KR101307181B1 - Preparation method of 5-hydroxymethyl furfural by dehydration of fructose using the metal halide catalysts and the ionic liquids - Google Patents

Abstract

The present invention relates to a method for producing 5-hydroxymethyl furfural (5-HMF) by dehydrating fructose using metal chloride as an acid catalyst in an ionic liquid. According to the preparation method of the present invention, 5-hydroxymethyl furfural can be produced in a remarkable yield within a low temperature and a very short reaction time which is mild compared to the reaction conditions of the conventional catalyst.

Description

PREPARATION METHOD OF 5-HYDROXYMETHYL FURFURAL BY DEHYDRATION OF FRUCTOSE USING THE METAL HALIDE CATALYSTS AND THE IONIC LIQUIDS}

The present invention relates to a method for preparing 5-hydroxymethyl furfural (5-HMF) by dehydration of fructose, and more particularly, to dehydration of fructose using metal chloride as an acid catalyst in an ionic liquid. The present invention relates to a method for producing 5-hydroxymethyl furfural (5-HMF) in remarkable yield under mild conditions.

Today fossil fuels are becoming increasingly depleted and adversely affect the environment due to increased usage in the industrial age. Therefore, the chemical industry can be used as a raw material of useful organic compounds and fuels, and interest in renewable feedstocks, particularly carbohydrates, is rapidly increasing.

Naturally occurring biomass is produced in massive amounts of 170 billion tons per year, of which 75% is in the carbohydrate family. Of the many chemicals that can be derived from carbohydrates, 5-hydroxymethylfurfural (hereinafter also referred to as 5-HMF) is useful as a precursor for transportation fuels, pharmaceuticals and other petroleum derived chemicals. Bifunctional moieties and 6-carbon molecules, similar to general purpose chemicals such as adipic acid and terephthalic acid, are useful for a wide variety of useful acids, aldehydes, alcohols and various disubstituted furan-based compounds such as 2,5-diformylfuran. ; 2,5-furandicarboxylic acid; It has been recognized as a novel base for the synthesis of 2,5-bis- (hydroxymethyl) furan and polymers.

The most suitable and efficient method for synthesizing 5-hydroxymethylfurfural in terms of chemical yield is acid-catalyzed triple dehydration of hexasaccharide. For the conversion of hexasaccharides, such as D-fructose, conventionally homogeneous acids, such as HCl, H ₂ SO ₄ , homogeneous acids which give 40-80% yield of 5-HMF, 36% 5- Ion exchange resins, solid acid catalysts such as sulfated zirconia and high polar organic solvents that provide HMF yields such as DMSO, DMF and high energy supply conditions such as high reaction temperatures and sub-critical or Super-critical solvents were used. Inorganic acids have been used extensively in terms of yield, but these methods have serious problems in terms of separation, the use of highly toxic solvents, and the need for high energy and complex equipment which causes relatively high manufacturing costs. In contrast, solid acid catalysts have proven to have very good performance in terms of high selectivity, low energy needs and safety. However, they also have the drawback that they tend to have low conversion and long reaction times. For industrial applications, methods based on solid acid catalysts have been considered in the preparation of 5-hydroxymethylfurfural, but to date satisfactory results have not been achieved in terms of catalyst performance.

It is an object of the present invention to provide a method for preparing 5-hydroxymethyl furfural, which performs dehydration of fructose to provide maximum yield under mild and environmentally friendly reaction conditions such as low reaction temperature and short reaction time. It is.

In order to achieve the above object, the present inventors have diligently studied, and use an ionic liquid with unique characteristics such as environmental friendliness, high boiling point, low volatility and high polarity as a single solvent, inexpensive, low toxicity and handling When the dehydration reaction of fructose was carried out using this easy metal halide as an acid catalyst, it was found that 5-hydroxymethyl furfural can be produced in a remarkable yield under mild reaction conditions, thereby completing the present invention.

The present invention provides a method for producing 5-hydroxymethyl furfural (5-HMF), wherein the fructose is dehydrated in a ionic liquid using a metal chloride as an acid catalyst in an ionic liquid.

[Reaction Scheme]

The present invention is characterized by using an ionic liquid as a solvent for the dehydration reaction of fructose. Ionic liquids are environmentally friendly solvents that can reduce environmental pollution and encourage green chemistry, which has the effect of lowering the reaction temperature due to the inherent properties of high boiling point, low volatility and high polarity.

As the ionic liquid according to the present invention, it is preferable to use imidazolium-based ionic liquid. As imidazolium-based ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIM Cl) or 1-ethyl-3-methylimidazolium chloride (EMIM Cl) is preferable, and 1-butyl-3-methyl Midazolium chloride is particularly preferred.

