JPH07572B2 - Method for oxidizing 2,6-diisopropylnaphthalene - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for oxidizing 2,6-diisopropylnaphthalene.

(Prior Art) 2,6-Diisopropylnaphthalene can be obtained by oxidizing 2,6-diisopropylnaphthalene to give 2,6-diisopropylnaphthalene dihydroperoxide and acid-decomposing it with an acidic catalyst. This 2,6-dihydroxynaphthalene is industrially useful as a raw material for synthetic resins, synthetic fibers, pharmaceuticals, agricultural chemicals, dyes and the like.

U.S. Pat.No. 4,503,262 discloses 2,6-diisopropylnaphthalene 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-diisopropyl. In the method for producing naphthalene dihydroperoxide, in particular, by using an aliphatic hydrocarbon solvent having 5 to 14 carbon atoms as the organic solvent, for example, n-heptane, the reaction rate and the yield of the desired dihydroperoxide are And that the purity can be improved.

However, conventionally, 2,6-diisopropylnaphthalene was oxidized with molecular oxygen in the presence of an aqueous base solution to give dihydroperoxide, which was acid-decomposed in the presence of an acidic catalyst to give 2,6-dihydroxyl. No industrial method for obtaining naphthalene is known, and β-isopropylnaphthalene, which is a compound similar to 2,6-diisopropylnaphthalene, is oxidized with molecular oxygen in the presence of an aqueous base solution to give β-isopropylnaphthalene. A method for producing isopropylnaphthalene hydroperoxide is disclosed in JP-A-51-34138 and JP-B-58.
No. 8391 and British Patent No. 654,035.

For example, among these prior arts, Japanese Patent Publication No. 58-8391
In the gazette, the proportion of β-isopropylnaphthalene in the oxidizing raw material is defined, and the oxidation reaction of β-isopropylnaphthalene is performed in a low reaction rate region, and a large amount of unreacted β-isopropylnaphthalene is reacted. Although a method for recovering and recycling is disclosed, this method aims at increasing the oxidation reaction rate.

On the other hand, for the oxidation of diisopropylbenzenes, for example, in JP-B-55-44066, while adjusting the amount of water in the reaction system in a predetermined range when oxidizing it in the presence of an alkaline aqueous solution, at a predetermined temperature. Describes a method of obtaining a high concentration of hydroperoxide by carrying out the reaction.

However, as described above, the oxidation of 2,6-diisopropylnaphthalene by molecular oxygen in the presence of an aqueous base solution is hardly known in the past, and is more severe than that of β-isopropylnaphthalene, for example. It is difficult to apply the oxidation method of β-isopropylnaphthalene to 2,6-diisopropylnaphthalene as it is, since it requires oxidizing conditions and as a result, the production of naphthoquinones that inhibit the oxidation reaction also increases.

Further, 2,6-diisopropylnaphthalene has different reactivity as compared to paradiisopropylbenzene and metadiisopropylbenzene, and the prior art relating to the oxidation reaction of diisopropylbenzene does not refer to the oxidizing raw material. I haven't.

(Object of the Invention) The inventors of the present invention oxidize 2,6-diisopropylnaphthalene with molecular oxygen in the presence of an aqueous base solution to dihydroperoxide (DHP) and / or monohydroperoxide of 2,6-diisopropylnaphthalene. Monocarbinol (HH
P) and / or a reaction for producing dicarbinol (DCA) was studied, and as a result, when the reaction rate of the raw material 2,6-diisopropylnaphthalene was low, the oxidation selectivity to give dihydroperoxide, which is one of the target compounds, was high. However, it was found that the yield is low, and on the other hand, when the reaction rate is increased, the produced dihydroperoxide is decomposed and the oxidation selectivity is lowered.

Therefore, the present inventors have proposed a method for producing a desired dihydroperoxide (DHP) and / or monohydroperoxide monocarbinol (HHP) and / or dicarbinol (DCA) of 2,6-diisopropylnaphthalene in a high yield. As a result of diligent research, the reaction rate of the raw material 2,6-diisopropylnaphthalene was suppressed to a low level to enhance the oxidation selectivity to dihydroperoxide, and the oxidation reaction intermediate was recovered from the reaction mixture formed. Again, 2,
Obtaining the target dihydroperoxide (DHP) and / or monohydroperoxide monocarbinol (HHP) and / or dicarbinol (DCA) in high yield by using it in the oxidation step of 6-diisopropylnaphthalene The present invention has been made by discovering that the above can be achieved.

