JPS6270334A - Production of 2,6-dihydroxynaphthalene - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield, by carrying out the acid decomposition of a reaction mixture produced by the oxidation of 2,6- diisopropylnaphthalene and subjecting the resultant crude 2,6-dihy droxynaphthalene to fractional sublimation, thereby effectively removing the by-products. CONSTITUTION:2,6-Diisopropylnaphthalene is oxidized with molecular O2 to produce 2,6-diisopropylnaphthalene dihydroperoxide. The 2,6- diisopropylnaphthalene monohydroperoxide which is an intermediate of the oxidation reaction is not completely removed from the resultant oxidation reaction product. 2,6-Diisopropyl-naphthalene dihydroperoxide containing at least a part of produced 2,6-diisopropylnaphthalene monohydroperoxide is decom posed with an acid in the presence of an acidic catalyst. Crude 2,6- dihydroxynaphthalene is separated from the acid decomposition reaction mixture and is subjected to the fractional sublimation to obtain the objective compound in high purity. USE:Raw material for synthetic resins, synthetic fibers, pharmaceuticals, agricultural chemicals, dyes, etc.

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-diitupropylnafculene to produce 2,6-
Diisopropylnaphthalene dihydroperoxide,
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-
Diituprobylnaphthalene is dissolved in an organic solvent and oxidized with molecular oxygen in the presence of a heavy metal salt catalyst, e.g. In the production method, the reaction rate, yield and purity of the desired dihydroperoxide can be improved by using an aliphatic hydrocarbon solvent having 5 to 14 carbon atoms, such as n-heptane, as the above-mentioned solvent. ,” it is stated that it can be done twice.

However, conventionally, 2,6-ditubrobylnaphthalene is oxidized with molecular oxygen in the presence of an aqueous base solution to form dihydroperoxide, and this is 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
- There are only a few prior art techniques regarding the oxidation reaction of analogous compounds of diitupropylnaphthalene and the subsequent acid decomposition reaction.

For example, Japanese Patent Application Laid-Open No. 51-34138 and British Patent No. 6
54, No. 035 describes a method for producing β-isobrobylnaphthalene hydroperoside by oxidizing β-isopropylnaphthalene with molecular oxygen in the presence of an aqueous base solution. Furthermore, Japanese Patent Publication No. 55-31764 discloses a method for producing hydroquinone or resorcinol by oxidizing diisopropylhenzene to form diisobrobylhenzene dihydroberoxide and decomposing it in the presence of an acidic catalyst. Are listed.

In this way, the few prior art techniques are mostly related to the oxidation reaction of related compounds and the subsequent acid decomposition reaction.
There is almost no prior art regarding the oxidation of 2,6-diitubropylnaphthalene with molecular oxygen in the presence of an aqueous base solution and the subsequent acid decomposition reaction. In particular, 2,6-diitubrobylnaphthalene is oxidized with molecular oxygen in the presence of an aqueous base solution to give 2,6-diisopropylnaphthalene dihydroberoxide, which is then decomposed with an acidic catalyst to give 2,6-diitubrobylnaphthalene. , 6-dihydroxynaphthalene, 6-isopropyl-2-naphtholka derived from the acid decomposition of 2,6-diisopropylnaphthalene monohydroperoxide, which is an intermediate to dihydroperoxide in the oxidation reaction, is used as the main by-product. However, until now, no method has been known for separating this by-product from the acid decomposition reaction mixture to obtain highly pure 2.6-dihydroxynaphthalene.

(Objective of the Invention) As a result of intensive research into a method for producing 2,6-dihydroxynaphthalene by oxidation of 2,6-diitupropylnaphthalene and subsequent acid decomposition reaction, the present inventors found that the reaction after the acid decomposition reaction After obtaining crude 2,6-dihydroxynaphthalene from the mixture, this is subjected to fractional sublimation to remove the 6-dihydroxynaphthalene coexisting with 2,6-dihydroxynaphthalene.
The present invention was developed based on the discovery that 2,6-dihydroxynaphthalene of extremely high purity can be easily obtained by effectively removing -isopropyl-2-naphthol and other by-products.

Therefore, in the present invention, an oxidation reaction mixture obtained by oxidizing 2,6-diitupropylnaphthalene is subjected to an acid decomposition reaction to obtain crude 2,6-dihydroxynaphthalene from the reaction mixture, which is fractionated and sublimated to obtain high purity. An object of the present invention is to provide a method for producing 2,6-dihydroxynaphthalene.

