JPS5813576A - Production of 2,5-dimethylfuran - Google Patents

Abstract

PURPOSE:5-Chloromethylfurfural is used as a starting material and subjected to hydrogenolysis with hydrogen or hydrogen-transfer hydrogenation with a hydrogen donor in the presence of a specific amount of palladium catalyst in an organic solvent to produce the titled compound readily in high yield. CONSTITUTION:5-Chloromethylfurfural is subjected to hydrogenolysis with hydrogen in an organic solvent such as N,N-dimethylformamide, methanol or benzene in the presence of a palladium catalyst containing more than 5wt% methallic palladium based on the starting substance or to hydrogen-transfer hydrogenation with a hydrogen donor such as cyclohexene or cyclooctene to give 2,5-dimethylfuran. This process is not accompanied by side reactions such as hydrogenation of the furan ring and reduces both of the chloromethyl in the 5-position and the aldehyde in the 2-position to methyls selectively. USE:Synthetic intermediate of fungicidal or antiulcerative.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 2.6- This article relates to a new method for producing dimethylfuran.

More specifically, the present invention uses a palladium-based catalyst of 6 weight or more as pure palladium on a starting material in the presence of an organic solvent, and performs a hydrogen-transfer hydrogenation reaction using hydrogen decomposition or a hydrogen donor. characterized by
The present invention relates to a method for producing 2,5-dimethylfuran from 6-chloromethylfurfural.

Conventional methods for producing 2.6-dimethylfuran include: ■ Dehydration and cyclization of acetonyl acetone using an acidic catalyst f! Method (8yntMsig, 1978J6209 etc.)
■ 2.5-furandicalgicaldehyde or b
- Wolff-Jishn@r reaction method in which methylfurfural is reacted with hydrous hydrazine and an alkali metal hydroxide (Zhur.

0bshohei, IChim, II! ,
899 (19$jl), IF, a, 8. R・81
．． 6 guns? (1978), etc.) ■ A method for hydrogenolyzing 6-7-droxymethylfurfural obtained from D-7 lactose using a palladium-based catalyst (Chemical Society of Japan Chin 4!1 Autumn Annual Meeting Proceedings, 4th Eng. 19 ) and other ink.

Among these, ■ and ■ are all industrially advantageous methods due to high raw material prices. raw material costs, such as the difficulty and instability of purification from an aprotic polar solvent, and the need to convert to a protic polar solvent as the optimal solvent for hydrolysis. It is difficult to say that this method is necessarily industrially advantageous.

Under the circumstances described above, the inventors of the present invention have conducted intensive studies on the industrial production method of 2,5-dimethylfuran. When hydrogen transfer hydrogenation reaction using a hydrogen donor is carried out on hydrolyzed stone, the 6-position a-romethyl group and the 2-position It was discovered that only the aldehyde group of can be selectively reduced to a methyl group in a good yield, and the present invention was completed.

That is, in the present invention, in the presence of an organic solvent, a palladium-based catalyst having a weight of 6 or more as pure palladium is used for 6-di"lolomethylfural, and 1-hydrolysis with hydrogen or water bulk This is a method for producing 2,6-dimethylfuran, which involves carrying out a hydrogen transfer water bulking reaction using a donor.

In this case, the activity of the palladium-based catalyst used is weak when the amount thereof is small, and 6-methylfurfural, in which only the chloromethylic group at the 5-position is reduced, is mainly produced.
The starting material for the process of the present invention, S-di-4-methylfurfural, which is 6% by weight of pure palladium relative to chloromethylfurfural, is a compound described in JP-A No. 58-60166, and therefore, the present invention Depending on the method, it is important as a synthetic intermediate for agricultural chemicals, mci, number etc., or as a gasoline additive, a liquid crystal photolysis inhibitor, a vinyl polymerization initiator, etc. ! 56-t
) Methylfuran can be produced on a scale of 100 yen in volume and in high yield? ”
The role it plays is extremely important.

As an organic solvent when performing hydrogenolysis with hydrogen,
It is preferable to use caramide compounds, alcohol compounds, amide compounds-alcohol compounds or alcohol compounds-tertiary amine compounds in which an organic solvent that dissolves the raw material 6-chloromethylfurfural is used. As the solvent, M, M-diethylformamide, M, M-diethylformamide, y-y-dimethylacedeamide, etc. are used, and as the alcohol-based compound, methanol, ethanol, isopropanol, etc. are used alone or as a mixed solvent. Ru.

In addition, sulfoxide-based polar solvents such as dimethyl sulfoxide and sulfolane, and aromatic hydrocarbon compounds such as benzene, toluene, and xylene are used alone or more preferably as a mixed solvent with an amide □-based compound.

In addition, when using alcoholic compounds, organic tertiary amine compounds such as triethylamine and pyridine can be used as tertiary amine compounds.
The amount of these tertiary amine compounds to be used is 0.6% per mole of 6-chloromethylfural as the raw material.
A suitable amount is 1 to 6 mol, preferably 0.6 to 1.6 mol.

The amount of these organic solvents in the hydrolysis reaction is not particularly limited, but usually 1 to 10 parts by weight of the organic S
A medium is preferably used.

