JPH07242574A - Method for producing alkenyl aromatic compound - Google Patents

Abstract

PURPOSE:To enable the control of the cis-trans ratio and obtain an alkenyl- aromatic compound useful as a raw material, etc., for producing naphthalenedicarboxylic acid in high purity and yield by reacting an alkyl- aromatic compound with butadiene under specific conditions while irradiating the reactional mixture with ultrasonic waves. CONSTITUTION:This method for producing an alkenyl-aromatic compound is to react (A) an alkyl-aromatic compound such as toluene with (B) 1,3-butadiene in the presence of a catalyst comprising metallic sodium, a potassium salt and an aromatic compound capable of forming a charge-transfer complex with the metallic sodium such as naphthalene at a temperature within the range of 80-180 deg.C by irradiating the reactional mixture with ultrasonic waves at 30-1000kHz frequency and an output within the range of 5X10<-6> to 1X10<6>W.cm<-2>. Furthermore, the reactional molar ratio of the components (A) to (B) is preferably within the range of 1/(0.05-0.2).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an alkenyl aromatic compound which is a raw material for producing naphthalene dicarboxylic acid useful as a polymer raw material such as polyethylene naphthalate (PEN) and which is industrially useful. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art Conventionally, a method for producing an alkenylbenzene by reacting an alkylbenzene with 1,3-butadiene in the presence of an alkali metal is a method using metal potassium as a catalyst. (Japanese Patent Publication No. 50-17973), a method of using metallic potassium and metallic sodium in combination (Japanese Patent Publication No. 56-34570).
No. 57-26489 and No. 50-17973).

However, these methods have the following problems. (1) Since expensive metal potassium is used, the manufacturing cost is high. (2) Metallic potassium has a high reactivity with water, air, etc., and it ignites only when it comes into contact with it, and acts as an ignition source for combustible raw materials and products. , It is very dangerous because it directly uses metallic potassium which has such an action.

Further, a method of using metallic sodium and an inorganic potassium salt without using metallic potassium having such a problem (Japanese Patent Laid-Open No. 47-31935, WO 91-1).
6284 and Japanese Patent Laid-Open No. 4-226927) are also known.

However, in this method, (3) it is necessary to use a special stirring device such as an emulsifying device, or it is necessary to use an inorganic potassium salt having a high degree of purification, which is not necessarily an industrially advantageous method. I can't.

By the way, the alkenyl aromatic compound includes
A system in which a trans form and a cis form exist, and a catalyst in which Na is supported on zeolite and benzene bromide are added [C. Dimi
trov, et. al. , Dokl. Borg. Aka
d. Nauk, 33 (3), 353 (1980)],
Amine (for example, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethyl-
1,3-propenediamine, morpholine, dibutylamine, etc.) [US Pat. No. 4,034,052]
(1977)], it is also known to obtain a alkenyl aromatic compound rich in trans form. However, these methods cannot produce (4) cis isomer-rich alkenyl aromatic compounds.

The present invention solves the problems (1) to (4) in the conventional methods as described above, and transforms an alkenyl aromatic compound from an alkyl aromatic compound and 1,3-butadiene. An object of the present invention is to propose a method for producing a high-yield alkenyl aromatic compound rich in cis isomer by controlling the ratio of cis isomer to cis isomer.

[0008]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the present inventor has used a potassium salt in place of the metal potassium in the above-mentioned conventional method,
Moreover, an alkenyl aromatic compound can be produced from an alkyl aromatic compound and 1,3-butadiene by using a small amount of sodium metal and using an aromatic organic compound and irradiating ultrasonic waves. Moreover, it has been found that the cis / trans ratio of the alkenyl aromatic compound can be controlled by controlling the ultrasonic irradiation conditions.

The present invention is based on the above findings, in which an alkylaromatic compound and 1,3-butadiene are allowed to exist in the presence of metallic sodium, potassium salt, and an aromatic compound which forms a charge transfer complex with metallic sodium. And a method for producing an alkenyl aromatic compound, which comprises reacting while irradiating ultrasonic waves.

The method of the present invention will be described in detail below.
The alkyl aromatic compound in the method of the present invention has 1 to 2 methyl groups or ethyl groups in the benzene nucleus, and specifically, toluene, ethylbenzene, o-
Examples include xylene, m-xylene, and p-xylene.
These alkyl aromatic compounds are preferably used alone, and when two or more thereof are mixed and used, it is difficult to isolate each of the desired products from the reaction product alkenyl aromatic compound with high purity. become.