(Structure of the Invention) The method for producing 2,6-cyhydrogysinaphthalene according to the present invention includes: (a) oxidizing 2,6-diitupropylnaphthalene with molecular oxygen to obtain 2,6-diisopropylnaphthalene dihydroperoxide; Step (b+) 2,6-diisopropylnaphthalene monohydroberoxide, which is an oxidation reaction intermediate, is not completely removed from the oxidation reaction product obtained by the above oxidation step, but some or all of it remains. , a step of acid decomposing 6-diisopropylnaphthalene dihydroperoxide in the presence of an acidic catalyst, (c1 a step of obtaining crude 2,6-dihydroxynaphthalene from the above acid decomposition reaction mixture, and +dl fractionation from the above crude 2,6-dihydroxynaphthalene) A process of obtaining 2,6-dihydroxynaphthalene by sublimation.

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:
Examples include sodium hydroxide J1, potassium hydroxide, sulfur and lithium carbonate, and 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 generally preferably 5 to 80% by weight of the reaction mixture, and particularly preferably in the range of 20 to 70% by weight. The amount of base aqueous solution used is 5% of the reaction mixture.
When the amount is less than the heavy weight percent, the dispersion state of the reaction solution consisting of oily unreacted 2,6-diitupropylnafculene and its oxidation product and aqueous base solution is not good, and the emulsification state is insufficient. , does not affect the oxidation reaction unfavorably. On the other hand,
It is also not preferable if the amount of the aqueous salt W solution used is more than 80% by weight because the emulsification state of the reaction system deteriorates. Also,
In the oxidation reaction, the pH of the aqueous base solution is usually 7 to 7.
12 range.

Note that 2,6-diisopropylnaphthalene and its oxidation product and an aqueous base solution can usually be sufficiently emulsified by mechanical stirring, but if necessary, conventionally known emulsions such as stearic acid, etc. The mixture may be stirred in the presence of an emulsifier.

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.

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 NN in terms of oxygen gas per 100 g of 2.6-diitubropylnaphthalene charged in the oxidation reaction tank.
/ 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 80% or more in order to increase the amount of dihydroperoxide produced. It is preferable that 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 above oxidation reaction of 2.6-diisopropylnaphthalene, a reaction initiator is preferably used.

As this reaction initiator, for example, α, α゛-azobis(cyclohexane-1-carbonitrile) can be used, but as will be described later, it can also be used as a secondary Biologically available 2,6-diisopropylnaphthalene monohydroperoxide can also be used. By using these, the reaction induction period can be shortened. The amount used is usually 0.00 parts by weight of the charged reaction mixture containing the raw material 2,6-diitupropylnaphthalene.
It is the weight of 5 to 1 double view part.

By the oxidation reaction of 2,6-diisopropylnaphthalene as explained above, in addition to 2,6-diitubropylnaphthalene dihydroperoxide (hereinafter referred to as DHP), 2-(2-hydroxy- 2-propyl)-6-(2-hydroperoxy-2-propyl)
naphthalene (hereinafter referred to as HHP), 2,6-bis(
2-hydroxy-2-propyl) naphthalene (hereinafter referred to as D
It's called CA. ), 2-isopropyl-6=(2-hydroxy-2-propyl)naphthalene (hereinafter referred to as MCA), and carbinols such as 2-isopropyl-6-(2-hydroperoxy-2- -propyl) naphthalene (hereinafter referred to as MHP) is produced.

To determine the composition of the reaction product from the above oxidation reaction, 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 by liquid chromatography. For example, unreacted 2,6-diisopropylnaphthalene and oxidation reaction products DHP, HHP,
DCA, MHpLMCA, etc. can be quantified.

In the present invention, in the oxidation reaction of 2,6-diisopropylnaphthalene, the conversion rate is preferably 80% or more, and the oxidation product containing unreacted 2,6-diisopropylnaphthalene and the above-mentioned hydroperoxycarbinols and carbinols is produced. The substance is subjected to the following acid decomposition reaction. In the method of the present invention, usually an appropriate amount of an appropriate organic solvent such as methyl isobutyl ketone is added to the oxidation reaction mixture,
The organic phase containing the oxidation products is separated from the aqueous phase and used to carry out the subsequent acid decomposition. Hereinafter, this organic phase may be referred to as an acid-decomposed raw material.

