JPH0432810B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing aromatic alcohols by reducing aromatic hydroperoxides with hydrogen. Aromatic alcohols are useful as crosslinking agents and serve as synthetic raw materials for producing peroxides such as dicumyl peroxide and di-(2-tert-butylperoxy-2-propyl)benzene. Regarding conventional methods for producing aromatic alcohols, methods for reducing aromatic hydroperoxides with hydrogen are described, for example, in British Patent No. 792,558 and Japanese Patent Publication No. 39-26961. However, these methods cause a decrease in catalytic activity,
The disadvantage is that the yield of the desired aromatic alcohol is low. Therefore, the present inventors investigated a method for producing aromatic alcohols in high yield through the hydrogen reduction reaction of aromatic hydroperoxides, and found that by performing the hydrogen reduction reaction in the coexistence of a hydrogen reduction catalyst and amines, The inventors have discovered that the desired aromatic alcohol can be obtained in high yield, and have completed the present invention. That is, according to the present invention, when an aromatic hydroperoxide is brought into contact with hydrogen in the presence of a hydrogen reduction catalyst to reduce the aromatic hydroperoxide, the reduction reaction is performed by converting the reduction reaction into amines or converting the aromatic hydroperoxide into amines during the hydrogen reduction reaction. Provided is a method for producing an aromatic alcohol, characterized in that the method is carried out in the coexistence of a compound to be obtained. In the method of the present invention, the aromatic hydroperoxide serving as a raw material for the hydrogen reduction reaction has the general formula [] and general formula [] (In both formulas, R ₁ and R ₄ represent an aromatic hydrocarbon group consisting of a monocyclic ring or two or more condensed rings,
R ₂ , R ₃₁ , R ₅ and R ₆ represent aliphatic hydrocarbon, alicyclic hydrocarbon or aromatic hydrocarbon groups, and n
represents an integer from 2 to 4. )
aromatic hydroperoxides are preferred. Specifically, these aromatic hydroperoxides include cumene hydroperoxide, m-form and p-form.
cymene hydroperoxide in -form, diisopropylbenzene monohydroperoxide in m-form and p-form, diisopropylbenzene dihydroperoxide in m-form and p-form, m-form and p-form
-(2-hydroxy-2-propyl)-α,
Examples include aromatic hydroperoxides having 9 to 16 carbon atoms such as α-dimethylbenzyl hydroperoxide, triisopropylbenzene trihydroperoxide, and isopropylnaphthalene hydroperoxide. In the method of the present invention, when aromatic hydroperoxides are used in the hydrogen reduction reaction, they may be used alone, or two or more aromatic hydroperoxides appropriately selected from the aromatic hydroperoxides described above may be used. The group hydroperoxides may also be used in the form of mixtures. In addition to this, aromatic hydrocarbons (compounds in which all -OOH groups are replaced with H atoms in both formulas) corresponding to the hydroperoxides represented by the above general formula [] or general formula [] can be An oxidation reaction product mixture containing the aromatic hydroperoxide obtained by oxidation with gas as a main component and containing alcohols and ketones as impurities may be used as a raw material for the hydrogen reduction reaction of the present invention. . In the hydrogen reduction reaction according to the method of the present invention, commonly known hydrogen reduction catalysts can be used,
For example, as the active component of the catalyst, metals such as nickel, cobalt, platinum, palladium and rhodium are combined with various carriers such as alumina, diatomaceous earth, activated carbon, fiber, calcium carbonate, silica, silica-alumina, barium sulfate or titanium oxide. Examples include catalysts supported on Raney nickel and Raney cobalt. Among these catalysts, it is preferable to use a catalyst containing palladium as an active component, which has high activity in the hydrogen reduction reaction and exhibits a small degree of decrease in catalyst activity that is normally observed as the reaction progresses. The amount of the hydrogen reduction catalyst used is usually 0.0005 to 50% of the active component of the catalyst per 1 mole of the aromatic hydroperoxide.
g, preferably 0.005 to 5 g. In the method of the present invention, the hydrogen reduction reaction is carried out in the presence of amines or compounds that can be converted into amines during the reaction. In this case, the amines include aliphatic amines such as propylamine, butylamine, cyclohexylamine, diethylamine and triethylamine, heterocyclic amines such as pyridine, pyrrole and quinoline, aniline, toluidine, xylidine, 4,4'-diamino Examples include aromatic amines such as diphenylmethane, 4,4'-diaminodiphenyl ether, diphenylamine and triphenylamine. Compounds that can be converted into amines during the hydrogen reduction reaction include nitro compounds such as nitromethane and nitrobenzene, acetonitrile,
Examples include nitrile compounds such as benzonitrile. The amount of these amines or compounds that can be converted into amines is usually 1 x 10 ^-6 per gram atom of the active component constituting the hydrogen reduction catalyst. to 1 mol, preferably 1
x10 ^-5 to 0.1 mole, and usually 1 to 1 mole per mole of aromatic hydroperoxide.