Further, the purity of the alkyl aromatic compound alone is preferably as high as possible in order to facilitate the isolation of the desired product, specifically, 95% or more, preferably 98.
It is better to set it to% or more. However, hydrocarbons having no alkyl group, such as benzene and cyclohexane, may be mixed in to some extent.

The water contained in the alkylaromatic compound causes deterioration of the catalyst, specifically deactivation of sodium metal. Therefore, the lower the water content of the alkylaromatic compound, the better. It is preferably below the measurement sensitivity of the Karl Fischer method, which is a measurement method, and specifically below several ppm. Therefore, it is preferable to use dehydrated alkyl aromatic compounds.

As the method for dehydrating the alkyl aromatic compound, for example, a method of adsorbing and separating water using a suitable desiccant (activated alumina, silica gel, molecular sieve, activated carbon, etc.), or a method of deep-chill separation In addition, there is a method of dehydrating by contacting with metallic sodium or metallic potassium. Preferred is a method of dehydrating by contact with metallic sodium or metallic potassium.

As the 1,3-butadiene to be reacted with the above-mentioned alkylaromatic compound, those produced by any method can be used. Further, the purity of 1,3-butadiene does not need to be as high as the above-mentioned alkylaromatic compound, and the reaction proceeds satisfactorily no matter what purity is used, and There are no obstacles to the isolation. For example, crude butadiene obtained by dehydrogenating butane or butene may be used as it is, or 1,3-butadiene obtained by purifying this crude butadiene by a method such as extraction may be used.

However, the water content of 1,3-butadiene is
For the same reason as in the case of the above alkyl aromatic compound, the lower the better, the more preferable is several ppm or less. Therefore, it is preferable to use dehydrated 1,3-butadiene.

As a method for dehydrating 1,3-butadiene,
For example, similar to the above-mentioned dehydration method of the alkyl aromatic compound, there is a method of adsorbing and separating water with an appropriate desiccant (activated alumina, silica gel, molecular sieve, activated carbon, etc.), or a method of deep-chill separation.

The catalyst for reacting the above-mentioned alkyl aromatic compound with 1,3-butadiene is sodium metal,
It is composed of a potassium salt and an aromatic compound which forms a charge transfer complex with metallic sodium, and it is preferable to use a metallic sodium which has been subjected to a dispersion treatment with a potassium salt.

The higher the purity of metallic sodium, the better, but it does not matter if it contains a trace amount of calcium, magnesium or potassium. As the purity, 90% or more, preferably 99.0% or more is suitable.

Examples of the potassium salt for dispersing metallic sodium include potassium oxide, potassium hydroxide, potassium carbonate, potassium chloride, etc. These may be used alone or in admixture of two or more. Of these, potassium hydroxide, potassium carbonate and potassium chloride are preferable.

These potassium hydroxide, potassium carbonate,
For potassium chloride, sodium carbonate or sodium chloride in a weight ratio of potassium salt: sodium salt ≈ 10: 1 to
The content may be 1:10, preferably about 10: 1 to 1: 1.

[0021] Potassium hydroxide, potassium carbonate, sodium carbonate and sodium chloride in potassium chloride may, in some cases, improve the function of the catalyst in the process of the present invention.

The above-mentioned potassium salt (including a mixture with a sodium salt, the same in the following description as "potassium salt") must be sufficiently dried. In particular, in order to improve the activity of the potassium salt as a carrier catalyst for metallic sodium, it is preferable to perform sufficient baking and drying at a high temperature of 200 to 600 ° C. The average particle size of the potassium salt is preferably 100 μm or less, and particularly preferably 10 to 50 μm. The particle size can be adjusted with a sieve or the like.

When metal sodium is dispersed with potassium salt, the ratio of these metal sodium and potassium salt may be any ratio, but the final ratio of metal sodium (the ratio at the time of using as a catalyst) Is 0.1 to 30% by weight, preferably 0.5 to 20%, and more preferably 1 to 10%.
This is because if the content of sodium metal is less than 0.1% by weight, the action as a catalyst in the method of the present invention becomes insufficient, and if it is more than 30% by weight, the action as a catalyst is saturated and it becomes uneconomical. .

