JPH08253435A - Production of high-purity 1,3-cyclohexadiene - Google Patents

Abstract

PURPOSE: To enable the suppression of the formation of hardly separable by- products and obtain an ultrahigh-purity 1,3-cyclohexadiene in high yield under liquid-phase reactional conditions. CONSTITUTION: This method for producing the high-purity 1,3-cyclohexadiene is to use an insoluble inorganic or organic ion exchanger in which at least a part of cations are a protonic type as a catalyst and previously make water coexist in the reactional system in the liquid-phase dehydrating reaction of 2-cyclohexen-1-ol. The inorganic ion exchanger is preferably a crystalline aluminosilicate and the organic ion exchanger is preferably a strong acidic cation exchange resin. The amount of the water previously made to coexist is 0.2-5000 times based on the amount of the 2-cyclohexen-1-ol.

Description

Detailed Description of the Invention

[0001]

The present invention relates to 2-cyclohexene-
The present invention relates to a method for producing 1,3-cyclohexadiene by a dehydration reaction of 1-ol. More specifically, high purity characterized by using an inorganic or organic ion exchanger insoluble in the liquid phase as a catalyst and at least a part of cations being proton type, and allowing water to coexist in advance in the reaction system. The present invention relates to a method for producing 1,3-cyclohexadiene. 1,3-Cyclohexadiene is a very useful compound as a raw material for synthesizing a 6-membered carbon ring derivative having a plurality of substituents and a derivative by the Diels-Alder reaction, and as a raw material for a diene polymer and a copolymer.

[0002]

2. Description of the Related Art By directly dehydrating alcohol,
There are many known examples of methods for obtaining the corresponding olefins. For example, J. By March ”
Advanced Organic Chemistr
y ", 3rd edition, paragraphs 901-903 (1985), these dehydration reactions usually use a strong acid catalyst such as sulfuric acid, phosphoric acid or sulfonic acid in the liquid phase.
Alternatively, it is performed at a high temperature using a metal oxide such as alumina in a vapor phase.

From 2-cyclohexen-1-ol 1,
As a method for synthesizing 3-cyclohexadiene, a dehydration reaction in a gas phase using an alumina catalyst (V
estsi Akad. Navuk Beloruss
k. SSR, Ser. Khim. Navuk, (2) 2
0-4 (1965)) and a method of carrying out the same dehydration reaction using an alumina-boria catalyst (Dokl. Akad.
Nauk. Belorussk. SSR, 14 (8) 7
34-7 (1970)) and the like. By these methods, 1,3-cyclohexadiene is obtained in a high yield of 90% or more.

A method of dehydration reaction in a liquid phase using an anhydrous copper sulfate catalyst (J. Org. Chem., 4
5, 917-919 (1980)) has been reported.
However, with this method, the yield is only as low as 52%.
3-Cyclohexadiene has not been obtained.

[0005]

The method by the vapor phase dehydration reaction from 2-cyclohexen-1-ol described above is an excellent method in that 1,3-cyclohexadiene can be obtained in a high yield. However, according to the studies by the present inventors, in the case of these gas phase dehydration reactions, methylcyclopentenes, cyclohexene, 1, and 1, as by-products due to the progress of isomerization reaction or disproportionation reaction of 1,3-cyclohexadiene produced. 4-Cyclohexadiene, benzene and the like are produced, and there is a problem that it is difficult to suppress them sufficiently under the high reaction temperature conditions required for the gas phase reaction. And, these by-products have a vapor pressure extremely close to that of 1,3-cyclohexadiene, and it is practically impossible to carry out the distillation separation which is usually used industrially. There has been a problem that a complicated separation and purification method is required to obtain cyclohexadiene.

On the other hand, in the liquid phase dehydration reaction of 2-cyclohexen-1-ol using a known acid catalyst such as sulfuric acid, phosphoric acid and sulfonic acid, the present inventors have found that
The selectivity of 3-cyclohexadiene was extremely low, which was not sufficient as an industrial method.

However, since the liquid phase dehydration reaction itself can select a low reaction temperature condition for the gas phase dehydration reaction, the above-mentioned isomerization reaction or disproportionation reaction of 1,3-cyclohexadiene can be suppressed. Since other by-products are compounds having a high boiling point, they have an advantage that highly purified 1,3-cyclohexadiene can be obtained by industrially convenient distillation separation.

