JPH04202145A - Production of 4-vinylbiphenyls - Google Patents

Abstract

PURPOSE:To obtain the title substance by subjecting a 4-ethylbiphenyl--containing mixture to dehydrogenating reaction while introducing steam to the mixture, adding a good solvent for the objective substance to the prepared reaction mixture, quenching and then concentrating. CONSTITUTION:A 4-ethylbiphenyl-containing hydrocarbon mixture is subjected to dehydrogenating reaction in the presence of an iron-based dehydrating catalyst at 580-640 deg.C while introducing 5-15 times as much steam as the mixture by weight. A good solvent (e.g. benzene or toluene) for the objective substance is added to the prepared reaction mixture, which is then quenched and concentrated. The concentrated solution is incorporated with 7-15 times volume of a lower alcohol (e.g. methanol) having 95% purity as the solution and the title substance is separated and purified by crystallization. The high-purity objective substance can be obtained by such simple reactional operation and separating and purifying operations. Especially, since long-term continuous operation of dehydrogenating reaction is possible, this process 15 advantageous as a large scale production method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing 4-vinylbiphenyls. The 4-vinylbiphenyls obtained according to the present invention are useful as monomers for polymerization or comonomers for various copolymerizations.

[Background Art] As a method for producing 4-vinylbiphenyls, there is a method using Grignard reaction (Burnagin N, 8.

et al, Metalloorg, Khim,...
1989.2(4) 893-897;Uglova
E, V, eL al, Izv, Akad, Nau
k 5SSR, Ser.

Khim, 1985. (9) 2120-2129)
It has been known. Although this method is suitable for small-scale production, it is not suitable for relatively large production volumes because it requires the use of highly pure starting materials and post-reaction treatment. . Also, a method using photolysis reaction (Takamura et al., Nikkashi 1984 (1) Ei7-74
) is also known, but this method cannot be said to be advantageous for relatively large-scale production either.

By the way, as a method for producing 4-vinylbiphenyls,
A monoethyl biphenyl composition obtained by transalkylating with biphenyl a light polyethylbenzene mainly composed of diethylbenzene, which is produced as a by-product when monoethylbenzene is produced by the ethylation reaction of benzene, and then distilling the resulting light polyethylbenzene is used as a starting material. , a method of dehydrogenating this to produce 4-vinylbiphenyl is considered, but since the monoethylbiphenyl composition that is the starting material contains 3-ethylbiphenyl in addition to 4-ethylbiphenyl, dehydrogenating it When reacted, 3-vinylbiphenyl is also produced in addition to 4-vinylbiphenyl. Furthermore, since the monoethyl biphenyl composition that is the starting material also contains biphenyl, 9-methylfluorene, etc. that do not undergo the dehydrogenation reaction, these substances remain in the reaction mixture even after the dehydrogenation reaction.

Furthermore, unreacted 4-ethylbiphenyl and 3-ethylbiphenyl also remain in the reaction mixture.

Therefore, 3-vinylbiphenyl, biphenyl, 9-methylfluorene, 4-ethylbiphenyl, 3-ethylbiphenyl, etc. are separated from this reaction mixture, and highly purified 4-
Although a purification step is required to obtain vinylbiphenyl, no method has been found to date to easily separate and purify 4-vinylbiphenyl to produce highly pure 4-vinylbiphenyl. For example, even if an attempt was made to separate and purify 4-vinylbiphenyl by distillation, it was difficult to adopt the distillation method because although it has a higher boiling point than 3-vinylbiphenyl, which is an impurity, there is almost no difference in boiling point. .

[Object of the Invention] Therefore, the object of the present invention is to produce highly pure 4-vinylbiphenyls through simple reaction operations and separation and purification operations using a hydrocarbon mixture containing 4-ethylbiphenyls as a starting material. The goal is to provide a method that can be used.

[Means for achieving the object] The present invention has been made to achieve the above object, and the method for producing 4-vinylbiphenyls of the present invention comprises 4-vinylbiphenyls.
A hydrocarbon mixture containing ethyl biphenyls is subjected to a dehydrogenation reaction in the presence of a dehydrogenation catalyst while blowing steam, and the dehydrogenation reaction product containing 4-vinylbiphenyls is added to the dehydrogenation reaction product containing 4-vinylbiphenyls. A good solvent is added and quenched, and then the good solvent solution of the dehydrogenation reaction product is concentrated, and a lower alcohol with a purity of 95% or more is added to the concentrated liquid to separate and purify 4-vinylbiphenyls by crystallization. It is characterized by

The present invention will be explained in detail below.

