JP2002205961A - Method for producing Diels-Alder reaction product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct a Diels-Alder reaction by heating an olefin compound and a cyclopentadiene and / or dicyclopentadiene without accumulating a polymer of an easily polymerizable component and effectively using an olefin. Improve the yield,
Provided is a method for producing a Diels-Alder reaction product that enables stable operation for a long period of time. When a mixture containing an olefin compound and a cyclopentadiene derivative is heated to perform a Diels-Alder reaction, a reaction solution inlet and an outlet are provided at both ends, and a rotating shaft vertically installed inside the container, A process for producing a Diels-Alder reaction product, wherein the mixture is continuously supplied to a vertical tank reactor equipped with a plurality of stages of stirring blades extending horizontally from the rotation axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a Diels-Alder reaction product, and more particularly, to a method for heating a olefin compound and a cyclopentadiene and / or dicyclopentadiene to carry out a Diels-Alder reaction. By continuously supplying these mixtures to the tank reactor, the Diels-Alder does not accumulate the polymer of easily polymerizable components, improves the effective olefin yield, and enables stable operation for a long period of time. The present invention relates to a method for producing a reaction product.

[0002]

2. Description of the Related Art The Diels-Alder reaction can be produced by a simple production apparatus because the reaction proceeds only by heat without using a catalyst, and is a reaction industrially used for producing norbornene and ethylidene norbornene. is there. The obtained ethylidene norbornene is copolymerized with ethylene and propylene at the olefin site of the norbornene ring using a Ziegler-based catalyst or a metallocene-based catalyst.
As widely used. In addition, norbornene is subjected to ring-opening polymerization at its olefin site to produce polynorbornene (norbornene rubber).

[0003] Recently, tetracyclododecene, which is a Diels-Alder reaction adduct of norbornene and cyclopentadiene, has a ring-opening polymer having excellent optical properties,
It attracts attention because of its high transparency, heat resistance, and oil absorption.

As an example of the production of tetracyclododecene, it is produced by subjecting ethylene, dicyclopentadiene, and norbornene to a Diels-Alder reaction. For example, in Japanese Patent Application Laid-Open No. Hei 6-72909, a high boiling point solvent is used to react therewith. ing. In Japanese Patent Application Laid-Open No. 6-94737, high-purity dicyclopentadiene is used for the Diels-Alder reaction of ethylene, dicyclopentadiene and norbornene.

However, in these conventional Diels-Alder reactions which are industrially carried out, since a complete mixing type or tubular type reaction apparatus is used, the reaction product is easily polymerized depending on the reaction conditions. There is a disadvantage that the polymer easily accumulates in the apparatus. Further, in the conventional Diels-Alder reaction, the olefin yield is not industrially sufficient. Further, there is a demand for a production method capable of stably operating without accumulating a polymer in an apparatus for a long period of time.

Japanese Patent Application Laid-Open No. 7-252169 discloses a method for producing a tetracyclododecene derivative in which a Diels-Alder reaction is performed in a piston flow reactor. However, in the invention described in the publication, there is no convection of the reactant before and after the flow direction, and the piston flow type reactor is a tubular reactor in which the concentration distribution of the substance in the direction perpendicular to the flow direction is substantially uniform. In these conventional reactors, stirring in the flow direction is not performed. Further, there is no detailed description of the reactor in other prior arts.

Here, the Diels-Alder reaction is an exothermic reaction that proceeds even without a catalyst. Therefore, if the mixing state is poor, local heat generation occurs in the reactor, causing a thermal gradient. In particular, when dicyclopentadiene is used, trimer or tetramer of cyclopentadiene is generated due to local heating, which may adhere to the reactor wall and cause clogging.

