JP2000026326A - Production of tetracyclododecene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for obtaining high-purity tetracyclododecene(TCD) in high yield while recovering high-purity norbornene and putting it to cyclic use. SOLUTION: This process for obtaining TCD comprises the following 5 steps: (1) a reaction is carried out between ethylene, dicyclopentadiene and norbornene to produce a reaction liquor containing TCD, norbornene and methyl tetrahydroindene, (2) the ethylene is separated and removed from the reaction liquor, (3) the norbornene is separated and recovered from the resulting reaction liquor, (4) the norbornene separated and recovered in the step 3 is circulated to the reaction system, and (5) the objective TCD is separated and recovered from the resulting reaction liquor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing tetracyclododecene (hereinafter sometimes referred to as TCD), and more particularly, to a process for producing substantially methyltetrahydroindene (hereinafter sometimes referred to as MTHI). The present invention relates to a method for producing tetracyclododecene using norbornene that is not contained and recycled.

[0002]

2. Description of the Related Art A cycloolefin (co) polymer has attracted attention as a polymer having excellent optical properties, high transparency, heat resistance and oil absorption, and a cyclic olefin represented by tetracyclododecene is useful as a raw material. It is. These cyclic olefins are subjected to polymerization using an organometallic complex catalyst. The polymerization method can be roughly classified into two. One is a method in which homopolymerization or copolymerization with a lower α-olefin at the olefin site of the cyclic olefin is advanced using a Ziegler catalyst or a metallocene catalyst. As another polymerization method, metathesis polymerization using a carbene-type complex is known.

As a method for producing tetracyclododecene, cyclopentadiene (hereinafter may be referred to as CPD) and / or dicyclopentadiene (hereinafter referred to as D
A typical method is to produce a reaction mixture containing tetracyclododecene and norbornene by heating and mixing norbornene with ethylene, and to recover and circulate norbornene. Here, for example, a method for producing tetracyclododecene for recovering norbornene produced and recycling it by recycling is disclosed in
Japanese Patent Application Laid-Open No. 128333/1994, Japanese Patent Application Laid-Open No. 6-9439, Japanese Patent Application Laid-Open No. 6-72909, and the like. However, in all cases, dicyclopentadiene is mixed in norbornene recovered and circulated.

[0004] DCPD is used as a raw material in all cases, but commercially available DCPD often contains MTHI as an impurity derived from the fact that the raw material is a pyrolysis oil such as naphtha. MTHI of impurities contained in commercial DCPD
If is mixed with norbornene to be recovered and recycled, methyltetrahydroindene having a high decomposition temperature tends to accumulate in the system, and as a result, other by-products are also generated in large amounts.
Note that DCPD also contains impurities other than MTHI, which are usually low in thermal decomposition temperature.
Different from HI. Further, simply decomposing MTHI in the reaction system by increasing the reaction temperature is not preferable because the yield of the target product is decreased and other by-products are generated.

[0005]

An object of the present invention is to provide a process for obtaining high-purity tetracyclododecene in high yield while recovering and recycling norbornene of high purity.

[0006]

The first aspect of the present invention relates to a method for continuously producing tetracyclododecene, comprising the following steps (1) to (4). (1) By supplying (a) ethylene, (b) cyclopentadiene and / or dicyclopentadiene and (c) norbornene to a reactor and reacting them, at least tetracyclododecene, norbornene and methyltetrahydroindene are contained. A step of preparing a reaction mixture, (2) a step of separating and removing ethylene from the reaction mixture, and (3) a separation and recovery of norbornene substantially free of methyltetrahydroindene from the reaction mixture after the step 2. A step of (4) circulating at least a part of the norbornene separated and recovered in the step 3 to the reactor, and (5) separating and recovering tetracyclododecene from the reaction mixture obtained in the step 3. The second aspect of the present invention relates to a method for continuously producing tetracyclododecene including the following steps (1) to (5). (1) By supplying (a) ethylene, (b) cyclopentadiene and / or dicyclopentadiene, (c) norbornene and (d) a solvent to a reactor and reacting them, at least tetracyclododecene, norbornene and methyl Producing a reaction mixture containing tetrahydroindene; (2) separating and removing ethylene from the reaction mixture; and (3) substantially containing no methyltetrahydroindene from the reaction mixture passed through step 2. A step of separating and removing a mixture of norbornene and a solvent,
(4) a step of circulating at least a part of the mixture of norbornene and solvent separated in the step 3 to the reactor, and (5) separating and recovering tetracyclododecene from the reaction mixture obtained in the step 3 Process. According to the method of the present invention, the norbornene to be recycled is substantially MTH.
It does not contain I, so that by-products are less likely to accumulate in the reaction system. In addition, it is possible to obtain tetracyclododecene with high purity. Hereinafter, the present invention will be described in detail.

[0007]

FIG. 1 is a process flow showing an example of an embodiment of the present invention. In FIG. 1, the norbornene supply line at the start of the reaction is omitted. In FIG. 1, reference numeral 1 denotes a solvent tank. It is preferable to use a solvent in the method of the present invention. The purpose is to reduce the concentration of each component, to reduce heavy components by-products,
And to prevent solidification of recovered norbornene described later. 2 shown in FIG. 1 is a tank of dicyclopentadiene. The cyclopentadiene used in the present invention is preferably one obtained by previously subjecting dicyclopentadiene to pyrolysis distillation. Cyclopentadiene is easily obtained by thermal decomposition of dicyclopentadiene, and under the usual reaction conditions in the present invention, DCPD is decomposed into CPD. DCPD is industrially easily available. Therefore, in the present invention, DC is preferably used as a raw material.
PD is used. As the dicyclopentadiene used in the present invention, those recovered from a thermally decomposed oil such as naphtha are preferable because they can be industrially obtained in large quantities and are inexpensive. However, such commercial products often contain MTHI and other impurities.

Reference numeral 3 shown in FIG. 1 is an ethylene tank.
The raw material of ethylene is not particularly limited, and in addition to polymerization-grade ethylene obtained by steam cracking a gas fraction obtained from naphtha, natural gas or petroleum refining, ethylene obtained by dehydrogenation of ethane or dehydration of ethanol is also used. Although it can be used, it is desirable to use a polymerization grade.

[0009] Norbornene is prepared by using ethylene and cyclopentadiene and / or dicyclopentadiene as raw materials at a reaction temperature of 100 to 350 ° C and a reaction pressure of 0.1 to 40M.
It can be synthesized under the conditions of Pa. If ethylene and dicyclopentadiene and / or cyclopentadiene coexist in the reaction system as in the production process of the present invention,
Norbornene can also be synthesized at the same time under the synthesis conditions of tetracyclododecene. Since norbornene is a compound that is difficult to obtain industrially, in the production process of the present invention, conditions under which norbornene does not increase or at least does not decrease after the reaction are selected. This makes it possible to continuously produce tetracyclododecene without apparently replenishing norbornene.

The cyclopentadiene and / or dicyclopentadiene are introduced into the reactor 5 by the transfer pump 4. In addition, ethylene is pressurized by a pressure booster (not shown) or the like and introduced into the reactor 5. The number of moles of cyclopentadiene and / or dicyclopentadiene supplied is
It is expressed in terms of the number of moles as dicyclopentadiene.
That is, a mixed solution of 2 mol of cyclopentadiene and 1 mol of dicyclopentadiene is regarded as 2 mol of dicyclopentadiene. In the present invention, the supply ratio (molar ratio) of norbornene / dicyclopentadiene expressed in this manner is from 1 to 1,000, preferably from 2 to 10
0, more preferably 3 to 10. When the amount of norbornene is large, the yield of heavy components in the reaction is relatively small, but the amount of norbornene used in circulation is large, and a large amount of energy is required for distillation. On the other hand, when the amount of dicyclopentadiene and / or cyclopentadiene is large, a large amount of heavy components is generated, and the effective utilization rate of the raw material decreases.

Using these as raw materials, tetracyclododecene is synthesized in a reactor 5. As the reactor 5, any of a complete mixing type and a piston flow type can be used. Commercial products of the piston flow type reactor include `` Static Mixer '' manufactured by Noritake Co., Ltd., `` Sluzer Mixer '' manufactured by Sumitomo Heavy Industries, Ltd.,
"Skaya Mixer" manufactured by Sakura Seisakusho Co., Ltd., and the like.
The reactor may have a single stage or a multi-stage structure of two or more stages. The complete mixing type reactor and the piston flow type reactor can be used in combination in series or in parallel.

As the reaction conditions in the reactor 5, the space velocity is 0.001 to 100 h ^-1 , preferably 0.1 to 100 h ^-1.
It is 50 h ^-1 , more preferably ¹ to 10 h ^-1 . When the space velocity exceeds 100 h ⁻¹ , unreacted substances increase, which is inappropriate. The reaction pressure is from 0.1 to 50 MPa, preferably from 0.5 to 40 MPa, more preferably from 1 to 50 MPa.
It is 10 MPa. The reaction temperature is 0 to 400 ° C, preferably 100 to 350 ° C, more preferably 200 to 3O0C.
00 ° C. In particular, when dicyclopentadiene is used as a raw material, it is preferable to set the reaction temperature to 100 ° C. or higher because dicyclopentadiene is easily decomposed into cyclopentadiene.

In the method of the present invention, it is preferable that ethylene is sufficiently dissolved in norbornene, cyclopentadiene and / or dicyclopentadiene in the reactor 5. When a solvent is used, it is preferable that the solvent is sufficiently dissolved in the solvent. The conditions for dissolution vary depending on the molar mixing ratio of norbornene, dicyclopentadiene and / or cyclopentadiene, and ethylene. For example, in the case of no solvent, the molar mixing ratio is norbornene / dicyclopentadiene / ethylene = 8 /. When the temperature is 180 ° C., a pressure of about 2.5 MPa or more is required. If the amount of ethylene is higher or the temperature is higher, a higher pressure is required. For example, at 260 ° C., about 3.9 MPa or more is required. When a solvent is used, ethylene can be dissolved even at a pressure lower than these, and the reaction pressure can be reduced. In either case, it is preferable to carry out the reaction in a liquid phase and to select the reaction conditions so that gaseous ethylene does not substantially exist in the reactor in order to obtain a high yield of TCD.

The reaction mixture continuously withdrawn from the reactor 5 is then sent to a distillation step. First, in FIG.
Is introduced into the first distillation column 6 to adjust the pressure to 0.1 to 1 MPa. Here, unreacted ethylene is mainly separated from the top of the column. Distillation conditions are as follows: a pressure of 100 to 1,000 kPa at the top, a temperature of 25 to 45 ° C.,
At the bottom, the pressure is 100 ~ 1,000kPa, temperature is 25 ~ 10
It can be arbitrarily selected from the range of 0 ° C. By making the pressure slightly higher than normal pressure, it becomes possible to condense the overhead gas with inexpensive seawater or industrial water.

From the bottom of the first distillation column 6, a mixed solution from which ethylene has been separated and removed is withdrawn, guided to the second distillation column 7, and separated and recovered from the top of the column. In the second distillation column 7, distillation conditions are set so that norbornene to be separated and recovered does not substantially contain MTHI. Here, if MTHI is mixed with norbornene to be recovered and reused, MTHI is not easily decomposed in the reactor because of its high decomposition temperature, and as a result, it accumulates in the reaction system and further generates heavy components. easy. Note that MTHI is contained as an impurity in DCPD as a starting material. Although DCPD contains impurities having other structures, MTHI is easily accumulated in the reaction system because MTHI has a high decomposition temperature as described above. The reaction conditions may be such that all of the starting DCPD is consumed in the reaction, in which case substantially no unreacted DCPD is present in the reaction mixture. However, depending on the reaction conditions, a small amount of unreacted DCPD may be present in the reaction mixture. In such a case, when removing MTHI from circulating norbornene by distillation, DCPD
Is often also removed.

The distillation conditions of the second distillation column 7 are not particularly limited, and distillation conditions and the like may be selected so that MTHI is not substantially contained in the norbornene to be recovered. That is, it varies depending on conditions such as the absolute amount of MTHI contained in the supplied raw material DCPD, its ratio, the amount of generated norbornene, its circulating amount, the amount of MTHI captured by the generated heavy materials, and the like, and its ratio. Usually, it is preferable to set the distillation conditions so that the amount of MTHI in the recovered norbornene is 700 ppm or less. Note that MTHI separated from norbornene and remaining in the reaction mixture is removed later in an appropriate purification step (not shown).

The specific distillation conditions of the second distillation column are as follows: a pressure of 1 to 200 kPa at the top, preferably 10 to 100 kP
a, the temperature is 35 to 96 ° C., and the pressure is 1 to 200 at the bottom of the column.
kPa, preferably 10-100 kPa, temperature 40-19
0 ° C. In order to increase the separation efficiency, the distillation column can be filled with various packing materials or refluxed. The theoretical plate number is 1 to 100 plates in each distillation column, preferably 2 to 50 plates, and more preferably 3 to 30 plates. The reflux ratio is determined depending on the separation state of each distillation column, but is suitably 1 to 50.

As described above, a solvent is preferably used in the present invention, for the purpose of preventing coagulation of recovered norbornene. Therefore, it is preferable to recover the solvent at the same time as recovering norbornene, that is, recover the solvent as a mixture of norbornene and the solvent. For this purpose, the reaction mixture is distilled, preferably in a recovery circulation line 8.
And the mixture is circulated to the reactor 5 as a mixture of norbornene and a solvent. Therefore, as the solvent, an organic solvent having a boiling point capable of flowing out simultaneously with norbornene, that is, an organic solvent having a boiling point close to norbornene is preferably used. Specifically, the boiling point is the boiling point of norbornene ± 10
Organic solvent having a boiling point of norbornene ± 5 ° C.

As a specific type of the solvent, an aromatic or aliphatic hydrocarbon having 6 to 8 carbon atoms is suitable. From the viewpoint of safety for the human body and the environment, alicyclic hydrocarbons and branched aliphatic hydrocarbons are more preferable, and specifically, isohexane, isoheptane, isooctane, dimethylcyclohexane and ethylcyclopentane are preferably used. Here, isohexane, isoheptane and isooctane refer to a compound having a methyl group or higher branch,
It can be used irrespective of the substitution position and the type of isomer. Specifically, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane, 2,2,3 -Trimethylbutane, 2-methylheptane, 3-methylheptane, 4
-Methylheptane, 2,3-dimethylhexane, 2,4-
Dimethylhexane, 2,5-dimethylhexane, 2,2,
3-trimethylpentane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane, 2,3,3-trimethylpentane, and the like. Dimethylcyclohexane, for example, 1,2-dimethylcyclohexane, 1,3-
Both dimethylcyclohexane and 1,4-dimethylcyclohexane can be used, and can be used irrespective of the substitution positions of two methyl groups.

Of these, branched aliphatic and alicyclic hydrocarbons having a boiling point close to the boiling point of norbornene of 95 ° C. as described above are preferred, and these are stably simultaneously recovered as a mixed solution with norbornene by distillation. And the problem of blockage of the recovery circulation line can be avoided. When norbornene is recovered together with the solvent, water can be used for cooling a distillation condenser (not shown), and industrial water or seawater is preferably used. The temperature of the refrigerant is 0 to 95 ° C., depending on the type and amount of the solvent used. However, since the boiling point of norbornene is 95 ° C., there is a concern that the norbornene may be discharged into the exhaust gas depending on the distillation pressure. From such a viewpoint, the pressure is preferably 10 to 20 as the top condition of the distillation column.
It is 0 kPa, more preferably 10 to 100 kPa.
The temperature of the refrigerant depends on the type and amount of the solvent to be used.
80 ° C. is suitable. However, norbornene, solvent, and the like lost in the exhaust gas during the distillation can be appropriately replenished and added to the raw material tank. Further, the norbornene increased by the reaction can be appropriately extracted to keep the concentration of each raw material in the reaction system constant.

From the reaction mixture extracted from the bottom of the second distillation column 7, TCD as a product is recovered by an appropriate method. Usually, distillation is preferred. In any case, since the target product, tetracyclododecene, decomposes at a high temperature, it is important to keep the maximum temperature at 200 ° C. or lower in each distillation column so that tetracyclododecene is not exposed to the decomposition atmosphere. .

In this reaction, an antioxidant, a polymerization inhibitor and the like can be appropriately added to the reaction raw materials. For example, hydroquinone, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 4
Phenolic compounds such as methoxyphenol, N, N
Hydroxylamine compounds such as -dimethylhydroxylamine and N, N-diethylhydroxylamine are preferably added. The addition amount is usually 10 to 10,000 pp with respect to the total amount of the reaction raw materials supplied into the reactor.
m, preferably in the range of 50 to 5,000 ppm.
It can be similarly added to tetracyclododecene as a product.

Hereinafter, the present invention will be described with reference to examples.

EXAMPLES Example 1 Continuous production of tetracyclododecene was performed according to the process flow shown in FIG. Norbornene / ethylcyclopentane (solvent) in a weight ratio of 85 /
The raw materials mixed in Step 15 were placed in a reactor, and commercially available dicyclopentadiene and ethylene were continuously introduced after the start of the reaction. At that time, norbornene / dicyclopentadiene /
The ratio of ethylene was 10/1/1 in a molar ratio. The purity of norbornene initially charged was 99.7%, and the purity of commercially available dicyclopentadiene and ethylene supplied continuously was 94.7% and 99.9%, respectively. In the continuous operation, the space velocity was 2 h ^{−1 based} on the mixture of norbornene and ethylcyclopentane, the temperature in the reactor 5 was 230 ° C., and the reaction pressure was 5 h.
MPa.

The first distillation column 6 had 20 theoretical plates, and was continuously operated at a pressure of 400 kPa to continuously separate ethylene from the top of the column. The mixed solution extracted from the bottom of the first distillation column was sent to the second distillation column 7 having 30 theoretical plates, and a mixed solution of norbornene and ethylcyclopentane was recovered under distillation conditions of a pressure of 20 kPa and a top temperature of 43 ° C.
The mixed solution of norbornene and ethylcyclopentane recovered from the top of the column contained substantially no MTHI. Since the recovered liquid showed a slight deviation from the initial weight ratio, i.e., norbornene / ethylcyclopentane = 85/15, due to the loss of the solvent, the loss of ethylcyclopentane was continuously supplied from the raw material tank. did.

The mixture extracted from the bottom of the second distillation column 7 was purified in a third distillation column (not shown) to obtain tetracyclododecene with a purity of 99.6%. No temporal change was observed in the above operation,
Stable continuous operation was possible for more than a day. The conversion of dicyclopentadiene was 92%, and the conversion of ethylene was 72%. The yield of tetracyclododecene having a purity of 99.6% is 76% (based on dicyclopentadiene).
Met.

Comparative Example 1 A continuous reaction was carried out in the same manner as in Example 1 except that the distillation conditions of the second distillation column 7 were changed to a pressure of 8 kPa and a column top temperature of 28 ° C. The purity of the target product, tetracyclododecene, was maintained at 99.6%, but MTHI was mixed into the recovered mixture of norbornene and ethylcyclopentane at 1,050 ppm, and as a result,
The production amount of heavy substances increased with time, and the yield of tetracyclododecene and the conversion of dicyclopentadiene and ethylene decreased over time.

[0027]

According to the method for producing tetracyclododecene of the present invention, high purity tetracyclododecene can be obtained by recovering and recycling norbornene substantially free of MTHI.

[Brief description of the drawings]

FIG. 1 is a process flow showing an example of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solvent tank 2 Dicyclopentadiene tank 3 Ethylene tank 4 Transfer pump 5 Reactor 6 1st distillation column 7 2nd distillation column 8 Recovery circulation line

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4H006 AA02 AB46 AC28 AD11 AD40 BA90 BA94 BB11 BB49 BC10 BC11 BC18 BC31 BC51 BD30 BD40 BD80 BJ30

Claims (2)

[Claims] 1. A method for continuously producing tetracyclododecene comprising the following steps (1) to (4): (1) (a) ethylene, (b) cyclopentadiene and / or dicyclopentadiene and (c) norbornene To produce a reaction mixture containing at least tetracyclododecene, norbornene and methyltetrahydroindene by supplying to a reactor, (2) a step of separating and removing ethylene from the reaction mixture, 3) a step of separating and recovering norbornene substantially free of methyltetrahydroindene from the reaction mixture after the step 2, and (4) circulating at least a part of the norbornene separated and recovered in the step 3 to the reactor. And (5) separating and recovering tetracyclododecene from the reaction mixture passed through the step 3 Process. 2. A method for continuously producing tetracyclododecene comprising the following steps (1) to (5): (1) (a) ethylene, (b) cyclopentadiene and / or dicyclopentadiene, and (c) norbornene. And (d) a step of producing a reaction mixture containing at least tetracyclododecene, norbornene and methyltetrahydroindene by supplying a solvent to the reactor to cause a reaction.
(2) a step of separating and removing ethylene from the reaction mixture, (3) a step of separating and removing a mixture of norbornene and a solvent substantially free of methyltetrahydroindene from the reaction mixture after the step 2, and (4) a step of circulating at least a part of the mixture of norbornene and the solvent separated in the step 3 to the reactor, and (5) a step of separating and recovering tetracyclododecene from the reaction mixture obtained in the step 3 .