Thus, the method of performing dehydration reaction in a liquid phase using a copper sulfate anhydride catalyst is an advantageous method for obtaining highly pure 1,3-cyclohexadiene. As shown, the yield of 1,3-cyclohexadiene is 52%.
However, industrially, a method for producing 1,3-cyclohexadiene in a higher yield was desired.

The present invention solves the above-mentioned problems of the prior art and is a method in which a liquid phase dehydration reaction is extremely advantageous for obtaining highly pure 1,3-cyclohexadiene from 2-cyclohexen-1-ol. It is an object of the present invention to provide a method for producing 1,3-cyclohexadiene at a high yield which has never been achieved while making use of the above points.

[0010]

In order to solve the above problems, the present inventors use 2-cyclohexen-1-ol as a starting material and industrially produce highly pure 1,3-cyclohexadiene. As a result of extensive studies on the method, the inventors have found that 1,3-cyclohexadiene can be produced in high yield under the liquid phase reaction condition with the catalyst of the present invention, and arrived at the present invention.

That is, according to the present invention, when 1,3-cyclohexadiene is produced from 2-cyclohexen-1-ol by a dehydration reaction in a liquid phase, it is insoluble as a catalyst,
A method for producing high-purity 1,3-cyclohexadiene, which comprises using an inorganic or organic ion exchanger in which at least a part of cations is a proton type and allowing water to coexist in the reaction system in advance.

According to this invention, 1,3-
Cyclohexadiene can be obtained, for example, when using a reactive distillation operation, usually about 70% or more, preferably 80% or more.
1,3-Cyclohexadiene can be obtained with a yield of at least%. At the same time, methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene, by-products such as benzene, which are difficult to easily separate from 1,3-cyclohexadiene, can be suppressed, and the reaction solution is simply purified by distillation. It is possible to obtain high quality 1,3-cyclohexadiene having a purity of 99.5% or more.

The present invention will be described in detail below. 2-Cyclohexen-1-ol used in the present invention is
What was manufactured by a well-known method can be used. For example, those produced by a method of decomposing cyclohexenyl hydroperoxide obtained by autoxidizing cyclohexene with an alkaline aqueous solution or a method of reducing 2-cyclohexen-1-one with a metal hydride or the like can be used.

In the present invention, an insoluble inorganic or organic ion exchanger in which at least a part of cations is a proton type is used as a catalyst. The inorganic ion exchanger is an ion exchanger having an inorganic substrate, and examples thereof include activated clay, diatomaceous earth, aluminum silicate, natural zeolites, and synthetic zeolites. It is preferable to use crystalline aluminosilicate, specifically, ferrierite, ZSM-5, ZSM-5 analogue, ZSM-
11, mordenite, X, L, Y type zeolite, zeolite β and the like can be used.

ZSM-5 as a zeolite similar to ZSM-5
-8 (see German Patent 2,049,755),
ZETA-1 (see German Patent 2,548,697), ZETA-3 (see British Patent 1,553,209), NU-4 (German Patent 3,268,50).
3), NU-5 (German Patent 3,169,
606), TZ-01 (US Pat. No. 4,58).
No. 1,216), Crystalline
aluminosilicate (US Pat. No. 4,955)
No. 4,326), TRS (German Patent 2,9)
24,870), MB-28 (European patent 2).
1,445), TSZ (JP-A-58-45)
111), AZ-1 (European Patent 113,1).
No. 16 specification).

It is more preferable to use a hydrophobic crystalline aluminosilicate in which the molar ratio of silica to alumina forming a crystal lattice is 10 or more, and specifically, Z is used.
It is preferable to use SM-5, zeolite β, or the like.

The crystalline aluminosilicate used in the present invention may be a proton-type ion-exchanged product by a well-known method. Some of the exchangeable cation species of the crystalline aluminosilicate are, for example, alkali metal elements. It does not matter even if it is replaced by an alkaline earth metal element or the like. As the crystalline aluminosilicate, one produced by a known method can be used, and it can be used as a powder or as a molded body depending on the reaction form used. At this time, the particle size is not particularly limited.

