JP2014047149A - Method for producing tetrahydrofuran compound, and catalyst for hydrogenation and method for producing the catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a tetrahydrofuran compound from a furan compound at high reaction rate in high yield and in highly selective manner even under low temperature.SOLUTION: There is provided a method for producing a tetrahydrofuran compound, the method comprising a step of bringing a furan compound having a specific substituent into contact with hydrogen to obtain a tetrahydrofuran compound represented by general formula (2) in the presence of a catalyst obtained by mixing a palladium compound with a metallic compound having at least one metal element belonging to groups V to IX on the periodic table as constituent elements and subjecting to reduction treatment. In the formula (2), Rrepresents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or hydroxymethyl group, and Rand Reach independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

Description

  The present invention relates to a method for producing a tetrahydrofuran compound, a hydrogenation catalyst used in the production method, and a method for producing the same.

  Of the tetrahydrofuran compounds that are derivatives of furan compounds, compounds having a hydroxymethyl group are useful as polymer raw materials such as polyesters, polycarbonates, and polyurethanes, as well as resin additives, medical and agrochemical intermediate raw materials, and various solvents. It is.

  Such a tetrahydrofuran compound is produced, for example, by hydrogen reduction of a furan compound having a formyl group or a hydroxymethyl group using a hydrogenation catalyst. As a hydrogenation catalyst used in such a reaction, a Raney nickel catalyst (see, for example, Non-Patent Document 1) or a palladium catalyst in which palladium is supported on activated carbon (for example, see Non-Patent Documents 2 and 3) is known. Yes.

J. et al. Am. Chem. Soc. 1955, 77, p. 393-396 Organic Process Research & Development, 2010, 14, p. 450-485 Catalysis Communications, 12 (2010), p. 154-156

However, in the conventional synthesis method using a hydrogenation catalyst, it is necessary to set the reaction conditions to high temperature and pressure, or to use a large amount of a hydrogenation catalyst or an organic solvent. That is, with the conventional hydrogenation catalyst, it was difficult for the reaction to proceed sufficiently. Further, the Pd—Ni / SiO ₂ catalyst has a problem in that Ni elutes into the reaction solution during the reaction and the catalyst life is shortened. Furthermore, in order to accelerate | stimulate reaction, there also existed a problem that an acetic acid had to be used for a reaction system. In addition to this, in the conventional hydrogenation catalyst, as shown in the following reaction formula, the double bond in the furan ring of the furan compound and the formyl group in the furan compound are not completely reduced, resulting in an incompletely reduced form. As a result, it accumulates as an intermediate product, whereby a polymer is easily generated. In the following reaction formula, a reaction using 5-hydroxymethyl-2-formylfuran as a starting material is exemplified, but as incomplete reduction (intermediate product) at that time, 5-hydroxymethyl-2- Formyl furan (A) and 2,5-dihydroxymethyltetrahydrofuran (B) are formed.

  For this reason, it is required to solve the above-mentioned problems and establish a production technique capable of industrially mass-producing a tetrahydrofuran compound from a furan compound.

  The present invention has been made in view of the above circumstances, and provides a production method capable of producing a tetrahydrofuran compound from a furan compound with high yield and high selectivity at a high reaction rate even at low temperatures. For the purpose. Another object of the present invention is to provide a hydrogenation catalyst capable of producing a tetrahydrofuran compound with high yield and high selectivity at a high reaction rate even at low temperatures, and a method for producing the same.

  In order to solve the above-mentioned problems, the present inventors prepared various hydrogenation catalysts and studied their reactivity. As a result, it has been found that the above problems can be solved by using a combination of a palladium compound and a metal compound having a predetermined metal element. That is, the present invention provides a compound represented by the general formula in the presence of a catalyst obtained by mixing and reducing a palladium compound and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element. There is provided a method for producing a tetrahydrofuran compound, comprising a step of bringing a furan compound of (1) into contact with hydrogen to obtain a tetrahydrofuran compound of the general formula (2).

In formula (1), R represents a formyl group or a hydroxymethyl group, R ^1a represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a formyl group or a hydroxymethyl group, and R ² and R ³ are Each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ^1a and R ² and R ² and R ³ are attached to the carbon adjacent, respectively may form a ring together.

In Formula (2), R ^1b represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, and R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Indicates. R ^1b and R ² and R ² and R ³ are attached to the carbon adjacent, respectively may form a ring together.

  In the method for producing a tetrahydrofuran compound of the present invention, a hydrogenation catalyst obtained by mixing and reducing a palladium compound and a metal compound having a predetermined metal is used. The production of organisms is suppressed, and the tetrahydrofuran compound represented by the general formula (2), which is the target product, can be obtained with high yield and high selectivity. If this catalyst is used, a tetrahydrofuran compound can be produced at a high reaction rate even at a low temperature. Therefore, the yield can be increased while avoiding the complexity of the manufacturing equipment. For these reasons, the method for producing a tetrahydrofuran compound of the present invention can be suitably applied to production on an industrial scale. The tetrahydrofuran compound having a hydroxymethyl group as represented by the general formula (2) is useful, for example, as a polymer raw material such as polyester, polycarbonate and polyurethane, a resin additive, a raw material for intermediates for medical and agricultural chemicals and various solvents.

  In the method for producing a tetrahydrofuran compound of the present invention, the tetrahydrofuran compound represented by the general formula (2) is obtained by bringing the furan compound of the general formula (1) into contact with hydrogen in a temperature range of 0 to 50 ° C. in the above step. It is preferable to obtain By carrying out the synthesis at a low temperature in this way, handling becomes easier and it becomes more suitable for production on an industrial scale.

  The above-mentioned problem can also be solved by bringing the furan compound into contact with hydrogen at a temperature lower than a predetermined temperature in the presence of a catalyst containing palladium. That is, in the present invention, a tetrahydrofuran compound represented by the general formula (2) is obtained by bringing the furan compound of the general formula (1) into contact with hydrogen in a temperature range of less than 10 ° C. in the presence of a catalyst containing palladium. A process for producing a tetrahydrofuran compound is provided.

  In the method for producing a tetrahydrofuran compound of the present invention, the catalyst containing palladium and the furan compound are brought into contact at less than 10 ° C. By this, the production | generation of a by-product by the incomplete reduction | restoration of a furan compound is suppressed, and the tetrahydrofuran compound represented with General formula (2) which is a target product with high yield and high selectivity can be obtained. In this production method, a tetrahydrofuran compound can be produced at a low temperature. Therefore, the yield can be increased while avoiding the complexity of the manufacturing equipment. For these reasons, the method for producing a tetrahydrofuran compound of the present invention can be suitably applied to production on an industrial scale. The catalyst described above is preferably obtained by reducing a palladium compound.

  The furan compound used in the method for producing a tetrahydrofuran compound of the present invention preferably contains at least one selected from the group consisting of furfural, 5-methylfurfural, 5-hydroxymethylfurfural, and 5-formylfurfural. This makes it possible to produce a useful tetrahydrofuran compound with higher yield and high selectivity.

  Further, the catalyst has (A) a support and palladium supported on the support, or (B) a support and palladium supported on the support and a metal belonging to Groups 5 to 9 of the periodic table, It is preferable that Such a solid catalyst is excellent in handleability while maintaining a sufficiently high activity. For this reason, it is easy to scale up to an industrial scale, and the catalyst life can be extended. More preferably, the carrier contains at least one selected from the group consisting of carbon, alumina, silica-alumina, zeolite, and silica. Such a solid catalyst can be produced at a relatively low cost while having the above-described characteristics, and the catalyst can be easily recovered. For this reason, the manufacturing cost of a tetrahydrofuran compound can be reduced.

  In another aspect, the present invention relates to a method for producing a hydrogenation catalyst for synthesizing a tetrahydrofuran compound represented by the general formula (2), wherein the palladium compound and the constituent elements in Groups 5 to 9 of the periodic table are used. There is provided a method for producing a hydrogenation catalyst, comprising a step of mixing and reducing a metal compound having at least one kind of metal belonging thereto to obtain a hydrogenation catalyst having palladium and the metal.

  The hydrogenation catalyst obtained by this production method is suitable for use in producing a tetrahydrofuran compound represented by the general formula (2). For example, when a furan compound of the general formula (1) is used as a raw material, a tetrahydrofuran compound can be generated at a high reaction rate even at a low temperature. Therefore, the yield can be increased while avoiding the complexity of the manufacturing equipment. For these reasons, the hydrogenation catalyst obtained by the production method of the present invention can be suitably used for the production of tetrahydrofuran compounds on an industrial scale.

  In still another aspect, the present invention provides a hydrogenation catalyst for synthesizing a tetrahydrofuran compound represented by the general formula (2), comprising a palladium compound and a metal belonging to Groups 5 to 9 of the periodic table as constituent elements. There is provided a hydrogenation catalyst comprising palladium and the metal obtained by mixing and reducing a metal compound having at least one of the above.

  This hydrogenation catalyst is suitable for use in producing a tetrahydrofuran compound represented by the general formula (2). For example, when a furan compound of the general formula (1) is used as a raw material, a tetrahydrofuran compound can be generated at a high reaction rate even at a low temperature. Therefore, the yield can be increased while avoiding the complexity of the manufacturing equipment. For these reasons, the hydrogenation catalyst of the present invention can be suitably used for the production of tetrahydrofuran compounds on an industrial scale.

  According to the present invention, it is possible to provide a production method capable of producing a tetrahydrofuran compound from a furan compound with high yield and high selectivity at a high reaction rate even at a low temperature. In addition, it is possible to provide a hydrogenation catalyst capable of producing a tetrahydrofuran compound with high yield and high selectivity at a high reaction rate even at low temperatures and a method for producing the same.

  Next, preferred embodiments of the present invention will be described in detail.

(First embodiment)
The method for producing a tetrahydrofuran compound of the present embodiment comprises a mixing step of preparing a mixture by mixing a palladium compound and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element. And a reduction step of obtaining a catalyst by reducing the mixture, and a reaction step of obtaining a tetrahydrofuran compound by contacting a furan compound and hydrogen in the presence of the catalyst. Details of each step will be described below.

  The mixing step is a step of preparing a mixture by mixing a palladium compound as a raw material of the catalyst and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element.

  The palladium compound is a compound having palladium as a constituent element, and examples thereof include palladium halides such as palladium chloride, palladium bromide and palladium iodide; palladium acid salts such as palladium acetate, palladium nitrate and palladium sulfate; palladium oxide and the like. Can be mentioned. You may use 1 type of these palladium compounds individually or in combination of 2 or more types. Of these palladium compounds, palladium halide is preferably used, and palladium chloride is more preferably used from the viewpoint of efficiently supporting palladium on the carrier and reducing the manufacturing cost. You may use a palladium compound in the state dissolved in the hydrate or aqueous solution.

  Examples of metals belonging to Groups 5 to 9 of the periodic table (sometimes referred to as the second metal “M”) include vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, Examples include cobalt, rhodium, and iridium. Of these, tungsten, molybdenum, rhenium, ruthenium, rhodium and iridium are preferable, and tungsten, molybdenum and rhenium are more preferable.

  The form of the metal compound having the above metal as a constituent element is not particularly limited. For example, any form such as a metal alloy, a metal salt, a metal complex, and a metal oxide may be used, and a hydrate or an adduct of an organic compound may be used. Of these, metal salts and metal complexes are preferred from the viewpoint of further improving the catalytic activity. Note that these metal compounds may have two or more metals belonging to Groups 5 to 9 of the periodic table as constituent elements. Moreover, you may use 1 type of the metal compound of various forms individually or in combination of 2 or more types.

  Specific examples of metal compounds having at least one metal belonging to Groups 5 to 9 of the periodic table as constituent elements include vanadium trichloride, vanadium oxide, divanadium trioxide, vanadium dioxide, vanadium pentoxide, dipentapentoxide. Vanadium, vanadium tribromide, potassium pyrovanadate, potassium tetraoxovanadate (V), potassium trioxovanadate (V), sodium trioxovanadate (V), sodium pyrovanadate, lithium trioxovanadate (V) Vanadium compounds such as molybdenum pentachloride, ammonium tetracosaoxoheptamolybdate (VI), potassium tetraoxomolybdate (VI), calcium tetraoxomolybdate, sodium tetraoxomolybdate (VI), tetraoxomolybdenum (V ) Molybdenum compounds such as magnesium acid, lithium tetraoxomolybdate (VI), molybdenum dioxide, molybdenum trioxide; rhenium trichloride, rhenium pentachloride, ammonium tetraoxorhenium (VII), potassium tetraoxorhenium (VII), Rhenium compounds such as sodium tetraoxorhenium (VII), rhenium hexachloride, tripotassium hexachloride, rhenium dichloride, rhenium dioxide, rhenium trioxide, dirhenium oxide; tungsten tetrachloride, tungsten hexachloride, tungsten pentabromide, Tungsten compounds such as hentetracontoxooxotungsten (VI) ammonium; ruthenium trichloride, ruthenium tribromide, ruthenium diammonium pentachloride, ruthenium triammonium hexachloride, ruthenium hexachloride Ruthenium compounds such as um, ruthenium hexachloride disodium, tripotassium hexabromide, dipotassium hexabromide; cobalt dichloride, cobalt dibromide, cobalt diiodide, cobalt difluoride, cobalt dinitrate, oxidation Cobalt compounds such as cobalt, cobalt phosphate and cobalt diacetate; rhodium compounds such as rhodium trichloride, rhodium triammonium chloride, tripotassium hexachloride, trisodium hexachloride, rhodium trinitrate, etc .; iridium trichloride, triodor Iridium iodide, iridium tetrachloride, iridium tetrabromide, ammonium iridate, hexaammineiridium trichloride, pentaamminechloroiridium dichloride, iridium hexachloride, triammonium hexachloride, tripotassium iridium hexachloride, trisodium iridium hexachloride, Tetrachloride Examples thereof include iridium compounds such as lithium diammonium, iridium hexachloride, diammonium hexachloride, iridium hexachloride, iridium hexachloride, and iridium hexachloride.

  Of the above metal compounds, preferably ammonium tetracosaoxoheptamolybdate (VI), ammonium tetraoxorhenium (VII), dirhenium heptoxide, ruthenium trichloride, rhodium trichloride, iridium trichloride, iridium tetrachloride Hexachloroiridium acid is used.

  There is no restriction | limiting in particular in the mixing method in a mixing process. A ball mill or a mortar may be used for mixing in a dry manner, or a solvent may be added and mixed in a wet manner to form a suspension. Further, when the palladium compound and / or the metal compound is in the state of a solution or suspension, it may be mixed as it is to form a solution or suspension. In this way, a mixture containing a palladium compound and a metal compound can be prepared.

  The compounding ratio of the metal compound to the palladium compound is preferably 1 to 200 mol%, more preferably 10 to 100 mol%, still more preferably 20 to 80 mol% on a molar basis in terms of each metal element. . By setting it as such a mixture ratio, the catalyst which can make a reduction in manufacturing cost and reaction activity compatible with a high level can be prepared.

  In the mixing step, in addition to the palladium compound and the metal compound, a component serving as a catalyst carrier may be blended. As the carrier to be used, a porous carrier is preferably used. Specifically, for example, silica, alumina, silica-alumina, ceria, magnesia, calcia, titania, silica-titania, zirconia, activated carbon, zeolite And mesoporous materials (mesoporous alumina, mesoporous silica, mesoporous carbon) and the like. Of these, silica, alumina, or activated carbon is preferably used from the viewpoint of achieving both a low production cost and a long catalyst life. The above carriers may be used singly or in combination of two or more.

  When mixing a palladium compound, a metal compound, and a support | carrier, the mixing order in particular is not restrict | limited. These three components may be mixed at the same time, and the support may be impregnated with the palladium compound and the metal compound simultaneously, or the support may be impregnated with the palladium compound and the metal compound sequentially in this order or vice versa. If a catalyst in a form in which palladium and metal are immobilized on a support is used, it is easy to remove the catalyst from the reaction product obtained in the reaction step described later, and it becomes easy to separate the target product.

  When the carrier is blended, the mixing ratio of the palladium compound and the metal compound is 0.1 to 20% by mass, preferably 0.5 to 10% by mass of palladium with respect to the carrier. The total amount of metals belonging to is 0.01 to 20% by mass, preferably 0.1 to 10% by mass. By mixing at such a ratio, the reaction rate in the reaction step can be further increased.

  The carrier may be blended separately from the palladium compound and the metal compound, but a commercially available palladium impregnated material in which the carrier is impregnated with the palladium compound may be used. In this case, if this palladium impregnated material and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element are mixed, the support is sequentially impregnated with the palladium compound and the metal compound. It will be. Further, a metal impregnated product in which a metal compound is impregnated in a support may be used. In this case, if the metal impregnated product and the palladium compound are mixed, the metal compound and the palladium compound are impregnated sequentially into the carrier. In this way, the palladium compound and the metal compound can be immobilized on the support.

  A method for preparing a catalyst raw material (hereinafter also referred to as “catalyst precursor”) in which a palladium compound and a metal compound are immobilized on a carrier is not particularly limited, and impregnation, precipitation, water absorption, etc. An appropriate method can be selected and employed as appropriate. Examples of the preparation method include a method of preparing a solution or dispersion containing a palladium compound by a co-precipitation method in addition to a carrier powder.

  The catalyst precursor may be calcined, or may be subjected to a reduction treatment in the next step (reduction step) as it is or after drying. The firing atmosphere in the case of firing may be a gas containing oxygen (for example, air) or an inert gas such as nitrogen. The firing temperature can be appropriately selected in consideration of the decomposition temperature of the palladium compound, the firing atmosphere, and the like, and the firing time can be appropriately selected between 0.5 hour and 24 hours. Thus, in the mixing step, a mixture containing a palladium compound and a metal compound and containing a carrier as an optional component is obtained.

  The reduction step is a step of obtaining a catalyst having palladium and a metal belonging to Groups 5 to 9 of the periodic table by reducing the mixture prepared in the mixing step.

  In this step, a catalyst is prepared by reducing a mixture containing a palladium compound and a metal compound and a carrier as an optional component. Examples of the reduction treatment include a method of bringing the mixture into contact with a reducing agent. As the reducing agent, any compound can be used as long as it has an ability to reduce palladium in an oxidized state.

  Examples of such a reducing agent include alcohols such as ethanol, 1-propyl alcohol, 2-propyl alcohol, ethylene glycol, and propylene glycol; aldehydes such as formaldehyde; acids such as formic acid and ascorbic acid; hydrazine; hydrogen; Olefins such as ethylene, propylene, 1-butene, 2-butene and isobutylene are used. The reduction treatment may be performed in either a gas phase or a liquid phase. When hydrogen is used as the reducing agent, the temperature is preferably 40 to 800 ° C., more preferably 50 to 500 ° C., and the hydrogen partial pressure is preferably normal pressure to 12 MPa from the viewpoint of allowing the reduction reaction to proceed more smoothly. More preferably, the pressure is normal pressure to 8 MPa. When the reduced catalyst is taken out into the air, it is taken out by performing Passivation (passivation treatment) with 2 mol% oxygen diluted with He or nitrogen at room temperature.

  When the mixture contains the catalyst precursor obtained by the previous method, the catalyst can be obtained by reducing the mixture. The mixing step and the reduction step may be performed continuously, or the mixing step and the reduction step may be performed at the same time by adopting a method of reducing treatment while mixing. The catalyst obtained in the reduction step may have palladium and a simple metal belonging to Groups 5 to 9 of the periodic table, or may have an alloy or compound containing one or both of them.

  In the catalyst, the molar ratio of metals belonging to Groups 5 to 9 of the periodic table to palladium (in terms of metal element) is preferably 1 to 200 mol%, more preferably 10 to 100 mol%, and still more preferably 20 to 20 mol%. 80 mol%. By setting it as such a molar ratio, reduction of the manufacturing cost of a catalyst and reaction activity can be made compatible at a high level.

  When the catalyst is in a form supported on a support, the supported amount of palladium is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass with respect to the support. By containing palladium in such a range, it is possible to achieve both a reduction in catalyst production cost and reaction activity at a higher level. The total supported amount of metals belonging to Groups 5 to 9 of the periodic table is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass with respect to the support. By containing a metal belonging to Groups 5 to 9 of the periodic table within such a range, it is possible to achieve both a reduction in catalyst production cost and reaction activity at a higher level.

  The catalyst obtained by the above mixing step and reduction step has a hydrogenation action, and since it has a reduction action, it can also be referred to as a reduction catalyst or a hydrogenation catalyst. If this catalyst is used, the formyl group bonded to the furan ring together with the internal olefin of the furan compound can be reduced to produce a tetrahydrofuran compound with high selectivity and high yield.

  In the reaction step, a furan compound and hydrogen are brought into contact with each other in the presence of the catalyst prepared in the reduction step to obtain a tetrahydrofuran compound. The furan compound in this embodiment is a compound represented by the following general formula (1), and has a formyl group or a hydroxymethyl group.