Accordingly, the present invention oxidizes 2,6-diisopropylnaphthalene to give dihydroperoxide (DHP) and / or monohydroperoxide monocarbinol (HHP) and / or 2,6-diisopropylnaphthalene in high yield. It is an object to provide a method for oxidizing 2,6-diisopropylnaphthalene for producing dicarbinol (DCA).

(Structure of the Invention) The oxidation method of 2,6-diisopropylnaphthalene according to the present invention is a method of oxidizing 2,6-diisopropylnaphthalene with molecular oxygen in the presence of an alkaline aqueous solution to obtain dihydrogen of 2,6-diisopropylnaphthalene. Peroxide (DHP)
And / or a method for producing monohydroperoxide monocarbinol (HHP) and / or dicarbinol (DCA), wherein the oxidation reaction mixture is mixed with a hydrocarbon solvent or a halogenated hydrocarbon solvent to obtain an oil phase and an aqueous phase. A liquid phase is formed or crystals are precipitated, and then unreacted 2,6-diisopropylnaphthalene and monohydroperoxide, oxidation reaction intermediates such as monocarbinol are recovered from the oil phase, and 2,6- It is characterized by being reused in the oxidation step of diisopropylnaphthalene.

In the method of the present invention, the oxidation reaction of 2,6-diisopropylnaphthalene is carried out by adding 2,6-diisopropylnaphthalene to a base aqueous solution in a reaction vessel, or dihydroperoxide recovered together with the oxidation reaction mixture and the oxidation reaction to the dihydroperoxide. It is carried out by adding an intermediate and mechanically mixing it into an emulsified state, and blowing a substrate containing molecular oxygen into the emulsion.

As described above, when the reaction rate of 2,6-diisopropylnaphthalene is too high, the yield of dihydroperoxide is degraded because the formed dihydroperoxide is decomposed. On the other hand, when it is too low, the reaction rate of dihydroperoxide to dihydroperoxide is decreased. The oxidation selectivity is high, but the yield is low. Therefore, in the method of the present invention, the reaction rate of 2,6-diisopropylnaphthalene is in the range of 60 to 90%, particularly preferably 70 to 85%. Here, the reaction rate is the reaction of 2,6-diisopropylnaphthalene not only in the first reaction but also in the reaction performed by using the oxidation reaction intermediate recovered from the oxidation reaction mixture as a raw material together with 2,6-diisopropylnaphthalene. The reaction rate (%) is represented by 100- (unreacted rate of 2,6-diisopropylnaphthalene)).

An alkali metal compound is preferably used as the base. As the alkali metal compound, specifically,
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Examples thereof include potassium carbonate. 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 preferably accounts for 5 to 80% by weight of the reaction mixture, and more preferably 20 to 70% by weight. When the amount of the basic hydroxyl group 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 basic aqueous solution are not well dispersed and the emulsified state is insufficient. Therefore, it adversely affects the oxidation reaction. On the other hand, when the amount of the aqueous base solution used is more than 80% by weight, the emulsified state of the reaction system deteriorates, which is not preferable. In addition, in the oxidation reaction, the pH of the aqueous base solution is usually maintained in the range of 7-12.

In addition, with diisopropyl naphthalene and its acidic product,
The basic aqueous solution can usually be sufficiently emulsified by mechanical stirring, but may be stirred in the presence of a conventionally known emulsifier such as stearic acid, if necessary.

As the base, an alkaline earth metal hydroxide such as calcium hydroxide, magnesium hydroxide or strontium hydroxide can also be used. Particularly, calcium hydroxide is 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 the charged diisopropylnaphthalene mixture 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, although it varies depending on the conditions such as the reaction temperature. The reaction is usually 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,
In particular, a reaction initiator is preferably used in the initial oxidation reaction. Examples of the reaction initiator include α,
It is possible to use α'-azobis (cyclohexane-1-carbonitrile), DHP, MHP, etc. described later. By using these, the induction period of the reaction can be shortened. The amount used is usually in the range of 0.005 to 1 part by weight per 100 parts by weight of the charged reaction mixture containing the raw material diisopropylnaphthalene mixture. When the oxidation reaction intermediate is recovered from the oxidation reaction mixture and is oxidized together with 2,6-diisopropylnaphthalene, this oxidation reaction intermediate acts as a reaction initiator, so that it is particularly necessary to use a reaction initiator. There is no.

