JP6247882B2 - Method for producing 5-vinyl-2-norbornene and method for recovering polymerization inhibitor used therefor - Google Patents

Description

  The present invention relates to a method for producing 5-vinyl-2-norbornene from cyclopentadiene and 1,3-butadiene by Diels-Alder reaction, and a method for recovering a polymerization inhibitor used at that time.

  5-Vinyl-2-norbornene is produced by Diels-Alder reaction using cyclopentadiene and 1,3-butadiene as raw materials. 5-Vinyl-2-norbornene is mainly used as 5-ethylidene-2-norbornene which is useful as a diene monomer such as an ethylene-propylene-diene terpolymer by isomerization.

  The Diels-Alder reaction is carried out under heating where polymerization of conjugated dienes such as 1,3-butadiene as a raw material is likely to occur. When polymerization of the raw material occurs, the polymer adheres to the reactor wall, and the piping is clogged or the heat transfer efficiency is lowered. Therefore, the reaction does not proceed stably, leading to loss of 1,3-butadiene. -Alder reaction is carried out in the presence of a polymerization inhibitor.

  Examples of the polymerization inhibitor include phenolic compounds such as 4-tert-butylcatechol (TBC) (for example, Patent Document 1), p-phenylenediamine (for example, Patent Document 2), and 2,6-di-tert-butyl- 4-methylphenol (BHT) (for example, Patent Document 3), 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (for example, Patent Document 4), phenothiazine (for example, Patent Document 5), Hydroquinone (for example, Patent Document 6), which is a quinone compound, has been proposed. Of these, TBC is particularly preferable.

  The polymerization inhibitor was distilled after the Diels-Alder reaction to obtain the target 5-vinyl-2-norbornene, recovering 1,3-butadiene and cyclopentadiene as raw materials, and dimer such as dicyclopentadiene. It is contained in the distillation residue after separating by-products from the body and incinerated as fuel. However, from the viewpoint of production cost, it is desired to recover the polymerization inhibitor and recycle it into the reaction system.

  Although there is no prior art related to the recovery and recycling of polymerization inhibitors in the production of 5-vinyl-2-norbornene by Diels-Alder reaction, the polymerization inhibitors are aliphatics containing 3 or less carbon atoms from styrene distillation residue (styrene tar). Method of extracting oil using alcohols and ketones as extraction solvents (for example, Non-patent Document 1), or extracting styrene tar with oxygen-containing organic solvent, then mixing with aromatic organic solvent and polymerization inhibitor by distillation A method of recovering a polymerization inhibitor by separating it into an aromatic organic solvent solution and an oxygen-containing organic solvent (for example, Patent Document 7), or purifying acrylic acid by distillation in the presence of a polymerization inhibitor in the production of acrylic acid There is a method (for example, Patent Document 8) of recovering and recycling a polymerization inhibitor from the bottoms of the process using an aqueous medium.However, in these prior arts, the target reaction is not the Diels-Alder reaction, and the composition of the fraction or distillation residue containing the polymerization inhibitor is different from that obtained by the Diels-Alder reaction. In addition, no TBC particularly useful as a polymerization inhibitor in the Diels-Alder reaction is exemplified.

Japanese Patent Publication No.56-3854 Japanese Patent Publication No.57-7131 Japanese Patent Laid-Open No. 61-200930 JP 62-167735 A JP-A-5-271113 Special table 2008-527135 gazette Japanese Unexamined Patent Publication No. 63-230659 JP 2003-221357 A

"Aromatics", Volume 41, Nos. 7 and 8 (1989)

  Applying such conventional recovery and recycling of polymerization inhibitors to the production of 5-vinyl-2-norbornene by the Diels-Alder reaction, which is different from the raw material compounds and reaction types, and the polymerization inhibitors are different from these. I can't.

  It is economically advantageous to distill and isolate the polymerization inhibitor from the distillation residue of the purification process by distillation, which separates and recovers 5-vinyl-2-norbornene and raw materials and by-products from the reaction product of Diels-Alder reaction. In addition, it is preferable from the viewpoint of cost if the polymerization inhibitor can be recycled together with heavy impurities contained in the distillation residue, but in that case, the polymerization inhibition effect is maintained and the product in 5-vinyl-2-norbornene is It is desirable not to increase impurities. Furthermore, when such a recycling is repeated and the Diels-Alder reaction is performed using a polymerization inhibitor together with heavy impurities contained in the distillation residue, the monomer concentration in the reaction tank increases with the accumulation of heavy impurities in the system. There is a problem that the production rate of 5-vinyl-2-norbornene is lowered or the amount of polymerized product is increased due to a decrease in the number of by-products or an increase in by-products.