In the present invention, using the above-described acid-decomposed raw material, 2,6-diisopropylnaphthalene dihydroberoxide contained therein is acid-decomposed in the presence of an acidic catalyst.
- Cyhydrogysinaphthalene is produced. In this case, since the acid-decomposed raw material contains the above-mentioned carbinols as by-products of the oxidation reaction, hydrogen peroxide is allowed to coexist at the same time during the acid-decomposed reaction, and the by-product carbinols are Among them, 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-dihydroxynaphthalene can be produced in high yield. It is preferable because it can be obtained.

In the present invention, when the reaction rate of 2,6-diitubrobylnaphthalene is 80% or more, the yield of HHP and DCA in addition to DHP increases, but these HHP and DCA are If a method is adopted in which hydrogen peroxide is present at the same time during the reaction, it can be converted to DHP, so 2,6-dihydroxynaphthalene can be obtained in high yield. is preferable because it can reduce the yield of MHP that does not contribute to the production of 2,6-dihydroxynaphthalene. In particular, the yield of 2,6-dihydroxynaphthalene can be further increased by controlling the reaction rate of 2,6-diitubrobylnaphthalene to 90% or more, more preferably 95% or more.

As the above-mentioned hydrogen peroxide, in addition to hydrogen peroxide or an aqueous hydrogen peroxide solution, substances that generate hydrogen peroxide under 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. Furthermore, by using hydrogen peroxide under such conditions, it is also possible to significantly suppress the production of by-products due to condensation of carbinols.

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 the acidic catalyst to be used depends on its 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-diisopropylnaphthalene, 2.6
It is practically advantageous to transfer -diisopropylnaphthalene dihydroberoxide and by-products into an organic solvent such as MI BK and carry out the acid decomposition reaction using this organic solvent as a reaction solvent. However, the reaction solvent is not limited to MIBK at all, 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 at 20'c.
The temperature range is 80°C.

In the method of the present invention, crude 2,6-dihydroxynaphthalene is separated from the acid decomposition reaction mixture, and then highly pure 2,6-dihydroxynaphthalene is obtained from the crude 2,6-dihydroxynaphthalene by fractional sublimation. It will be done. In the present invention, this crude 2,6-dihydroxynaphthalene contains 6-isopropyl-2-naphthalene derived from acid decomposition of oxidation products such as 2,6-diisopropylnaphthalene monohydroberoxide (MHP). - Impurities such as metals may be present.

To further explain this point, when employing the method of fractional sublimation according to the present invention, the presence of a large amount of 6-isopropyl-2-naphthol in the crude 2,6-cyhydrokidinaphthalene does not unexpectedly occur. We have now discovered that 2°6-dihydroxynaphthalene can be isolated with high purity by employing this simple fractional sublimation method. Therefore, according to the method of the present invention, as described above, it is not necessary to completely remove 2,6-diisopropylnaphthalene monohydroberoxide from the oxidation reaction product in the step of acid decomposing the oxidation reaction product. It is. This is 2.
It is extremely advantageous and has great significance in the industrial production of 6-dihydroxynaphthalene.

In the method of the present invention, crude 2,
The method for separating 6-dihydroxynaphthalene is not limited in any way, but for example, the reaction mixture is concentrated by distilling off the solvent under reduced pressure, and then the concentrate is separated from an aromatic hydrocarbon such as hot cumene. Mix with solvent, cool, 2.
A method for obtaining 6-dihydroxynaphthalene crude crystals can be exemplified.

The fractional sublimation method used in the method of the present invention will be explained below. This separation method may be carried out by a conventional method, but for example, the crude crystals may be heated under an inert gas flow or a reduced pressure air flow, sublimated, accompanied by the air flow, and collected in a collection device. . 6-itubrobi-2 under normal pressure
- naphthol 70~180℃, preferably 110~1
60 °C, while 2,6-cyhydrokidinaphthalene sublimes at a temperature of 170 to 230 °C, preferably 190 to
Since it sublimes at a temperature of 230°C, 2,6-dihydroxynaphthalene can be separated from 6-itubroby-2-naphthol and isolated with high purity.

