JP2001278817A - Continuous method for producing tetracyclododecenes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing tetracyclododecenes, aiming at the effective utilization of a high boiling point byproduct and capable of securing a stable continuous operation. SOLUTION: This continuous method for producing tetracyclododecenes having a specific structure comprises (1) a process of reacting 2-norbornenes, cyclopentadiene or dicyclopentadiene with an olefin, (2) a process of separating and recovering the tetracyclododecenes and (3) a process of discarding at least 1 mass % of residual heavy substance to the out of system and recycling the rest.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for continuously producing tetracyclododecenes (hereinafter sometimes referred to as alkyltetracyclododecene).

[0002]

2. Description of the Related Art Cycloolefin (co) polymers have attracted attention as polymers having excellent optical properties, high transparency, heat resistance, and oil absorption, and tetracyclododecene (hereinafter, referred to as TCD) as a raw material thereof. Cyclic olefins represented by a) are useful. As a method for producing TCD as a representative of TCDs, cyclopentadiene (hereinafter may be referred to as CPD), dicyclopentadiene (hereinafter may be referred to as DCPD) or a mixture thereof, norbornene and ethylene are mixed by heating. Then, a reaction mixture containing TCD and norbornene is produced, and the norbornene is recovered and circulated. Substitution of other olefins, such as propylene, for ethylene results in alkyl TCDs such as methyl TCD. This method is described in, for example,
No. 28333, Japanese Unexamined Patent Publication No. Hei 6-9437 and the like.

[0003] Japanese Patent Application Laid-Open No. 6-72909 discloses that
In order to effectively use the bottom obtained by distilling and separating TCD, that is, a high-boiling by-product having a higher boiling point than TCD,
It has been proposed to circulate a heavy liquid consisting of high-boiling by-products through the reactor. The high-boiling by-product is said to contain tricyclopentadiene (TCPD) or an adduct of CPD and TCD. However, TC
Since PD is contained, it is unavoidable that a high polymer exceeding the trimer of CPD is actually formed. Such a highly polymerized tetramer or higher is hardly decomposed under ordinary TCD formation reaction conditions. As a result, the above-mentioned Japanese Patent Application Laid-Open No.
As described in Japanese Patent Publication No. 9 (1999), in a method of simply circulating a heavy liquid composed of high-boiling by-products in a reactor, even if the production of a high polymer is slight, a high polymer is contained in a circulating flow. Accumulated, it was found that continuous operation becomes difficult.

[0004]

An object of the present invention is to provide a TC
An object of the present invention is to provide a method for producing TCDs capable of effectively utilizing a high-boiling by-product having a boiling point higher than that of D and securing stable continuous operation.

[0005]

That is, the first aspect of the present invention is as follows.
The present invention relates to a method for continuously producing TCDs represented by the following general formula [III], comprising the following steps (1) to (3). (1) A 2-norbornene represented by the following general formula [I], CPD or DCPD, and an olefin represented by the following general formula [II] are supplied to a reactor to be reacted and represented by the following general formula [III]. Obtaining a reaction mixture containing TCDs,

Embedded image (However, R ₁ and R ₂ in each formula are the same or different groups and are each a hydrogen atom, a methyl group or an ethyl group.) (2) a step of separating and recovering TCDs from the reaction mixture; (3) discarding at least 1% by mass of heavy components remaining as a residue of the step (2) outside the reaction system;
Circulating the remaining heavy fraction to the reactor of step (1).

