JPH089605B2 - Method for producing α, β-cyclic unsaturated ether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention has a main chain having hydroxyl groups at both terminals of C ₄ or
Simultaneous catalytic dehydrogenation and dehydration of C ₅ alkane diols to produce α, β-cyclic unsaturated ethers, especially 2,3
-Dihydrofuran (hereinafter referred to as DHF), 3,4-dihydro-2-H-pyran (hereinafter referred to as DHP), and a method for producing an alkyl-substituted product thereof.

[alpha], [beta] -Cyclic unsaturated ethers are compounds useful for a wide range of organic synthetic reactions including intermediate raw materials for medicines and agricultural chemicals.

[Conventional technology]

Regarding the method for producing an α, β-cyclic unsaturated ether, particularly DHF, a furan hemihydrogenation method or 2-
A method of isomerizing butene-1,4-diol to DHF via 2,5-dihydrofuran is known. See also
5-16566 describes a method for producing DHF by treating 1,4-butanediol with a catalyst containing metallic cobalt. On the other hand, as a method of producing DHP, a method of producing tetrahydrofurfuryl alcohol through dehydration-ring expansion in the presence of a metal catalyst containing alumina as a main component is known. In addition, U.S. Pat.
A method for producing DHP by treating 1,5-pentanediol with a copper-silica gel catalyst is described.

[Problems to be solved by the invention]

However, all the conventional methods have complicated manufacturing methods. It was not a satisfactory method in terms of reaction activity, selectivity and catalyst life.

Particularly, in the conventional method, there is a small difference in boiling point from the target product, β, γ- or γ, δ- which is an undesirable by-product.
Cyclic unsaturated ethers such as 2,5-dihydrofuran and 5,6
A large amount of dihydro-2H-pyran and dehydration products such as tetrahydrofuran and tetrahydropyran are produced, which lowers the distillation efficiency and the product purity, which is a major obstacle to industrial use.

[Means for solving problems]

In view of the above-mentioned problems, the present inventors have made extensive studies from various points, and the main chain having hydroxyl groups at both ends simultaneously conducts catalytic dehydrogenation and dehydration of C ₄ or C ₅ alkanediol, α, In the method for producing β-cyclic unsaturated ether, by using metallic cobalt having a specific crystal structure as a catalyst, the reaction is performed with industrially satisfactory reaction activity, selectivity, and catalyst life, and a high yield is obtained. The inventors have found that the target product can be produced, and have completed the present invention.

 The present invention will be described in more detail below.

The alkanediol targeted in the present invention has a general formula having hydroxyl groups at both ends. (In the formula, R ¹ and R ² represent H or a lower alkyl group,
Each may be the same or different. n represents 4 or 5), and examples thereof include 1,4-butanediol and 1,5-pentanediol, and alkyl-substituted alkanediols such as 1-methyl-1,4
-Butanediol, 2-methyl-1,4-butanediol, 1-ethyl-1,4-butanediol, 2-ethyl-
1,4-butanediol, 1-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 1-ethyl-1,5-pentanediol, 2-ethyl-1,5-pentanediol And so on. The most preferred alkanediols of the present invention are 1,4-butanediol and 1,5-pentanediol.

The purity of the alkanediol is not limited at all, and mixed alkanediol may be used.

Metallic cobalt having a specific crystal structure used as a catalyst in the present invention is a powder X-ray diffraction analysis method using a CuKα ray that is generally used, and the measurement conditions include a tube voltage (Tube Voltage) of 40 KV and a tube current (( Tube Current) 40m
A, Divergence Slit 1 °, Receiving Slit 0.2mm, Scatter Slit
lit) The ratio (B / A) of the area B of the diffraction peak at the diffraction angle 2θ = 44.3 ° to the area A of the diffraction peak at the diffraction angle 2θ = 47.6 ° obtained at 1 ° (B / A) is 3.0 or more. . The areas of A and B in the present invention are 2θ = 40 ° and 2θ = 50 °.
It is calculated by the trigonometric method of peak A and peak B with the line connecting the diffraction intensities of 1 as the base line.