10 ^-8 to 1 mol, preferably 1×10 ^-7 to
It is in the range of 0.1 mole. In the method of the present invention, the hydrogen reduction reaction can be carried out in the absence of a solvent, but it is preferably carried out in the presence of a solvent. When carrying out the experiment in the presence of a solvent, it is preferable to use a water-insoluble solvent, such as benzene, toluene, xylene, cumene, cymene, m-form and p-form.
- aromatic hydrocarbons such as diisopropylbenzene, isopropylnaphthalene and diisopropylnaphthalene, pentane, hexane, heptane,
aliphatic hydrocarbons such as octane and nonane, halogenated hydrocarbons such as chloroform, carbon tetrachloride, dichloroethane, trichloroethane, trichrene, perchlorene, chlorobenzene and dichlorobenzene, ketones such as ityl isobutyl ketone, diisobutyl ketone and isophorone; Examples include ethers such as ethyl ether, propyl ether, butyl ether and pentyl ether, and alcohols such as hexanol, heptanol and octanol, among which particularly preferred water-insoluble solvents are aromatic hydrocarbons and ketones. The amount of solvent used varies depending on the type of aromatic hydroperoxide and the type of solvent, but usually the amount of aromatic hydroperoxide used is
Usually 5 to 5 parts of the water-insoluble solvent per 100 parts by weight.
10,000 parts by weight, preferably 20 to 1,000 parts by weight. In the method of the present invention, the hydrogen reduction reaction involves suspending the hydrogen reduction catalyst in a mixed solution containing the aromatic hydroperoxide, the amine or a compound that can be converted into an amine during the reaction, and optionally the solvent. This is done by introducing hydrogen. The hydrogen pressure during the hydrogen reduction reaction is usually 10 mmHg to 50 kg/cm ² in absolute pressure, preferably 0.1 to 10 kg/cm ² in absolute pressure. In this case, in addition to the method of using hydrogen alone, an inert gas such as nitrogen or helium may be used together with hydrogen. In the method of the present invention, when the water-insoluble solvent described above is used as a solvent when carrying out the hydrogen reduction reaction in the presence of a solvent, the hydrogen reduction reaction is carried out while removing water produced in the reaction from the reaction system. It is preferable to carry out the reaction because it increases the yield of the target aromatic alcohol. Examples of this method include azeotropic dehydration, in which the produced water is removed from the reaction system by forming an azeotrope with the water-insoluble solvent. It is preferable to adopt the method. When such an azeotropic dehydration method is adopted, the reaction temperature and reaction pressure of the hydrogen reduction reaction are such that the aromatic hydroperoxide is reduced with hydrogen,
It is necessary to set the conditions such that the azeotropic distillation can be carried out, and the reaction temperature in this case is preferably 20 to 200°C. In addition, the reaction pressure is usually 10 mmHg to 50 mmHg in absolute pressure.
Kg/cm ² , preferably 0.1 to 10 Kg/cm ² in absolute pressure
It is. The azeotropic mixture is condensed and separated outside the reaction system, and the water-insoluble solvent at this time can be recycled and used again in the hydrogen reduction reaction. The separated water is removed from the reaction system. In the method of the present invention, a reactor equipped with a hydrogen introduction device, a stirrer, and a distillation device is employed as a device for carrying out the hydrogen reduction reaction while performing azeotropic distillation of the produced water. Hydrogen reduction reaction is continuous method,
It can be carried out either by a semi-continuous method or a batch method. Stirring during the hydrogen reduction reaction is performed by a commonly known method. A liquid reduction reaction mixture is obtained by separating the hydrogen reduction catalyst from the mixture after the completion of the hydrogen reduction reaction by a decanting method, a filtration method, a centrifugation method, or the like. The reduction reaction mixture contains a water-insoluble solvent, aromatic alcohol, by-products, unreacted aromatic hydroperoxide, and the like. Specifically, a crystallization method, a distillation method, an extraction method, etc. can be employed as a method for separating the aromatic alcohol from the reduction reaction mixture. Examples of the crystallization method include a method in which the aromatic alcohol is crystallized from the reduction reaction mixture as it is or after being concentrated. If necessary, the aromatic alcohol thus obtained is recrystallized from the water-insoluble solvent, particularly preferably from the aromatic hydrocarbons or ketones mentioned above, to obtain an aromatic alcohol with higher purity. be able to. Next, the method of the present invention will be explained in more detail with reference to Examples. Example 1 A reaction having a reflux condenser with an oil-water separator attached to the top of the reactor, a hydrogen inlet tube, a stirrer, and a reaction liquid take-off tube equipped with a stainless steel filter (hole diameter 2 microns). volume
2% Pd/Al ₂ O ₃ in a 150 ml continuous hydrogen reduction reaction tank.
