JP2508700B2 - Method for producing hydroxynaphthalene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention oxidizes an alkylnaphthalene such as 2,6-diisopropylnaphthalene with molecular oxygen to contain carbinol and hydroperoxide and / or carbinol hydroperoxide. To produce an oxidation reaction mixture that
It relates to a method for producing hydroxynaphthalene from this oxidation reaction mixture. The compound is used as a raw material for intermediates in the production of medicines and agricultural chemicals and polymers.

[Conventional technology and problems]

Japanese Patent Application Laid-Open No. 61-28333 discloses 2,6-
The method of oxidizing diisopropylnaphthalene to obtain 2,6-diisopropylnaphthalene dihydroperoxide, and then subjecting this to acid decomposition to convert it to 2,6-naphthalenediol has a poor yield of dihydroperoxide and is difficult to separate. Therefore, there is a description that it is not industrially suitable.

In order to solve such a problem, the above-mentioned JP-A-61-28 has been proposed.
No. 2333 discloses that 2,6-diisopropylnaphthalenedicarbinol is oxidized and acid-decomposed by hydrogen peroxide in acetonitrile or dioxane in the presence of an inorganic acid in a single step.
A method of making 2,6-dihydroxynaphthalene is disclosed. However, the starting material used for the reaction in this process is dicarbinol in pure form without impurities.
It is known that when 2,6-diisopropylnaphthalene is oxidized with molecular oxygen, various oxides such as dihydroperoxide, monocarbinol monohydroperoxide and dicarbinol are produced and obtained in the form of a mixture. However, it is unclear whether the method can be similarly applied to the oxidation reaction product containing hydroperoxide in addition to such carbinol.

[Object of the Invention]

In view of the above-mentioned present situation, the present inventor oxidizes alkylnaphthalene with molecular oxygen to obtain α, α-dialkyl-α-hydroxymethyl group-containing naphthalene (a) and α, α-dialkyl-α-hydroperoxy group-containing Naphthalene (b)
And / or an oxidation reaction mixture containing a naphthalene (c) containing an α, α-dialkyl-α-hydroxymethyl group and an α, α-dialkyl-α-hydroperoxymethyl group is formed, and one step is prepared from this oxidation reaction mixture. The method of selectively producing hydroxynaphthalene by the above reaction in a high yield was examined.

[Outline of Invention]

As a result, they have found that the above object can be achieved by using the following method, and have completed the present invention. That is, according to the method of the present invention, an alkylnaphthalene substituted with at least one secondary alkyl group is oxidized with molecular oxygen to obtain an α, α-dialkyl-α-hydroxymethyl group-containing naphthalene (a). And α, α-dialkyl-α
A hydroperoxymethyl group-containing naphthalene (b) and / or an oxidation reaction mixture containing an α, α-dialkyl-α-hydroxymethyl group and a naphthalene (c) containing an α, α-dialkyl-α-hydroperoxymethyl group. The step of forming the reaction mixture, and the oxidation reaction mixture formed is adjusted to have a molar ratio of hydrogen peroxide to nitriles, an acid and the number of moles of α, α-dialkyl-α-hydroxymethyl group (carbinol group) present in the oxidation reaction mixture. A step of reacting in the presence of hydrogen peroxide at a ratio [H ₂ O ₂ / carbinol group] of 0.9 to 2.0 to form hydroxynaphthalene, and a method for producing hydroxynaphthalene is provided. It

[Specific Description of the Invention]

In the present invention, in the step of oxidizing alkylnaphthalene substituted with at least one secondary alkyl group with molecular oxygen, α, α-dialkyl-α-hydroxymethyl group-containing naphthalene (a) and α, Containing an α-dialkyl-α-hydroperoxymethyl group-containing naphthalene (b) and / or an α, α-dialkyl-α-hydroxymethyl group and a naphthalene (c) containing an α, α-dialkyl-α-hydroperoxymethyl group Oxidize to such an extent that an oxidation reaction mixture is formed. Although it is difficult to control the reaction conditions so that most of the product is α, α-dialkyl-α-hydroperoxymethyl group-containing naphthalene or α, α-dialkyl-α-hydroxymethyl group-containing naphthalene, It is easy to control the reaction conditions for producing the above-mentioned oxidation reaction mixture.