The organic ion exchanger used in the present invention is an ion exchanger having an organic substrate, for example, a copolymer of styrene and divinylbenzene having a polymer structure having a cation exchange group bonded thereto or acrylic acid. Alternatively, there may be mentioned insoluble resins obtained by copolymerizing methacrylic acid with divinylbenzene. It is preferable to use a strong acidic cation exchange resin in which a small amount of divinylbenzene is copolymerized with styrene of a polymerization system to form a three-dimensional network structure and a sulfonic acid group is introduced. More preferably, a macroporous strongly acidic cation exchange resin having a porous body with physical pores obtained by adding a special organic solvent during suspension polymerization when producing an ion exchange resin is used. Good.
The cation of the ion exchange resin can be used after being converted into a proton type at an arbitrary ion exchange rate by performing a normal ion exchange operation.

The ion exchange resin used in the present invention should be in the form of small particles or a fibrous shape depending on the reaction form used and reaction conditions, taking into consideration the resin pulverization due to mechanical disintegration and heat resistance. You can

The inorganic or organic ion exchanger in which at least a part of cations is a proton type used in the present invention is insoluble in the reaction system. In the case of a liquid phase dehydration reaction of 2-cyclohexen-1-ol using a known acid catalyst such as sulfuric acid, phosphoric acid or sulfonic acid, the corrosiveness of the device is large, and the catalyst is prepared from a homogeneous reaction liquid in which the catalyst is dissolved. Although there is a problem that a complicated operation is required when separating and recovering, the present invention has these drawbacks improved and has a great advantage in industrial implementation.

In the present invention, 2-cyclohexene-
When 1,3-cyclohexadiene is produced by a liquid phase dehydration reaction of 1-ol, it is characterized in that water is allowed to coexist in the reaction system in advance. The reaction of desorbing water from 2-cyclohexen-1-ol in the liquid phase is an equilibrium reaction, and it is possible to obtain 1,3-cyclohexadiene in good yield by allowing water to coexist in the reaction system beforehand.
This is a surprising finding that has never been expected. In the present invention, the amount of water to be coexisted in advance is in the range of 0.2 to 5000 times by weight the amount of 2-cyclohexen-1-ol, and can be changed depending on the reaction form and the type of catalyst used.

In the present invention, the catalyst in the reaction system is preferably present in the continuous phase of water which is allowed to coexist in advance. For example, in the case of the batch system, a large amount of water capable of dissolving the entire amount of charged 2-cyclohexen-1-ol may be allowed to coexist and brought into contact with the catalyst as an aqueous solution of a homogeneous phase. Further, it is possible to coexist with an amount of water in which the whole amount of the charged 2-cyclohexen-1-ol cannot be dissolved, but at that time, the catalyst may exist substantially in the aqueous phase separated into two phases. preferable.

In the present invention, the reason why it is preferable to allow water to coexist in the reaction system beforehand is that 1,3-cyclohexadiene produced by the dehydration reaction of 2-cyclohexen-1-ol is re-adsorbed on the catalytic active site. It is considered that this is because it is possible to significantly suppress As a result, formation of a polymer by-product due to a polymerization reaction of 1,3-cyclohexadiene having high reactivity is suppressed, and as a result, the yield of 1,3-cyclohexadiene can be improved. together,
The above-mentioned action of the cationic acid site of the proton type inorganic or organic ion exchanger having an appropriate strength is
Isomerization or disproportionation reaction of 3-cyclohexadiene can be significantly suppressed, and as a result, methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene, which are difficult to separate in the purification step of 1,3-cyclohexadiene. By-products such as benzene and benzene can be significantly reduced.

Due to these effects, 1,3-cyclohexadiene can be obtained in a high yield. For example, when a reactive distillation operation is used, it is usually about 70% or more, preferably 80%.
1,3-Cyclohexadiene can be obtained with the above yield. At the same time, methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene, by-products such as benzene, which are difficult to easily separate from 1,3-cyclohexadiene, can be suppressed, and the reaction solution is simply purified by distillation. High quality 1, with a purity of over 99.5%
3-Cyclohexadiene can be obtained.

The reaction temperature for carrying out the liquid phase dehydration reaction in the present invention is in the range of 50 ° C. to 160 ° C., preferably 60 ° C.
To 140 ° C, more preferably 70 ° C to 12
It is in the range of 0 ° C. If the reaction temperature is less than 50 ° C., the reaction rate will be extremely reduced, and if the reaction temperature exceeds 160 ° C., side reactions will increase rapidly, which is not preferable. This reaction temperature can be changed in the range of 50 ° C to 160 ° C depending on the type of catalyst used and other reaction conditions.