2.0 g was charged, and 50 ppm of aniline was added while maintaining the internal temperature of the reaction vessel at 150°C. 22wt%
A cumene solution containing cumene hydroperoxide and hydrogen gas were continuously supplied at a rate of 100 ml/hr and 45 Nl/hr, respectively, and the cumene hydroperoxide was continuously reduced with hydrogen under normal pressure. The cumene and water distilled out during the reaction are cooled with a reflux condenser,
After separation into an oil layer and a water layer using an oil-water separator, the oil layer was returned to the reaction system, and the water layer was removed from the reaction system. The reduction reaction mixture produced in the hydrogen reduction reaction was continuously drawn out of the reaction system in fixed amounts through a reaction liquid take-out tube equipped with a filter so that the average residence time in the reaction system was 1.5 hours. After 8 hours of reaction, 690 g of catalyst-free reduced reaction mixture was obtained.
The concentration of cumene hydroperoxide in the reduction reaction mixture was 0.02wt% or less, and the concentration of α-cumyl alcohol was 19.65wt%, and the yield of α-cumyl alcohol was based on the cumene hydroperoxide in the supplied raw material. The percentage was 98.8 mol%. Examples 2 to 6 Containing various amines shown in Table 1 at predetermined concentrations,
A hydrogen reduction reaction was carried out in the same manner as in Example 1, except that a cumene solution containing 22 wt% cumene hydroperoxide was used as a raw material. The results are shown in Table 1.

[Table] Cumene hydroperoxide standard Examples 7 and 8 The same method as in Example 1 except that a cumene solution containing 22wt% cumene hydroperoxide containing the nitro compound or nitrile compound shown in Table 2 at a predetermined concentration was used as the raw material. A hydrogen reduction reaction was carried out. The reaction results are shown in Table 2.

[Table] Example 9 Addition of 2% to the continuous hydrogen reduction reactor described in Example 1
Charge 2g of Pd/Al ₂ O ₃ and set the internal temperature of the reaction tank to
While maintaining the temperature at 116°C, 50 ppm of 4,4'-diaminodiphenylmethane was added. Methyl isobutyl ketone solution containing the air oxidation product of p-diisopropylbenzene (concentration of methyl isobutyl ketone
69 wt%, concentration of p-diisopropylbenzene dihydroperoxide 15.3 wt%, concentration of p-(2-hydroxy-2-propyl)-α,α-dimethylbenzyl hydroperoxide 6.1 wt%, 1,4-
Bis(2-hydroxy-2-propyl)benzene (concentration: 0.5wt%) and hydrogen gas (50ml each)
hr, and was continuously supplied at a rate of 30 NI/hr, and a continuous hydrogen reduction reaction was performed under normal pressure. The water and methyl isobutyl ketone that distilled out during the reaction were cooled in a reflux condenser and separated into an oil layer and a water layer in an oil-water separator.The oil layer was returned to the reaction system, and the water layer was removed from the reaction system. . The reaction contents were continuously drawn out of the reaction system in fixed amounts through a reaction liquid take-out tube equipped with a filter so that the average residence time in the reaction system was 3 hours. After 10 hours of reaction, 403 g of catalyst-free reduced reaction mixture was obtained. The hydroperoxide concentration in the reduction reaction mixture is 0.01 wt% or less (in terms of p-diisopropylbenzene monohydroperoxide), 1,4-bis(2-hydroxy-
2-propyl)benzene concentration is 19.48wt%,
p-diisopropylbenzene dihydroperoxide, p-(2-hydroxy-2-propyl)-α,α-dimethylbenzyl hydroperoxide and 1,4-bis(2-hydroxy-2-
1,4- based on the total amount of benzene (propyl)
The yield of bis(2-hydroxy-2-propyl)benzene was 98.2 mol/%. Example 10 As a hydrogen reduction catalyst, instead of charging 2g of 2%Pd/Al ₂ O ₃ , 2g of 5%Pd/C was charged, and the concentration of 4,4'-diaminodiphenylmethane in the raw material was adjusted from 50ppm to 100ppm. Example 9 except that
