阅读说明：本技术 环状醚的制造方法 (Process for producing cyclic ether ) 是由 清水亮佑 细野贵裕 荒谷一弘 河内亮 于 2018-12-04 设计创作，主要内容包括：本发明提供一种式(2)所示的环状醚的制造方法,其使式(1)所示的2-羟基环状醚与氢在催化剂的存在下发生反应。(Disclosed is a method for producing a cyclic ether represented by formula (2), wherein a 2-hydroxy cyclic ether represented by formula (1) is reacted with hydrogen in the presence of a catalyst.)

1. A process for producing a cyclic ether represented by the formula (2), which comprises reacting a 2-hydroxy cyclic ether represented by the formula (1) with hydrogen in the presence of a catalyst,

in the formula, n is an integer of 1-7; r¹～R⁵Each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms; r⁴And R⁵When a plurality of them are present, they are optionally different from each other,

the symbols in the formulae are as defined above.

2. The production method according to claim 1, wherein the reaction is carried out under a condition that the pH of the reaction mixture is in the range of 3 to 7.

3. The production process according to claim 1, wherein at least 1 acid selected from the group consisting of acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, heteropolyacids and peracids or a salt thereof is allowed to exist in the reaction mixture in an amount of 0.001 to 10% by mass relative to the reaction mixture, and is allowed to react.

4. The production process according to any one of claims 1 to 3, wherein the catalyst contains an element of groups 8 to 10 of the periodic Table.

5. The production process according to claim 4, wherein the element of groups 8 to 10 of the periodic Table of the elements is at least 1 selected from nickel, ruthenium, rhodium, palladium and platinum.

6. The production method according to claim 4 or 5, wherein the catalyst is a supported catalyst.

7. The production method according to any one of claims 1 to 6, wherein R is¹Is a hydrogen atom.

8. The production method according to any one of claims 1 to 7, wherein n is 2 or 3.

Technical Field

The present invention relates to a method for producing a cyclic ether.

Background

Conventionally, as a method for producing a cyclic ether, for example, a method of synthesizing tetrahydropyran by reacting 2-alkoxytetrahydropyran with hydrogen in the presence of an acid and a catalyst is known (patent document 1). However, the 2-alkoxytetrahydropyran used in this method cannot be obtained industrially at low cost, and the yield has room for improvement.

Further, as a method for synthesizing a cyclic ether from a hydroxy cyclic ether, the following methods are known: 3-hydroxy-3-methyltetrahydrofuran is dehydrated in the presence of an acidic substance to obtain 3-methyldihydrofuran, and then 3-methyltetrahydrofuran is synthesized in the presence of a hydrogenation catalyst (patent document 2). However, this method is not preferable from an industrial viewpoint because it uses a two-stage reaction, and the yield has room for improvement.

Further, a method of synthesizing tetrahydrofuran by reacting 3, 4-dihydroxytetrahydrofuran with hydrogen in the presence of a catalyst is known (patent document 3). However, this method does not give a high yield.

Disclosure of Invention

Problems to be solved by the invention

In view of the problems of the above-described conventionally known methods for producing cyclic ethers, an object of the present invention is to provide a method for producing a cyclic ether in a simple manner and in a good yield under mild conditions using a compound which is easily available.

Means for solving the problems

The inventors of the present invention have made diligent studies and, as a result, have found that: the above problems can be solved by reacting a predetermined 2-hydroxy cyclic ether with hydrogen in the presence of a catalyst, and the present invention has been completed.

The present invention relates to the following [1] to [8 ].

[1] A process for producing a cyclic ether represented by the formula (2) (hereinafter also referred to as "cyclic ether (2)") which comprises reacting a 2-hydroxycyclic ether represented by the formula (1) (hereinafter also referred to as "2-hydroxycyclic ether (1)") with hydrogen in the presence of a catalyst.

[ chemical formula 1]

(wherein n is an integer of 1 to 7; R¹～R⁵Each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. R⁴And R⁵When plural, they are optionally different from each other. )

[ chemical formula 2]

(wherein the symbols are as defined above.)

[2] The production method according to [1], wherein the reaction is carried out under a condition that the pH of the reaction mixture is in a range of 3 to 7.