In addition, the present invention is characterized by using a metal halide as an acid catalyst for fructose dehydration. The use of metal halides, particularly Group 5 transition metal halides, is an environmentally friendly alternative to previously reported inorganic acid catalysts as Lewis acid catalysts, which can provide the advantages of very high conversion rates, reduction of contaminants present in the waste, and easy product separation. have. In addition, in the dehydration reaction of fructose, it is possible to overcome the conventionally reported problems such as the formation of levulinic acid by rehydration reaction, long reaction time and harsh conditions.

The metal halide according to the present invention is preferably selected from the group consisting of VCl ₃ , NbCl ₅ and TaCl ₅ , with NbCl ₅ being particularly preferred. NbCl ₅ is a weak Lewis acid catalyst, which is inexpensive, less toxic and easier to handle, and can convert fructose to 5-HMF in a significant yield when applied to dehydration of fructose.

The dehydration reaction of fructose of the present invention can be carried out at a low temperature, in particular at a reaction temperature of 50 to 80 ℃, can be carried out for a reaction time of 30 minutes to 1 hour. A good yield of 5-hydroxymethyl furfural can be obtained within the reaction temperature and the reaction time.

In the dehydration reaction of fructose of the present invention, the contents of the metal halide, fructose and ionic liquid can be appropriately selected by those skilled in the art in a range where the yield is maximum depending on the reaction temperature and the reaction time. For example, when the ionic liquid is 1-butyl-3-methylimidazolium chloride (BMIM Cl) and the metal halide is NbCl ₅ , 1 mmol of fructose and ions at a reaction temperature of 80 ° C. and a reaction time of 30 minutes Particular preference is given to using metal halides at 0.020 mmol based on 10 mmol of the liquid liquid.

According to one embodiment of the invention, the ionic liquid is 1-butyl-3-methylimidazolium chloride (BMIM Cl), the metal halide is NbCl ₅ , and the dehydration reaction is carried out at 80 ° C. for 30 minutes. desirable.

Moreover, the manufacturing method of 5-hydroxymethyl furfural of this invention,

(S1) melting the ionic liquid; And (S2) adding a fructose and a metal halide catalyst to the ionic liquid and then heating it.

Since the ionic liquids according to the present invention are mostly in a solid state, the ionic liquids essentially include a melting step in use according to the preparation method of the present invention, and are added by heating with a fructose and a metal halide catalyst to the molten ionic liquid, followed by heating. This can produce 5-hydroxymethyl furfural in significant yields.

The ionic liquid according to the invention is 1-butyl-3-methylimidazolium chloride (BMIM Cl) and the metal halide is preferably NbCl ₅ .

In step S2 of the present invention, the fructose and the metal halide catalyst may be added simultaneously to the ionic liquid, or the fructose may be added to the ionic liquid and then the metal halide catalyst may be added. In addition, preferably, 5-hydroxymethyl furfural may be prepared by heating at 80 ° C. in step S2 for 30 minutes.

According to the present invention, dehydration of fructose in the presence of a metal halide catalyst using an ionic liquid as a solvent allows 5-HMF to be produced with relatively high selectivity and significant yield under mild reaction conditions. Compared to the previously reported dehydration of fructose, it can be produced with a more pronounced yield of 5-HMF for shorter reaction time at ambient reaction temperature, no side reaction, and easier dehydration reaction of fructose The advantage is that you can.

1 is a graph showing the yield of 5-HMF prepared according to Examples 1 to 3.

Hereinafter, preferred examples are provided to help the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it is apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It goes without saying that changes and modifications belong to the appended claims.

Example  One

10.0 mmol of 1-butyl-3-methylimidazolium chloride was placed in a 10 mL thick glass vial with a magnetic stirrer. The vial was capped and sealed and then heated to 150 ° C. to melt 1-butyl-3-methylimidazolium chloride with stirring for 20 minutes. After cooling to room temperature, 1.0 mmol of fructose and NbCl ₅ 0.20 mmol was added. It heated to 80 degreeC and made it react for 30 minutes. After completion of the reaction, the reaction mixture was aliquoted with a pipette and diluted with 5 mL of deionized water. The resulting solution was mixed and the insoluble humins were allowed to settle and the supernatant was filtered through a 0.2 μm nylon syringe filter. The filtered sample was analyzed by HPLC. Sample analysis was performed using a Waters HPLC system equipped with a RID-2414 detector and a Bio-Rad Aminex HPX-87H ion exclusion column (300 mm> 7.8 mm). 5 mM H ₂ S0 ₄ having a flow rate of 0.6 mL / min was used as the mobile phase. The column temperature was 60 ° C. and the detector temperature was set to 40 ° C. The yield of 5-hydroxymethyl furfural obtained in Example 1 was 79.3 mol%.

