JPH1121259A - Production of fluorine-containing ether compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound usable for a solvent, a detergent, a surface treating agent, etc., by reacting a specific hydroxy compound in a hydrogen atmosphere by using a catalyst. SOLUTION: A fluorine-containing hydroxy compound of the formula R- O-(AO)n -H (R is a fluorine substituent group-containing 1-40C alkyl, alkenyl or 3-12C cycloalkyl; A is a 2-12C alkylene; (n) is 0-200) such as 2,2,3,3,3- pentafluoropropanol or one or a mixture of two or more of fluorine-containing alcohols of the formula Rf1 (CCH2 )p OH (Rf1 is a 1-12C fluorine-containing alkyl; (p) is 1-10) is reacted in a hydrogen atmosphere in the presence of a palladium catalyst supported on carbon while removing water as a by-product to give the objective fluorine-containing ether compound of the formula R-O-(AO)n -(A' O)m -R' (R' is a fluorine substituent group containing 1-40C alkyl, etc.; A' is a 2-12C alkylene; (n) is 0-200) such as di 2-(perfluorohexyl)ethyl} ether simply and inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a fluorine-containing ether compound. More specifically, the present invention relates to a method for producing a fluorine-containing ether compound which can supply a fluorine-containing ether compound which can be widely used for a solvent, a cosmetic, a detergent, a lubricant, an emulsifier, a surface treatment agent and the like simply and at low cost.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a fluorine-containing ether compound, for example, the following formula (III) R "-CH ₂ OH (III) (where R" represents an alkyl group or a fluorine-containing alkyl group). It is known that a hydrocarbon-based or fluorinated alcohol is converted to an alcoholate such as Na or K and then reacted with an alkyl halide or a halogenated alkyl fluoride to synthesize a fluorinated ether.

In Japanese Patent Publication No. 8-30021, a fluoroolefin is used by reacting a fluoroolefin with a fluorine-containing carbonyl compound in the presence of AgF in an aprotic polar solvent having a hydrogen atom. Methods for obtaining the compounds are disclosed.

[0004] However, the former method requires an equivalent of alkali such as Na and K to the alcohol to be used, and also requires an equivalent of acid to neutralize the alkali after the reaction.
This method is not industrially preferable because a large amount of salt is by-produced. The latter method uses the catalyst AgF
Is a fluorine atom constituting the fluorinated ether compound, so that, relative to the fluorinated carbonyl compound as the raw material,
More than an equimolar amount is required, and further, there is a problem that it cannot be recovered and reused.

A fluorine-containing ether compound can be synthesized from a fluorine-containing alcohol and an ester compound.
Ester compounds are limited to dimethyl sulfate, diethyl sulfate and the like, and methyl ether and ethyl ether can be synthesized. However, it is difficult to synthesize a fluorine-containing ether compound having more carbon atoms than these compounds.

[0006]

As described above, fluorine-containing ether compounds are expected to be used, but cannot be used for general purposes because of difficulty in production, and are simple and inexpensive without requiring a purification step. There has been a demand for a process for producing a fluorinated ether compound which can be supplied to a polymer. Accordingly, an object of the present invention is to provide a fluorine-containing ether compound which can be used for a solvent, a cosmetic, a cleaning agent, a lubricant, an emulsifier, a surface treatment agent, and the like simply and inexpensively, that is, without accompanying coloration or odor deterioration. An object of the present invention is to provide a production method which can be supplied without performing purification by distillation or the like.

[0007]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies on a simple and inexpensive method for producing a fluorine-containing ether compound which can be used for general purposes. Under a hydrogen atmosphere,
The present inventors have found that by performing a reaction using a catalyst, a fluorinated ether compound can be obtained in one step with a high yield and without deterioration due to coloring or oxidation, and have completed the present invention.