By the oxidation reaction of 2,6-diisopropylnaphthalene as described above, in addition to 2,6-diisopropylnaphthalene dihydroperoxide (hereinafter referred to as DHP),
2- which is monohydroperoxide monocarbinol
(2-Hydroxy-2-propyl) -6- (2-hydroperoxy-2-propyl) naphthalene (hereinafter referred to as HHP), dicarbinol 2,6-bis (2-hydroxy-2-propyl) naphthalene ( Hereinafter, referred to as DCA.), 2-isopropyl-6, which is monocarbinol.
(2-hydroxy-2-propyl) naphthalene (hereinafter,
It is called MCA. Carbinols such as), and the monohydroperoxide 2-isopropyl-
6- (2-hydroperoxy-2-propyl) naphthalene (hereinafter referred to as MHP) is produced.

The target oxidation reaction product obtained by the oxidation method of 2,6-diisopropylnaphthalene of the present invention is the above-mentioned DHP and / or HHP and / or DCA, and according to the method of the present invention, Since the oxidation reaction intermediate consisting of 2,6-diisopropylnaphthalene, MHP and MCA in the reaction is reused in the oxidation step again, it can be produced with high selectivity and yield of DHP, HHP and DCA.

Incidentally, in order to obtain the composition of the reaction product by the oxidation reaction, the organic phase and the aqueous phase are separated after the reaction, the aqueous phase is extracted with ether or the like, and the organic phase and the ether extract are subjected to liquid chromatography. Analysis, the unreacted 2,6-diisopropylnaphthalene and the oxidation reaction products DHP, HHP, DC
A, MHP, MCA, etc. can be quantified.

In the method of the present invention, the oxidation reaction mixture obtained as described above is mixed with a dihydroperoxide and a hydrocarbon solvent or a halogenated hydrocarbon solvent that is a poor solvent for the carbinols, to obtain an oil phase and an aqueous phase. Two liquid phases are formed or crystals are precipitated, after which the unreacted 2,6
-Oxidation reaction intermediates of diisopropylnaphthalene and MHP and MCA are recovered, and are recycled to the oxidation step of 2,6-diisopropylnaphthalene.

The hydrocarbon solvent is, as described above, a poor solvent for dihydroperoxide and the carbinols, and these solvents have a low boiling point so that they can be easily separated from the mixture after being added to the oxidation reaction mixture. Preferably, the boiling point is 100 ° C. or lower.
Therefore, in the present invention, for example, hexane, an aliphatic hydrocarbon solvent such as heptane, an aromatic hydrocarbon solvent such as benzene, toluene, xylene, cyclohexane, a cycloaliphatic hydrocarbon solvent such as methylcyclohexane. As the halogenated hydrocarbon solvent, lower aliphatic halogenated hydrocarbon solvents such as chloroform and carbon tetrachloride, halogenated aromatic hydrocarbon solvents such as chlorobenzene, halogenated alicyclic hydrocarbons such as chlorocyclohexane can be used. A solvent can be preferably used.

The amount of the above solvent to be used is not particularly limited, but in consideration of easiness of treatment, it is usually within a range of 3 to 30 parts by volume with respect to 1 part by volume of the oxidation reaction mixture (oil phase). Yes, and preferably in the range of 6 to 20 parts by volume.

In the method of the present invention, preferably, after the completion of the oxidation reaction, the obtained oxidation reaction mixture is decomposed into an oil phase and an aqueous phase,
This oil phase is mixed with the above-mentioned heated solvent, if necessary, and stirred. Unreacted 2,6-diisopropylnaphthalene dissolves in this solvent, and the oxidation reaction product dissolves in the solvent or precipitates from the solvent, depending on the type and temperature of the solvent. For example, by adding a solvent to the oxidation reaction mixture, stirring and cooling, the oxidation reaction product can be precipitated. Further, a solvent is mixed with the oil phase, and by heating this, the oxidation reaction product is dissolved, and then by concentrating, the unreacted 2,6-diisopropylnaphthalene and the oxidation reaction The product can be recovered.

