JPS5929172B2 - Reductive addition reaction method for aromatic hydrocarbons - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides benzene or lower alkylbenzenes (hereinafter collectively referred to as aromatic hydrocarbons), a noble metal catalyst from group Ⅰ of the periodic table, a strong acid and water or a lower alkylcarboxylic acid (hereinafter simply referred to as an organic acid). The present invention relates to a method for obtaining cyclohexanol derivatives by hydrogenation in the presence of cyclohexanol derivatives.

Cyclohexanols or their esters are extremely important raw materials for the chemical industry, such as solvents and raw materials for synthetic polymer materials.

Conventionally, using cyclohexanol as an example, when starting from benzene, benzene was completely hydrogenated to cyclohexane using a metal catalyst from Group I of the periodic table, and then hydrogenated using a boric acid catalyst or a transition metal compound catalyst. A mixture of cyclohexanol and cyclohexanone is obtained by oxidizing with oxygen using sulfuric acid, sulfonating benzene with sulfuric acid to form an alkaline melt, or adding propylene to benzene in the presence of an acid catalyst to form cumene, which is then oxidized with oxygen. It has been produced as cumene hydroperoxide by decomposing it with an acid catalyst to first obtain phenol, and then hydrogenating it with a Group I metal catalyst to obtain cyclohexanol.

All of these conventional industrially implemented methods include a hydrogenation step, and as far as that step is concerned, the conversion rate of the raw material is sufficiently high, and the selectivity of the product is extremely high, resulting in almost quantitative results. is obtained. However, the process of introducing hydroxyl groups into cyclohexanes or benzene nuclei is never satisfactory because it requires a complex combination of steps and it is not possible to maintain high product selectivity unless the conversion rate is kept relatively low. There is a strong desire to develop a more rational method for producing cyclohexanol. On the other hand, if cyclohexene, which is an intermediate in the reduction reaction, can be efficiently removed when benzene is hydrogenated, cyclohexene can be hydrated relatively efficiently using a sulfuric acid catalyst, and this is an efficient method for producing cyclohexanol from benzene. Therefore, there are many attempts at selective partial reduction of benzene to cyclohexene.
For example, it has been proposed to use a platinum catalyst supported on nylon or polyacrylonitrile, a ruthenium catalyst in the coexistence of a lower alcohol, or a complex catalyst composition containing water, an alkaline agent, and a group element of the periodic table. has been done. However, in order to increase the selectivity of cyclohexene in these conventionally known methods, it is necessary to keep the conversion rate extremely low because cyclohexene is usually reduced more easily than benzene, and it is necessary to keep the conversion rate extremely low, or to increase the selectivity of cyclohexene. Because of the use of cyclohexene or cyclohexanol, it is extremely difficult to use them continuously on an industrial scale, and none of them has become a practical and economical method for producing cyclohexene or cyclohexanol. In view of the current situation, the inventors have intensively studied a new and economical method for producing cyclohexanol derivatives, and have prepared benzene or lower alkylbenzene in a medium of strong acid and water or lower alkyl carboxylic acid.
We have completed a reductive addition reaction method for aromatic hydrocarbons, which is characterized by producing a cyclohexanol derivative represented by the following general formula by reducing it with hydrogen in the presence of a noble metal catalyst from the periodic table group.

However, in the general formula, Ac is hydrogen or a lower alkyl carboxylic acid residue, R is a lower alkyl group, and n is an integer of 011 or 2.

Although the details of the reaction mechanism of the present invention are not necessarily clear, the practical advantages of the present invention over conventionally known techniques, particularly the selective partial reduction method from benzene to cyclohexene, are as follows. explained. The mechanism of the hydrogenation reaction of benzene is thought to be as follows.
Normally, with a benzene hydrogenation catalyst, reactions 1 to 5 are sufficiently fast compared to reaction 6, and almost no cyclohexene () is produced, but with the above-mentioned special catalyst system, reactions 1 to 5, especially The reaction rate of 6 was also accelerated compared to the reaction rate, and some formation of 6 was observed.