That is, the present invention relates to a compound represented by the general formula (I): RO- (AO) _n -H (I) wherein R is a linear or branched alkyl or alkenyl group having 1 to 40 carbon atoms, or A fluorine substituent in which at least one hydrogen atom of a cycloalkyl group of 3 to 12 is substituted by a fluorine atom, wherein A is an alkylene group having 2 to 12 carbon atoms, and n A's may be the same or different And n is a number from 0 to 200.) A compound represented by the general formula (1), wherein one or a mixture of two or more of the fluorine-containing hydroxy compounds represented by It is intended to provide a method for producing the fluorine-containing ether compound represented by II).

RO- (AO) _n- (A'O) _{n '} -R' (II) (wherein R, A and n have the above-mentioned meanings, and R 'is a straight chain having 1 to 40 carbon atoms) Or a fluorine-containing substituent in which at least one hydrogen atom of a branched alkyl group or alkenyl group, or a cycloalkyl group having 3 to 12 carbon atoms is substituted with a fluorine atom, wherein A 'is an alkylene group having 2 to 12 carbon atoms. Show,
The n 'A's may be the same or different. n 'is 0 to 200
Indicates the number of R and R ', A and A', and n and n 'may be the same or different. )

[0010]

Embodiments of the present invention will be described below in detail.

In the fluorine-containing hydroxy compound represented by the general formula (I) used in the present invention, R is a compound having 1 to 1 carbon atoms.
40 linear or branched alkyl or alkenyl groups,
Or a fluorine substituent in which at least one of hydrogen atoms of a cycloalkyl group having 3 to 12 carbon atoms is substituted with a fluorine atom, and a hydrogen atom of a hydrogen atom of a linear or branched alkyl group or alkenyl group having 1 to 40 carbon atoms. A fluorine substituent in which at least one is substituted by a fluorine atom is preferable, and has 1 carbon atom.
A fluorine substituent in which at least one of the hydrogen atoms of the alkyl groups of Nos. 1 to 22 is substituted with a fluorine atom is particularly preferred.

A represents an alkylene group having 2 to 12 carbon atoms, preferably an ethylene group or a propylene group, particularly preferably an ethylene group. n represents a number from 0 to 200,
The number 0 is preferred, and the number 0-30 is particularly preferred.

As the fluorine-containing hydroxy compound represented by the general formula (1), the following hydroxy compounds having no fluorine substituent, that is, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, n-butyl alcohol -Pentyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol, n-nonyl alcohol, n-decyl alcohol, n
-Undecyl alcohol, n-dodecyl alcohol, n
Straight-chain saturated alcohols such as tridecyl alcohol, n-tetradecyl alcohol, n-pentadecyl alcohol, n-hexadecyl alcohol, n-octadecyl alcohol and n-eicosyl alcohol, isopropyl alcohol, isobutyl alcohol, and 2-ethylhexyl alcohol , 2-hexyldecyl alcohol, 2-heptylundecyl alcohol, 2-octyldodecyl alcohol, 2-decyltetradecyl alcohol, 2-
(1,3,3-trimethylbutyl) -5,7,7-trimethyloctyl alcohol, the following formula

[0014]

Embedded image

(Where a and b are a + b = 14, and a = b
= Having a distribution having a peak at 7), saturated branched alcohols such as methyl-branched isostearyl alcohol, 2-tetradecyloctadecyl alcohol, 9-octadecenyl alcohol, farnesyl alcohol, abiethyl alcohol, oleyl alcohol, etc. Alkenyl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monoisopropyl ether (isopropyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve),
Monoethers of ethylene glycol such as ethylene glycol monoisoamyl ether and ethylene glycol monohexyl ether, diethylene glycol monomethyl ether (methyl carbitol), diethylene glycol monoethyl ether (ethyl carbitol), diethylene glycol monoisopropyl ether (isopropyl carbitol), diethylene glycol Monoethers of diethylene glycol such as monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monohexyl ether, triethylene glycol monododecyl ether, triethylene glycol monotetradecyl ether, etc. Of triethylene glycol Noethers, 1,4-butanediol monohexyl ether, 2-methyl-1,3-propanediol monooctyl ether, 1,6-pentanediol monohexyl ether, 2,2′-dimethylpropanediol monooctyl ether, 3 -Methyl-1,
Alkylene glycol monoethers such as 5-pentanediol monohexyl ether; ethylene alcohol, propylene oxide or butylene oxide adducts of the above alcohols; cyclopentanols, cyclohexanols, and cycloalkanols such as cycloheptanol; Having no hydroxy compound, preferably an aliphatic alcohol having 1 to 40 carbon atoms, methyl cellosolve, ethyl cellosolve, isopropyl cellosolve,
Butyl cellosolve, methyl carbitol, ethyl carbitol, isopropyl carbitol, butyl carbitol, ethylene oxide adduct of an aliphatic alcohol having 1 to 40 carbon atoms (average addition mole number 0.1 to 20), or 5 carbon atoms
And a fluorine-containing hydroxy compound in which at least one hydrogen atom of an alkyl group, an alkenyl group, or a cycloalkyl group in a hydroxy compound having no fluorine-containing substituent selected from the group consisting of cycloalkanols of Nos. 8 to 8 is substituted with a fluorine atom. However, the present invention is not necessarily limited to these.