A second aspect of the present invention is the following steps (1) to (1).
The general formula [III], characterized by comprising (8).
The present invention relates to a method for continuously producing TCDs represented by the formula: (1) a step of continuously supplying 2-norbornenes represented by the general formula [I], DCPD, and an olefin represented by the general formula [II] to a reactor to cause a reaction;
(2) a step of separating the olefin represented by the general formula [II] from the reaction mixture; (3) a step of circulating at least a part of the olefin separated in the step (2) to the reactor; (2) separating 2-norbornenes from the reaction mixture from which the olefin has been separated in step (2), (5) circulating at least a portion of the 2-norbornenes substantially free of C ₁₀ unsaturated hydrocarbons into the reactor. (6) a step of separating an unreacted DCPD fraction from the reaction mixture from which the 2-norbornenes are separated in the step (4), and (7) a reaction in which an unreacted DCPD fraction is separated in the step (6). (8) separating and recovering TCDs from the mixture, (8) discarding at least 1% by mass of heavy residue as a residue of the step (7) outside the reaction system, and removing the remaining heavy fraction by the above-described process. Step of circulating the reactor (1).
According to the method of the present invention, by circulating the heavy components to the reaction step, the TCD is efficiently used by effectively utilizing the by-product heavy components.
Can be manufactured, and the operation can be stably and continuously continued.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The olefin represented by the general formula [II] used in the present invention is specifically ethylene, propylene, 1-butene, trans-2-butene, cis-2-butene and the like. The 2-norbornenes represented by the general formula (I) used in the present invention include:
Specifically, 2-norbornene, 5-methyl-2-norbornene (methylnorbornene), 5-ethyl-2-norbornene (ethylnorbornene), 5,6-dimethyl-
2-norbornene (dimethylnorbornene) and the like.
These compounds have stereoisomers such as endo- and exo-forms, and any of the isomers can be employed.

The TCDs represented by the general formula [III] used in the present invention are specifically TCD (1,4,5,8-dimethano-1,2,3,4,4a, 5,8, 8a-octahydronaphthalene), methyl TCD (2-methyl-1,
4,5,8-Dimethano-1,2,3,4,4a, 5
8,8a-octahydronaphthalene), ethyl TCD
(2-ethyl-1,4,5,8-dimethano-1,2,2
3,4,4a, 5,8,8a-octahydronaphthalene) and dimethyl TCD (2,3-dimethyl-1,
4,5,8-Dimethano-1,2,3,4,4a, 5
8,8a-octahydronaphthalene). These compounds include, as stereoisomers, endo-exo isomers, endo-endo isomers, exo-endo isomers, exo-exo isomers,
Further, stereoisomers due to substituents may exist, but any isomer may be employed.

FIG. 1 is a process flow showing an embodiment of the present invention. In FIG. 1, the supply line of norbornenes at the start of the reaction is omitted. In FIG. 1, reference numeral 1 denotes a solvent tank. In the method of the present invention, it is preferable to use a solvent having a boiling point at normal pressure of 50 to 180 ° C. The purpose is to reduce the concentration of each component in the reaction, to reduce heavy components which are by-products, and to prevent solidification of circulating norbornene, especially when 2-norbornene is used. That is, as a preferred method, norbornene is recovered together with the solvent from the reaction mixture by distillation. At this time, if the norbornene is dissolved in the solvent, solidification is prevented. Therefore, it is preferable that the solvent used has a boiling point close to that of 2-norbornene and can be easily separated by distillation or the like. Aromatic or aliphatic hydrocarbons having 6 to 8 carbon atoms are suitable.

Specific solvents include benzene, toluene, xylene, cyclohexane, methylcyclohexane, dimethylcyclohexane and the like. However, 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, cyclohexane, methylcyclohexane, dimethylcyclohexane and ethylcyclopentane are preferable. used.
Here, isohexane, isoheptane and isooctane refer to a compound having a methyl group or higher branch, and can be used regardless of the substitution position, isomer and the like.
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-trimethyl Pentane,
2,3,4-trimethylpentane and 2,3,3-trimethylpentane. Dimethylcyclohexane can also be used, for example, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane and 1,1
Any of 4-dimethylcyclohexane can be used, and there is no limitation on the relative substitution positions of two methyl groups.

When norbornene is recovered together with the solvent as described above, water can be used for cooling a distillation condenser (not shown), and industrial water and seawater are preferably used. The temperature of the refrigerant is 0 to 95 ° C., depending on the type and amount of the solvent used. Further, since the boiling point of norbornene is 95 ° C., there is a concern that norbornene flows out into the exhaust gas depending on the distillation pressure, resulting in a loss.
From such a viewpoint, the pressure at the top of the distillation column for recovering norbornene is preferably 10 to 2 times.
The temperature of the refrigerant is preferably from 0 to 80 ° C., although it depends on the type and amount of the solvent used. However, the solvent or the like which has been lost by flowing into the exhaust gas during the distillation can be appropriately replenished from the raw material tank.

In the above formula [I], when both R ₁ and R ₂ are not hydrogen atoms, that is, when _2- olefins other than ethylene are used as olefins, 2-norbornenes are liquid at room temperature, It is not necessary to use a solvent to prevent solidification as in 2-norbornene where R ₁ and R ₂ are hydrogen atoms. Therefore, no solvent tank is required. However, even in such a case, as long as the solvent is used, the components to be circulated,
That is, the solvent is preferably a solvent that can be recovered at the same time as the olefin or the norbornene, and among them, a solvent that can be recovered at the same time as the norbornene is preferable. Therefore, it is preferable to use a solvent having a boiling point close to that of the norbornenes, and in many cases, a solvent having the same carbon number as the norbornenes may be used.

Reference numeral 2 in FIG. 1 denotes a tank for coarse DCPD. Crude CPD can also be used as a raw material. CPD
Is easily obtained by thermal decomposition of DCPD, but crude DCP
The CPD obtained from D contains impurities. Under the reaction conditions of the present invention, DCPD decomposes into CPD. Therefore, the following industrially available crude DCPD is preferably used as a raw material for CPD. That is, what is recovered from by-product oil obtained at the time of thermal cracking or catalytic cracking of light hydrocarbons such as naphtha to produce lower olefins such as ethylene is industrially obtained in large quantities and is inexpensive. It is preferred.

Reference numeral 3 in FIG. 1 denotes an olefin tank. As mentioned above, specific olefins are ethylene, propylene, 1-butene, trans-2-butene and cis-2-butene. The amount of olefin used is DC
PD (when using CPD, convert to DCPD)
To 0.5 to 50, preferably 1
~ 40, more preferably 1.2 ~ 30. When the molar ratio of olefin to DCPD is less than 0.5, the amount of norbornenes formed is small, the amount of norbornenes used in the synthesis of TCDs is large, and the amount of norbornenes that can be recycled is increased. Is undesirably reduced. Addition of a large excess of olefin is not preferable because a large amount of energy is consumed during olefin recovery.

[0015] Norbornenes can be used in combination with olefins and crude CPD and / or DCPD regardless of the number of carbon atoms in the olefins.
Can be synthesized under the conditions of a reaction temperature of 100 to 350 ° C. and a reaction pressure of 0.1 to 40 MPa. Therefore, if olefins and DCPD and / or CPD coexist in the reaction system as in the production process of the present invention, norbornenes can be synthesized simultaneously under the conditions for synthesizing TCDs.

The crude DCPD is transferred from the tank 2 to the transfer pump 4
To the reactor 5. The olefin is pressurized by a pressurizer (not shown) or the like and is continuously introduced into the reactor 5.

The amount of continuously supplied crude DCPD and / or CPD is converted to the number of moles of DCPD (that is, a mixture of 2 moles of CPD and 1 mole of DCPD is regarded as 2 moles of DCPD), and the norbornenes / DCP
It is adjusted so that D (molar ratio) = 2 to 20, preferably 3 to 15, and more preferably 4 to 10. When the amount of norbornenes is large, the yield of heavy components in the reaction is relatively small, but the amount of norbornene used in circulation increases, and a large amount of energy is required for distillation, which is not very advantageous. On the other hand, when the amount of DCPD and / or CPD is large, a large amount of heavy components is generated, and the effective utilization rate of the raw material decreases.

Reference numeral 5 in the figure denotes a reactor, which continuously supplies the above-mentioned raw materials to the reactor 5 to synthesize TCDs. As the reactor 5, any of a complete mixing type and a piston flow type can be used. Examples of commercially available products of the piston flow type reactor include "Static Mixer" manufactured by Noritake Co., Ltd., "Sluzer Mixer" manufactured by Sumitomo Heavy Industries, Ltd., and "Skeya Mixer" manufactured by Sakura Seisakusho Co., Ltd. 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 reaction temperature is 170-280 ° C., preferably 180-26 ° C.
0 ° C, more preferably 200 to 250 ° C. When the reaction temperature is high, heavy components are easily generated, and when the reaction temperature is low, the reaction does not easily proceed, and in either case, efficient production cannot be performed. The space velocity in the reaction is
LHSV = 0.5-10, preferably 0.7-8, more preferably 1-6. When LHSV exceeds 10,
The amount of unreacted substances increases, and efficient production becomes impossible. On the other hand, if the LHSV is less than 0.5, the production of heavy substances increases, the effective yield of the raw material decreases, and the production amount per hour also decreases.

In the method of the present invention, it is preferable that low-boiling olefins are sufficiently dissolved in norbornenes, CPD and / or DCPD in the reactor 5. When a solvent is used, it is preferable that the solvent is sufficiently dissolved in the solvent. Conditions for achieving such a state include norbornenes, DCPD and / or C
Although it depends on the molar mixing ratio of PD and olefin, for example, without solvent, the molar mixing ratio is norbornene / DCPD / ethylene = 8/1/1, and the temperature is 180 ° C.
, A pressure of about 2.5 MPa or more is required. If the ethylene content is higher or the temperature is higher, a higher pressure is required, e.g.
In the case of (1), about 3.9 MPa or more is required. When a solvent is used, the olefin can be dissolved even at a pressure lower than these, and a reduction in the reaction pressure can be achieved. In any case, it is desirable to maintain the liquid phase under the reaction conditions and to select the reaction conditions so that substantially no gas phase is present in the reactor in order to obtain TCDs in high yield.

The reaction mixture continuously withdrawn from the reactor 5 is then led to distillation as a purification step. The purification process mainly consists of separation of olefins, separation of norbornenes, DC
It consists of separation of PD fraction and separation of TCDs. To extract these components from the top of the distillation column, four distillation columns are required. Of course, other combinations of distillation columns can be employed. In the distillation step, first, the reaction mixture extracted from the reactor 5 in FIG. 1 is introduced into the first distillation column 6, and the pressure is adjusted to 100 to 1000 kPa. Here, unreacted olefin is mainly extracted from the top of the column.
The distillation conditions are as follows: a pressure of 100 to 1000 kP at the top of the column.
a, from a temperature range of 25 to 45 ° C., a pressure of 100
To 1000 kPa and a temperature of 25 to 100 ° C. By slightly increasing the pressure from the normal pressure, the overhead gas can be condensed using inexpensive seawater or industrial water.

At this time, at least a part of the olefin extracted here can be circulated to the reactor 5 through the line 10 and reused as a raw material. The method of introducing the recovered olefin into the reaction system may be any method as long as it is a method of returning the recovered olefin to the reactor. For example, once the olefin is returned to the olefin tank 3, it can be mixed with the supplied olefin and used for the reaction. Alternatively, it can be circulated and introduced from the line 10 to the reactor 5 as shown in the figure via a booster (not shown) as required. By separating and recovering the unreacted olefin and reusing it as a raw material, the yield per olefin is improved.

Under the reaction conditions, CPD used as a raw material or CPD generated by decomposition of DCPD is present in the reaction mixture. CPD can be reused as a reaction raw material, but since its boiling point is close to that of olefins,
When distilling olefins, some CPD tends to accompany the olefins. In the present invention, the conditions of the first distillation column are appropriately adjusted so that at least a part of CPD accompanies the olefin distilled from the top of the first distillation column. CPD
This operation is easier as the carbon number of the olefin and the olefin are closer, and the entrainment phenomenon is unavoidable rather depending on the distillation conditions. Therefore, when the olefin is reused, the accompanying CPD can be reused as a raw material at the same time, which is extremely preferable. In this case, if the method of separating olefins by depressurization and discarding them outside the system is used, C
PDs are also not preferred because they also result in being discarded.

From the bottom of the first distillation column 6, a reaction mixture obtained by separating and removing olefin and a part of CPD is withdrawn and introduced into the second distillation column 7. In the second distillation column 7, norbornenes or, in the case of using a solvent, norbornenes containing a solvent are separated and recovered from the top of the column, circulated to the reactor 5 through the line 11, and used. The distillation conditions of the second distillation column are a pressure of 0.1 to 200 kPa at the top, preferably 1 to 100 kPa, and a temperature of 35 to 96 ° C.,
At the bottom of the column, the pressure is 0.1 to 200 kPa, preferably 1 to 100 kPa, and the temperature is 40 to 190 ° C.
In order to improve the separation efficiency, the distillation column can be appropriately filled with various packing materials or refluxed. The theoretical plate number is 1 to 100 plates, preferably 2 to 50 plates, and more preferably 3 to 30 plates in each of the following distillation columns. The reflux ratio is determined according to the separation state of each distillation column, but is suitably 1 to 50.

The circulating norbornenes or, in the case of using a solvent, a mixture of the solvent and the norbornenes is returned to the upstream of the reactor through the circulation line 11 and reused as a raw material. In other words, the norbornenes can be appropriately supplied from the solvent tank 1 and the DCPD tank 2 with the solvent or D
It is mixed with CPD and introduced into the reactor 5 by the transfer pump 4. In addition, C which was not completely separated in the first distillation column
Low boiling compounds such as PD may be mixed into circulating norbornenes. However, since norbornenes are recovered and recycled for reuse, contaminated CPD can be effectively reused as a result. Reusing norbornenes containing CPD as a raw material as described above is a preferable method because the yield per CPD or DCPD is improved.

The circulating norbornenes recovered from the top of the second distillation column are further subjected to a separation operation such as distillation (not shown) to separate them into two fractions of high-purity norbornenes and circulating norbornenes. Alternatively, high purity norbornenes can be simultaneously obtained from recovered norbornenes by separating into three fractions of a low boiling point component such as CPD, a high purity norbornene and a circulating norbornene. In the above, when a low-boiling point compound such as CPD mixed with the circulating norbornenes is separated, it is preferable to re-mix the circulating norbornenes and circulate them together to reuse them as raw materials.

The raw material DCPD contains isoprene,
A compound (carbon number: 10) having the same carbon number as DCPD caused by piperylene is contained as an impurity. These cause skeletal isomerization during the reaction in the reactor 5,
Some are converted to methyltetrahydroindene (hereinafter sometimes referred to as MTHI). Since MTHI has low reactivity in the Diels-Alder reaction, it is preferable not to mix MTHI in the circulating norbornene fraction.
That is, in the present invention, and circulation of norbornenes containing no C ₁₀ unsaturated hydrocarbons such as MTHI substantially
Reuse. The recycle stream to the reactor 5, the there is also circulation of unreacted olefin, in any case, in the present invention, substantial circulating flow is a C ₁₀ unsaturated hydrocarbon to be recycled to the reactor 5 The distillation operation is performed so as not to be included in the above.
In Figure distillation step, performs operations to include the C ₁₀ components to the distillate during the withdrawing from the bottom of the second distillation column 7.

The reaction mixture extracted from the bottom of the second distillation column 7 is sent to the third distillation column 8, and a fraction mainly composed of DCPD as an unreacted component is separated from the top of the third distillation column 8. The pressure at that time is preferably 50 kPa or less. A fraction from which unreacted DCPD has been removed is withdrawn from the bottom of the third distillation column 8 and sent to the fourth distillation column 9. In the fourth distillation column 9,
The target TCDs are extracted from the top of the column, and a fraction containing heavier components is extracted from the bottom of the column. As the operating conditions of the fourth distillation column 9, it is preferable that the pressure at the bottom of the column is 30 kPa or less and the temperature is 200 ° C. or less.

The liquid withdrawn from the bottom of the fourth distillation column is
It contains high-boiling by-products having a higher boiling point than TCD, and its composition is mainly an adduct or TCPD obtained by adding CPD to TCDs, but it may also contain other heavy substances such as CPD tetramers or more. In the method of the present invention, at least 1% by mass of high-boiling by-products having a higher boiling point than TCD is discarded outside the reaction system. The disposal can take place via line 12 in the figure. When the entire amount is returned to the reactor as described above, heavy substances accumulate and long-term operation becomes impossible. However, continuous operation becomes possible by discharging part of the system out of the system. That is, when heavy matter is circulated to the reactor, a reverse Diels-Alder reaction occurs in the reactor,
Since the raw materials such as TCDs, CPD, and DCPD and the target products are produced, the effective yield of the raw materials is improved. Further, as described above, some parts are further heavier. In addition, it is difficult to separate only the adduct or TCPD obtained by adding CPD to the TCDs in the heavy component from the heavy component by distillation, because high-temperature distillation is required to cause decomposition, polymerization, and the like. Therefore, after the TCD is separated and recovered, it is recovered as a high-boiling by-product having a boiling point higher than that of the TCD without performing distillation or the like, and at least a part thereof is discarded. Circulate to

That is, in the method of the present invention, TC
At least one of the high-boiling by-products having a boiling point higher than D
The mass% is discarded outside the reaction system and the remaining high-boiling by-products are circulated to the reactor. The amount circulated to the reactor is 1-99%. If it is less than 1%, the effective yield of the raw material cannot be expected to improve, and if it exceeds 99%, heavy substances accumulate. The formation of heavy matter is caused by the addition of CPD by the Diels-Alder reaction, so that an increase in heavy matter means a decrease in the effective yield of raw material DCPD and / or CPD. It is preferable that a certain amount of heavy matter is always circulated. However, since the rate of formation of heavy substances varies depending on the raw material composition, reaction temperature, space velocity, and the like, the amount discharged to the outside of the system may be determined in consideration of these factors.

As for the discharge amount, a rough guide can be obtained as follows. For example, suppose that part A of heavy matter is generated for one part of all new raw materials in the first reaction. When the second reaction is similarly performed by reusing all of the heavy materials, the total raw material supply amount is (1 + A) parts.
It is considered that the amount of heavy matter obtained after the second reaction is the total (A + xA) part of the part A generated from one part of the new raw material and the xA part in which the recycled heavy part A has changed. Here, x indicates the rate of change of the heavy matter, which varies depending on the temperature of the reactor, the residence time, and the composition of the heavy matter. Therefore, in order for a certain amount (= part A) of heavy matter to be always present, it is necessary to discharge only part xA out of the system. x
As described above, the reaction is carried out at a predetermined temperature and a predetermined space velocity using the (1 + A) part of the raw material, and
It can be obtained by dividing part A by A.

Discarding the entire amount of heavy materials is not preferable because effective use of heavy materials cannot be achieved. However, as described above, the heavy components may be further heavier due to heating in the reactor, and the polymer obtained by such heavier has insoluble and infusible properties.
There is a concern that the reactor may be blocked. Therefore, in order to prevent the reactor from being clogged, the heavy substances can be completely discarded at an arbitrary frequency as appropriate during continuous operation. That is, it is preferable to once discard the entire amount of CPD tetramer after clearly confirming the formation of the CPD tetramer in the composition of the heavy matter to be circulated, and then restart circulation.

In the reaction used in the present invention, an antioxidant and a polymerization inhibitor can be appropriately added to the reaction raw materials. For example, hydroquinone, 2,6-di-tert-
Phenolic compounds such as butylphenol, 2,6-di-tert-butyl-p-cresol, 4-methoxyphenol, N, N-dimethylhydroxylamine, N, N-
A hydroxylamine compound such as diethylhydroxylamine is preferably added. The addition amount is usually 10 to 1 to the total amount of the reaction raw materials supplied into the reactor.
It is in the range of 0.00000 ppm, preferably 50-5,000 ppm. Of course, it can be similarly added to TCD as a product. In this way, the TCDs as the target can be efficiently produced by effectively utilizing the raw materials.

[0034]

The present invention will be described below with reference to examples. <Example 1> Continuous production of ethyltetracyclododecene was performed using the apparatus shown in FIG. 5-Ethyl-2-norbornene, commercially available dicyclopentadiene and 1-butene were continuously introduced into the reactor 5. At that time, the molar ratio of ethyl norbornene / dicyclopentadiene / butene was 3 /
It was 1/8. The purity of ethyl norbornene initially charged was 99.7%, and the purity of continuously supplied commercially available dicyclopentadiene and butene was 9% each.
4.7% and 99.9%. In the continuous operation, the space velocity was 2 h ⁻¹ and the temperature in the reactor 5 was 250 ° C. The reaction pressure was 5 MPa.