As a method for dispersing metallic sodium with a potassium salt, for example, a method in which metallic sodium is dispersed and supported on fine particles of potassium salt is adopted. As the method, an inert solvent dispersion supporting method is preferable. In order to carry metallic sodium in an evenly dispersed state by an inert solvent dispersion supporting method so as to be 0.1 to 30% by weight with respect to a potassium salt, a masterbatch method or an individual dispersion liquid is mixed. It is preferable to adopt the method of

That is, for example, when 3% by weight of metallic sodium is dispersed and supported on a potassium salt, 3 parts by weight of metallic sodium and 97 parts by weight of a potassium salt are simultaneously added to 1333 parts by weight of a solvent (alkyl aromatic compound). , 11
A method of stirring at high speed at 0 to 130 ° C. is adopted, but a dispersion liquid in which metallic sodium and potassium salt are dispersed at an appropriate dispersion ratio is prepared in advance, and this dispersion liquid is further mixed with a solvent (alkyl aromatic). It is also possible to employ a method in which the compound is dispersed with a potassium salt.

A liquid obtained by emulsifying and dispersing 3 parts by weight of metallic sodium in 333 parts by weight of an alkyl aromatic compound and 97 parts by weight of a potassium salt as a solvent (alkyl aromatic compound) 10
It is also possible to employ a method in which a liquid dispersed in 100 parts by weight is mixed and dispersed and supported.

Further, 3 parts by weight of metallic sodium and 47 parts by weight of potassium salt are mixed with 50 parts of a solvent (alkyl aromatic compound).
It is also possible to employ a method of mixing and dispersing a liquid having 0 parts by weight dispersed therein and a liquid having 50 parts by weight of potassium salt dispersed in 833 parts by weight of a solvent (alkyl aromatic compound).

Even when the solvent (alkyl aromatic compound) is not used, the dispersion-supporting method is carried out by the masterbatch method, and further the inert solvent dispersion-supporting method is carried out.
It is also possible to prepare a homogeneous catalyst having excellent activity and selectivity.

In the above-mentioned method for supporting the dispersion of an inert solvent, it is industrially preferable to use an alkyl aromatic compound as a reaction raw material as the inert solvent as described above.

In the method of the present invention, examples of the aromatic compound which forms a charge transfer complex with sodium metal, which is used together with the above-mentioned dispersion-supported catalyst of sodium metal and potassium salt, include naphthalene, anthracene, phenanthrene, pyrene, Condensed aromatic compounds such as perylene, pentacene, coronene, quinone, benzoquinone, anthraquinone, graphite (graphite), triphenyl,
Polycyclic aromatic compounds such as tetraphenyl, and their cyano, nitro, halogen-substituted compounds, paracyclophane, cyanobenzene, dicyanobenzene, tetracyanobenzene, nitrobenzene, trinitrobenzene, dichlorotetracyanobenzene, tetracyanoquinodiene Examples include methane, dichloroquinone, tetracyanoquinone, and the like.

These aromatic compounds may be used in any proportion with respect to the above dispersion-supported catalyst, but if the amount is too small, no effect is obtained, and if the amount is too large, the effect is saturated. Therefore, in the method of the present invention,
Generally, 0.001 to 5 per mol of sodium metal
It is 0 mol, preferably 0.01 to 10 mol, and more preferably 0.05 to 2 mol.

The timing of adding these aromatic compounds to the above-mentioned catalyst of metal sodium and potassium salt is, for example, before or after the addition of metal sodium during the preparation of the mixed dispersion of metal sodium and potassium salt, or It may be any after preparation of the mixed dispersion liquid of metallic sodium and potassium salts. From the viewpoint of dispersibility of metallic sodium, it is preferably added after preparation of a mixed dispersion of metallic sodium and potassium salt.

The catalyst composed of an aromatic compound which forms a charge transfer complex with metallic sodium, potassium salt and metallic sodium described above introduces 1,3-butadiene and reacts with 1,3-butadiene and an alkyl aromatic compound. Before starting the mixture of the catalyst with an alkylaromatic compound,
The activity can be improved by pretreatment at 100 to 200 ° C. for 1 to 5 hours.

In the process of the present invention, the reaction molar ratio of the alkyl aromatic compound and 1,3-butadiene is appropriately selected within the usual conditions. For example, alkyl aromatic compound: 1,3-butadiene≈1: 0.001 to 0.5, preferably 1: 0.01 to 0.3, more preferably 1:
It is 0.05 to 0.2. In this molar ratio, the alkyl aromatic compound is a ratio including that used as a solvent when the above-mentioned metallic sodium is dispersed in potassium salt.