Specific examples of these fluorine-containing hydroxy compounds include 2,2,3,3,3-pentafluoropropanol, 2- (perfluorohexyl) ethanol,
2- (perfluorooctyl) ethanol, 2- (perfluorodecyl) ethanol, 6- (perfluoroethyl) hexanol, 6- (perfluorobutyl) hexanol, 6- (perfluorohexyl) hexanol,
6- (perfluorooctyl) hexanol, 2,2
3,4,4,4-hexafluorobutanol, 2,2
3,3-tetrafluoropropanol, 1H, 1H, 5
H-octafluoropentanol, 1H, 1H, 7H-
Linear fluorinated alcohols such as dodecafluoroheptanol, 1H, 1H, 9H-hexadecafluorononanol, 2- (perfluoro-3-methylbutyl) ethanol, 2- (perfluoro-5-methylhexyl) ethanol, 2- (perfluoro-7-methyloctyl) ethanol, 2- (perfluoro-9-methyldodecyl) ethanol, 6- (perfluoro-1-methylethyl) hexanol, 2- (perfluoro-3-methylbutyl)
Branched fluorinated alcohols such as hexanol, 6- (perfluoro-5-methylhexyl) hexanol and 6- (perfluoro-7-methyloctyl) hexanol;
Examples of these fluorine-containing alcohols include ethylene oxide, propylene oxide, and butylene oxide adducts. Among them, aliphatic alcohols having 1 to 22 carbon atoms having a fluorine substituent are preferable, and particularly, a general formula
(IV) Rf ₁ (CH ₂ ) _p OH (IV) (wherein, Rf ₁ represents a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, and p represents a number of 1 to 10). ) Is preferred. These fluorinated hydroxy compounds can be used alone or as a mixture of two or more, but it is preferable to use one kind.

In the present invention, the catalyst used for reacting the above-mentioned fluorine-containing hydroxy compound is not particularly limited as long as it has a hydrogenating ability, but a palladium catalyst; palladium hydroxide, palladium oxide, etc. Palladium compound; ruthenium, rhodium or platinum catalyst; ruthenium oxide, rhodium oxide, platinum oxide and the like. Further, a catalyst such as iridium, osmium, rhenium or the like can be used. These catalysts
It may be appropriately supported on a carrier such as carbon, alumina, silica alumina, silica, and zeolite. Among these catalysts, preferably a palladium-based catalyst, more preferably carbon, alumina, palladium catalyst supported on silica alumina or silica, palladium hydroxide or palladium oxide, particularly preferably a palladium catalyst supported on carbon .

In the present invention, the catalyst is usually used at a ratio of 2 to 10% by weight based on a carrier such as carbon or alumina, but it may be used without being supported on the carrier. Further, it may be a water-containing product of about 20 to 60% by weight. The catalyst is preferably used in an amount of 0.1 to 10% by weight based on the fluorine-containing hydroxy compound to be used, for example, if the catalyst is supported at 5% by weight based on the carrier. If the amount is less than 0.1% by weight, the reaction proceeds, but the reaction is slow and not preferable. When the amount is more than 10% by weight, the reaction is fast, but on the contrary, a side reaction proceeds, which is not preferable. More preferably 0.5
~ 5% by weight. The catalyst can be used in all pH ranges, but is preferably pH 8-2, more preferably pH 7.5.
~ 3 catalysts are preferred. The pH of the catalyst as used herein refers to the pH of an aqueous solution obtained by dispersing 2 g of catalyst powder in 30 g of ion-exchanged water.
H.