The reaction mixture withdrawn from the reactor 5 is
It was sent to the distillation column 6. The number of theoretical plates of the first distillation column 6 was 20, and the butene was continuously separated from the top of the column by performing continuous operation at 200 kPa. The separated butene was pressurized by a pressurizer and returned to the reactor 5 for circulating use. The mixed liquid extracted from the bottom of the first distillation column 6 was cooled to 10 theoretical plates.
To the second distillation column 7 of the stage, 20 kPa, the top temperature of 80 to
Ethyl norbornene was recovered under distillation conditions at 90 ° C. This recovered liquid was continuously mixed with the raw material dicyclopentadiene and sent to the reactor 5 by the transfer pump 4 for reuse as a raw material. The mixed liquid extracted from the bottom of the second distillation column 7 was sent to the third distillation column 8 to separate dicyclopentadiene and methyltetrahydroindene from the top. The mixed liquid extracted from the bottom of the third distillation column 8 is mixed with the fourth distillation column 9
And ethyl tetracyclododecene was extracted from the top of the column. 50% of the liquid obtained from the bottom of the fourth distillation column
Was sent to the transfer pump 4 by the heavy circulation line 13 and circulated to the reactor 5, and the remainder was discharged out of the system through the heavy circulation line 12. In the above operation, stable continuous operation was possible over 250 days or more without any change over time without disposing of the entire bottom liquid of the fourth distillation column. As a result, ethyltetracyclododecene having a purity of 97.0% was obtained, and the yield was 75% (based on charged dicyclopentadiene).

Comparative Example 1 The procedure of Example 1 was repeated, except that the heavy liquid circulation line 12 was not used and the entire amount of the heavy liquid obtained from the bottom of the fourth distillation column was circulated to the reactor 5. Performed similarly. Two days after the start of the reaction, tetramers of cyclopentadiene were found in the heavy liquid extracted from the bottom of the fourth distillation column and circulated, and the amount gradually increased. Therefore, the operation was stopped four days after the start of the reaction. When the operation was stopped, ethyltetracyclododecene having a purity of 97.0% was obtained, and the yield was 65% (based on the charged dicyclopentadiene).

[0037]

According to the method of the present invention, by circulating the heavy components to the reaction step, TCD can be efficiently produced by effectively utilizing the by-produced heavy components, and the TCD can be stably continuously produced. The operation can be continuously continued.

[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 Crude DCPD tank 3 Olefin tank 4 Transfer pump 5 Reactor 6 1st distillation column 7 2nd distillation column 8 3rd distillation column 9 4th distillation column 10 Olefin collection and circulation line 11 Norbornene collection and circulation line 12 Heavy waste disposal line 13 Heavy waste circulation line

Claims (2)

[Claims] 1. A method for continuously producing tetracyclododecenes represented by the following general formula [III], comprising the following steps (1) to (3): (1) the following general formula [ 2-norbornenes represented by the formula (I), cyclopentadiene or dicyclopentadiene, and an olefin represented by the following general formula [II] are supplied to a reactor to react with each other, and tetracyclododecene represented by the general formula [III] is reacted. Obtaining a reaction mixture containing the following: (However, R ₁ and R ₂ in each formula are the same or different groups and are each a hydrogen atom, a methyl group or an ethyl group.) (2) Separation and recovery of tetracyclododecenes from the reaction mixture And (3) a step of discarding at least 1% by mass of the heavy matter remaining as a residue of the step (2) outside the reaction system, and circulating the remaining heavy matter to the reactor of the step (1). 2. A method for continuously producing tetracyclododecenes represented by the following general formula [III], comprising the following steps (1) to (8): A process of continuously supplying 2-norbornenes, dicyclopentadiene, and olefins represented by the following general formula [II] to the reactor to react them: (2) a step of separating the olefin represented by the general formula [II] from the reaction mixture; (3) a step of circulating at least a part of the olefin separated in the step (2) to the reactor; (2) separating 2-norbornenes from the reaction mixture from which the olefin has been separated in step (2), (5) circulating at least a portion of the 2-norbornenes substantially free of C ₁₀ unsaturated hydrocarbons into the reactor. (6) a step of separating an unreacted dicyclopentadiene fraction from the reaction mixture from which the 2-norbornenes are separated in the step (4); (7) an unreacted dicyclopentadiene fraction in the step (6) Separating and recovering tetracyclododecenes from the reaction mixture obtained by separating (8) at least 1% by mass of the heavy component remaining as the residue in the step (7). Discarded outside reaction system, the step of circulating the heavies remaining in the reactor of the step (1).