JP2904250B2 - Method for producing monoalkenylbenzenes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing monoalkenylbenzenes by alkenylating an aromatic hydrocarbon compound with a conjugated diene having 4 or 5 carbon atoms. Monoalkenyl benzenes are useful as intermediate materials for various organic compounds including high-molecular monomers, for example, 5- (o-tolyl) -2- produced from o-xylene and 1,3-butadiene. After ring closure, pentene can be converted to 2,6-naphthalenedicarboxylic acid industrially useful as a polymer material by dehydrogenation, isomerization and oxidation.

[0002]

2. Description of the Related Art An aromatic hydrocarbon compound having 4 or 5 carbon atoms is used.
In order to produce monoalkenylbenzenes by side-alkenylation using conjugated dienes of the above, there is known a method of using an alkali metal such as sodium or potassium or an alloy thereof as a catalyst. For example, German Patent 55751
No. 4 describes a method using sodium metal as a catalyst, which is described in Eberhardt et al., J. Org. Chem., Vol. 30, p82-84 (19)
65) describes a method of using sodium metal supported on an alkaline earth metal oxide. In addition, 50
No. 17773 describes a method using metal potassium, and is described in JP-B-50-17975 and JP-B-51-8.
No. 930 and the like describe a method using a potassium-sodium alloy or a mixture of metallic potassium and metallic sodium. Also, U.S. Pat.
J. Org. Chem., Vol. 30, p82-84 (1965) describes a method of using potassium metal supported on an alkali metal oxide or an alkaline earth metal oxide. Further, JP-A-47
-29929 and JP-A-47-31935 disclose a potassium compound and metallic sodium at 300 ° C or 350 ° C.
A method using a mixture obtained by heat treatment at the above temperature as a catalyst is described.

[0003]

In the case where metal sodium is used as it is or as a catalyst supported on an alkaline earth metal oxide, the activity and selectivity are not sufficient and are not practical. Further, a method using a metal potassium catalyst, a potassium-sodium alloy or a mixture of metal potassium and metal sodium as a catalyst,
Although its activity as a catalyst is high, it is not safe to use it industrially because it uses a large amount of highly ignitable potassium metal, and it is economical because it uses a large amount of expensive potassium metal. There is also a problem in terms of gender. On the other hand, the method of using a mixture obtained by heat-treating a metal sodium and a potassium compound at a high temperature as a catalyst has the feature that metal potassium or a potassium alloy is not directly used, but has insufficient activity, and also has an inflammable metal sodium. There is also an industrial problem from the viewpoint of safety in handling methane at high temperatures. In view of the above, an object of the present invention is to provide a high-yield, low-cost, and safer method for a method of alkenylating an aromatic hydrocarbon compound with a side chain using a conjugated diene having 4 or 5 carbon atoms. To provide a method for producing monoalkenylbenzenes by using the method.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have proposed an excellent method for producing monoalkenylbenzenes by alkenylating the α-position of an aromatic hydrocarbon compound with a conjugated diene having 4 or 5 carbon atoms to form a side chain. As a result of intensive studies for the purpose of developing a method that uses a composition obtained by heat treatment of an alkali metal and boron nitride under an inert gas as a catalyst, or boron nitride pre-containing potassium compound and By using a composition obtained by heat-treating an alkali metal and an inert gas under an inert gas as a catalyst, it has been found that monoalkenylbenzenes can be produced in a high yield, at low cost, and in a highly safe manner, The present invention has been completed.

The catalyst prepared by the method of the present invention has a remarkably high activity in the side chain alkenylation reaction of an aromatic hydrocarbon compound with a conjugated diene. Monoalkenylbenzenes are obtained, and the catalyst life is long. Further, the ignitability of the alkali metal is remarkably suppressed, and the handling of the catalyst becomes easy. That is, the present invention relates to monoalkenylbenzenes obtained by alkenylating a side chain of an aromatic hydrocarbon compound having one or more hydrogen atoms bonded to the α-position of the side chain using a conjugated diene having 4 or 5 carbon atoms. In producing, using a composition obtained by heat treatment of an alkali metal and boron nitride under an inert gas as a catalyst, or boron nitride and an alkali metal previously containing a potassium compound under an inert gas It is characterized in that a composition obtained by heat treatment is used as a catalyst. Hereinafter, the present invention will be described in more detail.

