JPH0730011B2 - Diisopropylbenzene oxidation method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for oxidizing diisopropylbenzene,
More specifically, it relates to a method for producing hydroperoxide in which diisopropylbenzene is oxidized with molecular oxygen in the presence of a base.

Technical Background of the Invention and Problems Thereof When diisopropylbenzene is oxidized with molecular oxygen in the presence of a base, diisopropylbenzene dihydroperoxide [hereinafter sometimes abbreviated as DHP], (2-hydroxy-2-propyl) (2- Hydroperoxy-2-propyl) benzene [hereinafter sometimes abbreviated as HHP], isopropyl- (2-hydroperoxy-2-propyl)
Various hydroperoxides such as benzene [hereinafter sometimes abbreviated as MHP] and acetyl- (2-hydroperoxy-2-propyl) benzene [hereinafter sometimes referred to as KPO], bis (2-hydroxy-2-) It is known that carbinol such as propyl) benzene [hereinafter sometimes abbreviated as DCA] and isopropyl- (2-hydroxy-2-propyl) benzene [hereinafter sometimes referred to as MCA] is produced. It has been well known that industrially useful resorcin or hydroquinone can be obtained by acid decomposition of DHP among these oxidation products using an acid catalyst such as sulfuric acid.

This method is a useful process for obtaining resorcin or hydroquinone from diisopropylbenzene, but in order to obtain more resorcin or hydroquinone from diisopropylbenzene, diisopropylbenzene is efficiently oxidized to produce hydroperoxide, especially DHP. It is highly desirable to produce in high yield.

By the way, it has been attempted to oxidize diisopropylbenzene with molecular oxygen in the presence of a base to produce DHP with higher yield. For example, JP-A-53
-82732 discloses that when a secondary alkyl group-containing aromatic hydrocarbon such as diisopropylbenzene is oxidized to produce a hydroperoxide, the reaction rate is improved by allowing picoline, pyrrole or thiophene to coexist in the oxidation reaction system. It is described that it can be increased and the production yield of the hydroperoxide is improved. Further, in JP-A-55-151554, when diisopropylbenzene is oxidized with molecular oxygen in the presence of a base to produce DHP, ammonia, ammonium hydroxide or ammonium carbonate is added to the oxidation reaction system. , The production yield of DHP is improved.

However, even with the method disclosed in the above publication,
There was a problem that hydroperoxides such as DHP could not be obtained from diisopropylbenzene in a sufficiently satisfactory yield and in a short time.

OBJECT OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, in which diisopropylbenzene is oxidized with molecular oxygen in the presence of a base to produce hydroperoxide at a high level. It is an object of the present invention to provide a method for oxidizing diisopropylbenzene, which can be obtained in a yield and in a short time.

SUMMARY OF THE INVENTION The method for oxidizing diisopropylbenzene according to the present invention comprises the steps of oxidizing diisopropylbenzene with molecular oxygen in the presence of a base to produce hydroperoxide, and carrying out the oxidation reaction in the presence of imidazoles. It has a feature.

In the present invention, since the oxidation reaction of diisopropylbenzene is carried out in the presence of imidazoles, the reaction rate of diisopropylbenzene to hydroperoxide can be remarkably increased, and thus the reaction time can be shortened and the purpose It is possible to increase the yield of hydroperoxide such as DHP which is a compound.

DETAILED DESCRIPTION OF THE INVENTION The method for oxidizing diisopropylbenzene according to the present invention will be specifically described below.

First, as the starting material, diisopropylbenzene, which is an m- or p-isomer, is mainly used.

Such an oxidation reaction of diisopropylbenzene is carried out by adding diisopropylbenzene to an aqueous base solution, mechanically mixing it well to obtain an emulsified state, and blowing a gas containing molecular oxygen into the emulsion state.

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. In addition, the amount of the aqueous base solution used in the reaction mixture usually accounts for preferably 5 to 80% by weight of the reaction mixture, and particularly preferably 10 to 50% by weight. When the amount of the aqueous base solution used is less than 5% by weight of the reaction mixture, the unreacted diisopropylbenzene in the form of oil 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,
When it is more than 80% by weight, the emulsified state of the reaction system is deteriorated, 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.

The diisopropylbenzene 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. 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 charged diisopropylbenzene for the oxidation reaction
It is in the range of 5 to 15 Nl / hour in terms of oxygen gas per 100 g, but is not particularly limited.