Examples of the use of a tank reactor include Japanese Patent Publication No. 6-89047, Japanese Patent Application Laid-Open No. 4-335001, Japanese Patent Application Laid-Open No. 58-122901, and Japanese Patent Application Laid-Open No. 57-1.
No. 25202, JP-A-53-99290, etc., which are used for radical polymerization of ethylene, efficiently stir high-viscosity liquid polyethylene to eliminate abnormally-retained portions, To prevent quality deterioration. However, there is no mention in these prior arts that the tank reactor is adaptable to the Diels-Alder reaction.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a process for heating a olefin compound and cyclopentadiene and / or dicyclopentadiene to carry out a Diels-Alder reaction without accumulating a polymer of an easily polymerizable component. Further, it is an object of the present invention to provide a method for producing a Diels-Alder reaction product which improves the effective yield of olefins and enables stable operation for a long period of time.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, in a method for producing a Diels-Alder reaction product, an olefin compound and a cyclopentadiene derivative were added to a tank reactor. The reaction can proceed smoothly by heating and mixing.
This has led to the completion of the present invention, which is highly efficient and can be operated stably for a long period of time. That is, the method for producing a Diels-Alder reaction product of the present invention includes the steps of: heating a mixture containing an olefin compound and a cyclopentadiene derivative to perform a Diels-Alder reaction; The mixture is continuously supplied to a vertical tank-type reactor equipped with a plurality of stages of rotating shafts installed vertically in the inside thereof and stirring blades extending horizontally from the rotating shafts.

Hereinafter, the present invention will be described in detail. The tank-type reactor used in the present invention is a vertical cylindrical container as shown in FIG. 1, and has a rotating shaft 3 and a plurality of stirring blades 2 extending in a direction perpendicular to the rotating shaft 3 at the center. It has a structure in which the motor 1 and the stirring shaft are connected directly or indirectly to rotate the rotating shaft 3 and to stir the contents with the stirring blade 2.

The ratio between the inner diameter D and the length L of the cylindrical container,
The so-called L / D is 1-30, preferably 1-25, more preferably 2-20. When the L / D is 30 or more, the reaction tank and the rotating shaft become long, and the operation from a long time causes a deviation from the center line of the rotating shaft, and the motor energy for stirring increases, which is not preferable. .

As the shape of the stirring blade 2, any shape such as a paddle type, a turbine type, and a propeller type as shown in FIG. 2 can be used. In the present invention, the reaction liquid present in the n-th stage is sent to the next stage (n + 1) through the gap between the stirring blade and the inner cylinder. The portion is reflected by the inner cylinder surface and returned to the n-th stage without being sent to the next stage. It is preferable that agitating in a vortex parallel to the flow direction of the reaction liquid, that is, so-called back mixing occurs. Therefore, it is preferable to use a turbine-type blade having a disk for preventing the flow of fluid in the rotation axis direction and performing stirring in a direction perpendicular to the rotation axis direction at the interface with the inner cylinder.

The flow direction of the reaction solution may be upward or downward, and the fluid is pushed up or down by a vertical vortex generated by stirring, so that the efficiently stirred reaction solution is transported. In addition, the transported reaction liquid is subjected to the same stirring by the next stirring blade, and more efficient stirring is performed.
This is performed as many times as the number of installed blades.

Further, it is possible to improve the stirring efficiency by installing a partition plate between the stirring blade of the next stage. In that case, it is preferable that the partition plate is welded to the inner cylinder surface so that the fluid moves through the gap with the rotation shaft.

In general, when dicyclopentadiene and / or cyclopentadiene are heated, a polymer of cyclopentadiene is generated, which has a problem that it precipitates on the inner surface of the reactor or the flow channel. In the tank-type reactor used in the present invention, such a problem does not occur because the stirring blade forcibly stirs the inner cylinder surface and stirs in such a manner as to swirl in the vertical direction. To put it bluntly, scale may adhere to the upper and lower parts of the reactor and the stationary parts, so-called flange parts. However, if it is a lower part, the lowermost blade has a scraping effect, and if it is an upper part, the uppermost blade has a scraping effect, so that the scale can be prevented from adhering.

Further, when heating the reactor, it is common to attach a jacket or the like and heat from the outer surface of the reactor. In the tank reactor used in the present invention, the reaction fluid is highly stirred. Therefore, heat exchange with the inner wall is performed smoothly, and the generation of cyclopentadiene multimer by local heating is very unlikely to occur.