The aromatic hydrocarbon compound having one or more hydrogen atoms bonded to the α-position of the side chain used in the present invention includes:
The following compounds are used. Monocyclic aromatic hydrocarbons include toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, n-butylbenzene, sec-
Monoalkylbenzenes such as butylbenzene and isobutylbenzene, o-, m- and p-xylene, o-, m- and p-
Dialkylbenzenes such as ethyltoluene, o-, m- and p-diethylbenzene, trialkylbenzenes such as mesitylene and pseudocumene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene And polyalkylbenzenes such as pentamethylbenzene and hexamethylbenzene. As the polycyclic aromatic hydrocarbon, 1- and 2-methylnaphthalene, dimethylnaphthalenes, alkyltetrahydronaphthalene, alkylindane and the like are used. Carbon number 4 as the other raw material
Alternatively, the conjugated dienes of 5 include 1,3-butadiene,
3-pentadiene and isoprene are used.

The alkali metal used in the catalyst of the present invention includes lithium, sodium, potassium, rubidium, cesium, etc., preferably sodium, potassium or an alloy comprising sodium and potassium, more preferably potassium or sodium and potassium. Is most preferred. Further, as the potassium compound previously contained in boron nitride, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, potassium phosphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, potassium aluminate, potassium chloride, and / or Examples include potassium alcoholates, potassium carboxylate, and potassium phenolates.

The preparation of a catalyst by mixing boron nitride and an alkali metal is carried out by heating and mixing at a temperature higher than the melting point of the alkali metal in an inert gas. The inert gas referred to here is a gas that does not substantially react with the alkali metal and the prepared catalyst under the catalyst preparation conditions, and specifically includes nitrogen, helium, argon and the like. However,
When lithium is used as the alkali metal, the use of lithium is not preferred because lithium reacts with nitrogen. The temperature of the heat treatment is preferably in the range from the melting point of the alkali metal to 500 ° C, more preferably in the range from the melting point to 300 ° C. At a temperature lower than the melting point of the alkali metal, since the alkali metal does not melt, it is difficult to uniformly disperse and effectively contact the boron nitride and the alkali metal when reacting with the alkali metal, and it takes a long time to prepare, and it is practical. I can't say. On the other hand, although a catalyst can be prepared at a temperature of 500 ° C. or higher, handling of ignitable substances at high temperatures is not preferable in industrial practice. The time for the heat treatment is usually in the range of 5 minutes to 300 minutes.
The amount of the alkali metal used in the catalyst preparation is 0.02 to 0.40 per 1 part by weight of boron nitride.
Parts by weight, preferably in the range of 0.05 to 0.25 parts by weight. When the amount of the alkali metal used is smaller than this range, sufficient catalytic activity cannot be obtained, and when the amount is too large, the alkali metal is not sufficiently occluded and adsorbed by boron nitride, so that handling of the catalyst is difficult. This is not only difficult but also economical.

On the other hand, preparation of a catalyst by mixing a boron nitride previously containing a potassium compound with an alkali metal is also carried out by heating and mixing at a temperature higher than the melting point of the alkali metal under an inert gas. As a method for preparing the boron nitride containing a potassium compound, any method of wet or dry method may be adopted as long as both can be mixed and dispersed, but for the purpose of uniformly dispersing, a wet method is used. Is preferred. As a method of preparing by a wet method, there is a method of impregnating or kneading an aqueous solution of a potassium compound into boron nitride, followed by drying or firing. The temperature for firing is 300 to 1000 ° C., preferably 350 to 700 ° C.
° C, and firing may be performed in air or in an inert gas. When the calcination temperature is lower than 300 ° C., a highly active catalyst cannot be obtained when subsequently reacted with an alkali metal, and a temperature higher than 1000 ° C. is economically undesirable.

The mixing ratio of the potassium compound to boron nitride is 0.02 to 0.40 part by weight, preferably 0.05 to 0.1 part by weight, as a potassium atom per 1 part by weight of boron nitride.
25 parts by weight. When the mixing ratio of the potassium compound is smaller than this range, the produced alkenylbenzene further reacts with the conjugated diene to easily increase the amount of by-products of the high-boiling compound, and the catalytic activity tends to decrease. In order to maintain the activity, a large amount of a catalyst is required, which causes inconvenience such as complicated treatment after the reaction. On the other hand, when the mixing ratio of the potassium compound is large, it takes a long time to mix with the alkali metal to obtain a highly active catalyst,
In addition, the effect of using boron nitride as a carrier, such as the necessity of heat treatment at a higher temperature, is hardly exhibited, which is not preferable. The ratio between the alkali metal and the potassium compound is 0.01 to 10, preferably 0.02 to 10, in terms of the atomic ratio of the added alkali metal to the potassium atom in the potassium compound.
5 range. If the ratio is out of this range, the effects of the alkali metal and potassium compounds are not sufficiently exhibited, and a large amount of catalyst must be used to obtain the required catalytic activity, which is not preferable.