(Effects of the Invention) As described above, according to the method of the present invention, in the oxidation of 2,6-diisopropylnaphthalene, its reaction rate is suppressed to be low, and the oxidation selectivity to dihydroperoxide is increased, and the hydrocarbon solvent is used. Alternatively, by using a halogenated hydrocarbon solvent, dihydroperoxide and an oxidation reaction intermediate thereof are recovered from the obtained oxidation reaction mixture, of which the oxidation reaction intermediate is again oxidized with 2,6-diisopropylnaphthalene. Therefore, DHP, HHP, and DCA can be produced with high selectivity and high yield.

(Examples) Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1 50 g of 2,6-diisopropylnaphthalene 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 at a predetermined concentration, 4.5%
Charge 100 g of aqueous sodium hydroxide solution and 0.1 g of α, α'-bis (cyclohexane-1-carbonitrile), and stir the contents vigorously at a reaction temperature of 90 ° C and a pressure of 5 kg / cm ² G while adding 20 l of air. It was blown in at a rate of / hour and reacted for 7 hours.

The resulting oxidation reaction mixture was separated into an oil phase and an aqueous phase under heating, and the oil phase was poured into about 700 ml of heated hexane with stirring, and then cooled to mainly 2,6-diisopropyl. Crystals of naphthalene containing dihydroperoxide, monohydroperoxymonocarbinol and dicarbinol 19.0
g was precipitated.

After the crystals were filtered off, the filtrate was concentrated under reduced pressure and unreacted.
37.1 g of a mixture of 2,6-diisopropylnaphthalene and an oxidation reaction intermediate was recovered.

Table 1 shows the reaction rate in the oxidation reaction of 2,6-diisopropylnaphthalene and the production rate of dihydroperoxide and the oxidation reaction intermediate.

In addition, as described above, unreacted 2,6-
The recovered mixture of diisopropylnaphthalene and the oxidation reaction intermediate and the oxidation reaction mixture were put into warm hexane, cooled, and the composition of the crystals precipitated from hexane was 2nd.
It is as shown in the table.

Then, a mixture of the unreacted raw material obtained above and the recovered oxidation reaction intermediate 35 g, 2,6-diisopropylnaphthalene 15 g and 4.5
% Aqueous sodium hydroxide solution (100 g) was charged into the autoclave in the same manner as above and reacted under the same reaction conditions for 4.5 hours.

After the reaction was completed, the oxidation reaction mixture was analyzed, and the production rate of the product was as shown in Table 3.

Example 2 In the same manner as in Example 1, an oxidation reaction mixture of 2,6-diisopropylnaphthalene was obtained, from which an oil phase was separated, and the oil phase was mixed with 1 volume of a stirrer, a thermometer and a reflux condenser. The mixture was placed in a flask, about 700 ml of hexane was added thereto, and the mixture was vigorously stirred at a temperature of 40 ° C for about 30 minutes. After this,
The contents of the flask were allowed to stand, only the above hexane phase was extracted, and this was concentrated under reduced pressure to obtain 36.5 g of an unreacted raw material and an oxidation reaction product. The composition is shown in Table 4.

Claims (1)

[Claims] 1. A method of oxidizing 2,6-diisopropylnaphthalene with molecular oxygen in the presence of an aqueous alkaline solution to obtain 2,6-diisopropylnaphthalene
A method for producing dihydroperoxide (DHP) and / or monohydroperoxide monocarbinol (HHP) and / or dicarbinol (DCA) of diisopropylnaphthalene, wherein the oxidation reaction mixture is mixed with a hydrocarbon solvent or a halogenated hydrocarbon solvent. To form two liquid phases, an oil phase and an aqueous phase, or to precipitate crystals, and then from the oil phase together with unreacted 2,6-diisopropylnaphthalene, 2
-Isopropyl-6- (2-hydroperoxy-2-propyl) naphthalene (MHP) and 2-isopropyl-6-
(2-Hydroxy-2-propyl) naphthalene (MCA)
A method for oxidizing 2,6-diisopropylnaphthalene, characterized in that it is separated and recovered from an oxidation reaction intermediate containing and is reused in the oxidation step of 2,6-diisopropylnaphthalene.