In the present invention, it is preferable to carry out the reaction while removing water by-produced by the reaction. As a method of removing water by-produced by the reaction, a method of removing water by performing a reaction in the presence of a dehydrating agent, a method of distilling water by azeotropic dehydration, or the like, while flowing a gas such as hydrogen Examples of the method include a method of removing water.

In the method for removing water by carrying out a reaction in the presence of a dehydrating agent, the dehydrating agent used includes a so-called drying agent used for drying a liquid. In general, the expression of the dehydrating ability of a dehydrating agent is based on physical adsorption, chemical adsorption or chemical reaction of water. However, the dehydrating agent used in the present invention is not particularly limited in the mechanism of the dehydrating ability, and the dehydrating ability or water absorbing ability Any one may be used as long as it substantially removes water produced as a by-product of the reaction and allows the desired etherification reaction to proceed rapidly.
In addition, among the dehydrating agents, it is not preferable to use a reaction other than the dehydration ability substantially, such as a strong acid or a strong alkali that dissolves the catalyst, but the strong acid or the strong alkali also does not directly contact the reaction system. Needless to say, it can be used if devised in such a way.

Preferred dehydrating agents used in the present invention include inorganic salts such as magnesium sulfate, sodium sulfate, calcium sulfate, copper sulfate and calcium chloride, preferably anhydrides thereof, hydroxides such as calcium hydroxide, and oxides. Examples thereof include oxides such as magnesium, crystalline zeolites such as molecular sieves, and silica gel, but are not necessarily limited thereto. Among these dehydrating agents, anhydrides of inorganic salts and crystalline zeolites are preferred, and anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium sulfate, and molecular sieves are particularly preferred.

In the present invention, the amount of the dehydrating agent used is not particularly limited, but is preferably 0.1 to 50 mol%, more preferably 1 to 30 mol%, based on the fluorine-containing hydroxy compound used. Such a method of removing water by performing a reaction in the presence of a dehydrating agent is very preferable because a special reaction device is not required and water can be easily removed simply by adding a dehydrating agent.

In the present invention, water produced as a by-product of the reaction can be removed from the reaction system by distilling it off. The method for distilling water is not particularly limited, and examples thereof include a method such as azeotropic dehydration. At this time, a method of distilling off water together with unreacted raw materials is preferable.
After the distillation, it is preferable that water and unreacted raw materials are separated, and the unreacted raw materials are returned to the reaction system. As a method of azeotropic dehydration,
For example, using an azeotropic dehydration apparatus, not only a method of continuously performing the reaction and the distillation of water, but also, for example, once the reaction is performed,
A method of performing the reaction and distilling off water stepwise, such as performing azeotropic dehydration and performing the reaction again, may be used. It is preferable to carry out the reaction continuously to make the reaction proceed smoothly. In order to perform dehydration efficiently, azeotropic dehydration may be performed while flowing hydrogen.

In the method of the present invention for carrying out the reaction by removing water by azeotropic dehydration, the azeotropic solvent used may be a fluorinated hydroxy compound as a raw material for the reaction, or a solvent having no adverse effect on the reaction. Is also good. When azeotropic dehydration is performed using a solvent having no adverse effect on the reaction, preferred solvents used include, but are not necessarily limited to, toluene, xylene, benzene and the like. When a solvent that does not adversely affect the reaction is used, the amount of the solvent used is not particularly limited, but is preferably 1 to 2 times the volume of the reaction solution.