At this time, the amount of the catalyst containing the above-mentioned metal sodium, potassium salt, and aromatic compound forming a charge transfer complex with metal sodium is 0.01 to 50 with respect to 100 parts by weight of the alkylaromatic compound. Parts by weight, preferably 0.05 to 30 parts by weight, more preferably 0.1.
10 to 10 parts by weight.

In the method of the present invention which is carried out in the presence of the above catalyst and under the irradiation of ultrasonic waves described below, the reaction between the alkyl aromatic compound and 1,3-butadiene is made substantially free of water and oxygen. It is important to do in. This is because water causes deactivation of metal sodium (changes to sodium hydroxide) as described above, and oxygen deactivates the catalyst forming the charge transfer complex.

Therefore, as the raw materials introduced from the outside of the system into the reaction system, that is, the alkyl aromatic compound and 1,3-butadiene, it is desirable to use dehydrated products as described above. In addition, the space of the reaction system is also filled with a dry inert gas such as dry nitrogen or dry argon, or the reaction is carried out at a temperature not lower than the boiling point of the alkyl aromatic compound so that oxygen and water are not substantially present. When the reaction is carried out under the pressurized reaction condition (1), it is desirable to fill the space with vapor such as an alkyl aromatic compound.

In the present invention, if the frequency or output of the ultrasonic wave is too low, the ultrasonic wave irradiation effect for making the cis body rich is weakened. Conversely, if it is too high, the raw materials or products are destroyed. The frequency is about 20
kHz to about 3 MHz, preferably about 30 kHz to about 1M
Hz, more preferably about 30 kHz to about 1000 kHz
Within the range of, the output is 5 × 10 ⁻⁶ to 1 × 10 ⁶ W · c
Within the range of m ⁻² , it is carried out while appropriately adjusting according to the desired cis- / trans-form ratio of the alkenyl aromatic compound.

The ultrasonic irradiation is carried out during the reaction between the alkyl aromatic compound and 1,3-butadiene in the presence of the above catalyst, but it may also be carried out during the dispersion treatment of metallic sodium in potassium salt. Of course, irradiation may be carried out before the reaction into the reaction solution (the above-mentioned catalyst and the alkylaromatic compound as the reaction raw material are present, but the 1,3-butadiene is not present). By doing so, In some cases, the catalyst is activated and is preferred.

The ultrasonic irradiation is preferably combined with ordinary mechanical stirring of the reaction solution, but in some cases, the ultrasonic irradiation may be performed alone.

In the method of the present invention, the reaction is about 50 to
It is preferably carried out within the range of 200 ° C. When the temperature is lower than 50 ° C, a side reaction product is generated or the reaction time of the main reaction is long, and when the temperature is higher than 200 ° C, the side reaction product is increased, which is not preferable. The preferred reaction temperature is 80 to 180.
℃.

The reaction time is preferably in the range of 0.05 to 10 hours. The reaction time is a catalyst amount (g-catalyst), catalyst composition (g-metal sodium, g-potassium salt, aromatic compound forming a charge transfer complex with g-metal sodium), reaction rate (° C), ultrasonic irradiation. It is related to the conditions and the molar ratio of the alkyl aromatic compound to 1,3-butadiene (g-alkyl aromatic compound / g-1,3-butadiene), and the purity of the target product and the usage pattern of the catalyst ( For example, the appropriate time is adopted based on whether or not the material is recycled. Generally, if the values of these factors decrease, the reaction time increases, but the preferred reaction time is
It is 0.1 to 8 hours, more preferably 0.3 to 4 hours.

In the reaction, the raw materials (alkyl aromatic compound, 1,3-butadiene) and catalyst (comprising metallic sodium, potassium salt and aromatic compound forming a charge transfer complex with metallic sodium) are simultaneously charged from the beginning, and the reaction is carried out. Batch reaction, first charging an alkylaromatic compound and a catalyst, and then semi-batch reaction in which 1,3-butadiene is quantitatively introduced with the lapse of reaction time, an alkylaromatic compound, 1,3-butadiene and a catalyst in a reactor. Any reaction method of continuous reaction may be adopted,
Also, a combination of them may be used.
A semi-batch reaction or a continuous reaction is preferable from the viewpoint of suppressing the production of by-products such as a polymer of 3-butadiene and a compound in which two or more 1,3-butadienes are added to an alkyl aromatic compound.