As a comparison with other general reactors, first, in the piston flow type reactor, dicyclopentadiene and / or cyclopentadiene are heated without forcible stirring in the direction perpendicular to the fluid flow. In this case, heat exchange is not performed, and cyclopentadiene multimer is generated by local heating, contaminating the inner wall and closing the pipe. This is particularly noticeable when the Reynolds number is small. Further, heat exchange can be performed efficiently by reducing the diameter, but for that purpose, it is necessary to increase the tube length.

It is disclosed that a static mixer is used to stir in a direction perpendicular to the flow of the fluid (for example, JP-A-7-252169). This is due to the fact that the mixing element allows the fluid to move vertically by dividing and diverting the fluid. However, since the edge portion of the mixing element or the contact surface between the mixing element and the inner wall is a so-called stagnant portion, the adhesion of scale cannot be avoided. Further, the effect of the stirring depends on the Reynolds number of the fluid, and the flow rate may be limited when the reaction raw material is constant, that is, when the viscosity is constant. In general, unless the flow velocity is high, that is, the state is not high, the effect does not appear.

In a complete mixing type reactor, a short path is unavoidable, so it is considered preferable to carry out the reaction by connecting several units. However, in such a case, since the rotating shafts are independent from each other, the number of motors required is equal to the number of reactors. Further, the scale adheres to the stationary flange portion. That is, a portion to which scale adheres is generated in proportion to the number of installed reactors. Further, since the connecting portion of the complete mixing type reactor is performed by piping, the connecting portion corresponds to the case where the fluid under reaction is flowing through the piston flow type reactor, and causes the above-described inconvenience. For the reasons described above, it can be seen that it is particularly preferable to use a tank-type reactor having a small number of places where scale adheres in order to carry out the Diels-Alder reaction.

Also, for example, a case where tetracyclododecene is synthesized in the presence of ethylene, dicyclopentadiene and norbornene will be described. In the tank-type reactor used in the present invention, the tank is divided into small tanks by a rotary blade, and the small tank divided has a smaller capacity as compared with the complete mixing type having the same capacity, and the small tank is connected. You can see. In the first stage, dicyclopentadiene is decomposed into cyclopentadiene and its concentration is reduced, so that a heavy substance such as a cyclopentadiene trimer due to the reaction between the generated cyclopentadiene and dicyclopentadiene is small. Cyclopentadiene mainly reacts only with ethylene and norbornene to produce norbornene and tetracyclododecene, respectively. However, since the amount of tetracyclododecene generated in the first stage is very small, cyclopentadiene and tetracyclododecene are generated. The generation of heavy substances due to the reaction with decene is small. When such a reaction solution is sent to the next stage, the cyclopentadiene having a reduced absolute amount selectively reacts with norbornene having an increased absolute amount, and therefore, the yield of the target product is improved. The cyclopentadiene and the target product are generated by the decomposition of newly supplied dicyclopentadiene because they are sufficiently mixed even at a flow rate that causes forced convection in the flow direction due to forced stirring by the rotor blades. The reaction with tetracyclododecene and the reaction between generated cyclopentadiene and newly supplied dicyclopentadiene are suppressed. This results in a high product yield.

When the same synthesis as described above is carried out in a piston flow type reactor, convection in the flow direction occurs when the flow rate is low, so that cyclopentadiene generated by decomposition of dicyclopentadiene is converted into tetracyclododecene or Reacts with dicyclopentadiene, increasing the amount of by-products generated. Therefore, the yield of products based on dicyclopentadiene and / or cyclopentadiene is reduced. Even when a device having a mixing element, for example, a static mixer is used, such a phenomenon cannot be avoided if the flow rate is low. For these reasons, it is necessary to increase the flow velocity, and there is a limit to the flow velocity.

In the complete mixing type reactor, when the dissociation reaction of dicyclopentadiene into cyclopentadiene proceeds, the concentration of the product tetracyclododecene is higher than that in the tank type reactor or the piston flow reactor. High, so that heavy by-products of cyclopentadiene added to tetracyclododecene are generated. Similarly, since the concentration of dicyclopentadiene is also increased, a polymer of cyclopentadiene is easily formed.

