JPH07118177A - Production of 1,3-cyclohexadiene - Google Patents

Abstract

PURPOSE:To obtain 1,3-cyclohexadiene selectively in high yield. CONSTITUTION:1,3-cyclohexadiene can be obtained by bringing cyclohexene oxide into contact with a phosphate as catalyst in a gaseous phase. In this case, it is preferable that the phosphate contain a group IIA metal (esp. calcium or magnesium), being a tertiary phosphate. By using this catalyst, the objective 1,3-cyclohexadiene can be obtained selectively in high yield. Along with this, by-products hard to separate from the 1,3-cyclohexadiene can be suppressed significantly, therefore, obtaining the objective high-quality 1,3-cyclohexadiene in high stability. These aspects are very advantageous in conducting the above production on an industrial scale.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 1,3-cyclohexadiene. More specifically, the present invention relates to a catalyst having excellent activity and selectivity which is useful in producing 1,3-cyclohexadiene from cyclohexene oxide.

1,3-Cyclohexadiene is a very useful compound as a raw material for synthesizing a carbon 6-membered ring derivative having a plurality of substituents and a derivative by the Diels-Alder reaction, and as a raw material for diene polymers and copolymers. is there.

[0003]

2. Description of the Related Art Conventionally, 1,3-cyclohexadiene is
It is known that they can be produced by methods such as dehydrohalogenation of 3-halogenocyclohexene and 1,2-dihalogenocyclohexane, deacetic acid of 3-acetoxycyclohexene, dehydration of 1,4-cyclohexanediol, etc. However, it has drawbacks such as a low reaction selectivity and is not sufficient as an industrial production method.

On the other hand, 1,3 from cyclohexene oxide
As a method for producing cyclohexadiene, a method of contacting cyclohexene oxide with alumina, titania, zirconia or the like in a gas phase (Billettan of Chemical Society of Japan, Vol. 49, 563)
, 1976), and a method of contacting cyclohexene oxide with silica-titania or silica-titania-magnesia in a liquid phase (JP-A-57-26).
The method described in Japanese Patent No. 628) is disclosed.

[0005]

However, in the above method, the conversion ratio of cyclohexene oxide to 1,3-cyclohexadiene is still low, and although it has not been illustrated, according to the studies by the present inventors, 1, As a by-product, methylcyclopentenes, cyclohexene, 1,
It was found that 4-cyclohexadiene, benzene and the like were produced in large amounts.

These by-products are 1,3-target products.
It has a vapor pressure very close to that of cyclohexadiene and is difficult to easily separate from 1,3-cyclohexadiene by a conventional purification method such as distillation. However, it has drawbacks such as reduced purity.

Further, since the amount of production of these undesired by-products increases in proportion to the conversion of cyclohexene oxide, when it is attempted to obtain 1,3-cyclohexadiene in high yield and high purity, It is expected that a great deal of labor will be required for separating and refining the product, and this is not sufficient as an industrial production method. In addition, the method (1) requires a large amount of catalyst and a long reaction time, and the productivity of 1,3-cyclohexadiene is low. Furthermore, since it is difficult to control the contact time between the produced 1,3-cyclohexadiene and the catalyst, 1,3-cyclohexadiene itself is polymerized and consumed in the reaction solution, or the catalyst is formed by the produced polymer. It easily deteriorates. The fact is that this problem must always be taken into consideration as long as the reaction is carried out by the liquid phase method.

[0008]

The present inventors have used cyclohexene oxide as a starting material to solve the above problems,
As a result of extensive studies on a method for industrially producing 1,3-cyclohexadiene, it was found that 1,3-cyclohexadiene can be stably produced with high selectivity and high yield, and the present invention has been completed. Came to do. That is,
The present invention relates to a method for producing 1,3-cyclohexadiene, which comprises contacting cyclohexene oxide with phosphate in a gas phase.

According to the method of the present invention, 1,3-cyclohexadiene can be produced usually in a yield of about 60% or more, preferably 80% or more. At the same time, by-products such as methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene and benzene, which are difficult to be easily separated from 1,3-cyclohexadiene, can be significantly suppressed, and the reaction solution is purified by distillation. By itself, high-quality 1,3-cyclohexadiene having a purity of 98% or more can be obtained. Further, it is possible to suppress the deterioration of the catalyst which is considered to be caused by the polymerization reaction of 1,3-cyclohexadiene, and it is possible to stably produce 1,3-cyclohexadiene.