Further, from the above-mentioned oxidation reaction mixture, α, α-dialkyl-
α-hydroperoxymethyl group-containing naphthalene or α,
Although it is difficult to separate the α-dialkyl-α-hydroxymethyl group-containing naphthalene, in the present invention, the above-mentioned oxidation reaction mixture is used as it is as a raw material for producing hydroxynaphthalene in the next step without separating them. .

Specific examples of the alkylnaphthalene substituted with at least one secondary alkyl group according to the present invention include β-isopropylnaphthalene, 2,6-diisopropylnaphthalene, 2,6-di-sec-butylnaphthalene, 2,7
-Diisopropyl naphthalene, etc. can be illustrated. Of these, 2,6-diisopropylnaphthalene is preferable.

In the present invention, the alkylnaphthalene is oxidized with molecular oxygen by a conventionally known oxidation method to obtain α, α-dialkyl-α-hydroxymethyl group-containing naphthalene (a) and α, α-dialkyl- α-hydroperoxymethyl group-containing naphthalene (b) and / or α, α-dialkyl-α-hydroxymethyl group and α,
An oxidation reaction mixture containing naphthalene (c) containing α-dialkyl-α-hydroperoxymethyl groups is formed. Hereinafter, this point will be described in detail. Here, the molecular oxygen is oxygen gas, and as the gas, a gas obtained by diluting oxygen gas with an inert gas such as nitrogen, for example, air can be used. The oxidation reaction with molecular oxygen is usually carried out in the presence of a base. Specifically, alkylnaphthalene can be oxidized under the conventionally known conditions by supplying molecular oxygen into the system in the presence of a radical initiator and an alkaline aqueous solution, if necessary (for example, JP-A-61). -100558, No. 61-93156, No. 61-191638, and Japanese Patent Application No. 61-215161 can be used). Examples of the alkaline aqueous solution include aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate and the like, and the amount of the alkaline aqueous solution used at this time is usually 5 to 70% of the reaction system.
It is a degree. The reaction temperature and time vary depending on the type of alkylnaphthalene, but are usually 70 to 150 ° C, preferably 2
~ 100hr. After completion of the oxidation reaction by molecular oxygen, the oil phase is separated by oil-water separation. When separating this oil and water
If necessary, an aromatic hydrocarbon such as benzene or toluene or a solvent such as methyl isobutyl ketone may be added to the product after the oxidation reaction, and then the oil phase may be separated.

In addition, even if this solvent is a water-soluble solvent such as acetone or acetonitrile, it is compatible with water by combining it with a solvent that is poorly soluble in water such as benzene, toluene, or methyl isobutyl ketone. Can be used if it can be reduced. In the separated oil phase, α, α-dialkyl-α-hydroxymethyl group-containing naphthalene (a) [hereinafter sometimes abbreviated as carbinol (a)] and α, α-dialkyl-
Naphthalene containing α-hydroperoxymethyl group (b)
[Hereinafter, it may be abbreviated as hydroperoxide (b)]
And / or a naphthalene (c) containing an α, α-dialkyl-α-hydroxymethyl group and an α, α-dialkyl-α-hydroperoxymethyl group (hereinafter, may be abbreviated as carbinol hydroperoxide (c)) However, in the present invention, the oxidation reaction mixture containing the carbinol (a) and the hydroperoxide (b) and / or the carbinol hydroperoxide (c) is used as a raw material for producing hydroxynaphthalene according to the present invention. .

Specific examples of the carbinol (a) according to the present invention include 2- (α, α-dimethyl-α-hydroxymethyl).
Naphthalene, 2,6-bis (α, α-dimethyl-α-hydroxymethyl) naphthalene (abbreviated as DC), 2-isopropyl-6- (α, α-dimethyl-α-hydroxymethyl) naphthalene (abbreviated as MC) Etc. can be illustrated.