However, if an attempt is made to increase the conversion rate of benzene (1) and the yield of the desired product, the reverse reaction 7 of 6 cannot be ignored, making it difficult to increase the yield. However, in the present invention, it goes without saying that it is possible to generate by such a route,
Furthermore, since acid or water is added to the highly reactive reduced intermediate (and), the production of the unintended completely hydrogenated product cyclohexane () can be suppressed. Furthermore, the product cyclohexanol derivative is relatively stable under such reaction conditions, and the reverse reaction 7 can be suppressed, making it possible to increase the conversion rate of I and increase the yield of the desired product, the cyclohexanol derivative. . Other advantages include that a cyclohexanol derivative, which is more useful than cyclohexene, can be directly obtained as a product in a single reaction, and that it can be easily separated from the raw material benzene and the by-product cyclohexane. Next, embodiments of the present invention will be described.

As described above, the aromatic hydrocarbons that can be used as starting materials in the present invention are lower alkylbenzenes such as benzene, toluene, ethylbenzene, cumene, and xylene, and benzene is particularly preferred. There is no particular restriction on the quality of the catalyst as long as it does not contain components that significantly poison the activity of the group noble metal catalyst, and those of the level used in ordinary hydrogenation are preferably used. Next, the strong acid of the catalyst used in the addition reaction of aromatic hydrocarbons to the hydrogenation intermediate is 2
A protic acid having an acidic dissociation constant Pka in water at 5° C. of less than 3.0 or a Lewis acid having an acid catalytic ability of the same level or higher under the reaction conditions is preferred. More specific examples of preferred strong acids include sulfuric acid, phosphoric acid, sodium hydrogen sulfate, potassium hydrogen sulfate, ammonium hydrogen sulfate,
trifluoroacetic acid, trifluoromethanesulfonic acid,
Heteropolyacids such as benzenesulfonic acid, toluenesulfonic acid, alkanesulfonic acid, cation exchange resin, boron trifluoride, phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, silicomolybdic acid, and alumina, silica, silica alumina, titania, various Solid acids such as zeolites or mixtures thereof can be mentioned. Furthermore, water and organic acids are used as addition reaction reagents. Organic acids, that is, lower alkyl carboxylic acids having 6 or less carbon atoms, include formic acid, acetic acid, propionic acid, isobutyric acid,
Mention may be made of caproic acid, glycolic acid, ε-oxycaproic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid, with acetic acid being most preferred. The amount of strong acid to be used is 0.00000000000000000000000000000000,000.
01 mol% or more, preferably 2 mol% or more. Note that when the concentration of protic oxyacid is high, there is a tendency for the proportion of cyclohexyl ester of a strong acid to be high in the product.

In addition, the concentration of aromatic hydrocarbons as raw materials in the reaction system is 0.1~
70m01% is preferable, and further 2.0 to 40m01%
is particularly preferred. The periodic table group noble metal catalyst used in the present invention may be any of ruthenium, rhodium, palladium, osmium, iridium and platinum, with ruthenium and rhodium being particularly preferred. There are no particular restrictions on the shape, as long as it can be used for the hydrogenation of ordinary aromatic hydrocarbons, such as sponge-like, fine powder like platinum black or ruthenium black, and colloidal. Alternatively, those with carriers such as activated carbon, alumina, silica, silica-alumina, polyas, zeolites, asbestos, barium sulfate, ion exchange resins, solid acids, and alloys with copper, silver, gold, etc. are preferable. Can be used. In addition, as mentioned above, noble metals of Group Group of the Periodic Table can be used in the reaction system not only as free metals but also as compounds such as oxides and chlorides. When the strong acid used in the present invention is insoluble in the reaction system, it is fully possible to use the insoluble strong acid as a strong acid catalyst and at the same time as a carrier for the hydrogenation catalyst.

Furthermore, in carrying out the present invention, in addition to the aromatic hydrocarbon as the raw material, the addition reaction reagent and its catalyst as a strong acid, water and an organic acid, and the hydrogenation catalyst containing a group noble metal element of the periodic table, cyclohexane, n- Solvents such as octane, diethyl ether, methanol, and ethanol, and salts such as aluminum sulfate, ferric sulfate, zinc sulfate, and zinc acetate may coexist.