The reaction temperature is usually 70 to 150 ° C., preferably 90 to 130 ° C., and the reaction time is usually 6 to 50 hours, although it varies depending on 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 diisopropylbenzene, a reaction initiator is preferably used. For example, α, α '
-Azobis (cyclohexane-1-carbonitrile) or diisopropylbenzene dihydroperoxide 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 0.005 to 100 parts by weight of the charged reaction mixture containing the raw material diisopropylbenzene.
It is in the range of 1 part by weight.

The present invention is characterized in that when oxidizing diisopropylbenzene with molecular oxygen in the presence of a base to produce hydroperoxide as described above, this oxidation reaction is carried out in the presence of imidazoles.

This imidazole is 0.001 to 0.1 mmol, preferably 1 mol of diisopropylbenzene as a raw material.
It is preferably present in an amount of 0.01 to 0.05 mmol. When the imidazoles are present in an amount of less than 0.001 mmol per mol of diisopropylbenzene, the production rate of hydroperoxide is usually low, which is not preferable. On the other hand, the imidazoles are present in an amount of 0.1 mmol per mol of diisopropylbenzene. The additive is usually used in the above range because its effect of accelerating the rate of formation of hydroperoxide is capped even if it is present in an amount exceeding the above range. The imidazoles may be added all at once to the reaction mixture before the reaction, or in some cases, may be added little by little.

In the present invention, the amount of the base used is as described above, but when a sodium compound such as sodium hydroxide or sodium carbonate is used as the base, the abundance ratio of Na to diisopropylbenzene (DIPB) during the oxidation reaction (Na
/ DIPB [g-equivalent / mol]) is usually 0.001 to 0.05
The range is preferable because the oxidation rate is improved.

Examples of the imidazoles used in the present invention include N-methylimidazole having a substituent such as a lower alkyl group such as a methyl group and an ethyl group in addition to imidazole, and N.
-Ethylimidazole and the like can also be used.

In the present invention, the above imidazoles can be used alone or in combination of two or more. When imidazoles are used, the production rate of hydroperoxides should be increased compared to the case where the oxidation reaction of diisopropylbenzene is performed using picoline, pyrrole, thiophene, ammonia, ammonium hydroxide, ammonium carbonate, etc. You can The present inventors also examined the effect of addition of ammonium salts of organic acids, such as ammonium acetate, ammonium hydrogen tartrate, and ammonium benzoate, but found that these did not have the effect of accelerating the oxidation rate of diisopropylbenzene. ing.

EFFECTS OF THE INVENTION In the present invention, since the oxidation reaction of diisopropylbenzene is carried out in the presence of imidazoles, the reaction rate of diisopropylbenzene to DHP, HHP, MHP to hydroperoxide can be remarkably increased, and therefore the reaction time Can be shortened and the yield of hydroperoxide such as DHP, which is the target compound, can be increased.

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

Examples 1 to 5 130 g of m-diisopropylbenzene (hereinafter m-DIPB) and a hydroperoxide of m-DIPB (hereinafter HPO) were placed in a glass reactor equipped with a stirrer, an oxygen blowing tube, a thermometer and a reflux condenser. 3.6g, 4.5wt% sodium hydroxide aqueous solution 7.5g,
And 23.2 g of water were charged and vigorously stirred. Table 1 shows the reaction system
While maintaining the temperature shown in Table 1 and introducing oxygen at 0.7 / min under normal pressure, imidazole was fed at a ratio of the number of moles shown in Table 1 to 1 mole of m-DIPB per hour, and the reaction was carried out for 12 hours. During this period, the pH of the aqueous layer of the reaction solution was constantly maintained at 9 or higher. The progress of the reaction was determined by measuring the transition of the hydroperoxide (HPO) concentration in the oil layer by the iodometry method and converting the hydroperoxides such as DHP, HHP, MHP to MHP to obtain the amount. The final oxidation product was subjected to composition analysis by liquid chromatography.

The HPO accumulation rate was expressed by dividing the amount of MHP-equivalent hydroperoxide produced after a reaction time of 12 hours by 3 to obtain the HPO accumulation rate in% by weight / 4 hours.

The results are shown in Table 1.

Comparative Examples 1 to 10 Reactions were carried out in the same manner as in Examples 1 to 5 under the conditions shown in Table 1 without adding imidazole or using the additives shown in Table 1.

The results are shown in Table 1.

Claims (1)

[Claims] 1. A method for oxidizing diisopropylbenzene, which comprises oxidizing diisopropylbenzene with molecular oxygen in the presence of a base to produce hydroperoxide, and performing the oxidation reaction in the presence of imidazoles.