Example  2

Dehydration of fructose was carried out in the same manner as in Example 1 except that VCl ₃ (vanadium chloride) was used instead of NbCl ₅ . The yield of 5-hydroxymethyl furfural obtained in Example 2 was 65.0 mol%.

Example  3

NbCl ₅ instead of the same as in Example 1, except that the TaCl ₅ (tantalum chloride) was carried out to the dehydration of fructose. The yield of 5-hydroxymethyl furfural obtained in Example 3 was 69.8 mol%.

The result obtained in Examples 1-3 was shown in FIG. In all cases 5-hydroxymethyl furfural could be produced in good yields, especially in Example 1 with NbCl ₅ it was possible to produce ₅ -hydroxymethyl furfural in remarkable yields.

Example  4 (Measurement of yield depending on ionic liquid and catalyst content)

The yield of 5-hydroxymethylfurfural obtained in the same manner as in Example 1 was measured except that the type of ionic liquid, reaction time and content of NbCl ₅ , which were catalysts, were slightly different. Indicated.

Ionic liquid Content of Catalyst (NbCl ₅ ) (mmol) Yield of 5-HMF (mol%)
1-butyl-3-methylimidazolium
Chloride (Reaction time: 30 minutes)

0 0 0.05 66.6 ± 1.2 0.10 71.4 ± 1.3 0.20 79.3 ± 1.1 0.30 67.0 ± 1.2 0.40 63.5 ± 1.2
1-ethyl-3-methylimidazolium
Chloride (Reaction time: 60 minutes)

0 0 0.05 58.5 ± 1.2 0.10 66.3 ± 1.0 0.20 69.6 ± 1.4 0.30 57.8 ± 1.2 0.40 57.5 ± 1.1

As can be seen from Table 1, dehydration of fructose using NbCl ₅ as catalyst in an ionic liquid according to the present invention yields 5-hydroxymethylfur in good yield for a short reaction time of 30 minutes or 60 minutes. Fural can be prepared.

Comparative example

The dehydration reaction of fructose was carried out in the same manner as in Example 1 except that only the ionic liquid was used without adding NbCl ₅ . The yield of 5-hydroxymethyl furfural obtained in the comparative example was 0 mol%. That is, 5-hydroxymethyl furfural was not produced when dehydration of fructose in ionic liquid without metal halide.

Materials Used

Fructose, VCl ₃ (97%), NbCl ₅ (99.9%) and TaCl ₅ (99.9%) used in all examples and comparative examples of the present invention were purchased from Sigma-Aldrich and were ionic liquid 1-butyl- 3-methylimidazolium chloride (BMIM Cl) and 1-butyl-3-methylimidazolium chloride (BMIM Cl) were used from Acros Organics. All chemicals used reagent grade or higher and were used directly without further purification. In addition, the ionic liquid was used after drying under high vacuum using a 60-70 degreeC vacuum oven before reaction.

Claims (15)

As shown by the following scheme,
5-hydroxymethylfur, characterized in that fructose is dehydrated at 50-80 ° C. for 30 minutes to 1 hour using NbCl ₅ as an acid catalyst in 1-butyl-3-methylimidazolium chloride (BMIM Cl) solvent. Method for preparing fural (5-HMF):
[Scheme]

delete delete delete delete delete delete delete The method of claim 1,
The dehydration reaction is a method for producing 5-hydroxymethyl furfural, characterized in that carried out for 30 minutes at 80 ℃.
(S1) melting 1-butyl-3-methylimidazolium chloride (BMIM Cl); And
(S2) adding fructose and NbCl ₅ catalyst to the 1-butyl-3-methylimidazolium chloride (BMIM Cl) and then heating
Method for producing 5-hydroxymethyl furfural comprising a.
delete delete The method of claim 10,
The fructose and NbCl ₅ catalyst in the step S2 is a method for producing 5-hydroxymethyl furfural, characterized in that the simultaneous addition to 1-butyl-3-methylimidazolium chloride (BMIM Cl).
The method of claim 10,
The method of preparing 5-hydroxymethylfurfural, wherein the fructose is added to 1-butyl-3-methylimidazolium chloride (BMIM Cl) in step S2 and then an NbCl ₅ catalyst is added.
The method of claim 10,
Method of producing 5-hydroxymethyl furfural, characterized in that the reaction for 30 minutes by heating to 80 ℃ in the S2 step.

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