JPS6270333A - Production of 2,6-dihydroxynaphthalene - Google Patents

Abstract

PURPOSE:To obtain the objective material by oxidizing 2,6-diiso propylnaphthalene, subjecting the resultant dihydroperoxide to acid decomposi tion, adding an aromatic hydrocarbon to the reaction mixture to extract and remove the by-products and contacting the remaining solution with activated carbon. CONSTITUTION:An oxidation reaction mixture containing 2,6-diiso propylnaphthalene dihydroperoxide and by-products and produced by the oxida tion of 2,6-diisopropylnaphthalene is added with methyl isobutyl ketone and an organic phase is separated from the mixture. The organic phase is used as a raw material for acid decomposition and subjected to acid decomposition in the presence of an acidic catalyst and hydrogen peroxide. An aromatic hydro carbon (e.g. benzene, cumene, etc.) is added to the reaction mixture to extract the by-products and precipitate the titled substance in the form of crude crystal. The crystal is dissolved in a solvent such as a mixture of water and acetone under heating, treated with activated carbon and cooled to obtain the purified objective compound. EFFECT:The objective compound can be produced in an extremely high purity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing 2,6-dihydroxynaphthalene, and more particularly to a method for producing highly pure 2,6-dihydroxynaphthalene.

(Prior art) Oxidizing 2,6-diisopropylnaphthalene to produce 2,6-
Diitubropyrnafclean dihydroberoxide,
2,6-dihydroxynaphthalene can be obtained by acid decomposing this with an acidic catalyst. This 2,6
-Dihydroxynaphthalene is industrially useful, for example, as a raw material for synthetic resins, synthetic fibers, pharmaceuticals, agricultural chemicals, dyes, and the like.

U.S. Pat. No. 4,503,262 includes 2,6-
In a method for producing 2,6-diitubrobylnaphthalene dihydroberoxide by dissolving diitupropylnaphthalene in an organic solvent and oxidizing it with molecular oxygen in the presence of a heavy metal salt catalyst, such as organic acid cobalt. , in particular, an aliphatic hydrocarbon solvent having 5 to 14 carbon atoms as the organic solvent;
For example, it is stated that by using n-hebutane, the reaction rate, yield and purity of the desired dihydroperoxide can be improved.

However, in the past, 2,6-diitubropylnaphthalene was oxidized with molecular oxygen in the presence of an aqueous base solution to form dihydroperoxide, and this was acid-decomposed in the presence of an acidic catalyst to produce 2,6-dihydroxynaphthalene. There is no known industrial method to obtain it, and only 2.6
- A method for producing β-isopropylnaphthalene hydroperoxide by oxidizing β-isopropylnaphthalene, which is a related compound of diisopropylnaphthalene, with molecular oxygen in the presence of an aqueous base solution has been disclosed in JP-A-51-119. -'3413
It is only described in Publication No. 8 and British Patent No. 654,035. Additionally, Japanese Patent Publication No. 55-31764 describes a method for producing hydroquinone or resorcinol by oxidizing diisopropylphenzene to produce diisopropylphenzene dihydroberoxide and decomposing it in the presence of an acidic catalyst. has been done.

As described above, there are several prior art techniques regarding the oxidation of 2,6-diitupropylnaphculene and the acid decomposition reaction after the oxidation reaction of its analogues. Regarding the acid decomposition reaction of oxides, almost no prior art has been found so far. especially,
2.6-diitupropylnaphthalene is oxidized with molecular oxygen in the presence of an aqueous base solution to give 2,6-diitupropylnaphthalene dihydroberoxide, which is then decomposed with an acidic catalyst to produce 2. In the reaction to obtain 6-dihydroxynaphthalene, 6-isopropyl-2-naphthol derived from the acid decomposition of 2,6-diitupropylnaphthalene monohydroperoxide, which is an intermediate to dihydroperoxide in the oxidation reaction, is Although 2,6-dihydroxynaphthalene is produced as a main by-product, conventionally nothing is known about a method for separating this by-product from the acid decomposition reaction mixture to obtain highly pure 2,6-dihydroxynaphthalene.