All of the catalysts obtained by the above-mentioned preparation methods are:
This is different from a conventional catalyst in which an alkali metal is supported using a metal oxide as a carrier. That is, in the conventional catalyst in which an alkali metal is supported on a carrier, the alkali metal is simply dispersed on an inert carrier, and there is no strong interaction between the carrier and the alkali metal. Therefore, the alkali metal supported on the carrier is partially eluted into the reaction product solution, and when the reaction is repeatedly performed by this elution, the amount of the alkali metal component in the catalyst gradually decreases, and finally, a sufficient amount of the alkali metal component in the catalyst is obtained. The reaction result cannot be obtained. In addition, when the target product is separated by distillation of the reaction solution, isomerization of the monoalkenylbenzenes generated by the eluted alkali metal components into a compound other than the target product due to the transfer of double bonds, reverse reaction, and high molecular weight substances Is generated. Further, the eluting alkali metal component precipitates in the distillation column, and a phenomenon that the distillation efficiency is reduced and finally the distillation column is blocked also occurs.

On the other hand, the catalyst of the present invention, that is, a composition obtained by heat-treating an alkali metal and boron nitride in an inert gas or boron nitride preliminarily containing a potassium compound and an alkali metal are used. When the composition obtained by heat treatment under an active gas is used as a catalyst, the amount of the eluted alkali metal component is greatly reduced, and the above-mentioned problem does not occur. This is a composition obtained by heat-treating an alkali metal and boron nitride under an inert gas, or a composition obtained by heat-treating a boron nitride preliminarily containing a potassium compound and an alkali metal under an inert gas. In this case, the alkali metal is not merely retained on the boron nitride, but has a strong interaction with the boron nitride. This interaction is similar to what is known as the intercalation of alkali metal into graphite, and because boron nitride also has a similar structure to graphite, there is a strong interaction with alkali metal. It is believed that there is. Further, it is known that not only intercalation but also other interactions exist between boron nitride and the alkali metal, and it is not necessary to keep the ratio between the alkali metal and boron nitride constant. The ratio can be arbitrarily arbitrary.

The use of boron nitride as a substance containing a potassium compound has an advantage over the use of graphite in addition to the ratio of alkali metal to boron nitride. For example, when baking after previously impregnating or kneading a potassium compound by a kneading method, when baking is performed in the air, a phenomenon occurs in which graphite is partially oxidized and burns and disappears. However, boron nitride is excellent in oxidation resistance and has the characteristic that the carrier does not change even if it is fired in air.

As described above, a composition obtained by heat-treating an alkali metal and boron nitride under an inert gas, or a heat-treatment of a boron nitride previously containing a potassium compound and an alkali metal under an inert gas. In using the obtained composition as a catalyst in the reaction, various reaction systems are employed. For example, a method of supplying a raw material to a reactor charged with a catalyst by a batch method or a semi-batch method, or a complete mixed flow method of continuously supplying a catalyst and a raw material to a reactor,
Alternatively, a fixed bed flow system or the like in which a catalyst is filled in a reactor and a raw material is flowed can be adopted. The reaction system should be appropriately selected depending on the type of the desired reaction product,
Generally, when an aromatic hydrocarbon, which is one of the raw materials, is present in excess relative to the conjugated diene, the selectivity to monoalkenylbenzenes can be improved. For that purpose, a method in which conjugated dienes are continuously supplied to the reaction system by a semi-batch method is preferable.When the reaction is continuously performed by a complete mixing method, a fixed bed flow method, or the like, a reactor is required. Divide into multiple stages and supply conjugated dienes to each stage, etc.
It is preferable to employ a reaction system that can reduce the concentration of the conjugated diene in the reactor in that a high selectivity can be obtained.