The reaction pressure is not particularly limited as long as it can maintain the reaction system in the liquid phase. It can be performed under reduced pressure or increased pressure in addition to atmospheric pressure conditions. The liquid phase reaction system of the present invention may be a conventional batch system, semi-batch system, or continuous system.

The amount of the catalyst used varies depending on the type and form of the catalyst used, the amount of water to be coexisted in advance, and the reaction mode, and therefore cannot be specified unconditionally. For example, in a batch reaction mode, charged 2-cyclohexene is used. −
When coexisting with an amount of water in which the total amount of 1-ol cannot be dissolved, it is preferable that the catalyst is present in an aqueous phase substantially separated into two phases. In this case, charged 2-cyclohexene-1 is used. -The catalyst may be added in an amount of 0.01 to 10 times by weight the amount of all, and the reaction may be performed under stirring within the above temperature range.

In the case of the continuous system, the catalyst concentration may be higher due to the relationship between the dehydration reaction rate and the 2-cyclohexen-1-ol feed rate. The reaction time varies depending on the type of catalyst used, the reaction conditions and the desired reaction rate, but is usually in the range of 0.1 to 8 hours. This reaction can be carried out in the presence of an inert gas such as nitrogen, hydrogen, helium or argon.

The present invention is not limited to the reaction system as long as the reaction is carried out in the liquid phase. For example, a so-called fixed bed flow reaction may be used in which a pellet-shaped catalyst is packed in an adiabatic or isothermal reactor, and 2-cyclohexen-1-ol and a predetermined amount of water are simultaneously supplied thereto, or a batch system. Although 2-cyclohexen-1-ol, a predetermined amount of water and a catalyst are charged into a stirred tank reactor and reacted for a predetermined time, the reaction product can be separated from the catalyst and recovered, but in any case. Also, the reaction is preferably carried out so that the produced 1,3-cyclohexadiene and water can be removed from the reaction system as quickly as possible.

The reason is that it is possible to prevent the 1,3-cyclohexadiene produced from being polymerized and consumed by contact with the catalyst for a long time, and it is possible to further exhibit the effect of allowing water to coexist in the reaction system in advance. For example, in the case of a batch reaction, a so-called reactive distillation type reaction form in which 1,3-cyclohexadiene produced by the reaction and water are withdrawn from the upper part of a distillation column installed in the upper part of the reactor can be preferably used.

According to the method of the present invention, 1,3-
Cyclohexadiene can be obtained, for example, when using a reactive distillation operation, usually about 70% or more, preferably 80% or more.
1,3-Cyclohexadiene can be obtained with a yield of at least%. At the same time, methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene, by-products such as benzene, which are difficult to easily separate from 1,3-cyclohexadiene, can be suppressed, and the reaction solution is simply purified by distillation. It is possible to obtain high quality 1,3-cyclohexadiene having a purity of 99.5% or more.

[0032]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Example 1 1) Synthesis of crystalline aluminosilicate 128 g of sodium silicate (water glass No. 3) was dissolved in 120 g of water (solution A). 2. Aluminum sulfate octadecahydrate
9 g and 4 g of concentrated sulfuric acid were dissolved in 40 g of water (solution B).
20 g of 1,3-dimethylurea was dissolved in 80 g of water.
(C liquid). Using a homogenizer, solution A was vigorously stirred and mixed with solutions B and C, and stirring was continued for 1 hour.

The gel thus obtained was heated and crystallized at 150 ° C. for 40 hours while stirring at a stirring peripheral speed of 2 m / sec. The obtained product was filtered, washed with water, dried at 120 ° C. for 5 hours, and then baked in air at 500 ° C. for 5 hours to remove organic substances. Then, this product was subjected to ion exchange in 1N nitric acid for 8 hours, filtered, washed, and dried at 120 ° C. for 6 hours to obtain a proton type crystalline aluminosilicate. The obtained product was analyzed by X-ray diffraction and found to be zeolite ZSM-
5 was identified.

2) Dehydration reaction of 2-cyclohexen-1-ol 200 g of water was charged into a 500 ml glass flask attached to a small distillation column filled with Dixon packing and 20 g of the crystalline aluminosilicate obtained in 1).
To suspend. Then, 100 g of 2-cyclohexen-1-ol was added, and a small amount of nitrogen gas was blown thereinto, and the mixture was stirred while being heated in an oil bath set to 100 ° C. The mixture of 1,3-cyclohexadiene and water that distilled out was collected while receiving it in a receiver.