(Effects of the Invention) As described above, according to the method of the present invention, when producing 2,6-dihydroxynaphthalene by acid decomposing the reaction mixture obtained by the oxidation reaction of 2,6-diisopropylnaphthalene, the acid decomposition 6- which is the main by-product of the reaction
Effectively separates 2,6-dihydroxynaphthalene from isoprobyl-2-naphthol to produce extremely pure 2,6-dihydroxynaphthalene.
6-Sihydrokidinaphthalene 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 500ml capacity autoclave (SUS316
2,6-diisopropylnaphthalene 50g, 1
% Sourium hydroxide aqueous solution and 0.2 g of 2,6-diitupropylnaphthalene hydroperoxide as a reaction initiator were charged, and the reaction temperature was 100°C and the pressure was 5K.
g/cn! The reaction was carried out for 9 hours by blowing air at a rate of 206/hour while stirring the contents vigorously at G. The reaction rate of 2.6-diitupropylnaphthalene is 98.
It was 1%.

Methyl isobutyl ketone 10 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 found to be: D HP 14.1% by weight H
HP 7.9wt%DC
A 1.4% by weight M HP
6.8wt% M CA
1.4% by weight and 6.2% by weight of others (assuming the molecular weight is 212).

Next, 1! equipped with a rotary stirrer, a reflux condenser, an acid decomposition raw material supply pipe, and an acidic catalyst solution supply pipe! A volumetric glass reaction vessel was charged with 18.8 g of an acetone solution containing 1.7% by weight of sulfuric acid. The reaction vessel was placed in a hot water bath whose temperature was constantly maintained at 65°C. When the acetin begins to reflux due to heating, the oxidation product M is removed from the acid decomposition raw material supply pipe.
157 g of IBK solution (oil phase), 60% hydrogen peroxide solution5.
Feed of a mixture of 1 g and 50 g of acetone was started. Simultaneously with the start of the supply of the acid-decomposed raw material, the supply of 29 g of an 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.

After the reaction was completed, liquid chromatography and gas chromatography analysis revealed that the acid decomposition reaction product contained 9.0%
of 2,6-dihydroxynaphthalene.

The acid decomposition reaction product was concentrated under reduced pressure to remove acetone and MIBK, and the resulting concentrate was poured into hot cumene to precipitate crystals, which were filtered and dried under reduced pressure. Cumene was removed to obtain crude crystals.

The sublimation apparatus used was a modified rotary evaporator, as shown in the drawing, and a thermocouple sheath 2 was inserted into a sublimation flask 1 containing crude crystals, and the sublimation flask was cooled by a connecting pipe 3. 4.

A collection flask 5 is connected to this cooling section. During the sublimation operation, nitrogen gas is passed from the cooling section to the collection flask via the sublimation flask, and while the sublimation flask is rotated by the drive section 6, electricity is heated in the sublimation flask 7.

If the above-described crude crystals are placed in the sublimation flask of the sublimation apparatus and nitrogen gas is passed under normal pressure, the sublimation flask will be
It was heated to 50°C and the sublimed crystals were collected in a collecting flask. After sublimation stopped at this temperature, the collection flask was replaced and the heating temperature of the sublimation flask was gradually increased to 180°C. When sublimation started again, heating was once stopped, the entire device was washed and dried, and then sublimation was started again by heating. Finally, the sublimation flask was heated to 220°C, and the sublimate was collected in a collection flask.

In this way, 0.3 g of white crystals were obtained as a pre-distillate containing 6-isopropyl-2-naphthol, which is a pure substance, by sublimation operation at 150 °C, and 2
, 20 g of white crystals of 6-dihydroxynaphthalene were obtained. The purity of this 2,6-dihydroxynaphthalene crystal is 9
9.7%, melting point 221-223°C.

[Brief explanation of drawings]

The drawing is a sectional view showing an example of a sublimation apparatus used in the method of the present invention. DESCRIPTION OF SYMBOLS 1... Sublimation flask, 3... Connecting pipe, 4... Cooling part, 5... Collection flask, 7... Electric furnace.

Claims (1)

[Claims] (1) (a) A step of oxidizing 2,6-diisopropylnaphthalene with molecular oxygen to obtain 2,6-diisopropylnaphthalene dihydroperoxide, (b) From the oxidation reaction product obtained by the above oxidation step. 2,6-diisopropylnaphthalene monohydroperoxide, which is an oxidation reaction intermediate, is not completely removed, but some or all of it remains, and 2,6-diisopropylnaphthalene dihydroperoxide is decomposed in the presence of an acidic catalyst. (c) obtaining crude 2,6-dihydroxynaphthalene from the acid decomposition reaction mixture; and (d) obtaining 2,6-dihydroxynaphthalene from the crude 2,6-dihydroxynaphthalene by fractional sublimation. A method for producing 2,6-dihydroxynaphthalene, comprising: