JPS5914468B2 - Method for producing 5-methyl-2-furfural - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 5 The present invention relates to a method for producing 5-methyl-2-furfural represented by the general formula [1] [wherein R represents a hydrogen atom].

The compound is a compound useful as a synthetic intermediate for agricultural chemicals or fragrances. 10 For example, it is useful as an intermediate for the synthesis of fragrances such as cysudiasmones or 2-alkyl-3-methyl-2-cyclopenten-1-one, and is useful as an intermediate for the synthesis of tobacco flavorings (US Pat. No. 3,381,690) and pesticides (South African Pat. No. 7, 206, 590) and other applications have also been reported.

Conventionally, 5-methyl-2-furfural has been produced by using methylpentose such as rhamnose or fucose as a starting material and carrying out a thermal dehydration reaction using hydrochloric acid in a water-organic solvent system in the presence of a surfactant. How to get (
JP-A No. 53-50155) is known, but this method has problems such as the repeated sampling and addition operations using toluene, and the raw material methyl pentose is expensive, making it an industrially advantageous production method. It's hard to say.

25 Previously, the present inventors used fructose, which is abundant and inexpensive as a raw material, to synthesize the general formula [1] [
In the formula, R represents a hydroxyl group] 5-hydroxymethyl-2-furuf30 represented by
A method for producing Ral in high yield has been discovered (Japanese Patent Application Laid-open No. 15457-1983).

From this 5-hydroxymethyl-2-furfural, 5-
As a result of intensive research on the method for producing methyl-2-furfural, we found that the general formula [I] 35R-C-O [wherein R is 11, R, -O (R' is unsubstituted- or substituted alkyl or aryl] We have discovered a new method for producing derivatives represented by the following group with good yield by catalytic hydrogenation reaction, and after conducting various studies, we have finally completed the present invention.

General formula [1] R'-C-0 used in the present invention [wherein R is I:, R''-0 (-R'' represents an unsubstituted or substituted alkyl or aryl group] The represented compound is easily available from ζ 5-human b-ximethyl-2-furfural, R' represents a straight chain or branched alkyl group, and 6 or 6 substituent-containing compounds are available. Indicates an alkyl group.

Examples of substituents include halogen atoms, alkoxy groups,
Examples include aryl groups, which may be substituted with one or more of the same or different substituents, such as methyl, ethyl, propyl, chloromethyl, trifluoromethyl, benzyl, etc. I can do it. Further, R' represents an aryl group or an aryl group having a substituent, and examples of the substituent include a halogen atom, alkyl, nitro, and alkoxy group, among which one or more of the same or different It may be substituted with a substituent, such as phenyl, parachlorophenyl, paranitrophenyl, paraoxyphenyl, and the like. The catalyst used in the catalytic hydrogenation reaction in the present invention may include palladium, rhodium, platinum, nickel, etc., but palladium catalysts are preferred, followed by rhodium catalysts.

For example, it is a catalyst in which palladium or rhodium is supported on one kind of catalyst carrier such as carbon, alumina, silica, silica alumina, diatomaceous earth, barium sulfate, etc., and preferably a palladium catalyst supported on carbon powder. The amount of metal supported on the catalyst carrier is not particularly limited, but is preferably 0.1% by weight or more.

In carrying out the method of the present invention, although the purpose can be fully achieved in a system without the addition of a base, the selectivity for 5-methyl-2-furfural can be increased by carrying out the reaction with the addition of a base. can and also generated 5
It has been found that it is possible to suppress the side reaction of 5-methyl-2-furfuryl alcohol in methyl-2-furfural. The bases used include triethylamine, diethylamine, pyridine, piperidine,
Organic bases such as ammonia and alkalis such as sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and the like can be mentioned. Examples of the solvent used in the reaction include ethyl acetate, methanol, ethanol, cyclohexane, n-hexane, dioxane, and acetic acid, with ethyl acetate being particularly preferred. The reaction temperature in carrying out the reaction can be at room temperature, and if necessary, it can also be carried out under heating conditions.

As described in detail above, the present invention provides a novel manufacturing method for obtaining 5-methyl-2-furfural in high yield by a simple method.