The reaction temperature in the process of the present invention is 50 to
It is in the range of 300C, preferably 90-200C. When the temperature is lower than this, the reaction occurs, but a sufficient reaction rate cannot be obtained, and the selectivity tends to deteriorate. If the temperature is higher than this, by-products such as tar content increase, which is not preferable. The reaction pressure is sufficient that the starting aromatic hydrocarbon and the product are substantially present as a liquid under the reaction conditions, and is 0.05 to 50 atm, preferably 0.1 to 50 atm, in absolute pressure. The range is 20 atm. In the method of the present invention, the ratio of the conjugated diene having 4 or 5 carbon atoms as one raw material to the raw aromatic hydrocarbon is generally 0.01 to 1, preferably 0.03 to 0.5 in molar ratio.
Range. When the amount of diene is larger than this, the generated monoalkenylbenzene further reacts with the diene to increase the production of a compound in which two or more molecules of diene are added to one molecule of aromatic hydrocarbon, and the polymerization of diene is likely to occur. It is not preferable because the selectivity of alkenylbenzene deteriorates. The amount of the catalyst used in the method of the present invention is at least 0.01%, preferably at least 0.05% by weight based on the starting aromatic hydrocarbon.

The reaction time for carrying out the method of the present invention includes reaction time in a batch mode and a semi-batch mode,
Alternatively, the residence time in the completely mixed circulation system is 0.1 to
Ten hours are employed. In the case of the fixed bed circulation system, the LSV of the aromatic hydrocarbon is usually 0.1 to 10 h ^-1 . When the reaction is carried out by suspending the catalyst, the reaction solution and the catalyst after the reaction can be easily separated by a general method such as sedimentation, centrifugation, or filtration. The separated catalyst may be circulated to the reaction system, or may be circulated to the catalyst preparation step after necessary treatment such as removal of attached organic substances by air combustion and washing with an organic solvent or water. .

[0017]

Industrial Applicability The method of the present invention produces an industrially useful monoalkenylbenzene using an aromatic hydrocarbon compound and a conjugated diene compound in a high yield, at a low cost, and in a safer method for a long time. And its industrial significance is great.

[0018]

EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The amount of alkali metal eluted in the reaction product solution was quantified by ICP emission analysis after extracting metal ions with an aqueous HCl solution. Example 1 5.0 g of boron nitride was stirred at 200 ° C. in a nitrogen atmosphere.
After adding 1.0 g of metal K thereto, the mixture was stirred at that temperature for 1 hour. 1000 g of o-xylene dehydrated using molecular sieves was added to the catalyst powder thus obtained in a nitrogen stream and heated to 130 ° C. While stirring with heating, 70 g of 1,3-butadiene was introduced for 1 hour to cause a reaction. After cooling, a part of the reaction solution was collected by filtration and analyzed by gas chromatography. Table 1 shows the reaction results.
The amount of potassium eluted in the reaction product solution was 10.6 mg.
Met.

Examples 2 and 3 A catalyst was prepared in the same manner as in Example 1 except that the amount of potassium metal, the treatment temperature and the treatment time were changed as shown in Table 1, and the reaction was carried out in the same manner as in Example 1. Was. Table 1 shows the results.

Example 4 A catalyst was prepared in the same manner as in Example 1 except that 1.6 g of a sodium-potassium alloy (78% by weight of potassium) was used instead of metal potassium. The reaction was carried out in the same manner as described above. Table 1 shows the results. The amount of potassium eluted in the reaction product solution was 11.0 mg, and the amount of sodium was 1.7 mg.

Example 5 A catalyst was prepared in the same manner as in Example 1 except that the supply amount of 1,3-butadiene was changed to 50 g in one hour, and the reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that 1.0 g of potassium metal was used as a catalyst. Table 1 shows the results. The amount of potassium eluted in the reaction solution was 35 mg.

[0023]

[Table 1] ホ ウ 素 Boron nitride Metal treatment Treatment Treatment OTP * Elution Elution Amount used Temperature Time Yield K amount Na amount (g) (g) (° C) (min) (%) (mg) (mg) ───────────────────実 施 Example 1 5.0 K 1.0 200 60 82.3 10.6 − Example 2 5.0 K 1.0 100 60 80.4 12.3 − Example 3 5.0 K 0.5 200 30 79.6 12.5 − Example 4 5.0 Na-K (K 78%) 200 60 81.1 11.2 3.3 1.60 Example 5 5.0 K 1.0 200 60 88.4 8.6-Comparative Example 1 0.0 K 1.0 77.2 35.0-──────────── ──────────────────────── *) OTP: 5- (o-tolyl) -2-pentene