Specific examples of the hydroperoxide (b) according to the present invention include 2- (α, α-dimethyl-α-hydroperoxymethyl) naphthalene and 2,6-bis (α, α-dimethyl-α-hydroperoxymethyl). Naphthalene (abbreviated as DHP), 2-isopropyl-6- (α, α-dimethyl-α
Examples thereof include -hydroperoxymethyl) naphthalene.

Specific examples of the carbinol hydroperoxide (c) according to the present invention include 2- (α, α-dimethyl-α
-Hydroxymethyl) -6- (α, α-dimethyl-α-
Examples thereof include hydroperoxymethyl) naphthalene (abbreviated as HHP). The respective proportions in the oxidation reaction mixture in this case differ depending on the molar ratio of the oxygen reacted with the alkylaromatic hydrocarbon when the oxidation reaction is stopped, but generally, carbinol (a) is 0.1 to 5 parts by weight, hydroperoxide (b) is in the range of 30 to 70 parts by weight, and carbinol hydroperoxide (c) is in the range of 5 to 40 parts by weight.

The carbinol (a), hydroperoxide (b), and carbinol hydroperoxy (c) specifically exemplified above are oxidation products in the case where the alkyl group of the alkylnaphthalene is an isopropyl group. It goes without saying that oxidation products in the case of such other secondary alkyl groups are also included in the scope of the present invention.

In the present invention, in the oxidation reaction mixture containing carbinol (a) and hydroperoxide (b) and / or carbinol hydroperoxide (c), those in which the proportions thereof are usually within the above-mentioned range are related to the present invention. It is used as a raw material for the production of hydroxynaphthalene, and is directly used as a raw material for the next step without separating the synthetic components.

In the present invention, the above-mentioned carbinol (a) and hydroperoxide (b) and / or carbinol hydroperoxide (c) are reacted in the presence of nitriles, acid and hydrogen peroxide to obtain hydroxynaphthalene.

As the nitriles, specifically, acetonitrile, propionitrile, butyronitrile, aliphatic nitriles such as hexanenitrile, malonnitrile, succinonitrile,
Examples thereof include aliphatic dinitriles such as adiponitrile and aromatic nitriles such as benzonitrile and tolunitrile.
The amount of the nitriles used varies depending on the concentration of the target hydroxynaphthalene in the acid decomposition reaction solution, but the nitriles can be used as a solvent or as an additive.
It is usually in the range of 0.5 to 100 parts by weight, preferably 1 to 50 parts by weight, per part by weight of the total amount of carbinol (a) and hydroperoxide (b) and / or carbinol hydroperoxide (c). When the proportion of nitriles is usually less than 0.5, the selectivity and yield of the target hydroxynaphthalene are lowered. There is no particular upper limit on the proportion of nitriles used, but it is desirable to be in the above range for economic reasons.

Specific examples of the acid according to the present invention, and examples of the acidic catalyst in the acid decomposition reaction include inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, perchloric acid, and hydrofluoric acid; strongly acidic ion exchange resins; silica gel. Examples thereof include solid acids such as silica-alumina; organic acids such as chloroacetic acid, methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; heteropoly acids such as phosphotungstic acid and phosphomolybdic acid; and Lewis acids such as BF ₃ . These acidic catalysts may be added to the reaction system as they are, or may be dissolved in an appropriate inert solvent having solubility of these acidic catalysts and added to the reaction system. For example, when a soluble acid such as sulfuric acid or hydrochloric acid is used, the acid can be used by diluting the acid in nitriles. The amount of the acidic catalyst used depends on its type and reaction conditions, but is usually 0.005 to 10% by weight with respect to the total reaction mixture,
Particularly, the range of 0.01 to 1% is preferable.