Since the distillation was completed in about 4 hours, the organic layer and the aqueous layer were separated and the amount of the organic layer produced was measured and quantified by gas chromatography. Table 1 shows the production yield of the recovered 1,3-cyclohexadiene based on the charged 2-cyclohexen-1-ol. In addition, the purity of 1,3-cyclohexadiene fraction and 1,3-excluding traces of water are excluded.
The content of impurities in cyclohexadiene is shown.

According to this example, 1,
3-Cyclohexadiene was obtained. The organic layer substantially contains only 1,3-cyclohexadiene, and the content of impurities that are difficult to separate from 1,3-cyclohexadiene such as methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene and benzene is low, and 99. A high quality 1,3-cyclohexadiene having a purity of 5% or more was obtained.

Example 2 Zeolite β (C manufactured by PQ Corporation as a catalyst
-806β ion-exchanged to proton type) 20 g
Was used for the reaction in the same manner as in Example 1 for 4 hours. The results are shown in Table 1. Similar to Example 1, with high yield,
Moreover, high quality 1,3-cyclohexadiene was obtained.

Example 3 As a catalyst, 20 g of a strong acid cation exchange resin (trade name: Amberlyst 15) manufactured by Rohm and Haas was used.
Reaction was carried out for 4 hours in the same manner as in Example 1. The results are shown in Table 1. As in Example 1, high-quality and high-quality 1,3-cyclohexadiene was obtained.

Comparative Example 1 40 g of copper sulfate anhydride and 2-cyclohexen-1-ol 20 were used as catalysts in a 500 ml glass flask attached to a small distillation column filled with Dickson packing.
0 g was charged, and the system pressure was maintained at 600 mmHg while blowing a small amount of nitrogen gas. Then, the mixture was stirred while being heated in an oil bath set at 120 ° C. The mixture of 1,3-cyclohexadiene and water that distilled out was collected while receiving it in a receiver. Since the distillation was completed in about 2 hours, quantitative analysis was performed by the same operation as in Example 1. The results are shown in Table 1.
Shown in The yield is low as compared with Examples 1 to 3, and
No 1,3-cyclohexadiene having a purity of 99.5% or higher was obtained.

Comparative Example 2 The reaction was carried out for about 2 hours in the same manner as in Comparative Example 1 except that 10 g of concentrated sulfuric acid was used as the catalyst, the system pressure was atmospheric pressure, and the set temperature of the oil bath was 100 ° C. The results are shown in Table 1. The yield was remarkably low as compared with Examples 1 to 3, and 1,3-cyclohexadiene having a purity of 99.5% or more could not be obtained as in Comparative Example 1.

[0042]

[Table 1]

Example 4 200 g of water was charged into a small distillation apparatus equipped with a 500 ml flask, and 20 g of the crystalline aluminosilicate obtained in Example 1 was suspended. Then, 100 g of 2-cyclohexen-1-ol was added, and a small amount of nitrogen gas was blown thereinto, and the mixture was stirred while being heated in an oil bath set to 100 ° C. After a mixed liquid of 1,3-cyclohexadiene and water began to distill from the top of the distillation column, 22 g of 2-cyclohexen-1-ol was placed inside the reactor using a metering pump.
A mixture of 1,3-cyclohexadiene and water, which was continuously supplied at a speed of 1 / hour and continuously distilled, was received and collected in a receiver.

After the reaction was continued for 20 hours, the organic layer substantially containing only 1,3-cyclohexadiene was separated from the aqueous layer from the recovered fraction, and the recovered amount of the organic layer was measured.
It was quantified by gas chromatography. In this way, a total of 540 g of 2-cyclohexen-1-ol was reacted to obtain 371 g of 1,3-cyclohexadiene having a purity of 99.72%. The yield of 1,3-cyclohexadiene was 84%. Further, during this period, the amount of distillate was not significantly decreased, and 1,3-cyclohexadiene was stably obtained.

Comparative Example 3 A small distillation apparatus similar to that used in Example 4 was charged with 2-cyclohexene-
200 g of 1-ol and 40 g of the crystalline aluminosilicate obtained in Example 1 were charged, the pressure in the system was kept at 550 mmHg while blowing a small amount of nitrogen gas, and then the reaction was started in the same manner as in Example 4. . After a mixed liquid of 1,3-cyclohexadiene and water began to distill from the top of the distillation column, 2-cyclohexen-1-ol was fed into the reactor at a rate of 44 g / hour using a metering pump, The reaction was continuously performed in the same manner as in 4.