Here, A is a diffraction peak derived from the diffraction surface (101) of hexagonal metallic cobalt, and B is a cubic crystal (Cub).
ic) is a diffraction peak derived from the diffraction surface (111) of metallic cobalt.

Incidentally, metallic cobalt is generally produced as an ore of a compound of mainly sulfur and arsenic together with nickel naturally.
The normally available metallic cobalt can be obtained by roasting ores to form an oxide, and then reducing and refining them to have a hexagonal crystal structure and an area ratio B / A of 0 to 2.9.

When metallic cobalt having an area ratio B / A of less than 3.0 is used as a catalyst in the reaction of the present invention, the reaction activity is low and a large amount of dehydrated cyclized alkanediol is produced, which is not preferable for industrial use.

Regarding the method for producing metallic cobalt having a specific crystal structure defined in the present invention, for example, an area ratio B / A of generally available metallic cobalt having a value of 2.9 or less in an atmosphere of hydrogen gas, 500
Obtained by heating above ℃, or organic or inorganic acid salt of cobalt under hydrogen gas atmosphere at 500
There may be mentioned a production method obtained by heating to a high temperature of ℃ or higher, preferably 800 ℃ or higher. As such an organic acid salt,
For example, cobalt oxalate can be mentioned.

The area ratio of metal cobalt having a specific crystal structure used in the present invention is
B / A is 3.0 or more, preferably 5.0 or more, and more preferably 6.0 or more.

The purity and the metal particle size of metallic cobalt having a specific crystal structure are not particularly limited, but the purity is preferably 99% or more and the metal particle size is 10 μm or less.

The concentration of the catalyst used in the reaction is 0.01% by weight or more, preferably 0.1% by weight or more, and more preferably 1.0% by weight or more, based on the raw material alkanediol.

The method for producing the α, β-cyclic unsaturated ether may be a gas phase method or a liquid phase method, and the reaction form is not particularly limited, such as a flow system and a batch system, but for example, industrially advantageous As a method of carrying out, a liquid phase suspension reaction distillation system is preferable.

 Next, the reaction method of the present invention will be specifically shown.

The α, β-cyclic unsaturated ether is produced by heating the alkanediol and the catalyst together to the reaction temperature in a reaction vessel equipped with a stirrer while stirring them together.

The produced α, β-cyclic unsaturated ether is distilled out together with hydrogen and water produced at the same time, and is distilled off from the reaction vessel. At this time, by blowing an inert gas into the reaction vessel, α, β-
The cyclic unsaturated ether can be rapidly distilled out of the reaction system, which is advantageous for suppressing side reactions. Α was distilled off,
The β-cyclic unsaturated ether is separated by cooling so as to be separated from water, or is dissolved in an organic solvent such as toluene and collected.

Further, as a method for carrying out the reaction more efficiently, a high content of γ-butyrolactone, [2- (4'-hydroxybutyloxy) tetrahydrofuran], 1,4-bis (furfuryl-2-oxy) butane, etc. was previously prepared in the reaction vessel. If a boiling point solvent is added, α, β-cyclic unsaturated ether can be obtained in good yield.

The reaction temperature depends on the type of the raw material alkanediol used, but is usually in the range of 100 ° C to 300 ° C, and preferably
It is carried out in the range of 200 ° C to 250 ° C. The reaction pressure may be reduced pressure or increased pressure, but normal pressure is usually preferable.