In the present invention, a hydrocarbon mixture containing 4-ethylbiphenyls is used as a starting material. Here, "4-ethylbiphenyls" refers to 4-ethylbiphenyl itself and/or 4-ethylbiphenyls in which a substituent that does not undergo a dehydrogenation reaction (for example, a methyl group, a hydroxyl group, a halogen atom, etc.) is substituted on the biphenyl ring. -Means ethyl biphenyls. As a specific example of a hydrocarbon mixture containing 4-ethylbiphenyls as a starting material, (1) Light polyethylbenzene, which is mainly composed of diethylbenzene and is produced as a by-product when monoethylbenzene is produced by the ethylation reaction of benzene, is chlorinated with biphenyl. Examples thereof include a monoethylbiphenyl composition obtained by a transalkylation reaction in the presence of an aluminum catalyst, and (if) a monoethylbiphenyl composition obtained by an alkylation reaction of biphenyl with ethylene.

In the present invention, first, the above-mentioned 4-ethylbiphenyls-containing hydrocarbon mixture is subjected to a dehydrogenation reaction in the presence of a dehydrogenation catalyst while blowing steam into the mixture. Hydrocarbon mixture (
The weight ratio (S/O) of steam (S) to O) is 5 to
It is preferable to set it to 15. In particular, this weight ratio (S/O
) is small (if this happens, the yield of 4-vinylbiphenyl tends to be low, and polymers tend to accumulate in the reactor outlet piping, making continuous operation for one month or more more difficult), so it is preferable. In addition, as a dehydrogenation catalyst, it is preferable to use an iron-based dehydrogenation catalyst, and such an iron-based dehydrogenation catalyst has Fe20B as a main component, 20 as a second component, and Cr2O3, Ce2O3 as a third component. ,Mo
A catalyst containing one or more of O3, CaOlMgO, etc. is preferred.

The temperature of the dehydrogenation reaction is preferably 580 to 640°C. If the temperature of the dehydrogenation reaction is low, the yield of 4-vinylbiphenyls will decrease, and if the temperature is high, polymers will be more likely to form, so neither is preferable.

The dehydrogenation reaction is carried out using a fixed bed or fluidized bed reactor packed with a catalyst. This dehydrogenation reaction causes 4-
4-vinylbiphenyls are produced in which the biphenyl ring is substituted with vinylbiphenyl itself and/or a substituent that does not undergo a dehydrogenation reaction, such as a methyl group, a hydroxyl group, or a halogen atom.

After the dehydrogenation reaction, the obtained dehydrogenation reaction product containing 4-vinylbiphenyls is rapidly cooled by adding a good solvent for 4-vinylbiphenyls. As a good solvent, it is preferable to use aromatic solvents such as benzene, toluene, ethylbenzene, and xylene. The amount of good solvent added to the dehydrogenation reaction product is 5% based on the starting hydrocarbon mixture.
It is preferable to increase the capacity by ~15 times. In particular, if the amount of the good solvent is small, polymers tend to accumulate in the pipe at the outlet of the reactor, making long-term continuous operation difficult, which is not preferable.

Note that the used good solvent is usually recovered in the crystallization step and reused.

After rapid cooling, the good solvent solution of the dehydrogenation reaction product is concentrated. Concentration is preferably carried out until the concentration of the good solvent in the concentrate reaches a concentration of 10 to 30% by weight, more preferably until the concentration reaches a concentration of 20 to 30% by weight at which no crystals are deposited in the concentrate.

Next, a lower alcohol having a purity of 95% or more is added to the obtained concentrate to crystallize 4-vinylbiphenyls. Examples of lower alcohols include methanol, ethanol, n-
Examples include propa tools and isoprop tools. Here, "lower alcohol with a purity of 95% or more" means that the lower alcohol may contain less than 5% of other solvents such as water. The purity of the lower alcohol affects the recovery rate and purity of 4-vinylbiphenyls, and when obtaining high-purity 4-vinylbiphenyls with a low recovery rate, lower alcohols with high purity are preferable; In order to increase the alcohol content, it is recommended to use a lower alcohol with low purity. The amount of the lower alcohol with a purity of 95% or more is preferably 7 to 15 times the volume of the concentrate. The crystallized 4-vinylbiphenyls are separated by filtration, centrifugation, etc. If necessary, the 4-vinylbiphenyls after separation may be washed with a poor solvent for 4-vinylbiphenyls.

The 4-vinylbiphenyls separated and purified in this way have high purity. As a poor solvent for 4-vinylbiphenyls, methanol, ethanol, etc. are preferably used.