  Under these circumstances, a method for recovering a polymerization inhibitor suitable for the production of 5-vinyl-2-norbornene by the Diels-Alder reaction of cyclopentadiene and 1,3-butadiene and 5-vinyl-2-norbornene using the same There is a need for a production method.

  The present invention has been made in view of such problems, and is used when 5-vinyl-2-norbornene is produced on an industrial scale by Diels-Alder reaction of cyclopentadiene and 1,3-butadiene. When the polymerization inhibitor is continuously recovered and the recovered polymerization inhibitor is recycled, the quality of the product 5-vinyl-2-norbornene is not deteriorated by the components accompanying the polymerization inhibitor, and An object of the present invention is to provide a method for recovering a polymerization inhibitor that does not reduce productivity, and to provide a method for producing 5-vinyl-2-norbornene using the same.

The present invention relates to a reaction step for producing 5-vinyl-2-norbornene by a Diels-Alder reaction of cyclopentadiene and 1,3-butadiene in the presence of a polymerization inhibitor containing 4-tert-butylcatechol. Purification step of obtaining 5-vinyl-2-norbornene from the product by distillation, and from a distillation residue containing a polymerization inhibitor in the purification step, 100% by mass to 50% by mass of methyl alcohol and 0% to 50% by mass of water ( The present invention relates to a method for recovering a polymerization inhibitor comprising a solvent extraction step of extracting 4-tert-butylcatechol using an extraction solvent containing 100% by mass in total.

The present invention also provides a reaction step of producing 5-vinyl-2-norbornene by a Diels-Alder reaction of cyclopentadiene and 1,3-butadiene in the presence of a polymerization inhibitor containing 4-tert-butylcatechol. A purification step for obtaining 5-vinyl-2-norbornene by distillation from the reaction product, and a distillation residue containing a polymerization inhibitor in the purification step from 100% by mass to 50% by mass of methyl alcohol and 0% by mass to 50% by mass of water The present invention relates to a process for producing 5-vinyl-2-norbornene, characterized by having a solvent extraction step of extracting 4-tert-butylcatechol using an extraction solvent containing the following (100% by mass in total).

  According to the present invention, the polymerization inhibitor used in the industrial production process of 5-vinyl-2-norbornene can be continuously recovered. Further, even if the recovered polymerization inhibitor is recycled to the Diels-Alder reaction step, the yield and purity of 5-vinyl-2-norbornene are not adversely affected.

It is a systematic diagram which shows one Embodiment of the collection | recovery method of the polymerization inhibitor of this invention.

  The process for producing 5-vinyl-2-norbornene according to the present invention comprises 5-vinyl-2-norbornene by Diels-Alder reaction of cyclopentadiene (CPD) and 1,3-butadiene (BD) in the presence of a polymerization inhibitor. (VNB), a purification step for obtaining 5-vinyl-2-norbornene from the reaction product by distillation, and a distillation residue containing a polymerization inhibitor in the purification step, 100% by mass or less of methyl alcohol to 50% by mass %, And an extraction step for extracting the polymerization inhibitor using an extraction solvent containing 0% by mass or more and 50% by mass or less and water (100% by mass in total).

  Hereinafter, although it demonstrates with reference to FIG. 1 which shows an example of the manufacturing method of 5-vinyl- 2-norbornene of this invention, this invention is not limited to this.

  Cyclopentadiene (CPD), which is a raw material for the Diels-Alder reaction, is a conjugated diene, is highly reactive, and is easily dimerized to dicyclopentadiene (DCPD) even at room temperature. For this reason, it is preferable to supply cyclopentadiene to the Diels-Alder reaction (denoted as a reaction step in the figure) through a thermal decomposition step of thermally decomposing dicyclopentadiene into cyclopentadiene. Examples of the thermal decomposition process include a liquid phase method in which decomposition is performed in a liquid phase using a high-boiling auxiliary liquid, and a gas phase method in which DCPD is vaporized to decompose in a gas phase. Although the liquid phase method can be performed at about 250 ° C., since a multimer is generated as a by-product, the reaction conditions such as the type of auxiliary liquid, the amount added, and the shape of the heating device are selected. Needs to be controlled. On the other hand, the vapor phase method is advantageous in that the yield of CPD is high although an apparatus capable of withstanding high temperatures is required because CPD is produced by vaporizing the raw material and then heating to about 400 ° C. If necessary, the pyrolysis product obtained in the thermal decomposition step can be removed by a distillation column (not shown) to obtain cyclopentadiene, which can be supplied to the Diels-Alder reaction.

  As the other raw material for Diels-Alder reaction, 1,3-butadiene (BD) can be obtained by purification from naphtha. As a usage-amount of 1, 3- butadiene, the range of 0.35-17 can be mentioned as a molar ratio of 1, 3- butadiene with respect to cyclopentadiene.