As described above, a reaction in which a Diels-Alder reaction is continuously performed using ethylene, dicyclopentadiene, and norbornene as raw materials, that is, norbornene is synthesized from ethylene and cyclopentadiene, and the norbornene and cyclopentadiene are synthesized from norbornene and cyclopentadiene. In the case of synthesizing tetracyclododecene, the selectivity can be improved by changing the temperature of each stage. The by-product during the synthesis of the tetracyclododecene derivative is mainly a compound obtained by further adding cyclopentadiene to a cyclopentadiene trimer and a tetracyclododecene derivative. The former is likely to be produced when the concentrations of cyclopentadiene and dicyclopentadiene are high, and the latter is likely to be produced when the concentrations of the tetracyclododecene derivative and cyclopentadiene are high. Therefore, on the upstream side of the reactor, dicyclopentadiene is actively decomposed to generate cyclopentadiene, and the temperature is set so that ethylene is more likely to undergo an addition reaction than norbornene.On the downstream side, the condition is such that cyclopentadiene is easily added to norbornene. By selecting, the yield of the tetracyclododecene derivative can be improved. For such conditions, the reaction rate of each elementary reaction is measured, and the temperature conditions and the concentration of each raw material are set so that the target reaction proceeds selectively. It is difficult to set such a temperature condition in a piston flow type reactor described later.

The cyclopentadiene derivative used in the present invention is cyclopentadiene, dicyclopentadiene or methyldicyclopentadiene. Among them, cyclopentadiene and / or dicyclopentadiene are industrially available at a low cost. preferable.

The olefin used in the present invention includes ethylene, propylene, 1-butene and trans-2.
-Butene, cis-2-butene and the like. From such an olefin and a cyclopentadiene derivative, a norbornene derivative is synthesized by a Diels-Alder reaction. The norbornene derivatives specifically synthesized include 2-norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5,6-dimethyl-2-norbornene, 1-methyl-2-norbornene, 5-dimethyl-2-norbornene, 1-methyl-5-ethyl-2
-Norbornene, 1,5,6-trimethyl-2-norbornene, 2-methyl-2-norbornene, 2,5-dimethyl-2-norbornene, 2-methyl-5-ethyl-2
-Norbornene, 2,5,6-trimethyl-2-norbornene and the like. In addition, 5-ethylidene-2-norbornene can be used.

When such a norbornene derivative, an olefin and a cyclopentadiene derivative are mixed under heating, a tetracyclododecene derivative is obtained as a Diels-Alder reaction product. For example, ethylene, 2-
From norbornene, cyclopentadiene and / or dicyclopentadiene, tetracyclododecene (1,
4,5,8-Dimethano-1,2,3,4,4a, 5
8,8a-octahydronaphthalene, sometimes referred to as TCD), propylene, 5-methyl-2-norbornene, cyclopentadiene and / or dicyclopentadiene are converted to methyltetracyclododecene (2-methyl-1,4,4). 5,8-dimethano-1,2,3,4,4a,
From 5,8,8a-octahydronaphthalene), 1-butene, 5-ethyl-2-norbornene, cyclopentadiene and / or dicyclopentadiene, ethyltetracyclododecene (2-ethyl-1,4,5,8) -Dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene), 2-butene, 5,6-dimethyl-
From 2-norbornene, cyclopentadiene and / or dicyclopentadiene, dimethyltetracyclododecene (2,3-dimethyl-1,4,5,8-dimethano-
1,2,3,4,4a, 5,8,8a-octahydronaphthalene) are obtained.

Also, without using an olefin, for example,
From ethylidene-2-norbornene and dicyclopentadiene and / or cyclopentadiene, ethylidenetetracyclododecene (2-ethylidene-1,4,5,8-
(E.g., dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene), a tetracyclododecene derivative can be prepared from a norbornene-based compound and cyclopentadiene and / or dicyclopentadiene. .