According to the method for producing 4-vinylbiphenyls of the present invention,
4-ethylbiphenyls in the starting material are converted to 4-vinylbiphenyls through a single reaction operation (dehydrogenation reaction), and these 4-vinylbiphenyls can be purified with high purity through a simple separation and purification operation (crystallization). Since it is separated and purified, its industrial significance is extremely large.

[Examples] Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited to the Examples.

(A) Dehydrogenation reaction step (A1) As a starting material monoethyl biphenyl-containing hydrocarbon mixture, light polyethylbenzene (monoethylbenzene is distilled and separated from the reaction product obtained by the ethylation reaction of benzene, and then the residue is Furthermore, a distillate with a diethylbenzene content of 90 wt% obtained was obtained by distillation.
After transalkylation in the presence of biphenyl and an aluminum chloride catalyst, the product was separated by distillation. Its composition is shown below.

4-ethylbiphenyl 31.2wt%3-ethylbiphenyl 58.5biphenyl
3.09-Methylfluorene 7.3
As a reactor, a tube with an inner diameter of 25 mm and a length of 50 cm was equipped with an iron-based dehydrogenation catalyst (G84C manufactured by Nichiyo Girdler Catalyst Co., Ltd.: Fe20377%, K2O10%).
, Ce2035%, Mo 032°5%, CaO2,
2%, MgO' 2.2%, Cr2O3 <0.1%)
A fixed bed flow reactor filled with 100 cc was used.

From the inlet at the top of this reactor, the above-mentioned starting material hydrocarbon mixture was fed at a rate of 50 cc/hr, and at the same time steam was fed so that the weight ratio of steam/hydrocarbon mixture was 6. Then, dehydrogenation reaction was carried out at a reaction temperature of 610°C. In addition, LH8V is 0, 5 h
It was r-1.

At the bottom outlet of the reactor, the reaction product was quenched by adding toluene, a quenching agent, 10 times the volume of the hydrocarbon mixture. By performing rapid cooling after the dehydrogenation reaction, continuous operation for more than one month was possible without clogging the pipes due to polymers at the reactor outlet. Water was separated from the resulting reaction solution, and 1.11 parts of the toluene solution obtained was concentrated to about 1/9 volume. The composition of the obtained concentrate was analyzed by gas chromatography, and the results are as follows.

4-vinylbiphenyl 17.2wt%3-vinylbiphenyl 32.64-ethylbiphenyl
3.33-ethylbiphenyl 9.3
Toluene 23.7 Others
13.9 The measured 4-ethylbiphenyl conversion rate and vinylbiphenyl selectivity are shown in Table 1. Table 1 shows that both the ethyl biphenyl conversion rate and the vinyl biphenyl selectivity were high, indicating that the dehydrogenation reaction was carried out well.

(A2) The dehydrogenation reaction was carried out under the same conditions as in (A1) above except that S10 was set to 10, and as shown in Table 1, the reaction in (A1) above was carried out.
Similar good results were obtained.

(A3) Dehydrogenation reaction was carried out under the same conditions as in (A1) above except that S10 was changed to 14, and as shown in Table 1, the above (A1)
Similarly good results were obtained.

(A4) The dehydrogenation reaction was carried out under the same conditions as in (A2) above except that the reaction temperature was 620°C, and as shown in Table 1, the above (
Similar to A2), good results were obtained.

(A5) Dehydrogenation reaction was carried out under the same conditions as in (A2) above except that the reaction temperature was 650°C. As shown in Table 1, when the reaction temperature was as high as 650°C, the product yield slightly decreased and the catalyst activity also gradually decreased, but continuous operation for more than one month was possible. .

(A6) For comparison, a dehydrogenation reaction was carried out under the same conditions as in (A2) above, except that water, which is a poor solvent for 4-vinylbiphenyl, was used as a quenching agent. As a result, as shown in Table 1, 4-vinylbiphenyl precipitated in the pipe at the outlet of the reactor, clogging the pipe, and the reaction had to be stopped at the second white point.

(Blank below) (B) Crystallization step (B1) Add 99.5% methanol as a crystallization solvent to a concentrated liquid with a toluene concentration of 20% by weight obtained by concentrating in the same manner as in Example (Step A). Add 10 times the volume to the liquid, 10-15
The mixture was stirred at ℃ for 30 minutes to crystallize 4-vinylbiphenyl. Thereafter, suction filtration was performed using a 5A filter paper, and the concentrate was then washed with 99.5% methanol (preliminarily cooled to 10 to 15°C), which was 0.5 times the volume of the concentrate, to obtain a cake. Table -
As shown in Figure 2, the content of 4-vinylbiphenyl in this cake was 9B, 2 wt%, and the ratio of 4-vinylbiphenyl to the total amount of 4-vinylbiphenyl and 3-vinylbiphenyl was 98. It was 7wt%. Also 4
-Vinyl biphenyl recovery rate was 40 wt%.