The present invention will be described in detail below. The cyclohexene oxide used in the present invention may contain a small amount of alcohol or a small amount of water and may be used in particular. In the present invention, it is necessary to use phosphate as a catalyst. As the phosphate, apatite, orthophosphate, pyrophosphate, metaphosphate or the like can be used. If these are represented by general formulas, the following formulas (1), (2) and (3) can be used. It is either a formula or a formula (4).

[0011]

[Chemical 1] (Z in the formula is a hydroxyl group, a fluorine atom, or a chlorine atom. N represents a real number of 0 or more and 5 or less.)

[0012]

[Chemical 2] (N in the formula represents a real number of 0 or more and 3 or less.)

[0013]

[Chemical 3] (N in the formula represents a real number of 0 or more and 2 or less.)

[0014]

[Chemical 4] (N in the formula represents a real number of 0 or more and 2 or less.)

A and B in the formula (1), (2), (3) or (4) are metal cations, and examples of these are Mg, Ca, Sr, Ba, Ti and Z.
r, Hf, Cr, Mn, Fe, Co, Ni, Cu, Z
n, Cd and the like. As the phosphate, one containing one kind of metal cation or one containing two kinds of metal cations can be used.

Specifically, the phosphate is Mg ₃ (P
O ₄ ) ₂ , Mg ₂ P ₂ O ₇ , Mg ₂ (PO ₃ ) ₄ , Ca
₃ (PO ₄ ) ₂ , Ca ₅ (PO ₄ ) ₃ OH, Ca ₅ (P
O ₄ ) ₃ Cl, Ca ₅ (PO ₄ ) ₃ F, Ca ₂ P
₂ O ₇ , Ca (PO ₃ ) ₂ , (Ca ・ Cd) ₃ (P
O ₄ ) ₂ , (Ca ・ Ni) ₃ (PO ₄ ) ₂ , Sr ₃ (P
O ₄ ) ₂ , Sr ₂ P ₂ O ₇ , Ba ₃ (PO ₄ ) ₂ , Ba
₂ P ₂ O ₇ , Zr ₃ (PO ₄ ) ₂ , Co ₃ (P
O ₄ ) ₂ , Ni ₃ (PO ₄ ) ₂ , Cu ₃ (PO ₄ ) ₂ ,
Zn ₃ (PO ₄ ) ₂ or the like can be used. Of course, it does not matter if they are used together.

Preferably, a phosphate containing at least one group IIA metal of the periodic table, more preferably a phosphate containing Ca or Mg, or Mg ₃ (P
O ₄ ) ₂ , Ca ₃ (PO ₄ ) ₂ , Sr ₃ (PO ₄ ) ₂ ,
It is preferable to use a third phosphate containing a Group IIA metal of the periodic table such as Ba ₃ (PO ₄ ) ₂ .

The reason why these are more preferable is that two types of active sites, an acid site and a basic site, having appropriate strengths are simultaneously expressed on the surface of the phosphate catalyst, whereby cyclohexene oxide is converted into an allylic alcohol intermediate. It is considered that the dehydration reaction of the allylic alcohol intermediate can be promoted by the action of acid sites having appropriate strength while improving the isomerization reaction selectivity.

In addition, the action of acid points of appropriate strength can significantly suppress the isomerization or disproportionation reaction of the produced 1,3-cyclohexadiene, and as a result, 1,3
By-products such as methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene, and benzene, which are difficult to separate in the purification step of 3-cyclohexadiene, are significantly reduced, and the quality of 1,3-cyclohexadiene is improved.

Further, the action of acid points of appropriate strength can markedly suppress the polymerization reaction of the produced 1,3-cyclohexadiene, and as a result, the deterioration of the catalyst due to the adhesion of the polymer and the like can be significantly reduced. The amount can be reduced and 1,3-cyclohexadiene can be stably produced. As the phosphate, those produced by a known method can be used. In addition, the phosphate can be used as a powder or a molded body depending on the reaction method used. At this time, the particle size is not particularly limited.