In the present invention, it is also possible to remove water by-produced by the reaction out of the reaction system while flowing a gas such as hydrogen. The flow rate of hydrogen used in the present invention may be appropriately selected according to the scale of the reaction, and for example, is preferably 0.7 to 2100 ml / min, more preferably 0.7 to 700 ml / min for a 70 ml scale. By setting the flow rate of hydrogen to 0.7 ml / min or more, water is easily removed from the system, and the reaction speeds up. The flow rate of hydrogen is 2100ml / mi
It is preferable that the amount be less than n because the amount of the fluorine-containing hydroxy compound or the like to be removed together with water is reduced. However, even in this case, useful components such as unreacted raw materials and products, such as fluorine-containing hydroxy compounds, which are removed together with water, are returned to the reaction system again, for example, after water is removed by fractional distillation, liquid separation or a dehydrating agent. Alternatively, the reaction can be carried out without delay by adding a raw material corresponding to the amount removed. In addition, the flow of hydrogen may be performed continuously or intermittently during the reaction, but continuous flow is preferable in order to make the reaction proceed smoothly.

Further, the hydrogen circulated in the reaction system may be released to the atmosphere as it is. However, in order to use hydrogen effectively, the hydrogen which has come out of the system must be recirculated through a circulation line or the like. It is efficient and preferable to return the mixture to circulation and use it for the reaction while circulating. Such a method of removing water while circulating hydrogen is particularly preferable because it has the advantage that there is no reagent to be added, that hydrogen and water can be easily separated, and that post-treatment is simple.

In the present invention, the fluorinated hydroxy compound is reacted in a hydrogen atmosphere, but the hydrogen pressure is not particularly limited, and it may be either under pressure or under atmospheric pressure, from 1 (atmospheric pressure) to 300 kg / cm ^2. Preferably, 1 (atmospheric pressure) to 200 kg / cm
² is particularly preferred. In the present invention, the reaction temperature when reacting the fluorine-containing hydroxy compound is not particularly limited, but is preferably from 10 to 200 ° C, particularly preferably from 50 to 180 ° C. The reaction time may be appropriately selected depending on the reaction temperature, hydrogen pressure, amount of catalyst, and the like, but is usually 1 to 24 hours, preferably 1 to 12 hours.

In the present invention, the reaction may be carried out in the presence of a Lewis acid for the purpose of accelerating the reaction. Any Lewis acid may be used as long as it is an electron pair acceptor, but BF ₃ · OEt ₂ (boron trifluoride / diethyl ether complex), BF ₃ · 2CH ₃ CO ₂ H (boron trifluoride / acetic acid) Complex), BF ₃・ (CH ₃ ) ₃ COCH ₃ (boron trifluoride ・ t-
Butyl methyl ether _{complex), BF 3 · CH 3 OH} ( boron trifluoride-methanol _{complex), BF 3 · CH 3 (} CH 2) 2 OH ( boron trifluoride-propanol complex), TiCl ₄ (titanium tetrachloride) , SnCl ₄ (tin tetrachloride), AlCl ₃ (aluminum trichloride), TMSOTf (trimethylsilyl trifluoromethanesulfonate), Ti (Oi-Pro) ₄ (tetraisopropyl titanate), ZnCl ₂ (zinc dichloride), FeCl ₃ (Iron trichloride) and the like, with BF ₃ · OEt ₂ being particularly preferred. When a Lewis acid is used in the present invention, the amount thereof is not particularly limited, but is preferably 0.01 to 20 times, more preferably 0.1 to 10 times, more preferably 0.5 to 5 times, based on the fluorinated hydroxy compound. It is twice the mole.

In the reaction of the present invention, a solvent may be used in some cases. Any solvent can be used as long as it does not participate in the reaction, but hexane, heptane, tetrahydrofuran and the like are preferable.

[0030]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Di {2- (perfluorohexyl) ethyl} ether CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ OCH ₂ CH ₂ (CF ₂ ) ₅ CF _{3 A} hydrogen gas inlet tube and a stirrer were provided. 54.6 g of 2- (perfluorohexyl) ethanol in a 70 ml four-necked flask
(0.15 mol) and 2.2 g of 5% Pd-C (pH 6.8) as a catalyst were stirred at 130 ° C. for 10 hours while blowing hydrogen at a normal pressure at a rate of 18 ml / min. After completion of the reaction, the catalyst was removed by filtration, and nitrogen was blown in under reduced pressure to distill off low-boiling components, whereby 46.9 g (0.066 mol) of the desired di {2- (perfluorohexyl) ethyl} ether was obtained. Obtained as a clear, colorless liquid. The isolation yield was 88%.