(Objective of the Invention) The present inventors have produced 2,6-dihydroxynaphthalene by oxidation of 2,6-diitubrobylnaphthalene with molecular oxygen in the presence of an aqueous base solution and subsequent acid decomposition reaction using an acidic catalyst. As a result of intensive research on the method for producing 2,6-dihydroxynaphthalene, it was found that in the process of isolating 2,6-dihydroxynaphthalene from the reaction mixture after acid decomposition reaction, by adding an aromatic hydrocarbon to this mixture at any stage, 2,6-dihydroxynaphthalene can be produced.
, 6-dihydroxynaphthalene and other by-products coexisting with the 6-isopropyl-2-naphthalene can be effectively removed, and furthermore, the obtained solution of 2,6-dihydroxynaphthalene crude crystals can be treated with activated carbon. By,
The present invention was achieved by discovering that 2,6-dihydroxynaphthalene of extremely high purity can be easily obtained.

Therefore, in the present invention, an oxidation reaction mixture obtained by oxidizing 2,6-diitupropylnaphthalene is subjected to an acid decomposition reaction, and then subjected to a purification treatment to produce highly pure 2,6-cyhydroxidinafucrene. The purpose is to propose a method.

(Structure of the Invention) The method for producing 2,6-dihydroxynaphthalene according to the present invention is to oxidize 2,6-diisopropylnaphthalene with molecular oxygen to oxidize 2,6-diisopropylnaphthalene dihydroberoxide in the presence of an acidic catalyst. When producing 2,6-dihydroxynaphthalene by acid decomposition, after the acid decomposition reaction in step 1, aromatic hydrocarbons are added to the (al A step of extracting and removing living organisms, and fbl After contacting the solution containing crude 2,6-dihydroxynaphthalene with activated carbon, purification from this solution 2.6-
It is characterized by performing a step of isolating dihydroxynaphthalene.

The oxidation reaction of 2.6-diisopropylnaphthalene is carried out by adding 2,6-diisopropylnaphthalene to an aqueous base solution,
This is done by mechanically mixing to form an emulsified state, and then blowing a gas containing molecular oxygen into the emulsified state.

As the base, an alkali metal compound is preferably used. Specifically, this alkali metal compound includes:
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Examples include potassium carbonate. The concentration of these alkali metal compounds in the aqueous solution is preferably 20% by weight or less. Further, the amount of the aqueous base solution used in the reaction mixture is usually preferably from 5 to 80% by weight, particularly preferably from 20 to 70% by weight. The use of aqueous base solution is 5% by weight of the reaction mixture.
When the amount is less than 1, the dispersion state of the reaction solution consisting of oily unreacted 2,6-diitubrobylnaphthalene and its oxidation product and an aqueous base solution is not good, and the emulsification state is insufficient, leading to an insufficient oxidation reaction. adversely affect. On the other hand, if the amount of the aqueous base solution used is more than 80 parts, it is also not preferred because the emulsification state of the reaction system deteriorates. In addition, in the oxidation reaction, the pl+ of the base aqueous solution is usually 7 to 1.
2.

Note that 2,6-diitubropylnaphthalene and its oxidation product and the aqueous base solution can usually be sufficiently emulsified by mechanical stirring, but if necessary, for example, 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. Particularly preferred is calcium hydroxide. These alkaline earth metal hydroxides may be used alone or in combination with the alkali metal compounds.
ζ is also good.

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

The reaction temperature is usually 80 to 150°C, preferably 90 to 150°C.
The reaction time is usually 6 to 40 hours, although it varies depending on conditions such as reaction temperature.The reaction rate of 62,6-diisopropylnaphthalene is set to 80% or more in order to increase the amount of dihydroperoxide produced. It is preferable to do so. Incidentally, the reaction is usually carried out under normal pressure, but it can also be carried out under increased pressure or reduced pressure, if necessary.