The invention is characterized in that cyclohexene oxide is contacted with phosphate in the gas phase. As the gas phase reaction method, either a fixed bed or fluidized bed system can be used. The reaction is carried out in the temperature range of 200 to 500 ° C, preferably 250 to 400 ° C. 200
When the reaction temperature is lower than 0 ° C, the reaction rate is extremely decreased, and a large amount of gas must be supplied in order to keep the reaction system in a gas phase, which is not preferable. It is not preferable because it increases rapidly. The reaction temperature can be changed in the range of 200 to 500 ° C. according to 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 gas phase. It can be performed under reduced pressure or increased pressure in addition to atmospheric pressure conditions. The feed rate of the starting material cyclohexene oxide when continuously carrying out the reaction is 0.1 in terms of LHSV (a value obtained by dividing the supply volume of the liquid starting material per hour by the volume occupied by the catalyst phase).
It is about 10 to 10 hr ^-1 , preferably about 0.2 to 3 hr ^-1 . The starting cyclohexene oxide may be diluted and mixed with an inert gas such as nitrogen, helium, or argon at an arbitrary ratio and supplied to the catalyst phase.

The reaction product according to the present invention is mainly composed of 1,3-cyclohexadiene, and is usually about 60% or more,
Suitably, 1,3-cyclohexadiene can be stably obtained with a yield of 80% or more. In the reaction product,
A small amount of by-products such as methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene, and benzene, which have a boiling point extremely close to that of 1,3-cyclohexadiene, are contained, but the contents thereof are extremely small. Further, in addition to these, by-products such as formylcyclopentane and cyclohexanone are contained, but these have a large difference in boiling point from 1,3-cyclohexadiene like unreacted cyclohexene oxide, so that distillation It can be easily separated from 1,3-cyclohexadiene by operation.

However, some of these by-products having a large difference in boiling point form a minimum azeotrope with water, and in some cases it becomes difficult to separate 1,3-cyclohexadiene, so the distillation operation It is preferable to remove water generated from the reaction solution before the step. Even by such distillation operation, it is difficult to separate by-products such as methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene and benzene contained in 1,3-cyclohexadiene from 1,3-cyclohexadiene. However, since these by-products are extremely small, it is possible to obtain high-quality 1,3-cyclohexadiene having a purity of 98% or more.

[0025]

The present invention will be described in more detail with reference to the following examples, which do not limit the scope of the present invention. In the Examples and Comparative Examples, the reaction and evaluation methods were all performed as follows. A mixture of a predetermined amount of nitrogen and a predetermined amount of cyclohexene oxide is sequentially supplied from the outside under atmospheric pressure to a tubular preheater maintained at a predetermined temperature to be vaporized, and this gas is externally supplied. The heat is supplied to a tubular reactor whose temperature is well controlled (a catalyst in which a particle size is adjusted within a certain range is packed in a predetermined amount).

The gas containing the product coming out of the reactor is cooled to room temperature by the tubular cooler following the tubular reactor, and the liquefied component is collected in the first sample receiver.
Cool to 0 ° C. and collect again the liquefied component in the second sample receiver. The respective liquefied components collected in the first sample receiver and the second sample receiver are taken out and mixed every reaction time, and collected as a reaction liquid. The reaction liquid forms two liquid phases of oil water with the produced water. The oil phase and the water phase are analyzed by gas chromatography, respectively, and the conversion rate of the raw materials and the selectivity and yield of 1,3-cyclohexadiene are obtained. ,
Furthermore, the by-products are quantified.

Then, after separating the water produced from the reaction solution, a distillation operation is carried out to collect 1,3-cyclohexadiene, and the purity of 1,3-cyclohexadiene is quantified by gas chromatography.

Example 1 Ca ₃ (PO ₄ ) ₂ catalyst (commercially available β-type tricalcium phosphate was compression molded, and then 10
~ 20 mesh crushed and baked at 400 ° C) 9
The reaction tube was filled with milliliters, the preheater and the reactor were heated to 350 ° C., cyclohexene oxide was supplied to the preheater at 7.5 milliliters / hour, and nitrogen was supplied to the preheater at 3.6 normal milliliters / hour. The reaction was continuously performed under conditions of ° C and atmospheric pressure. After the reaction was carried out for a while to make it stationary, a liquefied sample for 4 to 6 hours after the start of the reaction was collected and quantitatively analyzed by the above-mentioned method.

Table 1 below shows the raw material conversion rate and 1,3-cyclohexadiene yield, and Table 2 shows the purity of 1,3-cyclohexadiene recovered by the distillation operation.
1,3-cyclohexadiene was obtained in high yield, and
The amount of by-products affecting the deterioration of the quality of 1,3-cyclohexadiene was extremely small, and a high-quality 1,3-cyclohexadiene having a purity of 98% or higher was obtained by the distillation operation.