Example 2 Di {2- (perfluorodecyl) ethyl} ether CF ₃ (CF ₂ ) ₉ CH ₂ CH ₂ OCH ₂ CH ₂ (CF ₂ ) ₉ CF ₃ Equipped with a hydrogen gas inlet tube and a stirrer. 56.4 g of 2- (perfluorodecyl) ethanol in a 70 ml four-necked flask
(0.1 mol), 2.3 g of 5% Pd-C (pH 7.2) as a catalyst
And stirred at 170 ° C. for 10 hours while blowing hydrogen at a normal pressure at a rate of 20 ml / min. After completion of the reaction, the catalyst was removed by filtration, and steaming was further performed under reduced pressure to remove low-boiling components, whereby 50.0 g (0.045 mol) of the desired di {2- (perfluorodecyl) ethyl} ether was obtained. Obtained as a white solid. The isolation yield was 90%. Examples 3 to 12 Using the fluorine-containing hydroxy compounds and catalysts shown in Tables 1 and 2, the reaction was carried out in the same manner as in Example 1 except for the reaction conditions shown in Tables 1 and 2. The obtained products and the yields are shown in Tables 1 and 2.

[0033]

[Table 1]

[0034]

[Table 2]

Claims (6)

[Claims] 1. A compound of the general formula (I) RO- (AO) _n -H (I) wherein R is a linear or branched alkyl or alkenyl group having 1 to 40 carbon atoms, or 3 to 12 carbon atoms. Represents a fluorine substituent in which at least one hydrogen atom of the cycloalkyl group is substituted with a fluorine atom, A represents an alkylene group having 2 to 12 carbon atoms, and n A may be the same or different. Is a number of 0 to 200.) A compound represented by the general formula (II), wherein one or a mixture of two or more kinds of the fluorine-containing hydroxy compounds represented by the general formula (II) is reacted with a catalyst in a hydrogen atmosphere. A method for producing a fluorinated ether compound represented by the formula: RO- (AO) _n- (A'O) _{n '} -R' (II) (wherein, R 1, A 2 and n have the same meanings as above. R 'is a linear or branched C 1 to C 40) An alkyl group or an alkenyl group, or a fluorine substituent in which at least one hydrogen atom of a cycloalkyl group having 3 to 12 carbon atoms is substituted with a fluorine atom, wherein A ′ represents an alkylene group having 2 to 12 carbon atoms;
The n 'A's may be the same or different. n 'is 0 to 200
Indicates the number of R and R ', A and A', and n and n 'may be the same or different. ) 2. The fluorinated hydroxy compound has 1 carbon atom.
~ 40 aliphatic alcohols, methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, isopropyl carbitol, butyl carbitol, carbon number 1
At least hydrogen atoms of an alkyl group, an alkenyl group or a cycloalkyl group of an ethylene oxide adduct of 40 aliphatic alcohols (average number of moles added: 0.1 to 20) or a hydroxy compound selected from cycloalkanols having 5 to 8 carbon atoms; 2. The method according to claim 1, wherein one of the compounds is substituted with a fluorine atom. 3. The fluorinated hydroxy compound has 1 carbon atom.
The method according to claim 2, wherein at least one of the hydrogen atoms of the alkyl group or the alkenyl group in the aliphatic alcohols is substituted with a fluorine atom. 4. A fluorine-containing hydroxy compound represented by the general formula:
(IV) Rf ₁ (CH ₂ ) _p OH (IV) (wherein, Rf ₁ represents a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, and p represents a number of 1 to 10). The method according to claim 3, which is a compound represented by the formula: 5. The catalyst according to claim 1, wherein the catalyst is a palladium catalyst supported on carbon, alumina, silica alumina or silica, palladium hydroxide or palladium oxide.
The production method according to any one of the above. 6. The production method according to claim 1, wherein the reaction is carried out while removing water produced as a by-product of the reaction.