(B2) Crystallization was carried out under the same conditions as in (B1) except that 98% methanol was used as the crystallization solvent and washing solvent, and the results shown in Table -
As shown in No. 2, the same good results as in (Bo) above were obtained.

(B3) Crystallization was carried out in the same manner as in (B1) above except that 96% methanol was used as the crystallization solvent and washing solvent, and as shown in Table 2, good results similar to those in (B1) above were obtained. Ta.

(B4) Crystallization was performed in the same manner as in (B3) above, except that no washing solvent was used. As shown in Table 2, although the purity of the obtained 4-vinylbiphenyl decreased slightly, very satisfactory results were obtained.

(B5) Crystallization was carried out in the same manner as in (B3) above, except that 96% methanol was used, the volume was 5 times that of the concentrate, and no washing solvent was used. As shown in Table 2, although the purity of the obtained 4-vinylbiphenyl decreased slightly, very satisfactory results were obtained.

(B6) For comparison, crystallization was carried out in the same manner as in (B1) above except that 90% methanol was used as the crystallization solvent, but Table 2
As shown in Figure 2, the crystals agglomerated into a viscous solid, giving unsatisfactory results.

(B7) For comparison, crystallization was carried out in the same manner as in (B1) above except that toluene was used as the crystallization solvent and n-hexane was used as the washing solvent. Recovery rate decreased significantly.

(Left below) Comprehensive evaluation of the results of the dehydrogenation reaction step shown in Table 1 and the results of the crystallization step shown in Table 2 shows that the method for producing 4-vinylbiphenyls of the present invention is simple. It has become clear that highly pure 4-vinylbiphenyls can be obtained through reaction operations and separation and purification operations.

It has also been found that particularly excellent results can be obtained by appropriately controlling S10, the temperature during the dehydrogenation reaction, the amount of quenching agent, and the amount of crystallization solvent.

As described in "Effects of the Invention" (2), according to the present invention, a hydrocarbon mixture containing 4-ethylbiphenyls is used as a starting material, and high-purity 4-vinyl A method has been provided by which biphenyls can be produced. In particular, since the dehydrogenation reaction can be operated continuously for a long period of time, it is extremely useful as a relatively large-scale production method for 4-vinylbiphenyls.

Applicant: Idemitsu Petrochemical Co., Ltd. Agent: Patent Attorney Shizuo Nakamura −2〇　−

Claims (4)

[Claims] (1) A hydrocarbon mixture containing 4-ethylbiphenyls is subjected to a dehydrogenation reaction in the presence of a dehydrogenation catalyst while blowing steam, and the resulting dehydrogenation reaction product containing 4-vinylbiphenyls is - Add a good solvent for vinyl biphenyls and quench it, then concentrate the good solvent solution of the dehydrogenation reaction product, add a lower alcohol with a purity of 95% or more to the concentrated solution, and crystallize 4-vinyl biphenyls. A method for producing 4-vinylbiphenyls, which comprises separating and purifying biphenyls. (2) The 4-ethylbiphenyls in the hydrocarbon mixture as a starting material are 4-ethylbiphenyl itself and/or 4-ethylbiphenyls in which the biphenyl ring is substituted with a substituent that does not undergo dehydrogenation reaction. Claim (1), wherein the target substance 4-vinylbiphenyl is 4-vinylbiphenyl itself and/or 4-vinylbiphenyl having a substituent that does not undergo dehydrogenation reaction substituted on the biphenyl ring. ). (3) Claim (1) wherein the dehydrogenation catalyst is an iron-based dehydrogenation catalyst.
) or the method described in (2). (4) adopt at least one of the following conditions;
The method according to any one of claims (1) to (3). (i) The weight ratio (S/O) of steam (S) to hydrocarbon mixture (O) is 5 to 15. (ii) The temperature during the dehydrogenation reaction is 580 to 640°C. (iii) The amount of good solvent added to the dehydrogenation reaction product is 5 to 15 times the volume of the starting hydrocarbon mixture. (iv) The amount of lower alcohol with a purity of 95% or more added to the concentrate is 7 to 15 times the volume of the concentrate.