Regarding the quality of hydrogen used in the present invention, it is sufficient that it does not contain any components that significantly poison the activity of the hydrogenation catalyst, and does not necessarily need to be pure, such as nitrogen, helium, argon, carbon dioxide, etc. There is no problem even if it contains an inert gas such as methane.

In addition, the hydrogen pressure (partial pressure) used is not particularly limited as it does not affect the essence of the reaction, but from the viewpoint of reaction rate and pressure resistance of the equipment, the hydrogen pressure (partial pressure) is 0.01 to 500k9/Cri (absolute pressure).
is preferable, and 0.5 to 150 kg/Cd (absolute pressure) is particularly preferable. The same goes for the reaction temperature, 0 to 30.
0°C is preferred, particularly 20-200°C. The cyclohexanol derivatives obtained according to the invention are also further hydrogenated, albeit more slowly, under the conditions of the invention. Therefore, in order to maintain high selectivity of cyclohexanol derivatives, it is better to always leave unreacted aromatic hydrocarbons in the reaction system, and the conversion rate of aromatic hydrocarbons should be kept at 80% or less. This is desirable. The main products obtained in the present invention are the target cyclohexanol derivative and the fully hydrogenated cyclohexane derivative.

In addition, the formation of cyclohexene derivatives or phenylcyclohexane derivatives, which are partial hydrogenation products, may also be observed, but since these by-products can be ignored under normal conditions, their separation, especially the desired product, is important. Separation can be accomplished very easily by conventional methods, as the properties are significantly different from those of other products. Furthermore, by-produced cyclohexane derivatives, cyclohexene derivatives, and phenylcyclohexane derivatives are often more valuable than the raw aromatic hydrocarbons and can be effectively utilized. In addition,
The reaction can be carried out either batchwise or continuously, and any reaction method such as fixed bed, fluidized bed, moving bed, suspended bed, etc. can be adopted.

The present invention will be specifically described with reference to the following Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.

In addition, the conversion rate, yield, and selectivity used in these Examples are defined by the following formula.

Example 1 Internal volume that can be stirred with one magnetic stirrer is approximately 10
10 ml of acetic acid and 4 ml of benzene in a 0 ml flat bottom flask.
1 Boron trifluoride monoacetic acid complex (BF3・2A
c0H) 1mj and Ruthenium (5%) activated carbon catalyst 5
00Tf19 was added, and the mixture was reacted for 10 hours at 70° C. under a hydrogen atmosphere at normal pressure using a normal hydrogenation device for normal pressure.

The product was neutralized with a 10% aqueous sodium carbonate solution, extracted with 60 ml of ether, and the ether layer was subjected to gas chromatography (25% DOP-C22, 120°C, 2 m.He30
m1/Mi), the benzene conversion rate was 1.
2%, selectivities for cyclohexyl acetate and cyclohexene of 4% and 1%, respectively, were obtained. Example
2 In the same manner as in Example 1, 13 ml of acetic acid, 5 ml of benzene, 1 ml of boron trifluoride monoacetic acid complex and 200 ml of ruthenium black were reacted under normal pressure hydrogen at 75° C. for 12 hours.

From the gas chromatogram of the product, the benzene conversion rate was 0.8.
%, cyclohexyl acetate and cyclohexene selectivities of 5% and 2%, respectively, were obtained.

Example 3 Same as Example 1, 10ml of acetic acid, 4ml of benzene
ml, boron trifluoride monoacetic acid complex 1ml and palladium (9%)-activated carbon catalyst 500η at normal pressure, 7
The reaction was carried out at 0°C for 6 hours.

From the gas chromatogram of the product, the benzene conversion rate was 4%.
A result with a selectivity of 1% for cyclohexyl acetate was obtained. Example 4 Same as Example 1: acetic acid 10ml 11 benzene 4ml
1 m' of boron trifluoride monoacetic acid complex and 200 η of platinum oxide (PtO2) were reacted at normal pressure and 70°C for 6 hours.

From the gas chromatogram of the product, the benzene conversion rate was 12%.
, a selectivity of cyclohexyl acetate of 0.6% was obtained. Example 5 Same as Example 1, 13 ml of 50% (by weight) sulfuric acid, 5 ml of benzene, and 500 η of ruthenium (5%) activated carbon catalyst.
were reacted at normal pressure and 70°C for 12 hours.