[3] The production method according to [1], wherein at least 1 acid or a salt thereof selected from the group consisting of acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, heteropoly acids, and peracids is present in the reaction mixture in an amount of 0.001 to 10% by mass relative to the reaction mixture, and is reacted.

[4] The production process according to any one of [1] to [3], wherein the catalyst contains an element of groups 8 to 10 of the periodic Table.

[5] The process according to [4], wherein the element belonging to group 8 to 10 of the periodic Table is at least 1 selected from the group consisting of nickel, ruthenium, rhodium, palladium and platinum.

[6] The production process according to [4] or [5], wherein the catalyst is a supported catalyst.

[7]According to [1]～[6]The production method of any one of, wherein R¹Is a hydrogen atom.

[8] The production method according to any one of [1] to [7], wherein n is 2 or 3.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the production method of the present invention, a cyclic ether can be produced easily and in good yield under mild conditions using a compound which is easily available.

Detailed Description

The present invention will be described in detail below.

The present invention is a method for producing a cyclic ether (2), which comprises reacting a 2-hydroxycyclic ether (1) with hydrogen in the presence of a catalyst.

In the 2-hydroxy cyclic ether (1), n is an integer of 1 to 7. Wherein n is preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and further preferably 2 or 3.

In the 2-hydroxycyclic ether (1), R¹～R⁵Each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 4 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. In addition, R is⁴And R⁵When plural, they are optionally different from each other. In other words, for example R⁴When 2 are present, 2 may be the same group, or may be different from each other such that 1 is a hydrogen atom and the other 1 is a methyl group. Among them, preferred is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and more preferred is a hydrogen atom or a methyl group. Further, it is further preferred that: r¹～R⁵Are all hydrogen atoms, or R¹～R⁵Any one of (R)⁴And R⁵When a plurality of them are present, 1 of all) are methyl groups, and the remainder are all hydrogen atoms. R¹Particularly preferred is a hydrogen atom.

The 2-hydroxy cyclic ether (1) can be easily obtained. For example, the catalyst can be produced by reacting a corresponding unsaturated alcohol (e.g., allyl alcohol) with a mixed gas of carbon monoxide and hydrogen in the presence of a rhodium catalyst according to the method described in Journal of molecular catalysis, volume 423, page 41 (2016).

The hydrogen used in the production method of the present invention is not particularly limited, and for example, electrolytic hydrogen and petroleum hydrogen can be used. Here, the electrolytic hydrogen is hydrogen produced by electrolysis of water, and the petroleum hydrogen is hydrogen obtained by cracking naphtha. Hydrogen can be diluted with an inert gas such as nitrogen or argon.

The catalyst used in the present invention is not particularly limited as long as it has an ability to hydrogenate the 2-hydroxy cyclic ether (1), and is preferably a catalyst containing an element of groups 8 to 10 of the periodic table.

Specific examples of the group 8 to 10 elements of the periodic table include cobalt, nickel, ruthenium, rhodium, iridium, palladium, platinum and the like. Among these, at least 1 kind selected from nickel, ruthenium, rhodium, palladium and platinum is preferable, and palladium is more preferable.

The catalyst used in the present invention is preferably a supported catalyst (supported catalyst) from the viewpoint of the surface area of the catalyst. Examples of the carrier include activated carbon, silica, alumina, titania, zeolite, and the like.

Specific examples of the supported catalyst include palladium-supported activated carbon, platinum-supported activated carbon, palladium-supported silica, palladium-supported alumina, palladium-supported titania, and the like.

The amount of the element supported on the supported catalyst is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and still more preferably 0.5 to 5% by mass, based on the entire catalyst. By setting the amount of the supported element to 0.01 mass% or more, the amount of the supported catalyst can be reduced, and adsorption of the product to the catalyst can be suppressed. Further, by setting the amount of the element to be supported to 20 mass% or less, a sufficient yield can be obtained and the amount to be used can be suppressed.

The method for producing the catalyst used in the present invention is not particularly limited, and for example, a method for producing a catalyst by dissolving or suspending nitrates, chlorides, and the like of elements constituting the catalyst such as the elements of groups 8 to 10 of the periodic table in water, an organic solvent, and the like, impregnating a catalyst carrier with the solution thus obtained, and then reducing the elements to a state of 0 valence by wet reduction using hydrazine or the like, dry reduction using hydrogen, and the like, can be mentioned. In this case, it is not necessary that all elements to be supported have a valence of 0.