The method of the present invention will be explained below with reference to examples, but the scope of claims of the present invention is not limited to the scope of the examples.
Example 1 0.25 g of 5-acetoxymethyl-2-furfural (
Dissolve 1.5 mmol of mono(c) in 15.0a of ethyl acetate, add 0.25 g of 5% Pd-carbon powder (0.12 mmol, Nippon Engelhard Co., Ltd.), and then place in an atmospheric hydrogenation device with stirring. The reaction was carried out for 50 minutes at a reaction temperature of 20°C.

As a result of analyzing the reaction solution by gas chromatography,
5-Methyl-2-furfural was obtained in a yield of 85 mol% based on 5-acetoxymethyl-2-furfural. Example 2 0.25 g of 5-acetoxymethyl-2-furfural (
1.5 mmol), triethylamine 0.042! IL
I (0.30 mmol) to ethyl acetate 15.0! ! Ll
0.25 g (0.1
2 mmol) and the same procedure as in Example 1 was carried out at 20°C.
The reaction was allowed to run for minutes.

As a result of analyzing the reaction solution in the same manner as in Example 1, 5-
Methyl-2-furfural is 5-acetoxymethyl-2
- Obtained in a yield of 94 mol% based on furfural. Example 3 5-acetoxymethyl-2-furfural 0.
0.26 g (0.5% Pd-alumina pellets) were prepared by dissolving 25 g (1.5 mm) in 15.0 a of ethyl acetate, pre-soaking in an aqueous triethylamine solution, washing with water, and drying.
．． 012 mmol, Nippon Engelhard Co., Ltd.) was added and the reaction was carried out at 20°C for 180 minutes in the same manner as in Example 1. As a result, 5-methyl-2-furfural was 87 mol based on 5-acetoxymethyl-2-furfural. % yield.

Example 4 0.25 g of 5-acetoxymethyl-2-furfural (
1.5 mmol(c), triethylamine 0.21a(
After dissolving 1.5 mmol) in 15.0 ml of methyl alcohol and adding 0.26 g of 5% Rh-carbon powder (0.13 mmol, Nippon Engelhard Co., Ltd.), the mixture was heated at 20°C in the same manner as in Example 1. As a result of carrying out the reaction for 100 minutes, 5-methyl-2-furfural was obtained in a yield of 50 mol% based on 5-acetoxymethyl-2-furfural.

Example 5 5-propionyloxymethyl-2-furfural 0.
30g (1.6 mmol), triethylamine 0.22
U (1.6 mmol) was dissolved in 15.0a of ethyl acetate, 0.25 g (0.12 mmol) of 5% Pd-carbon powder was added, and the reaction was carried out at 20°C for 50 minutes in the same manner as in Example 1. As a result, 5-methyl-2-furfural was converted into 5-methyl-2-furfural.
8 based on propionyloxymethyl-2-furfural
The yield was 6 mol%.

Example 6 5-ethoxymethyl-2-furfural 0.21 g (1
．． 4 mmol (c), triethylamine 0.9a (1.
4 mmol) in 15.01 fL1 of ethyl acetate,
0.20 g (0.09 mmol) of 5% Pd-carbon powder was added and the reaction was carried out at 20°C for 30 minutes in the same manner as in Example 1. As a result, 5-methyl-2-furfural was converted into 5-ethoxymethyl-2 - Obtained in a yield of 28 mol% based on furfural.

Example 7 5-benzoyloxymethyl-2-furfural 0.3
4g (1.5 mmol), triethylamine 0.042
a (0.30 mmol) was dissolved in 15.0 a of ethyl acetate, 0.25 g (0.12 mmol) of 5% Pd-carbon powder was added, and the reaction was carried out at 20°C for 40 minutes in the same manner as in Example 1. As a result, 65-methyl-2-furfural was 5
-9 based on benzoyloxymethyl-2-furfural
Obtained with a yield of 2 mol%.

Claims (1)

[Claims] 1 General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] [In the formula, R is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R'-O (R' is a non-formal formula, A compound represented by the general formula [I] [in which R is a hydrogen atom] is subjected to a catalytic hydrogenation reaction using a palladium or rhodium catalyst. A method for producing 5-methyl-2-furfural represented by: 2 General formula [I] [In the formula, R is ▲a mathematical formula, chemical formula, table, etc.▼, R'-
O (R' represents an unsubstituted or substituted alkyl or aryl group)] is subjected to a catalytic hydrogenation reaction using a palladium or rhodium catalyst, and is characterized by adding a base. A method for producing 5-methyl-2-furfural represented by the general formula [I] [wherein R represents a hydrogen atom].