The amount of distillate decreased with time, and no distillate was observed after 6 hours, so the reaction was terminated.
Thus, a total of 464 g of 2-cyclohexene-1
-Reacting all, with a purity of 99.61% 1,
204 g of 3-cyclohexadiene was obtained. The yield of 1,3-cyclohexadiene was 54%. Compared with the results of Example 4 in which water was previously allowed to coexist in the reaction system, the yield was low, and 1,3-cyclohexadiene could not be stably obtained.

Comparative Example 4 γ-alumina catalyst (manufactured by JGC Corporation: γ-trade name N611N)
Alumina was crushed to 10 to 20 mesh and calcined at 500 ° C.) 20 ml was packed in the center of a glass tubular reactor, and a glass ring was filled in the upper part of the reactor.
It was heated from the outside in an electric furnace. The catalyst layer was previously heated to a predetermined temperature in a nitrogen stream, and 2-cyclohexen-1-ol was injected from the top at 2.6 g / hour using a metering pump.

The reaction product solution exited from the lower part of the reaction and was collected using a water cooling tube, an ice trap, and a dry ice-methanol trap. The organic layer and aqueous layer of the collected liquid are separated,
Quantitative analysis of each layer by gas chromatography,
1, to the supplied 2-cyclohexen-1-ol
The production yield of 3-cyclohexadiene was determined. Then,
Separation and purification of 1,3-cyclohexadiene from the organic layer was performed by a distillation operation, and the purity of the collected 1,3-cyclohexadiene fraction and the content of impurities in 1,3-cyclohexadiene excluding a trace amount of water were measured. I asked. Table 2 shows the results
Shown in Although 1,3-cyclohexadiene can be obtained in high yield in these gas phase reactions, 1,3-cyclohexadiene has a large content of impurities which are difficult to separate from 1,3-cyclohexadiene, and 1,3-cyclohexadiene having a purity of 99.5% or more. No cyclohexadiene was obtained.

[0049]

[Table 2]

[0050]

As described above, the first and third aspects of the present invention
-A method for producing cyclohexadiene, in the dehydration reaction of 2-cyclohexen-1-ol, an insoluble inorganic or organic ion exchanger in which at least a part of cations is a proton type is used as a catalyst, and By allowing water to coexist in advance, it was possible to produce 1,3-cyclohexanediene with high yield and high purity.

That is, according to the method of the present invention, 1,3-cyclohexadiene can be obtained in a high yield. For example, it is usually about 70% or more, preferably 80% or more when a reactive distillation operation is used. 1,3-Cyclohexadiene can be obtained in a yield. At the same time, methylcyclopentenes,
By-products such as cyclohexene, 1,4-cyclohexadiene and benzene, which are difficult to be easily separated from 1,3-cyclohexadiene, can be remarkably suppressed. By distilling and purifying the reaction solution, 99.5% can be obtained. High-quality 1,3-cyclohexadiene having the above purity can be produced.

These excellent effects of the present invention are achieved by using an insoluble inorganic or organic ion exchanger in which at least a part of the cation is a proton type as a catalyst and allowing water to coexist in the reaction system in advance. However, it cannot be exhibited at all when an acid catalyst as disclosed above is used. As described above, the method for producing 1,3-cyclohexadiene of the present invention is excellent, and it can be said that the method has a high industrial utility value when obtaining highly pure 1,3-cyclohexadiene.

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Claims (4)

[Claims] 1. Inorganic or organic ion exchange, in which 1,3-cyclohexadiene is produced by a liquid phase dehydration reaction of 2-cyclohexen-1-ol, insoluble as a catalyst, and at least a part of cations is a proton type. A method for producing high-purity 1,3-cyclohexadiene, which comprises using a body and allowing water to coexist in the reaction system in advance. 2. The method according to claim 1, wherein the inorganic ion exchanger is a crystalline aluminosilicate. 3. The method according to claim 1, wherein the organic ion exchanger is a strongly acidic cation exchange resin. 4. The amount of water to be coexisted in advance is 0.2 to 5000 with respect to the amount of 2-cyclohexen-1-ol.
The method according to any one of claims 1 to 3, wherein the weight is multiplied by weight.