In the oxidation reaction of 2.6-diitubropylnaphthalene, 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 Usually, raw material 2
．． The weight is 0.005 to 1 part by weight per 100 parts by weight of the charged reaction mixture containing 6-diisopropylnaphthalene.

By the oxidation reaction of 2,6-diitupropylnaphthalene as explained above, 2,6-diisopropylnaphthalene dihydroberuoxide (hereinafter referred to as DHP) is produced.
In addition to 2-(2-hydroxy-2-
2,2 -isopropyl-6-(2
-hydroxy-2-propyl) naphthalene (hereinafter referred to as MC
It's called A. ), carbinols such as
2-isopropyl-6-(2-hydroperoxy-2-
propyl) naphthalene (hereinafter referred to as MHI). ) is formed.

To determine the composition of the reaction product from the oxidation reaction described above, separate the organic phase and aqueous phase after the reaction, extract the aqueous phase with ether, etc., and analyze the organic phase and ether extract using liquid chromatography. Then, unreacted 2,6-diisopropylnaphthalene and oxidation reaction products DHP, HHP,
, DCA, MHP, MCA, etc. can be quantified.

In the present invention, as mentioned above, in the oxidation reaction of 2.6-diisopropylnaphthalene, the reaction rate is preferably set to 80% or more, and unreacted 2,6-diisopropylnaphthalene, the above dihydroperoxide and The oxidation reaction mixture containing living organisms is subjected to a subsequent acid decomposition reaction. In the method of the present invention, an appropriate amount of an appropriate organic solvent such as methyl isobutyl ketone (MIBK) is usually added to the oxidation reaction mixture, the organic phase containing the oxidation reaction mixture is separated from the hydrated organic phase, and the organic phase is separated from the hydrated organic phase. Perform the following acid decomposition using Hereinafter, this organic phase may be referred to as an acid-decomposed raw material.

In the present invention, using the above-mentioned acid-decomposed raw material, 2,6-diitupropylnaphthalene dihydroberoxide contained therein is acid-decomposed in the presence of an acidic catalyst.
-dihydroxynaphthalene is produced. In this case, since the acid-decomposed raw material contains the carbinols mentioned above as by-products of the oxidation reaction, hydrogen peroxide is co-existed at the same time in the acid-decomposed reaction, so that the by-product carbinols are If a method of oxidizing HHP and DCA to dihydroperoxides and simultaneously decomposing these dihydroperoxides with an acidic catalyst is adopted as necessary, 2,6-hydroxynaphculene can be produced in high yield. This is preferable because it allows you to obtain

In the present invention, when the reaction rate of 2,6-diisopropylnaphthalene is 80% or more, the yield of HHP and DCA in addition to DHP increases, but these HHP and DCA are When adopting a method in which 2.6-dihydroxynaphthalene is made to coexist at the same time with 2.6-dihydroxynaphthalene, it is possible to convert it to DHP and obtain 2.6-dihydroxynaphthalene in high yield. This is preferred because the yield of MHP that does not contribute to the production of 6-dihydroxynaphthalene can be lowered. In particular, the reaction rate of 2,6-diisopropylnaphthalene is 90% or more, more preferably 90% or more.
By setting the content to 5% or more, the yield of 2,6-dihydroxynaphthalene can be further increased.

As the above-mentioned hydrogen peroxide, in addition to hydrogen peroxide or an aqueous hydrogen peroxide solution, substances that generate hydrogen peroxide under the reaction conditions, such as sodium peroxide and calcium peroxide, can be used. Preferably, an aqueous hydrogen solution is used. In particular, in the method of the present invention, 0.9 to 2 mol, preferably 1 mol, of hydrogen peroxide is added per mol of alcoholic hydroxyl group of the carbinols during the acid decomposition reaction.
．． By using it in a proportion of 0 to 1.5 moles, the desired 2,6-dihydroxynaphthalene can be obtained in high yield. In addition, when hydrogen peroxide is used under such conditions, at the same time, based on the condensation of carbinols (
This is preferable because the production of by-products can be significantly suppressed.