The amount of the catalyst used in the production method of the present invention is preferably 0.0001 to 10% by mass, more preferably 0.001 to 5% by mass, and still more preferably 0.01 to 3% by mass, based on the 2-hydroxycyclic ether (1). Sufficient reactivity can be obtained by setting the content to 0.0001 mass% or more. Further, by setting the amount to 10% by mass or less, a sufficient reaction rate can be obtained and the amount to be used can be suppressed.

In the production method of the present invention, the reaction is preferably carried out under a condition that the pH of the reaction mixture is within a range of 3 to 7, more preferably within a range of 3 to 6, and even more preferably within a range of 4 to 6. The reaction mixture refers to a reaction mixture at the time of reaction (typically, hydrogenation reaction), and the pH immediately before hydrogen is introduced can be regarded as the pH of the reaction mixture by measuring the pH.

The 2-hydroxycyclic ether (1) as a raw material is an unstable hemiacetal, and by reacting it under the condition that the pH of the reaction mixture is 3 or more, side reactions of the raw material and the intermediate are suppressed, and the yield is improved. Further, by setting the pH to 7 or less, the reaction rate becomes sufficient.

The pH can be measured using a commercially available pH METER (e.g., pH METER D-12 manufactured by horiba, Ltd.). Further, for convenience, commercially available pH test paper (for example, pH test paper WR1.0 to 14.0 manufactured by Toyo Filter paper Co., Ltd.) may be used.

In the production method of the present invention, it is preferable that the acidic substance is present in the reaction mixture to cause a reaction.

Examples of the acidic substance include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, sodium hydrogen sulfate, potassium dihydrogen phosphate, sodium hydrogen sulfite, and potassium hydrogen sulfite; sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; carboxylic acids such as acetic acid, propionic acid, benzoic acid, and terephthalic acid; heteropolyacids such as phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, silicomolybdic acid and the like; solid acids such as silica, alumina, silica-alumina, titania, silica-titania, niobium oxide, and activated clay; acidic ion exchange resins such as sulfonic acid ion exchange resins and carboxylic acid ion exchange resins; peracids formed by air oxidation of compounds present in the reaction mixture; and salts thereof, and the like.

Among them, at least 1 acid selected from acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, heteropoly acids and peracids or salts thereof is preferable.

These acidic substances may be used alone in 1 kind, or may be used in combination of 2 or more kinds. Further, the acidic substance may be supported on a carrier and used in the same manner as the solid acid.

The amount of the acidic substance used in the production method of the present invention is preferably in the range of pH of the reaction mixture from 3 to 7. The amount of the catalyst is 0.001 to 10% by mass, or 0.1 to 6% by mass, based on the reaction mixture.

The reaction in the present invention may be carried out in the presence or absence of a solvent. The solvent that can be used is not particularly limited as long as it does not adversely affect the reaction, and examples thereof include aliphatic hydrocarbons such as hexane, heptane, octane, nonane, decane, cyclohexane, etc.; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, and the like; alcohols such as methanol, ethanol, isobutanol, n-butanol, ethylene glycol, 1, 5-pentanediol; ethers such as tetrahydrofuran and tetrahydropyran; water, and the like. When a solvent is used, the amount thereof is not particularly limited, but is usually preferably in the range of 0.01 to 10 times by mass relative to the 2-hydroxycyclic ether (1), and more preferably in the range of 0.1 to 2 times by mass from the viewpoints of smooth progress of the reaction, volumetric efficiency, economy and the like.

The reaction temperature in the present invention is preferably in the range of 40 to 250 ℃, and more preferably in the range of 60 to 180 ℃. By setting the reaction temperature to 40 ℃ or higher, the reaction can be smoothly performed. Further, by setting the temperature to 250 ℃ or lower, the by-production of high boiling point compounds is suppressed, and the selectivity is improved.

The reaction pressure in the present invention is not particularly limited, but is preferably 1kPa to 20MPa, more preferably 0.2MPa to 10 MPa. By setting the pressure to 1kPa or more, a sufficient reaction rate can be obtained, and by setting the pressure to 20MPa or less, the cost required for equipment investment can be suppressed.