Example 2 A method exactly the same as in Example 1,
The reaction was continuously performed under the conditions. 100 ~ from the start of the reaction
Liquefaction samples for 102 hours were taken and similarly quantitatively analyzed. The results are shown in Tables 1 and 2. As is clear from comparison with the results of Example 1, even by a long-term continuous reaction,
Almost no deterioration of the catalyst was observed, and 1,3-cyclohexadiene was stably obtained.

(Example 3) Mg ₃ (PO ₄ ) ₂ catalyst (commercial magnesium triphosphate octahydrate was baked at 800 ° C., compression molded, crushed to 10-20 mesh, and 400 ° C.
The reaction was continuously carried out under the same method and conditions as in Example 1 except that 10 ml of the product (recalcined in step 1) was used and the reaction temperature was 300 ° C. The results are shown in Table 1 and Table 2.
Shown in. As in Example 1, high yield and high purity
3-Cyclohexadiene was obtained.

(Comparative Example 1) 9 ml of γ-Al ₂ O ₃ catalyst (manufactured by JGC Corporation: γ-alumina of trade name N611N was crushed to 10-20 mesh and calcined at 500 ° C.) was used, and the reaction temperature was used. The reaction was carried out by the same method and conditions as in Example 1 except that the temperature was 250 ° C. The results are shown in Tables 1 and 2. Compared to Examples 1 and 3, the yield of 1,3-cyclohexadiene was low, and
There were many by-products that affected the deterioration of the quality of 3-cyclohexadiene, and high-purity 1,3-cyclohexadiene could not be obtained.

(Comparative Example 2) The same method as in Comparative Example 1,
The reaction was continuously performed under the conditions. 12 to 1 from the start of the reaction
Liquefaction samples for 4 hours were taken and similarly quantitatively analyzed. The results are shown in Tables 1 and 2. As is clear from comparison with the results of Comparative Example 1, the deterioration of the catalyst was observed, and stable 1
3-Cyclohexadiene could not be obtained.

(Comparative Example 3) 9 ml of SiO ₂ —TiO ₂ catalyst (manufactured by Dia Catalyst Co., Ltd .: DC-4131, silica-titania, crushed to 10 to 20 mesh and fired at 500 ° C.) was used. , Reaction temperature 25
The reaction was carried out by the same method and conditions as in Example 1 except that the temperature was 0 ° C. The results are shown in Tables 1 and 2. Similar to Comparative Example 1, the yield of 1,3-cyclohexadiene was low, and highly pure 1,3-cyclohexadiene could not be obtained.

[0035]

[Table 1] In the table, 1,3-CHD means 1,3-cyclohexadiene.

[0036]

[Table 2]

In the table, 1,3-CHD: 1,3-cyclohexadiene, HE: cyclohexene, BZ: benzene, 1,4-CHD: 1,4-cyclohexadiene, MCPE: methylcyclopentenes are meant. To do.

[0038]

As described above, the first and third aspects of the present invention
-The method for producing cyclohexadiene makes it possible to stably produce 1,3-cyclohexanediene with high selectivity, high yield and by contacting cyclohexene oxide with a phosphate in a gas phase. . In addition, according to the method of the present invention, 1,3-cyclohexadiene can be usually obtained in a yield of about 60% or more, preferably 80% or more. At the same time, by-products such as methylcyclopentenes, cyclohexene, 1,4-cyclohexadiene and benzene, which are difficult to be easily separated from 1,3-cyclohexadiene, can be significantly suppressed, and the reaction solution is purified by distillation. As a result, high-quality 1,3-cyclohexadiene having a purity of 98% or more can be produced.

Further, it is possible to suppress the deterioration of the catalyst, which is considered to be caused by the polymerization reaction of 1,3-cyclohexadiene, and it is possible to stably produce 1,3-cyclohexadiene. These excellent effects of the present invention are achieved by using a phosphate as a catalyst, and cannot be exhibited at all when a metal oxide as already disclosed is used. . As described above, the method for producing 1,3-cyclohexadiene of the present invention is excellent and has a high industrial utility value.

Claims (4)

[Claims] 1. A method for producing 1,3-cyclohexadiene, which comprises contacting cyclohexene oxide with a phosphate in a gas phase. 2. The method for producing 1,3-cyclohexadiene according to claim 1, wherein the phosphate contains a Group IIA metal of the periodic table. 3. The method for producing 1,3-cyclohexadiene according to claim 1, wherein the phosphate salt contains calcium or magnesium. 4. The method for producing 1,3-cyclohexadiene according to claim 1, wherein the phosphate is a tertiary phosphate.