In addition, acidic catalysts for acid decomposition reactions include inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, strong acidic ion exchange resins, solid acids such as silica gel, and silica alumina, chloroacetic acid, methanesulfonic acid, benzenesulfonic acid, and toluenesulfone. Organic acids such as acids, heteropolyacids such as phosphotungstic acid, phosphomolybdic acid, etc. are preferably used. These acidic catalysts may be added to the reaction system as they are, or if these acidic catalysts have solubility, they may be dissolved in an appropriate inert solvent and added to the reaction system. The amount of acidic catalyst used depends on the type and reaction conditions, but is usually in the range of 0.5 to 10% by weight based on the total reaction mixture.

In the present invention, as described above, after the oxidation reaction of 2,6-diitubrobylnaphthalene, 2.6
- It is practically advantageous to transfer the dipropylnaphthalene dihydroberuoxide and the by-product into an organic solvent such as MIBK and carry out the acid decomposition reaction using this organic solvent as a reaction solvent. However, the reaction solvent is not limited to MTBK, and if necessary, other inert organic solvents, such as ketones such as acetone and methyl ethyl ketone, alcohols such as methanol and ethanol, etc.
Lower aliphatic carboxylic acids such as acetic acid and propionic acid, hydrocarbons such as benzene, toluene, xylene, hexane, and heptane, and mixtures thereof can also be used.

This acid decomposition reaction ranges from 0 to 100'c, preferably from 20 to
It is carried out at a temperature of 80°C.

In the method of the present invention, aromatic hydrocarbons are added to the acid decomposition reaction mixture obtained as described above, and 2.6-
By going through the steps of extracting and removing by-products coexisting with dihydroxynaphthalene, and contacting a solution containing crude 2,6-dihydroxynaphthalene with activated carbon, isolating 2,6-dihydroxynaphthalene from this solution. , to obtain highly pure 2,6-dihydroxynaphthalene.

In the method of the present invention, the aromatic hydrocarbon is added to the acid decomposition reaction mixture at any stage of isolating the reaction product 2,6-dihydroxynaphthalene using an appropriate method Q.
For example, the following method may be used.

First, after the acid decomposition reaction is completed, the acidic catalyst contained in the resulting reaction mixture is neutralized with an aqueous alkaline solution, and then,
The organic solvent is distilled off to obtain two liquid phases, an aqueous phase and an oil phase.Then, the oil phase is separated from the oil-water two liquid phases, and the organic solvent is further distilled off from the oil phase. This method involves adding hydrocarbons. According to this method, reaction by-products are extracted into aromatic hydrocarbons, while 2,6-di-droxynaphthalene is precipitated from aromatic hydrocarbons as crystals.

Second, water was added to the concentrate obtained as described above to form a slurry containing 2,6-dihydroxynaphthalene as a solid content, aromatic hydrocarbons were added to this, and the solid content was dissolved by heating. After that, if the oil phase is extracted and the water phase is cooled,
2,6-dihydroxynaphthalene precipitates out. On the other hand, reaction by-products are extracted and removed to aromatic hydrocarbons.

Thus, by concentrating the acid decomposition reaction mixture and mixing it with aromatic hydrocarbons in the presence or absence of water, the reaction by-products are extracted and removed to the aromatic hydrocarbons, and the main by-products are removed. 2°6-cyhydroxidinaphthalene from which most of the biological 6-itubroby-2-naphthol has been removed can be obtained as crude crystals. Aromatic hydrocarbons for this purpose include, for example, benzene, toluene,
xylene, trimethylbenzenes, cumene, cymene,
Diisopropylbenzene and the like are preferably used.

Next, according to the method of the present invention, the 2,6-diitubropylnaphthalene crude crystals are heated in a solvent suitable for recrystallization purification, such as water or a mixed solvent of water and acetone. By dissolving it into a solution, treating it with activated carbon, cooling it and recrystallizing it, even trace amounts of colored substances can be removed and almost pure 2,6-dihydroxynaphthalene can be obtained. Examples of the recrystallization solvent include water, lower alcohols such as methanol, ethanol, and propyl alcohol, aliphatic ketones such as acetone, methyl ethyl ketone, and MIBK, and chain or cyclic ethers such as diethyl ether, dioxane, and tetrahydrofuran. Further examples include acetonitrile, nitromethane, etc., which are used in East Germany or in combination.