Examples of organic solvents used in the water bulk transfer hydrogenation reaction include aromatic hydrocarbon compounds, aluminum compounds, alcohol compounds, and sulfoxide compounds among the organic solvents mentioned above that are used in the hydrogen-based hydrogenation reaction. Among these, it is preferable to use aromatic hydrocarbon compounds in place of benzene, toluene, and xylene, and the same amount as in the case of hydrolysis is used. It will be done.

In the hydrogen transfer water bulking reaction, an organic compound is used as the hydrogen source, and hydrogen activated by a catalyst acts as the hydrogen donor. In the method of the present invention, various hydrogen donors include aliphatic cyclics such as cyclohexene and lecrooctyne. Olefins are preferably used. These hydrogen donors are usually used in excess per mole of 6-chloromethylfurfural as a raw material.
~16 moles, preferably 8 to 12 moles is suitable.

Both supported and unsupported palladium-based catalysts can be used, but if the amount of pure palladium used is small relative to the starting material IC, the activity will be weak, and the selectivity storm < objective 2.
．． Since ξ makes it impossible to prepare 6-dimethylfuran,
It is necessary to use at least 6% by weight of pure palladium relative to the starting material 6-chloromethylfurfural. Supported catalysts include palladium-based catalysts with various support ratios, palladium-silica, palladium-alkaline catalysts, etc. However, palladium chloride, palladium black, etc. are used as unsupported catalysts. Of these, palladium-carbon, palladium chloride and the like having a loading rate of 6 to 10 degrees by weight are particularly preferably used.

The volume of water used in the hydrolysis reaction may be any ordinary commercially available water, and the amount used is particularly limited as long as it is at least the stoichiometric amount (S equivalent to 6-chloromethylfurfural) to complete the reaction. Although the pressure is not particularly limited, the reaction can be carried out at normal pressure or pressurized to promote the reaction in the container.

Although it is generally preferable to heat the mixture to promote the hydrolysis or hydrogen transfer hydrogenation reaction, a temperature of 160° C. or lower is recommended to suppress one reaction. Among the heat exchangers, the temperature is preferably in the range of 10 to 80°C when hydrolysis is carried out, and in the range of 60 to 180°C when hydrogen transfer hydrogenation reaction is carried out.

Furthermore, using an alcoholic compound as a solvent, 6 and h are preferably in the range of 10-40°C in the sense of suppressing the 1 reaction.Hereinafter, the present invention will be explained in detail with reference to Examples.
Of course, the present invention is not limited to these examples.

Example 1 0.28 t (1.6! mol) of b-chloromethylfurfural was placed in a three-necked flask equipped with a water introduction tube, a cooling tube, and a temperature needle, and dissolved in dimethylformamide 4-. Thereafter, 10G paralygin 5-carbon 0.14F (approximately 6.1 parts by weight of pure palladium based on 5-10 methylfurfural) was added.

After replacing the reaction container with hydrogen, 66
℃±2℃). Subsequently, the mixture was stirred at this temperature using a 7-magnetic stirrer for 8 hours. During this time, a volume of water was introduced at approximately 5 isi under atmospheric pressure through an inlet tube through a vinylette filled with a water volume sealed with water (the amount of hydrogen required for the reaction was approximately 5.13 electric moles).

After the reaction was completed, the catalyst was removed and the reaction solution was quantitatively analyzed by gas chromatography.The results are shown in Table 1.

Table 1 Example 2 After charging 0.28 f (1411 mol) of 6-chloromethylfurfural, 2-cyclohexene, and 4- toluene into a three-bottle flask equipped with a cooling tube and a pair of thermometers, 100 g of palladium-carbon 0,14 (approximately 6.1 weight of pure palladium based on 6-chloroutylfurfural) was added.

The reaction vessel was heated to 82° C.±2° C. in a water bath. Stirring and refluxing using a magnetic stirrer was performed at this temperature for 8.6 hours.

After the reaction was completed, the catalyst was removed and the reaction solution was quantitatively analyzed by gas chromatography, and the results were as shown in Table IF5.

Table 2 Examples 8-11 The reaction was carried out in the same manner as in Example 1.2.

The results are shown in Table 8, Table 1.

1'.

DMIFN, MUCA, MPAL, CI in the table
FAL means the same as in Table 1. In addition, in the same table, the amount of catalyst in the table means the weight of pure palladium relative to the starting material 6-chloromethylfurfural.

Claims (1)

[Scope of Claims] (1) Hydrogen is added to 6-chloromethylfurfural in the presence of an organic S medium using a palladium-based catalyst having a weight of 4 or more (as pure palladium) for the 5-chloromethylfurfural. 2.
Method for producing 5-dimethylfuran. ■ Claim 111, characterized in that the hydrolysis is carried out using an amide compound, an alcohol compound, an amide compound-alcohol compound, or an alcohol compound-tertiary amine compound as an organic solvent. 2゜Production method of 6-dimethylfuran. (8) A method for producing 2,6-dimethylfuran according to claim fB, item 1, characterized in that a hydrogen transfer hydrogenation reaction is carried out using an aromatic hydrocarbon or an elementary compound as an organic solvent. (4) A method for producing 2,6-dimethylfuran according to claim #1 or ga, characterized in that a hydrogen transfer hydrogenation reaction is carried out using cyclohexene or cyclooctyne as a hydrogen donor.・