As a method for efficiently synthesizing a tetracyclododecene derivative, it is preferable to heat and react an olefin, a norbornene derivative, cyclopentadiene and / or dicyclopentadiene.

When mainly synthesizing a tetracyclododecene derivative, the cyclopentadiene and / or dicyclopentadiene to be supplied is based on the number of moles of dicyclopentadiene (ie, a mixture of 2 moles of cyclopentadiene and 1 mole of dicyclopentadiene). The liquid is calculated to be 2 moles of dicyclopentadiene), and its supply ratio with norbornenes is 2 to 20 in terms of molar ratio of norbornenes / dicyclopentadiene, preferably 3 to 1
5, more preferably 4-10. When the amount of norbornenes is large, the yield of the reaction is relatively low. The norbornene derivative is preferably separated and recovered and reused. Therefore, a large amount of norbornene impregnated is not very advantageous because a large amount of norbornene increases the amount of circulation used and requires a large amount of energy for distillation. 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 is reduced.

The amount of olefin is 0.5 to 50 in molar ratio to dicyclopentadiene (converted to dicyclopentadiene when cyclopentadiene is used).
And preferably 1 to 40, more preferably 1.2.
~ 30. When the molar ratio of the olefin to DCPD is less than 0.5, the amount of norbornenes formed is small, the amount of norbornenes used in the synthesis of tetracyclododecenes is increased, and the norbornene derivative is recycled. Is undesirable because the amount of the norbornene derivative decreases. Further, addition of a large excess of olefin is not preferable because a large amount of energy is consumed during olefin recovery.

In this reaction, the reaction temperature is 170-28.
0 ° C. Preferably it is 180-260 degreeC, More preferably, it is 200-250 degreeC. If the reaction temperature is high, heavy components are easily generated, and if the reaction temperature is low, the reaction is difficult to proceed, and efficient production cannot be performed.

In the present invention, a preheater may be provided before the tank reactor. As the heating method, any heating method such as a method using hot oil in a double tube, a method using steam, and a method using electricity can be adopted.

In this reaction, the liquid hourly space velocity LHSV
= 0.1-10. Preferably LHSV = 0.3-
8, more preferably LHSV = 0.5-6. LH
If the SV exceeds 10, unreacted substances are large and efficient production cannot be performed. On the other hand, when the LHSV is less than 0.1, the production of heavy substances increases, and the effective yield of the raw material decreases. Also, the output per hour decreases.

Although the stirring rotation speed is optional,
It is preferable to increase the rotation speed because the Reynolds number increases. For example, it is preferable to select the rotation speed so that the Reynolds number is 1 or more.

In the present invention, the Diels-Alder reaction product can be purified from the reaction mixture by any method. Preferably, the method includes a step of separating an unreacted olefin, a step of separating a norbornene derivative, a step of separating unreacted dicyclopentadiene, and a step of separating and purifying a tetracyclododecene derivative. The olefin, norbornene derivative and dicyclopentadiene separated here can be reused as raw materials.

In the present invention, a solvent can be used. In the method of the present invention, the boiling point at normal pressure is 50
It is preferred to use a solvent that is ~ 180 ° C. Its purpose is to reduce the concentration of each component and to reduce heavy components which are by-products, and to prevent solidification particularly when 2-norbornene is used. Therefore, the boiling point is preferably close to that of 2-norbornene. Aromatic and aliphatic hydrocarbons having 6 to 8 carbon atoms are suitable.

Specifically, benzene, toluene, xylene, cyclohexane, methylcyclohexane, dimethylcyclohexane and the like can be mentioned. 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, methylcyclohexane, dimethylcyclohexane, and ethylcyclopentane are preferably used. Here, isohexane, isoheptane, and isooctane refer to compounds having a methyl group or higher branch, and can be used regardless of the substitution position, isomer, etc. 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-methyl Heptane,
2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, 2,
Examples include 3,4-trimethylpentane and 2,3,3-trimethylpentane. Dimethylcyclohexane, for example, any of 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, and 1,4-dimethylcyclohexane can be used, and can be used regardless of the relative substitution positions of two methyl groups.