Furthermore, the method of treating the 2,6-dihydroxynaphthalene crude crystal solution with activated carbon and the type of activated carbon used are not particularly limited, but for example, treatment using a packed column method Q using granular activated carbon is one of the preferred methods. It is one.

(Effects of the Invention) As described above, according to the method of the present invention, when producing 2,6-dihydroxynaphthalene by acid decomposition of the reaction mixture obtained by the oxidation reaction of 2,6-diisopropylnaphthalene, acid 6- is the main by-product of the decomposition reaction.
Extremely pure 2,6-dihydroxynaphthalene, which does not contain any coloring substances in addition to isoprobyl-2-naphthol, can be obtained.

(Examples) The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 A 500 ml capacity autoclave (SII3316
(manufactured by L), 75 g of 2,6-diitubrobylnaphthalene, 4
．． 75 g of 5% aqueous sodium hydroxide solution and α.

αゝ-bis(cyclohexane-1-carbonitrile) 0
．． Charge 1g, reaction temperature 100℃, pressure 5kg/cf
While vigorously stirring the contents with flG, air was pumped in at 207 °C.
! The reaction was carried out for 9 hours by blowing at a rate of 1/2 hour. 2
, 6-diitupropylnaphthalene reaction rate is 99.5%
Met.

Methyl isobutyl ketone 15 is added to the obtained oxidation reaction product.
After adding 0 g, the oil phase (methyl isobutyl ketone phase) and water phase were separated. As a result of liquid chromatography analysis, the composition of the oxidation products contained in this oil phase was determined to be: D HP 6.5% by weight H
HP 13.4% by weight DC
A 6.3 heavy view%M HP
2.7% by weight MCA
1.6% by weight of others (assuming the molecular weight is 212) and 7.6% by weight.

Next, 17! equipped with a rotary stirrer, a reflux condenser, an acid decomposition raw material supply pipe, and an acidic catalyst solution supply pipe! 28.3 g of an acetone solution containing 1.7% by weight sulfuric acid in a glass reaction vessel.
The reaction vessel was placed on a water bath at a temperature of 65°C. When acetone began to reflux due to heating, a mixture of 236 g of the MIBK solution (oil phase) of the oxidation product, 17.2 g of 60% hydrogen peroxide, and 73 g of acetone was started to be supplied from the acid decomposition raw material supply pipe. At the same time as the supply of the acid-decomposed raw material was started, the supply of 43 g of acetone solution containing 1.7% sulfuric acid was also started from the acidic catalyst solution supply pipe, and the supply was finished one hour later. Note that the feed amounts of the decomposition raw material and the acetone solution of sulfuric acid were determined using a small metering pump.

After this, the reaction was further carried out for 3 hours.

The acid decomposition reaction described above was carried out twice, and the resulting reaction mixtures were combined. As a result of liquid chromatography analysis, the composition of the acid decomposition reaction product is: 2□6-dihydroxynaphthalene 9.6% by weight 6-itubrobyl-2-naphthol 2.0% by weight 2.6-ditubycobylnaphthalene 0.11t % other (assuming the molecular weight is the same as 6-isopropyl-2-naphthol) was 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 in it, the I of the solution was
) A 2% aqueous sodium carbonate solution was gradually added until H was approximately 4. Thereafter, the following concentration operation was performed in order to remove acetone and l'11BK contained in the acid decomposition reaction mixture. That is, first, acetone was distilled off under normal pressure using a rotary evaporator to obtain two liquid phases, an aqueous phase and an oil phase, and the oil phase and the aqueous phase were separated. The separated oil phase is again
20-30++nHg in rotary evaporator
MTBK was distilled off under reduced pressure to obtain a concentrate. However, M
Distillation of rBK was stopped just before crystal precipitation began.

