JP5072348B2 - Method for producing furan ring compound - Google Patents

Description

  The present invention is effective from 2-formyl-5-hydroxymethylfuran under mild conditions and in high yield with 2,5-diformylfuran, 5-formylfuran-2-carboxylic acid, furan-2,5- The present invention relates to a method for producing a furan ring compound capable of obtaining a furan ring compound such as dicarboxylic acid.

  Furan ring compounds such as 2,5-diformylfuran (DFF), 5-formylfuran-2-carboxylic acid (CFF), furan-2,5-dicarboxylic acid (FDCA) are pharmaceuticals, agricultural chemicals, insecticides, and antibacterial agents. Useful as an intermediate in fragrances and other various fields. Hydroxymethyl group is selectively oxidized from 2-formyl-5-hydroxymethylfuran (5-hydroxymethylfurfural: 5-HMF) in dimethyl sulfoxide (DMSO) with nitric acid or dinitrogen tetroxide. A method of using aldehyde has been reported (Non-patent Document 1). In addition, there has been reported a method of oxidizing 5-HMF while performing air / oxygen bubbling at 150 ° C. or the like using a vanadium compound catalyst or the like in DMSO (Patent Document 1). In addition, a method of oxidizing 5-HMF with high-pressure oxygen in a solvent mixture containing an aliphatic monocarboxylic acid compound, preferably acetic acid, using a bromide catalyst of cobalt or manganese has been reported (Patent Document 2). .

However, the method described in Non-Patent Document 1 is difficult to handle dinitrogen tetroxide, DMSO has a high boiling point, high energy consumption for storage, and low yield of product. . In the methods described in Patent Documents 1 and 2, the reaction time is long, the production unit price is high, the production efficiency is low, and there is a problem in application to industrial production. In particular, in the method described in Patent Document 2, the DFF generation rate is as low as 63%.
Noguchi Laboratory Times, Vol. 22, pp. 24-26 US Patent 6,706,900 Special table 2003-528868

  An object of the present invention is to produce a furan ring compound capable of easily and efficiently producing a furan ring compound in a high yield under a mild condition by reducing energy consumption without using an expensive catalyst. It is to provide a method.

  The present inventors diligently studied on a method for producing a furan ring compound under mild conditions in order to reduce energy consumption. As a result, an azeotropic mixture of water and an aliphatic organic solvent having an ether bond and a mixed solvent of water and azeotropically remove the water out of the reaction system by dehydration of nitric acid, thereby removing 5-HMF. It has been found that the oxidative power for such as can be activated. As a result, it has been found that a furan ring compound can be produced efficiently and in high yield from 5-HMF by simply reacting under mild conditions without directly handling dinitrogen tetroxide which is difficult to handle. Based on this knowledge, the present invention has been completed.

That is, the present invention mixes 2-formyl-5-hydroxymethylfuran, an aqueous nitric acid solution, an aliphatic organic solvent having an ether bond that forms an azeotrope with water, and heats the water by azeotropy. The present invention relates to a method for producing a furan ring compound , characterized in that 2,5-diformylfuran, 5-formylfuran-2-carboxylic acid and furan-2,5-dicarboxylic acid are produced by removal from the reaction system. .

  The method for producing a furan ring compound of the present invention can reduce the energy consumption without using an expensive catalyst, and can efficiently produce the furan ring compound in a high yield under mild conditions.

  In the method for producing a furan ring compound of the present invention, 5-HMF, an aqueous nitric acid solution, and an aliphatic organic solvent having an ether bond that forms an azeotrope with water are used.

  5-HMF used in the method for producing a furan ring compound of the present invention is represented by the following chemical formula.

5-HMF is a furan compound obtained by subjecting glucose to a heat dehydration reaction in the presence of an acidic catalyst. Agricultural crops such as corn, sugar cane, cassava, wood, naphtha and the like can be used.

  The nitric acid aqueous solution used in the present invention is preferably concentrated nitric acid because the water content is small, and the concentration of the nitric acid aqueous solution is preferably 60% by mass or more. The amount of nitric acid used is preferably equimolar to 10 molar times with respect to 5-HMF. If it is equimolar or more, the hydroxyl group and formyl group of 5-HMF can be oxidized efficiently, and if it is 10 mol times or less, the destruction of the substrate and product can be suppressed. The amount of nitric acid used is more preferably 1.5 to 5 mole times.

  Furthermore, the organic solvent used in the present invention is an aliphatic compound that forms an azeotrope with water and has an ether bond. The organic solvent is azeotropically removed with water and removed from the reaction system, thereby dehydrating nitric acid and activating the oxidizing power. The azeotrope with water may have either a minimum azeotropic point or a maximum azeotropic point. As the aliphatic compound having an ether bond, a compound that does not contain a ketone group that does not have stability to nitric acid is preferable. For this reason, aromatic hydrocarbons such as toluene and ketones such as cyclohexanone and methyl isobutyl ketone are excluded from the organic solvents used in the present invention.

  Specific examples of the organic solvent include diisopropyl ether, dibutyl ether, dioxane, tetrahydrofuran, tetrahydropyran, cineol, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, Examples include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dibutyl ether. Of these, diethylene glycol dimethyl ether is particularly preferable because it is excellent in oxidation resistance to nitric acid and can form an azeotrope of 99.8 ° C. with water to maintain a preferable reaction temperature. These organic solvents may be used in combination of two or more, so long as they have an azeotropic point with water.