  The polymerization inhibitor used in the Diels-Alder reaction can be used as long as it can suppress the polymerization of the conjugated diene as a raw material, and is particularly preferably one that can efficiently suppress the polymerization of 1,3-butadiene. Specific examples of such polymerization inhibitors include phenolic compounds such as 4-tert-butylcatechol (TBC), 2,6-di-tert-butyl-4-methylphenol (BHT), and quinone compounds. Specific examples include hydroxyquinone, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, p-phenylenediamine and phenothiazine. These may be used alone or in combination of two or more. Of these, TBC is particularly preferred. As for the usage-amount of a polymerization inhibitor, 30-1000 mass ppm is preferable with respect to the total mass of the liquid in a reaction tank. The polymerization inhibitor is preferably added as a solution appropriately dissolved in a solvent. As the solvent, a low aliphatic alcohol such as methyl alcohol can be used, and the polymerization inhibitor is used, for example, as a polymerization inhibitor solution of TBC 80 mass% to 90 mass% and methyl alcohol 10 mass% to 20 mass%. Is preferred.

  The Diels-Alder reaction is preferably carried out with stirring. As preferable reaction conditions, the reaction temperature is 80 to 150 ° C., preferably 90 to 140 ° C., and the reaction time is about 0.5 to 3 hours.

  In addition to 5-vinyl-2-norbornene (VNB), various by-products are simultaneously generated by the Diels-Alder reaction. The main by-products are 3a, 4,7,7a-tetrahydroindene (THI), 4-vinyl-1-cyclohexene (VCH), dicyclopentadiene (DCPD), 1,5-cyclooctadiene (COD), etc. These are trimers (including those in which two molecules of a heterogeneous compound are bonded), and VNB and these dimers react with CPD or BD to produce various trimers (here, 3 compounds of different types of compounds). Including molecular bonds). Moreover, an oligomer and a polymer produce | generate by reaction of BD.

  After the reaction step, the target VNB is recovered from the reaction product by distillation. Further, unreacted raw materials BD and CPD and DCPD as a by-product dimer are respectively recovered and recycled as a reactive raw material as necessary. Other dimers may be appropriately distilled off from the reaction product. The distillation operation is collectively referred to as a purification step (referred to as a purification step in the drawing). The heavy component obtained as a distillation residue in the purification step is mainly composed of trimer by-products and contains a polymerization inhibitor.

  The polymerization inhibitor is recovered from the distillation residue by the following solvent extraction step. As an extraction solvent used for extraction of the polymerization inhibitor in the solvent extraction step, a mixture containing 100% by mass to 50% by mass of methyl alcohol and 0% by mass to 50% by mass (100% by mass in total) of water is used. When selecting the extraction solvent, the solubility of the heavy component as well as the solubility of the polymerization inhibitor must be considered. Solvents such as polar alcohols can be used as the extraction solvent, but isopropyl alcohol and ethyl alcohol have solubility of polymerization inhibitors, but they have high solubility in heavy components, so it takes time to separate the extract from the extraction residue. Since it requires, it is not preferable. Methyl alcohol is preferable because the solubility of the polymerization inhibitor can be satisfied and the solubility of heavy components is low. Further, when methyl alcohol is used as a solvent for the polymerization inhibitor solution in the reaction step, there is an advantage that no new substance is added to the reaction system. Furthermore, when a mixture of methyl alcohol and water is used as the extraction solvent, the solubility of heavy components in the extraction solvent can be reduced, and the purity of the polymerization inhibitor in the extract is improved. When the amount of water in the extraction solvent is 10% by mass, the extraction rate of the polymerization inhibitor becomes the highest, and the tendency is maintained up to 30% by mass. When the amount exceeds 30% by mass, the recovery rate of the polymerization inhibitor tends to decrease and 50% by mass. Exceeding this will significantly reduce the extraction rate. For this reason, the content of water in the extraction solvent is preferably 10% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. If the content of water in the extraction solvent is 50% by mass or less, the increase in the specific gravity of the extraction solvent is suppressed, the separation efficiency of the extraction liquid and the extraction residual liquid is reduced, the cost of the extraction equipment is increased, and the polymerization inhibitor is extracted. Reduction in rate is suppressed.

  The amount of the extraction solvent used is preferably 5 to 30% by mass with respect to the distillation residue. If the amount of the extraction solvent used is 5% by mass or more based on the distillation residue, the polymerization inhibitor can be extracted efficiently, and if it is 30% by mass or less, the burden on the apparatus is suppressed and the polymerization inhibitor is efficiently extracted. It can be recovered.

  The temperature of the extraction operation is preferably in the range of 20-50 ° C. If the temperature of the extraction operation is 20 ° C. or higher, the distillation residue can be efficiently extracted while suppressing the decrease in operability due to high viscosity, and if it is 50 ° C. or lower, the extraction efficiency of the polymerization inhibitor is reduced. Can be suppressed.