A continuous hydrogen reduction reaction of the p-diisopropylbenzene air oxidation product was carried out in the same manner as described in . As a result of analyzing the obtained reduction reaction mixture,
The hydroperoxide conversion rate was 100%, and p-diisopropylbenzene dihydroperoxide and p-(2-hydroxy-2-propyl)-
The yield of 1,4-bis(2-hydroxy-2-propyl)benzene is 98.1 based on the total amount of α,α-dimethylbenzyl hydroperoxide and 1,4-bis(2-hydroxy-2-propyl)benzene. It was in mol/%. Example 11 100 g of toluene, 2
%Pd/Al ₂ O ₃ 4.5 g and 4,4′-diaminodiphenylmethane 9 mg were charged, and while maintaining the internal temperature of the reactor at 122° C. and the hydrogen pressure (absolute pressure) at 1.5 Kg/cm ² , Air oxidation reaction product of m-diisopropylbenzene - toluene solution (toluene concentration 49wt%,
m-diisopropylbenzene dihydroperoxide 25.0wt%, m-(2-hydroxy-2-propyl)-α,α-dimethylbenzyl hydroperoxide 12.3wt%, 1,3-bis(2-hydroxy-
2-propyl) benzene 1.1wt%) 200g to 100
The hydrogen reduction reaction was carried out by continuously supplying hydrogen gas into the reaction system at a rate of 1 g/hr and a rate of 30 NI/hr. Toluene and water distilled out during the reaction were cooled with a reflux condenser and separated into an oil layer and a water layer with an oil-water separator.The oil layer was returned to the reaction system, and the water layer was taken out of the reaction system. After the addition of the raw materials was completed, the reaction was continued for 10 minutes, and then the catalyst was filtered off to obtain 292 g of a reduced reaction mixture. The hydroperoxide concentration in the reduction reaction mixture is 0.01 wt% or less (in terms of m-diisopropylbenzene monohydroperoxide), 1,
The concentration of 3-bis(2-hydroxy-2-propyl)benzene was 22.93wt%, and m-diisopropylbenzene dihydroperoxide and m
-(2-hydroxy-2-propyl)-α,α-dimethylbenzyl hydroperoxide and 1,3
-The yield of 1,3-bis(2-hydroxy-2-propyl)benzene based on the total amount of bis(2-hydroxy-2-propyl)benzene is
It was 98.7 mol/%. Comparative Example 1 A continuous hydrogen reduction reaction of cumene hydroperoxide was carried out in the same manner as described in Example 1, except that a cumene solution containing 22 wt% cumene hydroperoxide to which no aniline was added was used as a raw material. . As a result of analyzing the reduction reaction mixture,
The cumene hydroperoxide addition rate is 100%, α- based on the cumene hydroperoxide in the raw material.
The yield of cumyl alcohol was 87 mol%. Comparative Example 2 A method similar to that described in Example 9, except that a methyl isobutyl ketone solution containing the p-diisopropylbenzene air oxidation reaction product without addition of 4,4'-diaminodiphenylmethane was used as the raw material. The p-diisopropylbenzene air oxidation reaction product was subjected to hydrogen reduction. As a result of analyzing the reduction reaction mixture, the hydroperoxide addition rate was
p-diisopropylbenzene dihydroperoxide, p-(2-hydroxy-2-propyl)-α,α-dimethylbenzyl hydroperoxide and 1,4-bis(2-hydroxy-2-propyl)benzene in the raw materials. The yield of 1,4-bis(2-hydroxy-2-propyl)benzene based on the total amount of was 89 mol/%. Furthermore, p-diisopropylbenzene and p-isopropyl-α,α in the reduction mixture obtained in Example 9
-The concentration of dimethylbenzyl alcohol is
The concentrations of p-diisopropylbenzene and p-isopropyl-α,α-dimethylbenzyl alcohol in the reduction reaction mixture obtained in this reaction were each 0.5wt%.
It was found that hydrogenolysis of 1,4-bis(2-hydroxy-2-propyl)benzene was occurring in this reaction.

Claims (1)

[Claims] 1. When reducing aromatic hydroperoxide by contacting it with hydrogen in the presence of a hydrogen reduction catalyst,
A method for producing an aromatic alcohol, characterized in that the reduction reaction is carried out in the presence of an amine or a compound that can be converted into an amine during the hydrogen reduction reaction.