From the gas chromatogram of the product, the benzene conversion rate was 1.1.
%, and the selectivity for cyclohexanol was 1.8%. Example 6 10 m' of acetic acid was placed in a test tube-type pressure-resistant glass container with an internal volume of about 100 m1 that could be stirred with a magnetic stirrer.
, benzene 4.07, 1 m2 of borotrifluoride carbonacetic acid complex and 200 η of ruthenium (5%) activated carbon catalyst
was added, and the reaction was carried out at a hydrogen pressure (gauge pressure) of 5 atm, a temperature of 75° C., and a reaction time of 1 hour.

As a result of analyzing the reaction solution by gas chromatography, the benzene conversion rate was 5.2%, the cyclohexene selectivity was 0.8%,
The selectivity for cyclohexyl acetate was 3.4%. Example
7 In the same manner as in Example 6, 4.07 g of benzene, 8 ml of a 55% sulfuric acid aqueous solution, and 200 g of a ruthenium (5%) monoactivated carbon catalyst were reacted at a hydrogen pressure of 5 atm and at 70° C. for 4.5 hours.

Analysis by gas chromatography showed that the benzene conversion rate was 6% and the cyclohexanol selection rate was 1.5%. Example 8 Same as Example 6, toluene 4.07, acetic acid 10m',
Boron trifluoride monoacetic acid complex 1me and ruthenium (5%) monoactivated carbon catalyst 200η were heated at a hydrogen pressure of 7 atm.
The reaction was carried out at 70°C for 3.0 hours.

As a result of analysis by gas chromatography, the toluene conversion rate was 4.3%, and the selectivity for methylcyclohexyl acetate was 5.1.
It was %. Examples 9 to 26 In the same manner as in Example 6, 1 ml of acetic acid, 1 y of benzene, 0.5 ml of boron trifluoride monoacetic acid complex, and 50 η of various hydrogenation catalysts shown in the following table were mixed at a hydrogen pressure of 5 kg/CrAG, 7
The reaction was carried out at 5°C.

The reaction results are summarized in Table 1. In addition, since the conversion rate of benzene is expressed as follows, Table 1 shows the yield of cyclohexane and the selectivity of cyclohexyl acetate.

Furthermore, in the tables below, where the yield of the target product is not indicated, it is indicated in the same way. Example 27 A catalyst in which a noble metal was supported on an ion exchange resin was prepared as follows.

Tetraamine palladium chloride, Pd(NH3)4C12, 3.57 and Na type
! 1Amber1yst151 (cation exchange resin manufactured by Rohm and Haas) is mixed in 300 mj of water for 90 minutes.

After removing the resin, it is thoroughly washed with water, then with ethanol, and dried at 100° C. under reduced pressure.

this ! The resin is added to 300 ml of water and 80 ml of 80% hydrazine hydrate, and stirred at 80° C. for 40 minutes to reduce the palladium compound. Next, wash thoroughly with water after ▲, and
The resin, which has been ion-exchanged with % hydrochloric acid by a column method, is washed with water until no chloride ions are present, further washed with alcohol, and finally washed with ether, and then dried at 100° C. under reduced pressure for 2 hours. like this※? A catalyst is obtained in which palladium, which has been reduced in the following manner, is supported on an ion exchange resin (H type). This catalyst simultaneously functions as a hydrogenation catalyst and an acid catalyst. Next, an application example of the present invention to a reaction will be shown using this catalyst.

In the same manner as in Example 6, 3 ml of acetic acid, 27 ml of benzene, and 0.27 ml of the above catalyst were mixed at 110° C. under a hydrogen pressure of 5 k9/CdG.
Allowed time to react. The results were analyzed by gas chromatography, and it was found that the conversion rate of benzene was 4.6% and the selectivity of cyclohexyl acetate was 0.3%.
Examples 28 to 32 Ion exchange resin catalysts supporting various noble metals were prepared in the same manner as in Example 27, and reactions were carried out using these catalysts.