  A known solvent extraction apparatus can be preferably used for the solvent extraction step. Preferred examples are as follows.

  A method of mixing the extraction solvent and the distillation residue using a line mixer or a mixing tank equipped with a stirrer and then standing and separating in a stationary separation tank can be mentioned. As the line mixer, various types such as an internal filling type and a drive stirring type can be used. The standing time is set to an appropriate time in consideration of the relationship with temperature. 0.2-8 hours are preferred. In the case of 25 ° C., separation is almost completed in 0.5 hours, and separation into two layers is complete in 4 hours. Therefore, it is not necessary to spend excessive time. The lower layer liquid (extraction residual liquid) and the upper layer liquid (extraction liquid) are taken out in this order from the bottom of the stationary separation tank. It is also possible to provide a plurality of stationary tanks and sequentially discharge the extraction liquid and the extraction residual liquid by sequentially switching them. A centrifuge device can be used instead of the stationary separation tank.

  Alternatively, a method of supplying an extraction solvent from the lower part and a distillation residue from the upper part using a countercurrent contact type continuous extraction tower can be used. The extraction tower can be packed, tiered, or empty. However, the counterflow extraction device by reciprocating the perforated plate stack and two types of trays with vertical plates with openings are alternately used. A stacked weir plate type extraction device or the like is preferable. The number of trays varies depending on the type of extraction tower, but is preferably 3 to 60.

  In the solvent extraction process, an extract containing an extraction solvent and a polymerization inhibitor and an extraction residual liquid mainly containing heavy components are obtained. The extract is subjected to a concentration process in which the extraction solvent is separated by evaporation, if necessary. You may make it isolate | separate into a solvent and a polymerization inhibitor and collect | recover a polymerization inhibitor. The recovered polymerization inhibitor can be reused as a polymerization inhibitor in the Diels-Alder reaction, and can be used after being circulated in the subsequent reaction step. The recovered polymerization inhibitor can function as a polymerization inhibitor without adversely affecting the Diels-Alder reaction even when it is recycled. If desired, it can be further purified and reused as a higher concentration polymerization inhibitor.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following examples.
[Example 1-4, Comparative Example 1]
4-T-butylcatechol (hereinafter abbreviated as TBC) was used as a polymerization inhibitor, and 5-vinyl-2-norbornene and butadiene, cyclohexane were distilled from the Diels-Alder reaction product of cyclopentadiene and 1,3-butadiene. The composition of the remaining distillation residue obtained by separating pentadiene and dicyclopentadiene and other dimers, respectively, was 0.83% TBC and the remaining was 99.17% heavy hydrocarbon component. The heavy hydrocarbon component was mainly trimer.

  Using an extraction solvent having the composition shown in Table 1, an irregularly packed line mixer having an inner diameter of 27.2 mm and a length of 100 mm at a temperature of 25 ° C., the distillation residue was 300 kg / h, and the extraction solvent was 60 kg / h. The mixture was continuously supplied for a period of time, and the obtained mixed solution was supplied from the top to a 1,000 liter stationary separation tank and allowed to stand for 2 hours. Subsequently, the liquid was taken out in the order of the lower phase extraction residual liquid and the upper phase extraction liquid from the bottom of the stationary separation tank. Subsequently, the extraction solvent was evaporated and separated from the extract with a concentrating device to obtain recovered TBC. Table 1 shows the composition of the extract, the extraction residue, and the recovered TBC. The recovered TBCs of Examples 1 to 5 were recycled to the Diels-Alder reaction process, but there was no problem in the reaction.

Claims (2)

A reaction step for producing 5-vinyl-2-norbornene by Diels-Alder reaction of cyclopentadiene and 1,3-butadiene in the presence of a polymerization inhibitor containing 4-tert-butylcatechol, and distillation from the reaction product From the purification step for obtaining 5-vinyl-2-norbornene and from the distillation residue containing the polymerization inhibitor in the purification step, 100% by mass or less of methyl alcohol and 50% by mass or more and 0% by mass or more and 50% by mass or less of water (100% in total) %)), And a solvent extraction step of extracting 4-tert-butylcatechol . A reaction step for producing 5-vinyl-2-norbornene by Diels-Alder reaction of cyclopentadiene and 1,3-butadiene in the presence of a polymerization inhibitor containing 4-tert-butylcatechol, and distillation from the reaction product From the distillation step of the purification step for obtaining 5-vinyl-2-norbornene and the purification step containing the polymerization inhibitor in the purification step, 100% by mass to 50% by mass of methyl alcohol and 0% to 50% by mass of water (total) And a method for producing 5-vinyl-2-norbornene, which comprises a solvent extraction step of extracting 4-tert-butylcatechol using an extraction solvent containing 100 mass%).

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