In the case of this continuous reaction, two formats are adopted. That is, in the method of the present invention, since the catalyst is a solid fine powder catalyst in which sodium metal is dispersed in a potassium salt, (1) an alkyl aromatic compound is continuously flowed through a fixed bed of the catalyst to obtain an alkyl aromatic compound. 1,3 in
There are a method of carrying out a continuous reaction while introducing butadiene, and a method of carrying out the reaction while (2) a catalyst is dispersed and stirred in a reaction system of an alkyl aromatic compound and 1,3-butadiene. .

In the continuous reaction, any of a tube type reactor, a column type reactor and a tank type reactor may be used. A preferable method for continuous reaction is to provide a plurality of reaction zones,
This is a cross-flow type continuous reaction system in which 3-butadiene is quantitatively introduced into each reaction zone.

The reaction operation is not particularly limited as long as the alkyl aromatic compound and 1,3-butadiene can be sufficiently catalytically mixed in the presence of a catalyst.

However, if the catalyst is present in the reaction system 1,3-
In the method of introducing butadiene, a resin-like or gum-like substance, which is supposed to be a polymer of 1,3-butadiene, is attached to the vicinity of the inlet of 1,3-butadiene, which tends to cause a clogging phenomenon. To the reaction system in which is present, a mixed phase of 1,3-butadiene and an alkyl aromatic compound, for example, a liquid phase mixture of liquid butadiene and a liquid alkyl aromatic compound,
A method of introducing 1,3-butadiene and an alkylaromatic compound in the form of a gas-liquid mixture of gaseous 1,3-butadiene and a liquid alkylaromatic compound is preferable.

Alternatively, the clogging phenomenon can be prevented by supplying 1,3-butadiene to the reaction zone space to cause an absorption reaction on the surface of the reaction solution containing the catalyst.

When 1,3-butadiene is introduced,
It is possible to entrain the carrier gas and add a stirring effect simultaneously with the blowing. As the carrier gas at this time, an inert gas from which oxygen and water have been removed, such as nitrogen, argon or hydrogen is suitable.

Further, the reaction can be preferably carried out by adding mechanical stirring, but it is also possible to introduce 1,3-butadiene in the gas phase into the reaction system and to have a stirring effect by the gas. It is desirable that the stirring has a strength required to uniformly disperse the catalyst in the reaction system and to uniformly mix the raw material and the reaction product.

When the reaction is carried out in a liquid phase dispersion reaction system, after the reaction,
Separation of the used catalyst from the reaction product system can be carried out, for example, by using known means such as centrifugal sedimentation, gravity sedimentation, and separation of solid phase from liquid-solid phase at low temperature (eg, filtration, centrifugation, etc.). Good.

The separated catalyst can be recycled and reused in the reaction system. When the catalyst is deactivated and the catalytic function is lost,
The potassium salt phase remains covered with inactive sodium hydroxide. Therefore, it is oxidized and calcined with the organic substance attached, converted to a carbonate, and newly added with metallic sodium and an aromatic compound which forms a charge transfer complex with metallic sodium for regeneration and reuse.

According to the method of the present invention, when toluene is used as the alkylaromatic compound, 5-phenyl-
When penten is synthesized and o-xylene is used,
5- (o-tolyl) -pentene is 5- (p-tolyl) -pentene when p-xylene is used, and 5- (m-tolyl) -pentene when m-xylene is used. When ethylbenzene is used, 5- (phenyl) -hexene is synthesized.

[0054]

In the method of the present invention, the cis / trans ratio of the alkenyl aromatic compound obtained by adjusting the irradiation conditions of ultrasonic waves can be controlled in order to obtain the cis form, as compared with the trans form. A large amount of energy is required, and by adjusting the ultrasonic irradiation conditions, this energy can be adjusted, and by extension, the cis / trans ratio of the alkenyl aromatic compound can be controlled.

[0055]

【Example】

Example 1 A 500-ml three-necked flask equipped with a mechanical stirrer, a nitrogen introducing pipe, a 1,3-butadiene introducing pipe, a cooling pipe, and a calcium chloride pipe was put under a nitrogen atmosphere at a low temperature. 50 parts by weight of water o-xylene and 0.45 parts by weight of metallic sodium (purity 99.95%) were put in the flask, and the flask was placed in an ultrasonic reaction tank at 120 ° C.
Then, the metallic sodium was made into fine particles by a mechanical stirrer.