〔Example〕

The method of the present invention has been described in detail above, and will be described more specifically by the following examples. The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Cobalt oxalate was used as a catalyst under hydrogen gas flow at 600 ° C. for 1
Stirring 10 g of metallic cobalt (X-ray diffraction diagram is shown in Fig. 1) having a specific crystal structure in which the ratio of the area of B to the area of A obtained by the time reduction treatment is 6.6 and 50 g of 1.4-butanediol. A glass four-necked flask equipped with a machine, a liquid charging port, a gas blowing port, and a rectifying tube was charged, and nitrogen gas was continuously blown at a rate of 100 cc / min while stirring.
When heated to 210 ° C, a mixture of hydrogen, water and DHF was distilled out. Subsequently, the distillate mixture was introduced into a toluene dissolution tank, and the distillate mixture was separated into water and toluene to a DHF layer. Then, 250 g of the raw material 1,4-butanediol was continuously supplied over 50 hours to complete the reaction. DHF recovered from the toluene to DHF layer
Was obtained in a yield of 93% by weight, yielding 217 g. The amount of tetrahydrofuran, a by-product, was 1,3 g, and 2,5-dihydrofuran was not found.

The reaction was continuously performed for 150 hours thereafter, but the DHF production rate did not change.

Example 2 A obtained by reducing commercially available powdery metallic cobalt in the method of Example 1 in advance under hydrogen gas flow at 600 ° C. for 1 hour.
Was carried out in the same manner as in Example 1 except that metallic cobalt having a specific crystal structure in which the ratio of the area of B to the area of 3.5 was 3.5 was used.
g was obtained, and the production amount of tetrahydrofuran as a by-product was 1.1 g.

Example 3 In the method of Example 2, 10 g of γ-butyrolactone, 10 g of [2- (4′-hydroxybutyloxy) tetrahydrofuran] and 10 g of 1,4-bis (furfuryl-2-oxy) butane were charged in a flask in advance. Other than that, it was carried out in the same manner as in Example 2, and it was found that DHF was obtained in a yield of 96% by weight.
g was obtained, and the amount of the by-product tetrahydrofuran was 2 g.

Example 4 In the method of Example 2, 1,4-butanediol was replaced with 1,5
When the same procedure as in Example 2 was carried out except that pentanediol was replaced, 218 g of DHP was obtained at a yield of 90% by weight.

Comparative Example 1 DHF was obtained in a yield of 8 in the same manner as in Example 1 except that as the catalyst, a commercially available metallic cobalt in which the ratio of the area of B to the area of A was 2.9 was used as the catalyst.
2% by weight gave 191 g. However, as a by-product, tetrahydrofuran was obtained in an amount of 6.5% by weight based on the produced DHF, and 12.4 g was obtained. When the reaction was further continued for 150 hours thereafter, the DHF production rate decreased to 1/2.

Comparative Examples 2 to 6 The procedure of Example 1 was repeated except that various commercially available metallic cobalt having an area of B smaller than 3.0 with respect to the area of A was used as the catalyst in the method of Example 1, and the results are shown in Table 1. −
Shown in 1. An X-ray diffraction diagram of the catalyst of Comparative Example 3 is shown in FIG.

[Effects of the Invention] According to the present invention, a target product can be produced in high yield by using metal cobattle having a specific crystal structure as a catalyst, and its industrial significance is great.

[Brief description of drawings]

1 is an X-ray diffraction diagram of metallic cobalt used in Example 1, and FIG. 2 is an X-ray diffraction diagram of metallic cobalt used in Comparative Example 3.

Claims (1)

[Claims] 1. A main chain having hydroxyl groups at both ends is C ₄ or
Diffraction angle in powder X-ray diffraction analysis using CuKα ray as a catalyst for producing α, β-cyclic unsaturated ether by simultaneously performing catalytic dehydrogenation and dehydration in the presence of C ₅ alkanediol in the presence of a catalyst. The ratio (B / A) of the area B of the diffraction peak at the diffraction angle 2θ = 44.3 ° to the area A of the diffraction peak at 2θ = 47.6 ° is 3.0 or more, and metallic cobalt having a crystal structure is used. Method for producing α, β-cyclic unsaturated ether.