In the present invention, the reaction is usually carried out in the presence of a solvent, and specific examples of the solvent include benzene, toluene, xylene,
Aromatic hydrocarbons such as ethylbenzene, isopropylbenzene, diisopropylbenzene, triisopropylbenzene, chlorobenzene, etc., aliphatic hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, hexane, heptane, octane, nonane, cyclohexane, methanol, ethanol, etc. Alcohols such as isopropanol and butanol, ethers such as diethyl ether, diisopropyl ether, dibutyl ether and dioxane, acetone, methyl ethyl ketone (MEK),
Examples thereof include ketones such as diethyl ketone, methyl isobutyl ketone (MIBK) and acetophenone, and carboxylic acids such as acetic acid and formic acid. Of these, benzene, toluene, xylene, acetone and MIBK are preferred. The ratio of the solvent is usually in the range of 10 to 95% of the reaction system.

In the present invention, the use ratio of hydrogen peroxide (H ₂ O ₂ ) is carbinol (a) and hydroperoxide (b) and / or
Or α, α-dialkyl-α-present in an oxidation reaction mixture containing carbinol hydroperoxide (c)
Per hydroxymol group (abbreviated as carbinol group), that is, in the molar ratio of (H ₂ O ₂ / carbinol group), usually 0.9 to 2.0, preferably 1.0 to 1.5 is used. The reaction is carried out. When the molar ratio is less than 0.9, by-products are formed due to the condensation of (remaining) carbinols, and when the molar ratio exceeds 2.0, the hydroxy produced by the excess hydrogen peroxide is generated. Since the secondary reaction of naphthalene occurs and the yield of the desired product is lowered, it is carried out in the above range in the present invention.

The hydrogen peroxide source used in the acid decomposition,
In addition to hydrogen peroxide or an aqueous solution of hydrogen peroxide, a substance that generates hydrogen peroxide under reaction conditions, such as sodium peroxide or calcium peroxide, can be used. The reaction temperature may be slightly different depending on the refraction temperature of the solvent and the pressure of the reaction system (usually atmospheric pressure but may be increased if necessary), but it is usually 0 to 100 ° C, preferably 20 to 80 ° C. The reaction time is usually in the range of 5 minutes to 5 hours. The reaction can be performed by either a batch method or a continuous method.

After completion of the reaction, for example, the catalyst (acid) used in the present invention
Is optionally neutralized, and after recovering the by-produced ketone or solvent, hydroxynaphthalene is isolated by a purification method by performing recrystallization, if necessary, by an extraction operation or distillation. be able to. Specific examples of the hydroxynaphthalene include β-hydroxynaphthalene, 2,6-dihydroxynaphthalene, 2-isopropyl-6-hydroxynaphthalene and the like. Of these, 2,6-dihydroxynaphthalene is preferred.

〔The invention's effect〕

According to the method of the present invention, in the step of oxidizing alkylnaphthalene with molecular oxygen, an oxidation reaction mixture containing carbinol (a) and hydroperoxide (b) and / or carbinol hydroperoxide (c) is formed. Since it oxidizes to a certain degree, it is easy to control the reaction conditions. Moreover, since the mixture can be used as a raw material as it is without separating each component of the oxidation reaction mixture, the reaction process is simplified and the operation is facilitated. By reacting such an oxidation reaction mixture with a specific amount of hydrogen peroxide in the presence of nitriles and an acid, hydroxynaphthalene can be selectively obtained in a high yield in a one-step reaction. An efficient reaction can be performed.

〔Example〕

Hereinafter, the method of the present invention will be specifically described with reference to Examples.

Reference Example 1 2,6-Diisopropylnaphthalene (2,6-DIPN) 3000 parts by weight (2,6-DIPN purity 99.0%, 2,7-DIPN 0.8%), 4.5% by weight sodium hydroxide aqueous solution 6000 parts by weight Charge 10 mg of palladium chloride and 10 g of 2,6-DIPN oxide,
Under the conditions of ℃ and pressure of 5 kg / cm ² G, air was blown in at a rate of 1 Nm ³ / hour while stirring the contents to carry out a reaction for 23 hours. After completion of the oxidation reaction, add 60% of methyl isobutyl ketone (MIBK).
Add 00 parts by weight, remove the separated alkaline water layer, and
The obtained oil layer was washed with water and azeotropically dehydrated to obtain the composition shown in Table 1.