This concentrate contains 2,6-dihydroxynaphthalene21.
6% by weight and 6-itubrobyl-2-naphthol 4°4
% by weight.

290 g of cumene in a 500 ml separable flask equipped with a stirrer, thermometer, reflux condenser and concentrate dripping port.
was placed on a water bath at a temperature of 70"C. 69 g of the concentrate was gradually dropped into this flask to precipitate crystals. After the dropwise addition was completed, the temperature of the water bath was gradually lowered. ,
Further, crystals are precipitated and finally cooled to room temperature.1. Crystals were sufficiently precipitated.

Thereafter, the crystals were filtered 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% of 2,6-dihydroxynaphthalene.
7% by weight and 0.7 6-itubroby-2-naphthol
% by weight.

The dried crude crystals were added to 100 g of acetone/water (20/80) mixed solvent and dissolved by heating.

After adding 1 g of activated carbon powder to this solution and thoroughly stirring, the activated carbon was filtered off, and the resulting filtrate was transferred to a 300 ml volumetric flask equipped with a stirrer and left to cool while stirring.2. 6-dihydroxynaphthalene crystals were precipitated. After cooling to room temperature and sufficiently precipitating crystals, the crystals were filtered off and dried under reduced pressure.

The purity of this 2,6-dihydroxynaphthalene crystal was 99.9% as a result of gas chromatography analysis,
The melting point was 220.5-222.5°C.

Example 2 100 g of the acid decomposition reaction mixture obtained in Example 1 was taken, and the sulfuric acid was neutralized with a 2% aqueous sodium carbonate solution in the same manner as in Example 1, and the acetone was distilled off to separate the water phase and oil phase. Two liquid phases were obtained, and an oil phase and an aqueous phase were separated.

The separated oil phase was placed in a 300ml separable flask equipped with a stirrer, thermometer, distillate extractor and dropping funnel, and placed on an oil bath at a temperature of 100-110°C. was distilled off as an azeotrope.

The water lost from the reaction mixture as the azeotrope was distilled off was replenished from the dropping funnel in a timely manner. After MIBK was distilled off, the reaction mixture became a slurry.

Next, water was added to this slurry containing 2.6-dihi)'''logisinaphthalene to make 130 g, and the mixture was transferred to a 300 ml glass autoclave. After that, the contents were heated to 160°C and stirred. After the solid content was completely dissolved, heating and stirring were repeated for 1J, and the contents were left to stand. After extracting the oil phase from the contents, Then, stirring of the contents was started again, and the contents were allowed to cool.

When the contents reached approximately room temperature, the contents were removed and filtered to obtain wet crude crystals of 2,6-dihydroxynaphthalene 1
1.5g was obtained. 6-isopropyl-2 in this crude crystal
- The proportion of naphthol was 1.2% relative to 2,6-dihydroxynaphthalene.

11 g of the above crude crystals were dissolved in 135 g of a 20% acetone aqueous solution, and subjected to activated carbon treatment and recrystallization purification in the same manner as in Example 1. Purification 2, 6. 8.1 g of dihydroxynaphthalene crystals were obtained. Purity 99.8%, melting point 220.9~
It was 222.0°C.

Claims (1)

[Claims] (1) In producing 2,6-dihydroxynaphthalene by acid decomposing 2,6-diisopropylnaphthalene dihydroperoxide obtained by oxidizing 2,6-diisopropylnaphthalene with molecular oxygen in the presence of an acidic catalyst. , after the above acid decomposition reaction, (a) adding an aromatic hydrocarbon to the acid decomposition reaction mixture;
, a step of extracting and removing by-products coexisting with 6-dihydroxynaphthalene, and (b) contacting a solution containing crude 2,6-dihydroxynaphthalene with activated carbon, and then extracting purified 2,6-dihydroxynaphthalene from this solution. 1. A method for producing 2,6-dihydroxynaphthalene, which comprises performing a separating step.