  The amount of the organic solvent used needs to be able to discharge water out of the system by azeotropy, and the amount varies depending on the solvent, but is 0.1 to 100 parts by mass with respect to 1 part by mass of water contained in nitric acid. Is preferable, and 1-50 mass parts is more preferable.

  The mixing with 5-HMF, nitric acid aqueous solution and organic solvent may be in any order, method, etc., but 5-HMF is dissolved in organic solvent to form 5-HMF solution, and then 5-HMF solution is used. A method of preparing a mixed solution by mixing nitric acid and an aqueous nitric acid solution is preferable because dissolution is easy. The content of 5-HMF in the mixed solution is preferably in the range of 0.001 to 1 part by mass and more preferably 0.01 to 0.5 part by mass with respect to 1 part by mass of the solvent.

  In addition to the above, the above mixed solution may contain an additive as long as it does not impair the functions of 5-HMF, nitric acid aqueous solution, and organic solvent.

  Thereafter, the mixed solution is heated, water and an organic solvent are azeotroped to remove the solvent from the reaction system, and 5-HMF is oxidized. The heating temperature depends on the azeotropic temperature of the azeotrope, but can be, for example, 60 to 250 ° C., and 80 to 130 ° C. can be mentioned as a preferable range. If the reaction temperature is 60 ° C. or higher, the oxidation reaction rate can be increased, and if it is 250 ° C. or lower, decomposition of the raw material can be suppressed. By removing the azeotropic solvent out of the reaction system by heating in such a range, dehydration from water or nitric acid hydrated with nitric acid can be performed, and the oxidation activity of 5-HMF can be improved. The heating time can be 5 minutes to 2 hours or the like, and can be significantly shortened as compared with the time required for the reaction using conventional nitric acid and dinitrogen tetroxide.

  As the furan ring compound obtained by the above reaction, 2,5-diformylfuran (DFF)

5-Formylfuran-2-carboxylic acid (CFF)

And furan-2,5-dicarboxylic acid (FDCA)

が選択的に得られる。

Is selectively obtained.

  Although the manufacturing method of the furan ring compound of this invention is demonstrated concretely below in detail, the technical scope of this invention is not limited to these.

[Example 1]
In a round bottom flask, 126 mg (1 mmol) of 5-HMF (manufactured by Aldrich) and 3 g of diethylene glycol dimethyl ether (manufactured by Kishida) were stirred and dissolved, and 60% nitric acid (manufactured by Kishida Chemical, specific gravity 1.38) 0 .63 g was added and heated at 120 ° C. for 15 minutes to carry out the reaction while removing the vapor. The obtained product was analyzed by high performance liquid chromatography (HPLC) under the following conditions. The yields of DFF, CFF, and FDCA were 39 mol%, 52 mol%, and 9 mol%, respectively.

[HPLC measurement conditions]
HPLC: JASCO Corporation high-performance liquid chromatograph column: Shodex SUGAR SH1011 (one used)
Column temperature: 80 ° C
Mobile phase: 3 mM perchloric acid (perchloric acid made by Kishida Chemical diluted with ion-exchanged water)
Flow rate: 0.6 ml / min (0 to 20 min) and 1.4 ml / min (20 to 35 min)
Detector: RI
Retention time: 24.0 minutes for 5-HMF, 26.0 minutes for DFF, 18.0 minutes for CFF, 14.3 minutes for FDCA.

[Example 2]
The reaction was performed in the same manner as in Example 1 except that the heating time was 120 minutes. The yields of DFF, CFF, and FDCA obtained were 35 mol%, 44 mol%, and 9 mol%, respectively.

[Comparative Example 1]
The reaction was conducted in the same manner as in Example 1 except that 126 mg (1 mmol) of 5-HMF (manufactured by Aldrich) was dissolved in 3 g of toluene in place of 3 g of diethylene glycol dimethyl ether and the heating time was 120 minutes. The reaction solution became dark black with a strange odor, and the desired product was not obtained.

[Comparative Example 2]
The reaction was conducted in the same manner as in Example 1 except that 126 mg (1 mmol) of 5-HMF (manufactured by Aldrich) was dissolved in 3 g of methyl isobutyl ketone instead of 3 g of diethylene glycol dimethyl ether, and the heating time was 120 minutes. The reaction solution became dark black with a strange odor, and the desired product was not obtained.

  From the above results, it is apparent that 5-HMF, DFF, CFF, and FDCA can be obtained easily and in high yield in a short time according to the method for producing a furan ring compound of the present invention.

Claims (2)

2-Formyl-5-hydroxymethylfuran, nitric acid aqueous solution, water and an aliphatic organic solvent having an ether bond that forms an azeotrope are mixed and heated to remove water out of the reaction system by azeotropy. Thus , 2,5-diformylfuran, 5-formylfuran-2-carboxylic acid and furan-2,5-dicarboxylic acid are produced . The method for producing a furan ring compound according to claim 1, wherein the aliphatic organic solvent having an ether bond is diethylene glycol dimethyl ether.