added to the oxidation reaction mixture of diisopropylnaphthalene, the oxidation reaction product present in the oxidation reaction mixture is It is prevented from solidifying in the mixture, and since benzenes are added to the acid decomposition reaction mixture, dihydroxynaphthalene which is the target product does not become a solidified state like a lump, and its handling is easy. In addition, the reaction by-product is dissolved in benzene, so that the objective product, dihydroxynaphthalene, can be produced with a high recovery rate and a relatively high purity.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 2,6 in a 500 ml capacity autoclave (made of SUS 316L) equipped with a rotary stirrer, a gas blowing tube, a thermometer and a reflux condenser.
-75 g of diisopropylnaphthalene, 75 g of 4.5% sodium hydroxide aqueous solution and α, α ',-bis (cyclohexane-1)
-Carbonitrile) 0.1g, reaction temperature 100 ℃, pressure
While vigorously stirring the contents at 5 kg / cm ² G, add 20
The reaction was carried out for 9 hours by blowing in at a rate of / hour. 2,
The reaction rate of 6-diisopropylnaphthalene was 99.5%.

150 g of methyl isobutyl ketone was added to the resulting oxidation reaction product.
After adding, the oil phase (methyl isobutyl ketone phase) and the aqueous phase were separated. The composition of the oxidation products contained in this oil phase is
As a result of liquid chromatography analysis, DHP 6.5% by weight HHP 13.4% by weight DCA 6.3% by weight MHP 2.7% by weight MCA 1.6% by weight Others (the molecular weight is 212) was 7.6% by weight.

Next, 28.3 g of an acetone solution containing 1.7 wt% sulfuric acid was charged into a 1-volume glass reaction vessel equipped with a rotary stirrer, a reflux condenser, an acid decomposition raw material supply pipe and an acidic catalyst solvent supply pipe.
The reaction vessel was placed on a hot water bath at a temperature of 65 ° C. When acetone began to reflux by heating, a mixture of 236 g of a methyl isobutyl ketone solution (oil phase) of the oxidation product, 17.2 g of 60% hydrogen peroxide and 73 g of acetone was started from the acid decomposition raw material supply pipe. At the same time when the supply of the acid decomposition raw material was started, 43 g of an acetone solution containing 1.7% sulfuric acid was also started to be supplied from the acidic catalyst solution supply pipe, and the supply was finished after 1 hour. The supply amounts of the decomposition raw material and the acetone solution of sulfuric acid were determined by a small metering pump. After that, the reaction was further performed for 3 hours.

The above-mentioned acid decomposition reaction was performed twice, and the obtained reaction mixtures were combined. As a result of liquid chromatography analysis, the composition of the acid decomposition reaction product was found to be 2,6-dihydroxynaphthalene 9.6% by weight 6-isopropyl-2-naphthol 2.0% by weight 2,6-diisopurnaphthalene 0.1% by weight Same as 6-isopropyl-2-naphthol.) 4.0% by weight.

Next, 150 g of the above acid decomposition reaction mixture was taken, and in order to neutralize the sulfuric acid contained therein, a 2% sodium carbonate aqueous solution was gradually added until the pH of the solution became about 4. . Then, the following concentration operation was performed in order to remove acetone and methyl isobutyl ketone contained in the acid decomposition reaction mixture. That is, first, acetone was distilled off under a normal pressure with a rotary evaporator to obtain two liquid phases consisting of an aqueous phase and an oil phase, and then the oil phase and the aqueous phase were separated.
Next, cumene was added to the separated oil phase and then distilled to distill off and remove methyl isobutyl ketone in the presence of cumene, and when the weight ratio of methyl isobutyl ketone to cumene was 0.15. Stop distillation, 2,6-
Dihydroxynaphthalene was recovered as a cumene slurry and cooled to room temperature.

After that, the crystals were separated by filtration and dried to obtain 23 g of 2,6-dihydroxynaphthalene crude crystals (2,6-dihydroxynaphthalene crystallization recovery rate 80%). The crude crystals thus obtained were 50.7% by weight of 2,6-dihydroxynaphthalene and 0.7% by weight of 6-isopropyl-2-naphthol, and the solvent of cumene 36
%, The purity of 2,6-dihydroxynaphthalene was about 50% by weight, and the purity when cumene was removed was about 79% by weight. In the separated oil phase before addition of cumene and distillation, the purity of 2,6-dihydroxynaphthalene in the acid decomposition reaction product excluding the solvent and acetone was about 61% by weight.

Example 2 In Example 1, methyl isobutyl ketone was distilled off well, and the weight ratio of methyl isobutyl ketone to cumene was about
2,6-Dihydroxynaphthalene was recovered as a cumene slurry and separated in the same manner as in Example 1 except that the ratio was changed to 0.10.

The recovery rate of 2,6-dihydroxynaphthalene at this time is 87%
And the purity of the obtained 2,6-dihydroxynaphthalene is
It was 60% by weight (the purity excluding cumene was 82% by weight).

Example 3 2,6-dihydroxynaphthalene was separated and recovered in the same manner as in Example 1 except that the weight ratio of methyl isobutyl ketone and cumene was changed to about 0.075.

The recovery rate of 2,6-dihydroxynaphthalene was 93%, and the purity of the obtained 2,6-dihydroxynaphthalene was 58% by weight.
(The purity excluding cumene was 84% by weight).

Example 4 2,6-dihydroxynaphthalene was separated and recovered in the same manner as in Example 1 except that the weight ratio of methyl isobutyl ketone and cumene was about 0.05.

The recovery rate of 2,6-dihydroxynaphthalene is 95%, and the purity of the obtained 2,6-dihydroxynaphthalene is 55% by weight.
(The purity excluding cumene was 83% by weight).

Example 5 Same as Example 1 except that the weight ratio of methyl isobutyl ketone to cumene was about 0.02.
2,6-dihydroxynaphthalene was separated and collected.

The recovery rate of 2,6-dihydroxynaphthalene is 98.3%,
The purity of the obtained 2,6-dihydroxynaphthalene is 58% by weight.
(The purity excluding cumene was 82% by weight).

Example 6 In Example 1, cumene was added while distilling off the methyl isobutyl ketone from the separated oil phase under reduced pressure,
2,6-Dihydroxynaphthalene was separated and recovered in the same manner as in Example 1 except that the weight ratio of methyl isobutyl ketone and cumene in the oil phase when 2,6-dihydroxynaphthalene was precipitated was about 0.04.

The recovery rate of 2,6-dihydroxynaphthalene is 96%, and the purity of the obtained 2,6-dihydroxynaphthalene is 55% by weight.
(The purity excluding cumene was 81% by weight).

Claims (4)

[Claims] 1. An acid decomposition reaction mixture containing dihydroxynaphthalene by acid-decomposing an oxidation reaction product containing diisopropylnaphthalene dihydroperoxide obtained by oxidizing diisopropylnaphthalene with molecular oxygen in the presence of a water-insoluble dialkyl ketone. Then, acetone is distilled off from the acid decomposition reaction mixture, the water-insoluble dialkyl ketone is distilled off in the presence of benzenes, and dihydroxynaphthalene is recovered as a slurry of benzenes, and dihydroxynaphthalene is isolated from the slurry. A method for producing dihydroxynaphthalene, comprising: 2. The method according to claim 1, wherein the water-insoluble dialkyl ketone is methyl isobutyl ketone. 3. The method according to claim 1, wherein the benzenes are cumene. 4. The weight ratio (I / II) of water-insoluble dialkyl ketone (I) and benzenes (II) in the slurry from which dihydroxynaphthalene is isolated is 0.15 or less. The method described.