On the other hand, 50 parts by weight of low-moisture o-xylene was added to 15 parts by weight of potassium carbonate (finely divided into particles having an average particle size of 50 μm and then baked at 600 ° C. for 5 hours).
A potassium carbonate dispersion solution was prepared at 0 ° C. using a mechanical stirrer.

This potassium carbonate dispersion solution was poured into the above metal sodium fine particle dispersion solution, and ultrasonic waves were applied at a frequency of 4
While irradiating at 0 kHz and output 100 W, 10 minutes,
After stirring at high speed, 0.96 mol% of anthraquinone as an aromatic compound that forms a charge transfer complex with metallic sodium, and 100 parts by weight of o-xylene were added to the metallic sodium, and ultrasonic waves were applied at the same frequency as above. While irradiating with the same output, high speed stirring was performed at 140 ° C. for 1 hour. Then, at 140 ° C., the flow rate of 1,3-butadiene was 27.5 m.
It was introduced for 2 hours while irradiating with ultrasonic waves at the same frequency and the same output as above at L / min.

After completion of the reaction, immediately cool to 100 ° C.,
The catalyst and reaction solution were separated. After washing with distilled water, separating,
Excessive o-xylene was distilled off, and 5- (o
-Tolyl) -pentene was obtained. This 5- (o-tolyl)
-Determining pentene yield, purity, cis / trans ratio,
The results are shown in Table 1.

The Na and potassium salts in Table 1 are weight% with respect to the alkylaromatic compound, the aromatic compound forming a charge transfer complex with Na is mol% with respect to Na, and the cis / trans ratio is molar ratio. Yes (same in the table below).

In this example and the following examples, an ultrasonic reaction tank was used for ultrasonic irradiation. However, the tip of a probe type ultrasonic generator was put in another reaction port of the flask or the reaction solution. It is also possible to irradiate.

Examples 2 to 22 5- (o-tolyl) -pentene was obtained by the same procedure as in Example 1 except that the catalyst composition and ultrasonic irradiation conditions were as shown in Tables 1-5. . The yield, purity and cis / trans ratio of this 5- (o-tolyl) -pentene were measured, and the results are shown in Tables 1-5.

Comparative Examples 1 to 11 Tables 6 to 9 show the results of the same operations as in Examples 1 to 22 except that the ultrasonic wave was not applied.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

[Table 5]

[0068]

[Table 6]

[0069]

[Table 7]

[0070]

[Table 8]

[0071]

[Table 9]

Examples 23 to 44 The procedure of Example 1 was repeated, except that p-xylene was used in place of o-xylene and the composition of the catalyst was as shown in Tables 10 to 14, to give 5- (p- Trily) -pentene was obtained.
The yield, purity, and cis / trans ratio of this 5- (p-tolyl) -pentene were measured, and the results are shown in Tables 10-14.

Comparative Examples 12 to 22 Tables 15 to 18 show the results of the same operations as in Examples 23 to 45 except that the ultrasonic wave was not applied.

[0074]

[Table 10]

[0075]

[Table 11]

[0076]

[Table 12]

[0077]

[Table 13]

[0078]

[Table 14]

[0079]

[Table 15]

[0080]

[Table 16]

[0081]

[Table 17]

[0082]

[Table 18]

As is clear from Tables 1 to 18, according to the method of the present invention, the desired products of 5- (o-tolyl) -pentene and 5- (p-tolyl) -pentene were obtained. I know that I can get it. Further, it is understood that the cis / trans ratio can be controlled and the cis body can be made rich by adjusting the ultrasonic irradiation conditions (frequency and output).

[0084]

According to the method of the present invention, when an alkenyl aromatic compound is produced by reacting an alkyl aromatic compound with 1,3-butadiene, the alkenyl aromatic compound can be produced by simply irradiating ultrasonic waves. The ratio of the cis isomer to the trans isomer can be easily controlled, and a cis isomer-rich alkenyl aromatic compound advantageous for the cyclization reaction when synthesizing naphthalenedicarboxylic acid can be obtained.

Claims (1)

[Claims] 1. A reaction between an alkylaromatic compound and 1,3-butadiene in the presence of metallic sodium, potassium salt, and an aromatic compound forming a charge transfer complex with metallic sodium, and under irradiation of ultrasonic waves. A method for producing an alkenyl aromatic compound, comprising: