JP2016117716A - Method for producing 2-furaldehyde and composition for producing 2-furaldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a method for producing 2-furaldehyde from a sugar raw material containing hexose as a constituent component; and a composition for producing 2-furaldehyde.SOLUTION: There is provided a method for producing 2-furaldehyde by mixing and reacting a sugar raw material containing hexose as a constituent component, a catalyst and a solvent, wherein the catalyst is a boron compound and further (1) one or more acids selected from the group consisting of an inorganic acid (provided that boric acid is excluded) and an organic acid and/or (2) a metal compound are mixed and reacted.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing 2-furaldehyde using a saccharide as a raw material, and a composition for producing 2-furaldehyde.

2-Furaldehyde is a useful compound that can be used as a raw material for production of furan, tetrahydrofuran, furan resin and the like. Since 2-furaldehyde is usually not produced from petroleum-derived raw materials but produced from plant-derived saccharides, it is classified as a chemical product derived from plant raw materials rather than from chemicals derived from petroleum raw materials.
As a method for producing 2-furaldehyde, a method obtained by reacting a raw material containing a pentose such as pentosan or pentose in the presence of an acid catalyst and dehydrating the pentose has been known for a long time. Patent Documents 1 and 2). The pentose is contained in hemicellulose and the like contained in sugarcane pomace (bagasse), corn core, wood, etc., which are agricultural wastes. However, the above-mentioned agricultural waste, which is a representative raw material containing these pentose sugars, is limited in raw material accumulation. Furthermore, the content of hemicellulose contained in the representative raw material is not so high. For example, the content of hemicellulose in wood is at most about 25%. For this reason, in the method of obtaining 2-furaldehyde from pentose, there is a problem that the yield of 2-furaldehyde per raw material used is small. Therefore, a method for obtaining 2-furaldehyde from a constituent that is more abundant in plants is desired.

  Therefore, cellulose, which is a main component of wood and is abundant in nature as a natural fiber, has attracted attention. Cellulose is a linear polymer composed mainly of glucose, which is a hexose. However, since cellulose has high crystallinity, it is difficult to hydrolyze it into the hexose constituting the cellulose. Further, the hexose obtained by hydrolyzing cellulose is obtained by reacting in the presence of an acid catalyst in the same manner as the method for obtaining 2-furaldehyde from the pentose and dehydrating it. It is known that it is not converted to 5-hydroxymethyl-2-furaldehyde. (For example, Patent Document 1, Non-Patent Document 3)

  On the other hand, a method for producing 2-furaldehyde from a raw material containing hexose has also been proposed. Cellulose, which is the main component of wood, has glucose as a structural unit, which is hexose. Patent Document 2 and Non-Patent Document 4 propose a method of obtaining 2-furaldehyde by heating cellulose in an aprotic polar solvent in the presence of an acid or a base. Patent Document 3 proposes a method of obtaining 2-furaldehyde by heating cellulose in an aprotic polar solvent in the presence of a solid acid catalyst.

JP-A-10-265468 JP 2002-205970 A International Publication No. 2012/102347 Pamphlet

Journal of Scientific and Industrial Research, Vol. 41 (1982), p. 431-438. Chemical Innovation, April (2000), P.A. 29-32. Chem. Rev. 2007, 107, p. 2411. Journal of Wood Science, 53 (2007), p. 127-133.

  In Patent Document 2, sulfuric acid, phosphoric acid, polyphosphoric acid, complex phosphoric acid with W, Mo, V, and boric acid are used as inorganic acids, and sodium hydroxide, potassium hydroxide, and hydroxide are used as bases. Lithium, calcium carbonate, etc. are mentioned, but the production reaction of 2-furaldehyde specifically disclosed is that the cellulose as a raw material is collectively in a reaction solution in which an aprotic solvent and sulfuric acid coexist. This is a batch reaction for preparing 2-furaldehyde by charging. On the other hand, when the inventors conducted a continuous reaction in which the raw material, aprotic solvent, sulfuric acid, and water were continuously supplied to perform the reaction, the yield of 2-furaldehyde produced was (See Comparative Example 2 of the present application). Further, this yield was not improved even when the amount of the catalyst was increased (see Comparative Example 3 of the present application). The low yield in this continuous reaction is a problem when industrially producing 2-furaldehyde since the continuous reaction is industrially advantageous compared to the batch reaction.

On the other hand, the present inventors previously proposed the method of Patent Document 3 in which a continuous reaction is carried out using a solid acid catalyst. Although this method has an advantage of being a continuous reaction, it is necessary to prepare a solid acid catalyst in advance, and further improvement in the yield of the target product is desired.
Then, this invention makes it a subject to provide the manufacturing method of 2-furaldehyde industrially advantageous with a high yield also in a continuous reaction.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have surprisingly found that by using a specific boron compound as a catalyst and further using a certain kind of acid and / or metal compound, they can be used alone. As a result, the present inventors have found that 2-furaldehyde can be obtained in a high yield from a sugar raw material containing hexose as a constituent, compared with the case of using as a catalyst.
That is, the gist of the present invention is as follows.

[1] A method for producing 2-furaldehyde by mixing and reacting a sugar raw material containing hexose, a catalyst, and a solvent, wherein the catalyst is a boron compound, and (a) an inorganic acid A method for producing 2-furaldehyde, characterized in that one or more acids selected from the group consisting of organic acids (excluding boric acid) and / or (b) a metal compound are mixed and reacted.
[2] The method for producing 2-furaldehyde according to [1], wherein the boron compound is one or more selected from the group consisting of boric acid, boron oxide, boric acid ester, and boron halide. .
[3] The method for producing 2-furaldehyde according to [1] or [2], wherein the inorganic acid (excluding boric acid) is sulfuric acid or phosphoric acid, and the organic acid is a carboxylic acid.

[4] The sugar raw material, catalyst and solvent are further mixed with (a) one or more acids selected from the group consisting of inorganic acids (excluding boric acid) and organic acids, and (2) metal compounds. The method for producing 2-furaldehyde according to any one of [1] to [4], wherein the reaction is performed.
[5] The metal compound according to any one of [1] to [4], wherein the metal compound is a compound in which a hydroxide generated when the metal compound is hydrolyzed is amphoteric. A method for producing furaldehyde.
[6] The metal compound includes a metal selected from the group consisting of Al, Ga, In, Sn, Ti, Zr, Mn, Fe, Co, Ni, Cu, Pb, Bi, and Zn. [2-] The manufacturing method of 2-furaldehyde in any one of [1]-[5].
[7] The metal compound according to any one of [1] to [6], wherein the metal compound is selected from the group consisting of metal alkoxides, metal organic acid salts, metal halides, and metal sulfates. A method for producing furaldehyde.

[8] The method for producing 2-furaldehyde according to any one of [1] to [7], wherein the solvent is an aprotic polar solvent.
[9] The method for producing 2-furaldehyde according to any one of [1] to [8], wherein the solvent is a solvent having a boiling point higher than that of 2-furaldehyde.
[10] The method for producing 2-furaldehyde according to any one of [1] to [9], wherein the 2-furaldehyde produced by the reaction is reacted while being discharged out of the reaction system.
[11] The method for producing 2-furaldehyde according to any one of [1] to [10], wherein the reaction temperature is not lower than the boiling point of 2-furaldehyde and not higher than the boiling point of the solvent.

[12] The method for producing 2-furaldehyde according to any one of [1] to [11], wherein the sugar raw material, the catalyst, and the solvent are further mixed and reacted.
[13] The production of 2-furaldehyde according to any one of [1] to [12], wherein the sugar raw material contains at least one selected from the group consisting of cellulose, starch and hexose. Method.
[14] The method for producing 2-furaldehyde according to any one of [1] to [13], wherein the catalyst is supplied after being dissolved in water.

[15] The method for producing 2-furaldehyde according to any one of [1] to [14], wherein the catalyst is boric acid.
[16] (1) a sugar raw material comprising hexose as a constituent, (2) one or more acids selected from the group consisting of inorganic acids (excluding boric acid) and organic acids, and / or metal compounds, and (3) A composition for 2-furaldehyde production comprising a solvent.
[17] The composition for producing 2-furaldehyde according to [16], wherein the solvent is an aprotic polar solvent.

  According to the present invention, when 2-furaldehyde is produced using cellulose or the like containing hexose as a constituent as a saccharide raw material, the final target 2-furaldehyde is increased without preparing a solid acid catalyst in advance. It can be produced in a yield, and an industrially advantageous method for producing 2-furaldehyde can be provided.

Hereinafter, the present invention will be described in detail, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents. Various modifications can be made within the scope of the gist.
In the present specification, according to the production method of the present invention, “at least one of a sugar raw material, a solvent, a boron compound, and (a) one or more selected from the group consisting of inorganic acids (excluding boric acid) and organic acids” A liquid obtained by mixing “acid and / or (b) metal compound” is referred to as “reaction liquid”, and a reaction liquid in which a boron compound acts as a catalyst is referred to as “reaction system”.

[Method for producing 2-furaldehyde]
The production method of 2-furaldehyde of the present invention is a method in which at least a sugar raw material containing hexose, a catalyst, and a solvent are mixed and reacted, and the catalyst is a boron compound, and the reaction system includes ( a) One or more acids selected from the group consisting of inorganic acids (excluding boric acid) and organic acids, and / or (b) metal compounds are mixed and reacted.

<Sugar raw material containing hexose>
The sugar raw material having hexose as a constituent used in the present invention refers to a substance containing hexose (hexose sugar) having 6 carbons as a constituent.
The way in which hexose is included as a constituent component is not particularly limited, but it may be one containing hexose in the saccharide molecule or one containing hexose in the mixture, and saccharide containing hexose (for example, cellulose described later). Natural products that can be used as raw materials for polysaccharides such as

The hexose contained as a constituent component is not particularly limited, and may be any of aldose, ketose, and deoxy sugar.
Specifically, aldoses such as allose, talose, growth, glucose (glucose), altrose, mannose, galactose and idose; ketoses such as psicose, fructose (fructose), sorbose and tagatose; deoxy sugars such as fucose, fucose and rhamnose And the like. Preferably, glucose and fructose are preferable because the content in the sugar raw material described below is large, and glucose is more preferable because it can be obtained from a non-edible raw material. Moreover, the sugar raw material used in the present invention may contain one kind or two or more kinds of the above hexoses.

  Examples of the sugar raw material containing the hexose of the present invention as a constituent component include those containing hexose. Specifically, it is a saccharide containing hexose as a constituent component, which is a monosaccharide of the hexose; sucrose (sucrose), lactose (lactose), trehalose, isotrehalose, turanose, cellobiose, cordobiose, sophorose, nigerose, laminaribio Disaccharides containing hexoses such as sucrose, maltose (maltose), isomaltose, gentiobiose; Examples include oligosaccharides containing saccharides; polysaccharides containing hexoses such as cellulose, starch, and dextrin.

Examples of the sugar raw material containing hexose as a constituent in the present invention include those used as raw materials for these sugars, such as natural products, in addition to those containing the above hexose.
Specific sugar raw materials include raw materials containing cellulose such as wood, paper, cotton, rice straw and wheat straw, corn core, sugarcane pomace (bagasse); potatoes, sweet potatoes, rice, wheat, Examples include raw materials containing starch such as corn; fruit juice molasses containing a plurality of sugars such as fruit juice, syrup, and honey. The above raw materials may be used alone or in combination of two or more.

Moreover, the residue which extracted and utilized the pentose (pentose) component previously from the raw material which contains pentoses and hexoses, such as wood, as a structural component can also be used as a raw material of this invention. It is also effective to use waste containing a large amount of ash and coexisting components such as paper sludge as a raw material. On the other hand, depending on the type and mode of the raw material, it is possible to obtain furfural simultaneously from both pentose and hexose contained in the raw material by optimizing the constituent components and reaction conditions of the catalyst.
Among these, cellulose is present in a large amount as a main component of trees and grasses, and unlike starch and sucrose, it is a non-edible resource. Therefore, a material containing cellulose is preferable as a sugar raw material. Further, those containing starch are preferably used because highly pure ones can be easily obtained.

<Catalyst>
The boron compound used as the catalyst is preferably water-soluble or one that generates boric acid by hydrolysis with water. The reason is that the dispersibility and uniformity of the catalyst in the reactor due to the reaction between the catalyst and other components (sugar raw material containing hexose or any acid, metal compound, or water optionally contained), and This is because the affinity with a sugar raw material containing hexose as a constituent is increased, and as a result, high catalytic efficiency is obtained. For example, an acid anhydride produced by a reaction between boric acid and carboxylic anhydride can also be used as the boron compound. In addition, water solubility here means what melt | dissolves 1g or more in 100cc water at 25 degreeC.

Specific examples of the boron compound used as a catalyst in the present invention include boric acid, boron oxide, boric acid esters, and boron halides, boronic acids, boric acid and esters thereof. 1 or more selected from the group consisting of boron oxide, boric acid ester, and boron halide is preferable. Examples of boric acid ester (also called alkyl borate or boron alkoxide) include monomethyl borate, dimethyl borate, boric acid Examples thereof include mono-, di- and triesters of boric acid and an alkyl group having 1 to 4 carbon atoms such as trimethyl acid, triethyl borate, tributyl borate and the like.

Examples of the boron halide include boron trichloride, boron trifluoride, and boron tribromide.
Among these, boric acid, boron oxide, and boric acid ester are preferable, and boric acid is more preferable because it is inexpensive and easy to handle. Two or more boron compounds may be used in combination, or may be used as a complex such as a complex of boron trifluoride and ether.

As described above, the boron compound creates catalytically active species that are appropriately dispersed by reaction with the compound or hydrolysis, and has a role of adjusting the reaction system to an acidity suitable for the production of 2-furaldehyde. In addition, some think that the progress of the reaction to 2-furaldehyde is made advantageous by acting and reacting with saccharide raw materials and reaction intermediates containing hexose as a constituent and forming borate esters thereof. It is done.
In the present invention, a catalyst other than the boron compound may be used in combination as long as the effects of the present invention are not impaired.

<Solvent>
The solvent used in the present invention is not particularly limited as long as the object of the present invention is satisfied, but it is usually preferable to discharge the main 2-furaldehyde out of the reaction system by the reaction described later. Is preferably a solvent that can be reacted while being discharged in the gas phase, and among them, a solvent having a boiling point equal to or higher than that of 2-furaldehyde is preferable from the viewpoint of functioning stably as a solvent at the reaction temperature. Specific examples of such solvents include aprotic polar solvents, ionic liquids such as 1-ethyl-3methylimidazolium chloride, 1-ethyl-3methylimidazolium methylphosphonate, molten salts, supercritical carbon dioxide, and the like. Selected from.

  Among these solvents, the aprotic polar solvent is particularly inferior in reactivity with the raw material and the product 2-furaldehyde, and is stable with respect to the boron compound used in the reaction of the present invention. preferable. The type of the aprotic polar solvent is not particularly limited as long as the object of the present invention can be achieved. However, it is preferable to 2-furaldehyde in that it functions as a solvent stably at the reaction temperature. An aprotic polar solvent having a high boiling point, more specifically, a boiling point which is 20 ° C. or more higher than the boiling point of 2-furaldehyde is used.

Specifically, dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, hexamethylphosphoric triamide, dimethyl sulfone, sulfolane (tetrahydrothiophene-1,1-dioxide), phthalide (1,3-dihydro) Isobenzofuran-1-one) and the like, and dimethylsulfone, sulfolane, and phthalide are preferable in terms of the yield of 2-furaldehyde.

The above solvents may be used alone or in combination of two or more.
The amount of the solvent used in the present invention is not particularly limited as long as the object of the present invention is satisfied. Specifically, it is sufficient that the reaction raw material has an amount sufficient to dissolve an intermediate such as levoglucosan obtained by thermal decomposition and does not inhibit the conversion to 2-furaldehyde.
The specific usage-amount of a solvent is 1-1000 mass parts normally with respect to 1 mass part of sugar raw materials which use hexose as a structural component.

<Acid>
In the production method of the present invention, as described above, a boron compound is used as a catalyst, and the reaction system further includes (a) one or more selected from the group consisting of inorganic acids (excluding boric acid) and organic acids. (Hereinafter referred to as inorganic acid (excluding boric acid) and organic acid may be abbreviated as acids other than boric acid) and / or (b) a metal compound. Acids other than boric acid are separately added to the reaction system in order to adjust the acidity and the reactivity of the boron compound. Although the kind of acid to add is not specifically limited, Inorganic acids (however, except a boric acid) and organic acids, such as hydrogen halide, a sulfuric acid, phosphoric acid, an isopoly acid, heteropoly acid, are mentioned. Of these, sulfuric acid, phosphoric acid, pyrophosphoric acid, and organic acids are preferable, and sulfuric acid, phosphoric acid, and carboxylic acid are particularly preferable.

  Preferred organic acids include carboxylic acid, sulfonic acid and the like, and particularly preferred is carboxylic acid. The type of the carboxylic acid is not particularly limited, but is preferably a carboxylic acid that is less likely to volatilize even under high-temperature reaction conditions, and is preferably a carboxylic acid having a boiling point of 120 ° C. or higher, specifically succinic acid, fumaric acid, oxalic acid, Citric acid, tartaric acid, lactic acid, levulinic acid, gluconic acid, glucuronic acid, benzoic acid, phthalic acid, salicylic acid and the like can be mentioned.

Usually, it is not considered to use two or more kinds as catalyst components, but in the method of the present invention, the yield of 2-furaldehyde could be increased by adding an acid other than boric acid to the boron compound. The effect of this acid addition adjusts the degree of hydrolysis of the boron compound, which plays a major role as a catalyst, and the solubility in solvents and water, or prevents inactivation due to access to the raw material and reaction with the raw material, As a result, the catalytic activity is increased. The effect is particularly remarkable when herbaceous agricultural waste such as corn or bagasse is used as a raw material directly, and in the use of acid, minerals such as alkali contained in the raw material are the main catalyst components. Avoid inhibiting the reactivity of boron compounds.
Two or more acids other than boric acid may be used in combination.
The timing of addition of these acids is not particularly limited, but the amount of acid to be added is not particularly limited, but is usually added simultaneously with the introduction of the boron compound or mixed with the boron compound in advance. In a system, it is 0.01 mass part or more and 100 mass parts or less normally with respect to 1 mass part of total amounts of the boron compound used. In a continuous system, per 1 hour, the total amount of boron compounds supplied to the reactor per hour is usually 0.01 parts by weight or more and 100 parts by weight or less, preferably 0.02 parts by weight or more. The acid is continuously supplied so as to be 50 parts by mass or less, more preferably 0.05 parts by mass or more and 20 parts by mass or less. When supplying in the said range, it becomes the tendency for a yield to improve especially. However, if it is too much, separation after use of the reaction tends to become complicated.

<Metal compound>
As described above, in the production method of the present invention, (a) an acid other than boric acid and / or (b) a metal compound is mixed and reacted in the reaction system. The metal compound used together with the boron compound in the present invention is usually a compound that interacts with the boron compound and changes to a catalytically active species having the ability to produce 2-furaldehyde. Such a metal compound is preferably a compound in which the hydroxide produced when the metal compound is hydrolyzed is amphoteric in terms of obtaining 2-furaldehyde in a high yield. Here, being amphoteric means that it is basic to an acid and acidic to a base, specifically, Al, Ga, In, Sn, Ti, Zr, Mn, Fe, Examples thereof include a metal compound selected from the group consisting of Co, Ni, Cu, Pb, Bi, and Zn.

The catalytically active species obtained from these metal-containing compounds and boron compounds are adequately dispersed by hydrolysis of these metal-containing compounds and reaction with boron compounds, and do not aggregate as solid acid catalysts. In contact with a sugar raw material containing hexose as a constituent, the acidic catalyst can maintain a form that is more effective than a solid acid catalyst.
In particular, when the sugar raw material containing hexose as a raw material is a solid such as cellulose or biomass, the effectiveness is even more remarkable. Even if the solid acid catalyst is a solid acid catalyst having a high surface area, the contact portion with the solid sugar raw material is extremely small, but it is obtained from a compound containing these metals or a compound containing these metals and a boron compound. The resulting catalytically active species is highly hydrophilic, and when mixed with a solid sugar raw material, it can reach the inside of the solid sugar raw material through the media of water or solvent, and can effectively act on the sugar unit inside the solid. Become. As a result, it is considered that a higher yield of 2-furaldehyde can be obtained with a smaller amount than when a solid acid catalyst is used. Furthermore, since the catalytically active species obtained from compounds containing these metals and boron compounds are not as dehydrated and carbonizable as sulfuric acid, they are suitable for the production of 2-furaldehyde without causing a decrease in yield. it is conceivable that.

Among the above metal compounds, a metal compound containing an element selected from the group consisting of Al, Sn, Ti, Zr, Fe, Co, and Zn is preferably used in terms of the yield of 2-furaldehyde. A metal compound containing an element selected from Al, Fe, and Zn is more preferable.
In addition, the said metal compound may be used independently or may use 2 or more types.
Among the above metal compounds, preferred are metal alkoxides, metal organic acid salts, metal halides, metal sulfates and the like due to the good yield of 2-furaldehyde.

Illustrative of specific compounds taking Al as an example, metal alkoxides, such as aluminum isopropoxide, metal organic acid salts, such as aluminum benzoate, aluminum lactate, aluminum acetate, aluminum citrate, aluminum sebacate, etc. Examples of the halide include aluminum chloride and polyaluminum chloride, and further include aluminum sulfate and aluminum nitrate. Examples of other metal compounds include compounds in which the above exemplified Al is replaced with other metals.
Two or more metal compounds may be used in combination.
Although the timing of addition of these metal compounds is not particularly limited, they are usually added simultaneously with the introduction of the boron compound or mixed with the boron compound in advance.

The amount of the metal compound to be added is not particularly limited, but in the batch system, it is usually 0.01 parts by mass or more and 100 parts by mass or less with respect to 1 part by mass of the total amount of boron compounds used.
In a continuous system, per 1 hour, the total amount of boron compounds supplied to the reactor per hour is usually 0.01 parts by weight or more and 100 parts by weight or less, preferably 0.02 parts by weight or more. The metal compound is continuously supplied so as to be 50 parts by mass or less, more preferably 0.05 parts by mass or more and 20 parts by mass or less. When supplying in the said range, it becomes the tendency for a yield to improve especially. However, if it is too much, separation after use of the reaction tends to become complicated.

<Water>
In the production method of the present invention, it is preferable that water is present in the reaction system in order to advance the 2-furaldehyde production reaction. The role of water is to promote the expansion and hydration of the raw materials, promote the reaction to the intermediate leading to 2-furaldehyde, and also play the role of distilling the produced 2-furaldehyde out of the reaction system. Yes. Therefore, in the method for producing 2-furaldehyde of the present invention, water is preferably supplied to the reaction system. In particular, when an aprotic polar solvent is used as the solvent, it is preferable to use water in combination for the above reason.

  The method for supplying water is not particularly limited, and may vary depending on the reaction method, and examples thereof include a method of supplying as a liquid, a method of vaporizing and supplying as water vapor, and the like. Further, a sugar raw material containing hexose as a constituent component and a necessary amount of water may be mixed and charged in advance, or a substance that does not adversely influence the reaction and water may be mixed and charged. You may make it react, supplying water continuously or intermittently to a reaction system.

Although the supply amount in the case of supplying water is not particularly limited, it is usually 0.1 mass per 1 part by mass of 2-furaldehyde distilled together with water from the reactor in a batch system. In the continuous method, the amount is usually continuously supplied so as to be 0.1 parts by mass or more per hour with respect to 1 part by mass of 2-furaldehyde distilled off with water from the reactor per hour. . When supplying in the said range, it becomes the tendency for a yield to improve especially. However, if the amount is too large, the consumption of energy increases and the separation from the produced 2-furaldehyde tends to become complicated, so the upper limit of the water supply amount is distilled off together with water from the reactor in a batch system. For a total amount of 2-furaldehyde of 1 part by mass, usually about 100 parts by mass or less, and in a continuous system, usually with respect to 1 part by mass of 2-furaldehyde distilled off from the reactor together with water per hour. Usually, about 100 parts by mass or less per hour is preferable.
In the production method of the present invention, other components than the above may be mixed and reacted within a range not impairing the effects of the present invention.

<Reaction>
In the method for producing 2-furaldehyde of the present invention, a sugar raw material containing hexose as a constituent, a catalyst, and a solvent are reacted. The catalyst is a boron compound, and (a) other than boric acid is added to the reaction system. It is characterized by mixing and reacting an acid and / or (b) a metal compound, and more preferably, mixing and reacting with water. Usually, the reaction is carried out by heating, and the mixing method, order, and heating method are not particularly limited. For example, (1) the above sugar raw material, boron compound, solvent, (a) acid other than boric acid and / or (b) metal compound, and water are separately introduced into a reactor that has been set to a reaction temperature in advance, and the reactor (2) A method in which a sugar raw material, a boron compound, a solvent, (a) an acid other than boric acid and / or (b) a metal compound, and water are mixed and supplied to the reactor in advance (3) A method of mixing (a) a sugar raw material, a boron compound, (a) an acid other than boric acid and / or (b) a metal compound, and then introducing and mixing them in a solvent and water charged in the reactor, or (4) A method of mixing water and a boron compound, preferably dissolving the boron compound in water, and then adding and mixing a sugar raw material and a solvent, (a) an acid other than boric acid and / or (b) a metal compound, etc. Is mentioned. These mixtures are often in the form of a so-called slurry in which the appropriately dispersed and reacted compounds are mixed with the raw materials and the solvent, and a state suitable for the production of 2-furaldehyde is obtained.

In addition, when using the conventional solid acid catalyst, it is necessary to prepare and manufacture a catalyst suitable for the production of 2-furaldehyde, and the catalyst preparation and production are performed by mixing and stirring the catalyst raw materials, precipitation filtration, and evaporation drying. In many cases, the process such as baking is complicated and expensive. On the other hand, in the method of the present invention, a catalyst or a precursor thereof is obtained by contacting a sugar raw material containing a boron compound, (a) an inorganic acid other than boric acid and / or a metal compound, and hexose as constituent components. Since it is produced in the system and acts as a catalyst under the actual reaction conditions, there is an advantage that the preparation / manufacturing process of the catalyst is substantially unnecessary and the reaction can be carried out very simply.

<Reaction conditions>
In the method for producing 2-furaldehyde of the present invention, the reaction temperature is not particularly limited, but the reaction is carried out in a liquid phase, and as will be described later, the produced 2-furaldehyde is discharged out of the reaction system. However, it is preferable that the reaction is carried out while taking out in the gas phase from the viewpoint of obtaining 2-furaldehyde in a high yield. In this case, the reaction is performed at a temperature not lower than the boiling point of 2-furaldehyde and not higher than the boiling point of the solvent. It is preferable. The specific reaction temperature is, for example, 140 ° C. or higher, preferably 150 ° C. or higher, more preferably 160 ° C. or higher, further preferably 170 ° C. or higher, particularly preferably 180 ° C. or higher, most preferably 200 ° C. or higher, and usually 300 ° C or lower, preferably 280 ° C or lower, more preferably 260 ° C or lower, particularly preferably 250 ° C or lower. If the reaction temperature is too low, the reaction yield may be insufficient, and the reaction rate tends to be slow. Moreover, at the reaction temperature lower than the boiling point of 2-furaldehyde, the produced 2-furaldehyde may stay in the solvent or in the reaction system for a long time, thereby causing polymerization or excessive decomposition. On the other hand, if the reaction temperature is too high, side reactions of sugar raw materials and intermediates may become prominent, and there is a possibility that the solvent will not function sufficiently, for example, at a reaction temperature higher than the boiling point of the solvent.

The reaction pressure in the production method of 2-furaldehyde of the present invention is not particularly limited. The reaction system can be adjusted to any reaction pressure as long as the reaction system is maintained in a liquid phase and 2-furaldehyde produced can be distilled out of the reaction system together with water.
In addition, the reaction used in the present invention can be carried out in the presence of a substance that does not adversely influence the reaction, such as nitrogen, helium, argon, carbon dioxide, and the like.

<Reaction method>
The reaction system of the production method of 2-furaldehyde of the present invention can be carried out by a batch reaction or a continuous reaction.
In the case of batch reaction, specifically, a sugar raw material containing the above hexose as a constituent, (a) an acid other than boric acid and / or (b) a metal compound, a solvent, and a boron compound are charged into a reactor, The reaction is carried out with heating and stirring, preferably while supplying water, and the resulting 2-furaldehyde can be extracted from the reactor, preferably in the gas phase, and more preferably distilled off from the reactor together with water. In this case, sugar raw materials, boron compounds, (a) acids other than boric acid and / or (b) metal compounds are not charged all at once, and are supplied to the reactor in several batches or continuously to the reactor. A raw material supply method similar to the continuous method may be employed.

When a solid sugar raw material is used for the reaction, its shape is not particularly limited, but a small piece or powder of several cm or less is preferably used. Prior to subjecting to the reaction, a treatment of pulverizing or crushing inside or outside the reactor may be performed.
The reaction time in the batch reaction varies depending on the kind of raw material, the amount of catalyst used, the reaction temperature and the desired yield of 2-furaldehyde to be produced, and is not particularly limited. It is not less than time, preferably not less than 0.5 hour, usually not more than 50 hours, preferably not more than 20 hours.

  In the case of continuous reaction, specifically, from one end of the reactor, a sugar raw material, solvent, boron compound, (a) acid other than boric acid and / or (b) metal compound, The reactor continuously supplies water and discharges the generated 2-furaldehyde from the reaction system, preferably to the gas phase, and more preferably continuously with water to distill off from the reactor. The remaining reaction mixture can be continuously withdrawn from the other end.

In the continuous reaction, the residence time in the reactor is not particularly limited, but is usually 0.1 hour or longer, preferably 0.5 hour or longer, usually 50 hours or shorter, preferably 2
0 hours or less.
The amount of sugar raw material, boron compound, and solvent that use hexose as a constituent component is usually the amount of hexose used in a batch system in which a sugar raw material, solvent, and boron compound that contains hexose are added to a reactor and reacted. The boron compound is 0.0001 to 100 parts by mass, preferably 0.001 to 50 parts by mass, and the solvent is 1 to 1000 parts by mass, preferably 10 to 500 parts by mass, with respect to 1 part by mass of the sugar raw material. In this batch system, when the sugar raw material containing hexose as a constituent component is not charged all at once, when it is supplied to the reactor in several batches or continuously to the reactor, it is usually used in a single reaction. A boron compound is 0.0001-100 mass parts and a solvent is 1-1000 mass parts with respect to 1 mass part of total amounts of a starting material. In addition, the usage-amount of (a) acids other than boric acid and / or (b) a metal compound is as above-mentioned.

  From one end of the reactor, a sugar raw material containing hexose, a solvent, a boron compound, and water are continuously supplied, and 2-furaldehyde produced is discharged out of the reaction system, and the remaining reaction is performed from the other end of the reactor. In the case of a continuous system in which the mixture is continuously extracted, the amount of the sugar raw material containing hexose, the boron compound, and the solvent is usually 0. The amount is 00001 to 100 parts by mass, preferably 0.0001 to 50 parts by mass, and the solvent is 1 to 1000 parts by mass, preferably 10 to 500 parts by mass. In the batch system, the amount of water supplied is usually 0.1 parts by mass or more with respect to 1 part by mass of 2-furaldehyde distilled together with water from the reactor. It supplies continuously so that it may become 0.1 mass part or more per hour with respect to 1 mass part of 2-furaldehyde distilled off with water from a reactor per time. In addition, the usage-amount of (a) acids other than boric acid and / or (b) a metal compound is as above-mentioned.

There is no particular limitation on the supply form of the sugar raw material containing hexose as a constituent component in the continuous reaction, but it is preferably supplied in a solvent, particularly a solution or paste or slurry using water or an aprotic polar solvent. . In the continuous reaction, at least one of a boron compound, (a) an acid other than boric acid and / or (b) a metal compound, a sugar raw material containing hexose as a constituent, and a solvent is divided into a reactor. A method of supplying, a method of supplying stepwise, or a method of supplying to the reactor from another port or another nozzle is preferably used. Before being supplied to the reactor, a boron compound, (a) an acid other than boric acid and / or (b) a metal compound, a saccharide raw material containing hexose, a solvent, etc. may be mixed in advance. It doesn't matter.
In addition, when discharging | emitting 2-furaldehyde to produce | generate out of a reaction system in any case, it is so that content of 2-furaldehyde may be 10 mass% or less with respect to the solvent of a reaction system. It is preferable to take 2-furaldehyde out of the reaction system.

<Separation and recovery of 2-furaldehyde>
Separation and recovery of 2-furaldehyde produced by the present invention can be performed by a conventional method.
In particular, in the preferable reaction conditions of the present invention, the produced 2-furaldehyde is immediately converted into a gas and removed from the reaction system, so that the by-product remaining in the solvent and the reaction system, the metal compound, and the boron compound Separation does not require effort. Specifically, by cooling the effluent gas from the reactor and condensing sequentially from the high boiling point components, 2-furaldehyde is separated and recovered, or by cooling and once condensing and recovering all the liquid components, Next, water and 2-furaldehyde are separated and recovered by distillation. By this method, by-products such as formic acid, acetic acid and formaldehyde contained in the effluent gas from the reactor can be separated or recovered. The recovered water can be returned to the reaction system and reused.

It does not specifically limit as a method to refine | purify 2-furaldehyde manufactured by this invention, It can implement by a conventionally well-known method. Specifically, a precision distillation method is mentioned.
The method for preserving 2-furaldehyde produced according to the present invention is not particularly limited, and a conventionally known method can be used. For example, a method of preserving in a closed container near room temperature, a light-shielded inert gas atmosphere. And the like.

  In the reaction mixture after the reaction in the production method of the present invention, a saccharide raw material containing unreacted hexose, water, a solvent, a boron compound, (a) an acid other than boric acid and / or (b) a metal Compounds, by-products, etc. are included. The form and type of the by-product depends on the reaction temperature. For example, when a reaction temperature of 200 ° C. or higher is selected, the by-product is mostly char (polymerized solid) consisting of carbon, hydrogen, and oxygen, and has a molecular shape. There are very few by-products. In the present invention, the solvent and boron compound can be reused by filtering and washing the residue (polymerized solid as a main component) obtained by distilling and separating the volatile substance from the reaction mixture after the reaction. Along with the solvent and water used for washing (the water distilled from the reaction (water supplied to the reactor and water generated from the raw material) can be used) Mixing to produce 2-furaldehyde is also preferably performed. The boron compound adsorbed on the residue can be recovered as an oxide and reused after burning the residue.

  In addition, when distilling and separating volatile substances from the reaction mixture after the reaction, the solvent is separated and recovered by sequentially condensing from high-boiling components, or once cooled, all volatile substances are condensed and recovered. Then, it is separated and recovered by distillation. In the above preferred reaction conditions of the present invention, when the produced 2-furaldehyde is immediately converted into a gas and removed from the reaction system, the effluent gas from the reactor is cooled and condensed sequentially from the high-boiling components. Thus, the solvent is also preferably recovered. The recovered solvent can be recycled to the reaction system.

[2-Furaldehyde production composition]
As described above, the present invention is a method for producing 2-furaldehyde by mixing and reacting at least the sugar raw material, a boron compound, (a) an acid other than boric acid and / or (b) a metal compound, and a solvent. Therefore, from a composition containing the above components, that is, (1) a sugar raw material comprising hexose, (2) a boron compound, (3) an inorganic acid (excluding boric acid) and an organic acid A composition containing one or more acids and / or metal compounds selected from the group consisting of (4) a solvent is useful as a composition for producing 2-furaldehyde. The composition for producing 2-furaldehyde of the present invention preferably contains water and may contain the above-mentioned components used for the production of 2-furaldehyde.
In addition, each component is according to said description, and even if contained independently, 2 or more types may be contained.

<2-Furaldehyde>
The 2-furaldehyde obtained in the present invention can be used as a solvent. Moreover, it can be used for the use as manufacturing raw materials, such as furan, tetrahydrofuran, and furan resin, by a conventionally well-known method.
Specifically, furfuryl alcohol which is a raw material for producing furan resin can be obtained by performing a hydrogenation reaction of 2-furaldehyde in the presence of a catalyst. Further, furan can be obtained by subjecting 2-furaldehyde to a decarbonylation reaction in the presence of a catalyst. The furan thus obtained can be derived into tetrahydrofuran by performing a hydrogenation reaction in the presence of a catalyst.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.
In the following examples, the compounds used and the like represent those described below.
Cellulose: Cellulose, microcrs manufactured by Aldrich
talline, powder, ~ 20micron
Sulfolane: Special grade manufactured by Kishida Chemical Co., Ltd. Boric acid: Special grade manufactured by Kishida Chemical Co., Ltd. Sulfuric acid aqueous solution: Pure chemical Co., Ltd. Volumetric analysis standard solution 85% Phosphoric acid: Special grade manufactured by Wako Pure Chemical Industries, Ltd.

(Comparative Example A)
<Production of 2-furaldehyde from cellulose using boric acid>
14 g of cellulose, 126 g of sulfolane, 56 g of deionized water, 0.320 g of boric acid were added to a 300 ml eggplant-shaped flask containing a Teflon (registered trademark) stirrer and stirred for 5 hours to prepare a raw slurry. did.

  A 100 ml four-necked flask containing a Teflon (registered trademark) stirrer, a Teflon (registered trademark) -coated thermocouple (for measuring the reaction liquid temperature), a raw material slurry supply pipe, a reaction liquid volume control suction pipe, and a Claisen type connecting pipe And a Liebig condenser (for distillate cooling) and a 50 ml Erlenmeyer flask (distillate receiver) were set. The reaction liquid volume control suction tube was prepared in such a length that the reaction liquid volume was maintained at 34 ml during the reaction. The Claisen type connecting pipe part was wound with a tape heater and covered with a silicon rubber heat insulating material from above.

  Cooling water is passed through the condenser, the oil bath is preheated to 60 ° C, the Claisen-type connecting tube insulation tape heater is preheated to 120 ° C, and nitrogen is circulated through the 100 ml flask as a companion gas from the raw slurry supply tube at a supply rate of 40 ml / min. The extraction rate from the reaction liquid amount control suction tube was controlled to 1.5 ml / min. After 35 ml of the raw material slurry was charged, while stirring the inside of the 100 ml flask with a stirrer at a stirring speed of 400 rpm, the raw material slurry was supplied as cellulose at a feed rate of 1.259 g / h and at the same time the oil bath was 245 ° C. in 25 minutes. The time when the oil bath temperature reached 245 ° C. and the liquid temperature in the reactor was stabilized (about 225 ° C.) was defined as the reaction start time. Thereafter, the reactor internal temperature was maintained at 225 ° C. ± 2 ° C., and a continuous flow reaction was performed for a reaction time of 6.0 hours.

Using a 50 ml Erlenmeyer flask containing 30 ml of THF and 0.5 ml of triethylene glycol dimethyl ether (an internal standard material for GC analysis) as a distillate receiver, a distillate having a reaction time of 5.0 hours to 6.0 hours. After the collected receiver was shaken well and stirred well, the amount of 2-furaldehyde (hereinafter, FAL is abbreviated) was determined by gas chromatographic analysis (internal fraction standard method).
For the analysis of 2-furaldehyde, a gas chromatograph GC-2014 (FID) manufactured by Shimadzu Corporation was used. Chromatopack C-R8A manufactured by Shimadzu Corporation was used for the waveform processing.

GC analysis conditions Column: Thermon-3000 5% / SHIN CARBON A 60/80 3
m (glass)
Carrier gas: Nitrogen (30 ml / min)
Column temperature: 95 ° C. (0 min) → Temperature rise to 230 ° C. (3 ° C./min)→230° C. (0 min)
INJ: 200 ° C
DET: 240 ° C

The 2-furaldehyde (FAL) yield was determined from the following formula.
[FAL yield (mol%)] = [number of moles of FAL generated (gas chromatographic analysis value)] / [
Number of moles of hexose unit supplied per hour × 100]
The number of moles of the hexose unit is a polymer of 100% hexose cellulose ((C6
It was calculated assuming that H10O5) n, formula weight: (162.14) n).
The results are shown in Table-1.

(Comparative Example 1)
<Production of 2-furaldehyde from cellulose without catalyst>
Comparative Example A was carried out in the same manner as Comparative Example A, except that the raw material slurry was prepared without using boric acid. The results are shown in Table-1.

Example 1
<Production of 2-furaldehyde from cellulose using boric acid and sulfuric acid>
In Comparative Example A, in addition to 0.320 g of boric acid, a raw material slurry was prepared using 0.345 ml of 2.5 mol / l sulfuric acid aqueous solution (genuine chemical capacity analysis specified solution) (0.0847 g as sulfuric acid). Was carried out in the same manner as in Comparative Example A. The results are shown in Table-1.

(Comparative Example 2)
<Production of 2-furaldehyde from cellulose using sulfuric acid>
In Comparative Example A, Comparative Example A was prepared except that 0.345 ml of 2.5 mol / l sulfuric acid aqueous solution (pure chemical capacity analysis specified solution) (0.0847 g as sulfuric acid) was used instead of boric acid. It carried out like. The results are shown in Table-1.

(Comparative Example 3)
<Production of 2-furaldehyde from cellulose using sulfuric acid>
Comparative Example A was prepared in the same manner as in Comparative Example A except that 2.07 ml of 2.5 mol / l sulfuric acid aqueous solution (pure chemical capacity analysis standard solution) (0.508 g as sulfuric acid) was used instead of boric acid. It carried out like. The results are shown in Table-1.

(Example 2)
<Production of 2-furaldehyde from cellulose using boric acid and phosphoric acid>
Comparative Example A was carried out in the same manner as Comparative Example A, except that 0.0996 g of 85% phosphoric acid was used in addition to 0.320 g of boric acid to prepare a raw slurry. The results are shown in Table-1.

(Comparative Example 4)
<Production of 2-furaldehyde from cellulose using phosphoric acid>
In Comparative Example A, the same procedure as in Comparative Example A was performed except that 0.0996 g of 85% phosphoric acid was used instead of boric acid to prepare a raw slurry. The results are shown in Table-1.

(Example 3)
<Production of 2-furaldehyde from cellulose using aluminum isopropoxide-boric acid>
20 g of cellulose, 113 g of sulfolane, 40 g of deionized water and 0.1 g of boric acid were added to a 300 ml eggplant-shaped flask containing a Teflon (registered trademark) stir bar, and the mixture was stirred and mixed for 30 minutes. 7 g of aluminum isopropoxide was added and stirred for 5 hours to prepare a raw slurry.

  A 100 ml four-necked flask containing a Teflon (registered trademark) stirrer, a Teflon (registered trademark) -coated thermocouple (for measuring the reaction liquid temperature), a raw material slurry supply pipe, a reaction liquid volume control suction pipe, and a Claisen type connecting pipe And a Liebig condenser (for distillate cooling) and a 50 ml Erlenmeyer flask (distillate receiver) were set. The reaction liquid volume control suction tube was prepared in such a length that the reaction liquid volume was kept at 40 ml during the reaction. The Claisen type connecting pipe part was wound with a tape heater and covered with a silicon rubber heat insulating material from above.

  Cooling water is passed through the condenser, the oil bath is preheated to 60 ° C, the Claisen-type connecting tube insulation tape heater is preheated to 120 ° C, and nitrogen is circulated through the 100 ml flask as a companion gas from the raw slurry supply tube at a supply rate of 40 ml / min. The extraction rate from the reaction liquid amount control suction tube was controlled to 1.5 ml / min. While stirring the inside of a 100 ml flask with a stirrer at a stirring speed of 400 rpm, the raw material slurry is supplied as sulfolane at a feed rate of 1.0 g / min, and at the same time, the oil bath is heated to 245 ° C. in 40 minutes, and the amount of reaction liquid When the liquid comes out from the control suction pipe, the raw material slurry supply rate is changed to 2.0 g / h as cellulose, and when the oil bath temperature reaches 245 ° C. and the liquid temperature in the reactor is stabilized (About 225 degreeC) was made into reaction start time. Thereafter, the reactor internal temperature was maintained at 225 ° C. ± 2 ° C., and a continuous flow reaction was performed for 4.5 hours.

  Using a 50 ml Erlenmeyer flask containing 30 ml of THF and 0.5 ml of triethylene glycol dimethyl ether (an internal standard for GC analysis) as a distillate receiver, a distillate having a reaction time of 3.5 hours to 4.5 hours. After the collected receiver was shaken well and stirred well, the amount of 2-furaldehyde (hereinafter, FAL is abbreviated) was determined by gas chromatographic analysis (internal fraction standard method). The results are shown in Table-1.

(Comparative Example 5)
<Production of 2-furaldehyde from cellulose using aluminum isopropoxide>
In Comparative Example A, the same procedure as in Example 3 was performed except that boric acid was not used. The results are shown in Table-1.

Example 4
<Production of 2-furaldehyde from cellulose using zinc acetate dihydrate-boric acid>
The amount of boric acid used was changed to 0.2 g, 0.2 g zinc acetate dihydrate was used instead of aluminum isopropoxide, cellulose, sulfolane, deionized water, boric acid and zinc acetate dihydrate The same procedure as in Example 3 was performed except that the Japanese product was stirred and mixed for 5 hours. The results are shown in Table-1.

(Comparative Example 6)
<Production of 2-furaldehyde from cellulose using zinc acetate dihydrate>
The same procedure as in Example 4 was carried out except that boric acid was not used. The results are shown in Table-1.

(Example 5)
<Ferric citrate / n-hydrate-Production of 2-furaldehyde from cellulose using boric acid>
The amount of boric acid used was changed to 0.25 g, and 0.6 g of ferric citrate / n hydrate was used instead of aluminum isopropoxide, and cellulose, sulfolane, deionized water, boric acid and citric acid were used. The same operation as in Example 3 was conducted except that ferric n-hydrate was stirred and mixed for 5 hours. The results are shown in Table-1.

(Comparative Example 7)
<Production of 2-furaldehyde from cellulose using ferric citrate / n-hydrate>
The same procedure as in Example 5 was carried out except that boric acid was not used. The results are shown in Table-1.

(Example 6)
<Production of 2-furaldehyde from cellulose using aluminum chloride hexahydrate-boric acid>
The amount of boric acid used was changed to 0.2 g, 0.2 g of aluminum chloride hexahydrate was used instead of aluminum isopropoxide, cellulose, sulfolane, deionized water, boric acid and aluminum chloride.6 water The same procedure as in Example 3 was performed except that the Japanese product was stirred and mixed for 5 hours. The results are shown in Table-1.

(Comparative Example 8)
<Production of 2-furaldehyde from cellulose using aluminum chloride hexahydrate>
The same procedure as in Example 6 was performed except that boric acid was not used. The results are shown in Table-1.

(Comparative Example 9)
<Production of 2-furaldehyde from cellulose using solid acid catalyst (H-US-Y zeolite)>
The same procedure as in Example 3 was performed except that 0.2 g of H-US-Y zeolite was used instead of boric acid, stirring and mixing were not performed for 30 minutes, and aluminum isopropoxide was not used. The results are shown in Table-1.

(Example 7)
<Production of 2-furaldehyde from cellulose using boric acid and aluminum lactate>
Comparative Example A was carried out in the same manner as Comparative Example A, except that a raw material slurry was prepared using 0.253 g of aluminum lactate (Kishida Chemical) in addition to 0.320 g of boric acid. The results are shown in Table-1.

(Example 8)
<Production of 2-furaldehyde from cellulose using boric acid and aluminum sulfate>
In Comparative Example A, except that 0.320 g of boric acid and 0.136 g of aluminum sulfate (Al ₂ (SO ₄ ) ₃ · 14-18H ₂ O, Kishida Chemical) were used to prepare a raw slurry. It carried out like A. The results are shown in Table-1.

Example 9
<Production of 2-furaldehyde from cellulose using boric acid, aluminum sulfate, and sulfuric acid>
In Comparative Example A, 0.136 g of boric acid and 0.136 g of aluminum sulfate (Al ₂ (SO ₄ ) ₃ · 14-18H ₂ O, Kishida Chemical) and 0.063 g of sulfuric acid were used to prepare a raw slurry. The same procedure as in Comparative Example A was carried out except that it was prepared. The results are shown in Table-1.

(Example 10)
<Production of 2-furaldehyde from cellulose using boric acid and salicylic acid>
Comparative Example A was carried out in the same manner as Comparative Example A, except that 0.119 g of salicylic acid (Kishida Chemical Co., Ltd.) was used in addition to 0.320 g of boric acid. The results are shown in Table-1.

(Example 11)
<Production of 2-furaldehyde from sawdust using boric acid, aluminum sulfate and sulfuric acid (continuous method)>
Preparation of sawdust grains When applying real biomass as an example of the present invention, sawdust grains as raw materials were prepared as follows. Add about 1 part by weight of ion-exchanged water to sawdust (completely dry ultrafine particles / tree species: persimmon, cedar, persimmon, rice pine, etc.) obtained from Kiju-sha, granulate to 2-4 mm, and then distribute dry nitrogen The bottom was dried at 110 ° C. for 4 hours. In addition, the organic solvent soluble content, holocellulose, α-cellulose, and hemicellulose in the dried sawdust used were analyzed according to the wood science experiment manual (edited by the Wood Society of Japan, P.92) and were as follows.

Organic solvent soluble component (ethanol-toluene extraction method) 3wt%
Holocellulose (sodium chlorite method) 71wt%
α-cellulose (17.5% sodium hydroxide method) 47wt%
Hemicellulose (the above holocellulose-α-cellulose) 24 wt%

2- Furaldehyde production As a supply liquid for continuous distribution, (a) a mixture of 126.0 g sulfolane and 35.0 g of ion-exchanged water, (ii) boric acid / aluminum sulfate / sulfuric acid (weight composition 2.0 / An aqueous solution in which a catalyst consisting of 5.0 / 0.1) was dissolved in 21.0 g of ion-exchanged water was prepared in advance. As actual biomass raw materials, 0.420 g sawdust particles divided into vials were prepared for the number of additions.
Charge 34.0 g of sulfolane to a reaction vessel (100 ml four-necked flask) with a reaction solution holding capacity of 34 ml, pour cooling water through the condenser, and heat the oil bath to 60 ° C and the heat insulation tape heater to 120 ° C under a nitrogen atmosphere. Preheating, a feed line was installed in the reactor so that the mixture (a) and (b) or a mixed slurry could be fed to the reactor, and 0.667 g of silicon rubber tube connected to the top of the reactor distillation head A vial containing sawdust particles was placed, and the middle of the silicone rubber tube was stopped with a pinch cock.
400r. p. m. Nitrogen was circulated through the reaction vessel at a supply rate of 20 ml / min as an entrained gas while stirring at an agitation rate of 1, and the temperature of the reactor was increased so that the temperature inside the reactor reached a predetermined temperature in 20 minutes. Started. When the temperature of the liquid in the reactor reaches a predetermined temperature, supply of (a) and (b) is started (a supply rate of 11.33 g / h as sulfolane and 4.0 g / h as ion-exchanged water, At the same time, the pump was operated to control the extraction rate from the retained reaction liquid amount control suction pipe to 1.5 ml / min, and the slurry in the reaction vessel was kept at about 34 ml.
Open the pinch cock of the silicon rubber tube at the top of the distillation head and start 0.45 g of sawdust particles to the reactor while tilting the vial to start the reaction. Each was fed into the reactor from the top of the distillation head. The sawdust / sulfolane / water ratio fed to the reactor per hour is 1.0 / 9.0 / 4.0 weight ratio, and the sawdust / boric acid / aluminum sulfate / sulfuric acid ratio is 100/2. The weight ratio was 0 / 5.0 / 0.1.
The reactor internal temperature was maintained at 225 ° C. ± 2 ° C., and a continuous flow reaction was performed for a reaction time of 7.0 hours. Prepare a 50 ml Erlenmeyer flask containing 30 ml of THF and 0.5 ml of triethylene glycol dimethyl ether (an internal standard material for GC analysis) as many times as the number of samplings as a receiver for sampling the distillate. Change sampling receiver every time (0-1 hours, 1-2 hours, 2-3 hours, 3-4 hours, ...), collect the distillate, and shake the collected receiver After stirring well, GC analysis (1.0 μl injection) was performed to determine the amount of 2-furaldehyde produced and the amount of distillate sulfolane. Table 1 shows the results obtained by fractionating the distillate having a reaction time of 6.0 hours to 7.0 hours and determining the yield of 2-furaldehyde.

As is clear from the comparison of the above examples and comparative examples, although a boron compound is used,
A) Comparative Example A without boric acid and / or (b) Comparative Example A using no metal compound, Non-Catalyst Comparative Example 1, Comparative Examples 2 and 3 using sulfuric acid but using no boron compound, Comparison using phosphoric acid Example 4, Comparative Examples 5 to 9 using a metal compound and a solid acid catalyst without using a boron compound, according to the present invention, at least the sugar raw material, solvent, boron compound, (a) acid excluding boric acid and It turns out that Examples 1-10 which mixed / reacted the metal compound and / or (b) can manufacture the target 2-furaldehyde with a high yield.
Moreover, also in Example 11 using a real biomass raw material, it turns out that the target 2-furaldehyde can be manufactured with a high yield.

  The production method of 2-furaldehyde of the present invention is satisfactory in that it is economically satisfactory even in a continuous reaction that is industrially advantageous compared to a batch reaction from a sugar raw material containing hexose such as cellulose as a constituent. This is advantageous in that 2-furaldehyde can be obtained in a yield.

Claims (17)

  A method for producing 2-furaldehyde by mixing and reacting a sugar raw material comprising hexose, a catalyst, and a solvent, wherein the catalyst is a boron compound, and (a) an inorganic acid (provided that (1) one or more acids selected from the group consisting of organic acids and / or (b) metal compounds are mixed and reacted to produce a method for producing 2-furaldehyde.   The method for producing 2-furaldehyde according to claim 1, wherein the boron compound is one or more selected from the group consisting of boric acid, boron oxide, boric acid ester, and boron halide. The method for producing 2-furaldehyde according to claim 1 or 2, wherein the inorganic acid (excluding boric acid) is sulfuric acid or phosphoric acid, and the organic acid is a carboxylic acid.   The sugar raw material, catalyst, and solvent are further mixed with (a) one or more acids selected from the group consisting of inorganic acids (excluding boric acid) and organic acids, and (2) metal compounds. The method for producing 2-furaldehyde according to any one of claims 1 to 3, wherein:   5. The compound of 2-furaldehyde according to claim 1, wherein the metal compound is a compound in which a hydroxide generated when the metal compound is hydrolyzed becomes amphoteric. Production method.   The metal compound includes a metal selected from the group consisting of Al, Ga, In, Sn, Ti, Zr, Mn, Fe, Co, Ni, Cu, Pb, Bi, and Zn. The manufacturing method of 2-furaldehyde of any one of 1-5.   7. The 2-furaldehyde according to claim 1, wherein the metal compound is selected from the group consisting of metal alkoxides, metal organic acid salts, metal halides, and metal sulfates. Production method.   The method for producing 2-furaldehyde according to any one of claims 1 to 7, wherein the solvent is an aprotic polar solvent.   The method for producing 2-furaldehyde according to any one of claims 1 to 8, wherein the solvent is a solvent having a boiling point higher than that of 2-furaldehyde.   The method for producing 2-furaldehyde according to any one of claims 1 to 9, wherein the 2-furaldehyde produced by the reaction is reacted while being discharged out of the reaction system.   The method for producing 2-furaldehyde according to any one of claims 1 to 10, wherein the reaction temperature is not less than the boiling point of 2-furaldehyde and not more than the boiling point of the solvent.   The method for producing 2-furaldehyde according to any one of claims 1 to 11, wherein water is further mixed and reacted with the sugar raw material, the catalyst, and the solvent. The method for producing 2-furaldehyde according to any one of claims 1 to 12, wherein the sugar raw material contains at least one selected from the group consisting of cellulose, starch, and hexose. The method for producing 2-furaldehyde according to any one of claims 1 to 13, wherein the catalyst is supplied after being dissolved in water. 2. The process according to claim 1, wherein the catalyst is boric acid.
-Method for producing furaldehyde.   (1) a sugar raw material comprising hexose as a constituent, (2) one or more acids selected from the group consisting of inorganic acids (excluding boric acid) and organic acids, and / or metal compounds, and (3) A composition for producing 2-furaldehyde, comprising a solvent.   The composition for producing 2-furaldehyde according to claim 16, wherein the solvent is an aprotic polar solvent.