Example 1 A flask equipped with a stirrer, a reflux condenser, and a thermometer was charged with 0.05 g of sulfuric acid and 19.0 g of acetonitrile, and heated in a water bath at 50 ° C. 25.6 g of an acetonitrile solution containing 6.6 g of 60% hydrogen peroxide and MIBK of 2,6-DIPN oxide of Reference Example 1
A mixture of 100 g of solution and 47.3 g of acetonitrile, respectively.
It was fed for 1 hour with a metering pump through another feed tube (H ₂ O ₂ / carbinol molar ratio 1.2, sulfuric acid DHP + HHP +
The ratio to DC is 0.16 wt%). Then, the reaction was continued for 1 hour. The reaction product was analyzed for 2,6-DHN by liquid chromatography, and the yield of 2,6-DHN was 97%.

Reference Example 2 The MIBK solution of the 2,6-DIPN oxide obtained in Reference Example 1 was distilled off under reduced pressure, and toluene was added to the bottom of the kettle. Repeat this twice,
The solvent was replaced with MIBK and toluene. The resulting solution is
The oxide content was 34.9% and the solvent content was 65.1%.

Example 2 In the same apparatus as in Example 1, 0.05 g of sulfuric acid, acetonitrile
9.5 g was charged and heated in a water bath at 50 ° C. 60% hydrogen peroxide water 5.8g, (H ₂ O ₂ / carbinol molar ratio 1.2,
35.8 g of an acetonitrile solution containing 0.13 wt% of sulfuric acid relative to the oxidation) and a mixture of 110 g of a toluene solution of 2,6-DIPN oxide of Reference Example 2 and 33.9 g of acetonitrile were pumped through separate feed pipes at a constant rate. It was supplied for 1 hour.
Then, the reaction was continued for 1 hour. The yield of 2,6-DHN was 99% or more, which was quantitative.

Example 3 The same procedure as in Example 2 was repeated except that the amount of 60% aqueous hydrogen peroxide was 5.0 g (H ₂ O ₂ / carbinol molar ratio was 1.0). 2,6
-DHN yield was 95%.

Example 4 The same procedure as in Example 2 was repeated except that 60% hydrogen peroxide solution was 4.5 g (H ₂ O ₂ / carbinol molar ratio was 0.9). 2,6
-DHN yield was 82%.

Comparative Example 1 An oxidation reaction mixture having the same composition as in Table 1 was used except that MIBK was changed to dioxane in Table 1, and the same reaction was performed in Example 2 except that acetonitrile was changed to dioxane. 2,
The 6-DHN yield was 65%.

Claims (2)

(57) [Claims] 1. An alkylnaphthalene substituted with at least one secondary alkyl group is oxidized with molecular oxygen,
α, α-dialkyl-α-hydroxymethyl group-containing naphthalene (a) and α, α-dialkyl-α-hydroperoxymethyl group-containing naphthalene (b) and / or α, α-dialkyl-α-hydroxymethyl group and α , Α
-Forming an oxidation reaction mixture containing a naphthalene (c) containing a dialkyl-α-hydroperoxymethyl group, and forming the oxidation reaction mixture with nitriles, an acid and α, α- present in the oxidation reaction mixture. The ratio of the number of moles of hydrogen peroxide to the number of moles of dialkyl-α-hydroxymethyl group (carbinol group) [H ₂ O ₂ / carbinol group] is expressed in the presence of 0.9 to 2.0 hydrogen peroxide. And a step of producing hydroxynaphthalene, the method for producing hydroxynaphthalene. 2. When the oxidation reaction mixture is reacted in the presence of nitriles, an acid and hydrogen peroxide, the amount of hydrogen peroxide used is the amount of α, α-dialkyl-α-hydroxy present in the oxidation reaction mixture. Methyl group (carbinol group)
The ratio of the number of moles of hydrogen peroxide to the number of moles of [H ₂ O ₂ / carbinol group] is 1.0 to 1.5, and the reaction is performed, and the reaction is performed according to claim (1). Method for producing hydroxynaphthalene.