EXAMPLE 6 10.0 g of boron nitride powder was added to an aqueous solution containing 3.59 g of potassium hydroxide and impregnated at 45 ° C. for 1 hour with stirring. After impregnation, water was distilled off at 70 ° C under reduced pressure and the temperature was reduced to 120 ° C.
And then calcined at 500 ° C. in air. 5.0 g of this potassium-containing boron nitride powder was placed in a nitrogen atmosphere for 20 g.
After stirring at 0 ° C, 0.60 g of metallic sodium was added thereto, and the mixture was stirred at that temperature for 1 hour. To the catalyst powder thus obtained, 1000 g of o-xylene dehydrated using molecular sieves was added in a nitrogen stream.
Heated. While stirring vigorously, 70 g of 1,3-butadiene
Was introduced for 1 hour to cause a reaction. After cooling, a part of the reaction solution was collected by filtration and analyzed by gas chromatography.
Table 2 shows the reaction results. The amount of potassium eluted in the reaction product solution was 12.6 mg, and the amount of sodium was 2.5 mg.

Examples 7 to 10 A catalyst was prepared in the same manner as in Example 6 except that the potassium compound to be mixed with boron nitride was changed as shown in Table 2, and the reaction was carried out in the same manner as in Example 6. Was. Table 2 shows the results.

Comparative Example 2 4.34 g of sodium hydroxide instead of potassium hydroxide
A catalyst was prepared and used for the reaction in the same manner as in Example 6, except that was used. Table 2 shows the reaction results. The amount of sodium eluted in the reaction solution was 42 mg.

Example 11 A catalyst was prepared in the same manner as in Example 6, and the reaction was carried out in the same manner. After cooling, the catalyst was settled and the upper layer of the reaction solution was taken out. 1000 g of o-xylene was added to the reaction layer from which the reaction solution was extracted under a nitrogen stream, and the same reaction was repeated 5 times. The yield of 5- (o-tolyl) -2-pentene by the fifth reaction was 78.4%. The amount of potassium eluted in the reaction product was 7.9 mg, and the amount of sodium was 4.3 mg.

Comparative Example 3 10 g of potassium carbonate powder calcined at 500 ° C. was heated to 200 ° C. under nitrogen, and 0.5 g of sodium metal was added while stirring.
0 g was added and heated at that temperature for a further 120 minutes. After allowing to cool, the reaction was carried out in the same manner as in Example 1. By this reaction 5
The yield of-(o-tolyl) -2-pentene was 73.0%.
The amount of potassium eluted in the reaction product solution by this reaction was 58 mg, and the amount of sodium was 83 mg.

[0029]

[Table 2] ──────────────────────────────────── Mixed compound K compound-Metal treatment Treatment OTP * 1 Elution Elution Boron nitride Na amount Temperature Time Yield K amount Na amount (wt%) * 2 Used amount (g) (g) (° C) (min) (%) (mg) (mg) mg実 施 Example 6 KOH 5.0 0.60 200 60 80.6 12.6 2.5 (20) Example 7 K ₂ CO ₃ 5.0 0.60 200 60 79.8 13.5 3.9 (20) Example 8 K ₃ PO ₄ 5.0 0.60 200 60 80.1 14.1 5.1 (20) Example 9 tBuOK 5.0 0.60 200 60 79.5 13.3 4.5 (20) Example 10 CH ₃ COOK 5.0 0.60 200 60 77.8 14.9 5.6 (20) Comparative Example 2 NaOH 5.0 0.60 200 60 3.7 − 42.0 (20) ──────────────────────────── * 1) OTP: 5- (o-tolyl) -2-pentene * 2) Amount of alkali metal supported on boron nitride

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C07C 15/44 B01J 27/24 C07C 2/72

Claims (3)

(57) [Claims] An aromatic hydrocarbon compound having at least one hydrogen atom bonded to the α-position of a side chain has 4 or 5 carbon atoms.
In producing monoalkenylbenzenes by alkenylation using conjugated dienes of the above, using a composition obtained by heat-treating boron nitride containing boron nitride or a potassium compound and an alkali metal under an inert gas as a catalyst A method for producing monoalkenyl benzenes, characterized by the following. 2. The method according to claim 1, wherein the alkali metal is sodium, potassium,
2. The method according to claim 1, wherein the alloy is a sodium-potassium alloy. 3. The method according to claim 1, wherein the potassium compound is potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, potassium phosphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, potassium aluminate, potassium chloride, and / or potassium alcoholates. The method according to claim 1, which is at least one selected from the group consisting of potassium carboxylate and potassium phenolate.