In this reaction, an antioxidant and a polymerization inhibitor can be appropriately added to the reaction raw materials. For example, phenolic compounds such as hydroquinone, 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol, 4-methoxyphenol, N, N-dimethylhydroxylamine, A hydroxylamine compound such as N, N-diethylhydroxylamine is suitably added. The addition amount is usually in the range of 10 to 10000 ppm, preferably 50 to 5000 ppm, based on the total amount of the reaction raw materials supplied into the reactor. Of course, it can be similarly added to tetracyclododecene as a product. Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.

[0040]

EXAMPLE 1 Norbornene and dicyclopentadiene having a purity of 95% were mixed at a molar ratio of 4: 1 and fed using a pump, and ethylene was mixed with the norbornene at a molar ratio of 1: 4.
Were continuously combined using a mass flow controller, and introduced continuously at a LHSV = 1 from the lower part of a tank reactor having an inner diameter of 100 mm and a length of 300 mm. In this tank reactor, six turbine blades with a diameter of 98 mm were installed,
It is stirred at 500 revolutions per minute.

The mixed solution was continuously withdrawn from the upper part of the reactor, and the reaction system was maintained at 5 MPa using a pressure regulating valve. The reactor was maintained at 200 ° C. (reactor inlet temperature) to 230 ° C. (reactor outlet temperature) with hot oil. The yield of tetracyclododecene was 8 based on the charged dicyclopentadiene.
8%, 1% of an adduct of tetracyclododecene and cyclopentadiene, 3% of cyclopentadiene trimer, 4% of norbornene yield, and 4% of raw material recovery.
Met. The continuous operation for 250 days was able to be performed smoothly, and no deposits were found on the inner wall of the reactor.

[0042]

Comparative Example 1 The procedure was performed in the same manner as in Example 1 except that the vessel type reactor had one blade and was a complete mixing type reactor. The yield of tetracyclododecene is 84% based on the charged dicyclopentadiene, the adduct of tetracyclododecene and cyclopentadiene is 6%, and cyclopentadiene 3
The monomer was 7%, the norbornene yield was 0%, and the raw material recovery was 3%. Although the continuous operation for 250 days was able to be performed smoothly, deposits were found on the inner wall of the reactor, particularly on the upper part.

[0043]

Comparative Example 2 Noritake Static Mixer (C2
6-18 series, inner diameter 8 mmφ, 12 elements, total length 155 mm) and the reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 230 ° C. The yield of tetracyclododecene was 87% based on the charged dicyclopentadiene, the adduct of tetracyclododecene and cyclopentadiene was 5%, and the trimer of cyclopentadiene was 5%.
The norbornene yield was 0% and the raw material recovery was 3%. Although the continuous operation for 250 days was able to be performed smoothly, deposits were found on the element and the inner wall of the reactor.

[0044]

According to the method for producing a Diels-Alder reaction product of the present invention, the Diels-Alder reaction proceeds smoothly by passing an olefin compound and a cyclopentadiene derivative through a tank reactor and mixing by heating. In the production of tetracyclododecene derivatives using norbornene as a raw material, stable operation over a long period of time is possible, and in particular, efficient stirring is performed in the production of tetracyclododecene, and prevention of adhesion of deposits such as polymers is achieved. The target object can be manufactured efficiently.

[Brief description of the drawings]

FIG. 1 shows a sectional view of a tank reactor used in the present invention.

FIG. 2 shows a stirring blade for a tank reactor used in the present invention.

[Explanation of symbols]

1: stirrer, 2: stirring blade, 3: rotating shaft, 4, 5: inlet and outlet of fluid.

Claims (1)

[Claims] When a Diels-Alder reaction is carried out by heating a mixture containing an olefin compound and a cyclopentadiene derivative, a reaction solution inlet and an outlet are provided at both ends, and a rotating shaft vertically installed inside the container is provided. A method for producing a Diels-Alder reaction product, wherein the mixture is continuously supplied to a vertical tank reactor equipped with a plurality of stages of stirring blades extending horizontally from the rotation axis.