3ml of acetic acid, 27ml of benzene and 0.27ml of catalyst under hydrogen pressure of 5
The reaction was carried out under kg/Cd. The results are shown below. Examples 33 to 38 In the same manner as in Example 6, 37 acetic acid, 27 benzene, 0.17 hydrogenation catalyst and 0.1y heteropolyacid were heated under a hydrogen pressure of 5 kg.
/Cd at 95°C.

The reaction results are shown in the table below. In addition, in all of these Examples, it was observed that cyclohexanol and phenylcyclohexane were produced in trace amounts as by-products.

Examples 39-47 Same as Example 6, benzene 27,
3 ml of acetic acid was mixed with 0.0 ml of a catalyst in which precious metals were supported on various solid acids.
95°C under a hydrogen pressure of 5k9/CdG in the presence of 27
The reaction was carried out.

The reaction results were as follows. The catalyst is prepared by supporting a predetermined amount of a noble metal halide on a solid acid by a kneading method, then drying it in air at 110°C, and then drying it at 150°C in a hydrogen stream.
It was prepared by reducing for 5 hours. NeObeadMSC,. N
eObeadP and SilbeadW are silica-alumina solid acids manufactured by Mizusawa Chemical Industry Co., Ltd. Example 45
TiO2-Al2O3 is a binary metal oxide with a molar ratio of 1:9, and was prepared by a coprecipitation method.

Examples 48 to 52 Similar to Example 6, a reaction was carried out using formic acid as the starting material.

The reaction product was only cyclohexyl formate, and almost no cyclohexanone was observed. The reaction conditions and results are shown in the table below. The reaction time in all cases was 48 hours.

The catalyst of Example 48 had 1% (by weight) of palladium supported on a mixture of molybdenum oxide and phosphotungsten in a weight ratio of 4:1.

Examples 53-55 Similar to Example 6, aromatic hydrocarbon 2V and carboxylic acid 4
m1 in the presence of 5% Ru-carbon 0.11 and an acid catalyst,
The reaction was carried out at 75° C. under a hydrogen pressure of 5 kg/Cd.

The results are shown in the table below. Examples 56 to 59 In the same manner as in Example 6, 1y of benzene, 2ml of 50% sulfuric acid, and 20~ of hydrogenation catalyst were heated under a hydrogen pressure of 50k9/CniG at 70°C.
The reaction was carried out at ℃.

The results are shown in the table below. Examples 60 to 64 In the same manner as in Example 6, benzene IV, 2 ml of 50% sulfuric acid, and 20 hydrogenation catalysts were immediately added with various organic solvents to produce 50 kg/CwL.
The reaction was carried out at 70° C. under a hydrogen pressure of 70°C.

The results are summarized in the table below. Examples 65 to 66 In the same manner as in Example 6, 2 ml of benzene and 5 me of water were reacted with phosphotungstic acid and 2% Rh-WO3 catalyst in the presence of 0.2 V under a hydrogen pressure of 10 kg/CrAG at 95°C. .

The results were as shown in the table below. Examples 67 to 77 In the same manner as in Example 6, 1 y of benzene, 2 ml of 50% sulfuric acid, and 0.4 ml of methanol were reacted at 70° C. in the presence of 20 to 20 hydrogenation catalysts.

The reaction results were as shown in the following table. Examples 78-89 Same as Example 6, benzene IV, 2 ml of 50% sulfuric acid,
Add a predetermined amount of sulfate to hydrogenation catalyst 20Tn9 to make 5k
9/CdG under hydrogen at 70°C.

The results were as follows. Examples 90 to 95 Same as Example 6, benzene 17, 50% sulfuric acid *<2 m
1 and a hydrogenation catalyst of 0.17 were reacted under a hydrogen pressure of 5k9/CdG.

Claims (1)

[Scope of Claims] 1. Benzene or lower alkylbenzene in a contact with a strong acid and water or a lower alkylcarboxylic acid according to the periodic table.
A reductive addition reaction method for aromatic hydrocarbons, characterized by producing a cyclohexanol derivative represented by the following general formula by reducing it with hydrogen in the presence of a group VIII noble metal catalyst; ▲Mathematical formulas, chemical formulas, tables, etc. ▼ However, in the above general formula, Ac is hydrogen or a lower alkyl carboxylic acid residue, R is a lower alkyl group, and n is an integer of 0, 1 or 2.