In general formula (1), R represents a formyl group or a hydroxymethyl group, R ^1a represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a formyl group, or a hydroxymethyl group, and R ² and R ³ are And each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ^1a is specifically a hydrogen atom; a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a formyl group, or a hydroxymethyl group. These groups include various isomers. R ^1a and R ² and R ² and R ³ are attached to adjacent carbon ring bonded to each other (e.g., cyclohexane ring) may form a.

R ^1a is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a formyl group, or a hydroxymethyl group, more preferably a hydrogen atom, a methyl group, or a formyl group, from the viewpoint of facilitating the reaction more smoothly. Or it is a hydroxymethyl group. From the same viewpoint, R ² and R ³ are each independently preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group.

  Examples of the furan compound represented by the general formula (1) include furfural (2-formylfuran), 5-methylfurfural, 5-ethylfurfural, 5-propylfurfural, 5-butylfurfural, 5-pentylfurfural, 5- Examples include hydroxymethylfurfural and 5-formylfurfural. Of these, furfural, 5-methylfurfural, 5-hydroxymethylfurfural and 5-formylfurfural are preferably used.

  The amount of the catalyst used in the reaction step is preferably 0.0001 to 0.1 mol, more preferably 0.0005 to 0.08 mol per 1 mol of the furan compound in terms of palladium atom. By setting it as this range, a tetrahydrofuran compound can be obtained with a higher yield and selectivity while sufficiently increasing the reaction rate. In addition, you may use a catalyst combining the multiple types of catalyst containing the different component prepared separately.

  The hydrogen used in the reaction step can be supplied using a compound that generates hydrogen. Examples of such compounds include reducing gases such as hydrogen gas and ammonia gas; water; alcohols such as methanol, ethanol and isopropyl alcohol; organic acids such as formic acid, acetic acid and chloroformic acid; and inorganic acids such as hydrochloric acid and sulfuric acid. Can be mentioned. Of these, from the viewpoint of further increasing the reaction rate, reducing gas or hydrogen gas, more preferably hydrogen gas, is used. Note that the reducing gas described above may be diluted with an inert gas such as nitrogen, helium, or argon.

  The amount of hydrogen is preferably 5 to 200 mol, more preferably 10 to 160 mol in terms of a hydrogen atom with respect to 1 mol of the furan compound. By using this amount, a tetrahydrofuran compound can be obtained with a higher yield and selectivity without stopping with an incomplete reductant while obtaining a sufficient reaction rate.

  The tetrahydrofuran compound in this embodiment is a compound represented by the following general formula (2), and has a hydroxymethyl group.

In General Formula (2), R ^1b represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, and R ² and R ³ are each independently a hydrogen atom or alkyl having 1 to 5 carbon atoms. Indicates a group. R ^1b is specifically a hydrogen atom; a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hydroxymethyl group. These groups include various isomers. R ^1b and R ² and R ² and R ³ are attached to adjacent carbon ring bonded to each other (e.g., cyclohexane ring) may form a.

  In the reaction step of this embodiment, a solvent may or may not be used. Examples of the solvent include water; alcohols such as ethanol, 1-propanol, 2-propanol, n-butanol, t-butanol, and ethylene glycol; hydrocarbons such as heptane, hexane, cyclohexane, and toluene; N, N— Amides such as dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; Ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol diethyl ether; Halogenated fats such as methylene chloride and dichloroethane Group hydrocarbons and the like can be used. Of these, water is preferred. The above-mentioned solvents may be used alone or in combination of two or more.

  The amount of the solvent used is preferably 50 g or less, more preferably 25 g or less with respect to 1 g of the furan compound. This improves the stirring ability. The solvent may contain a salt that does not inhibit the reaction.

  The reaction step can be performed by either a batch (batch) method or a continuous method, depending on the form of the catalyst. Further, it can be carried out in either a homogeneous system or a heterogeneous system (suspension reaction) depending on the nature of the catalyst. When the catalyst is a solid catalyst having a support, palladium supported on the support and at least one metal belonging to Groups 5 to 9 of the periodic table, the reaction can be continuously performed using a fixed bed.

  In the reaction step, for example, a furan compound, a catalyst, and a solvent as necessary are mixed, and the reaction is allowed to proceed with stirring in the presence of hydrogen. The reaction temperature in that case becomes like this. Preferably it is 0-200 degreeC, More preferably, it is 0-100 degreeC, More preferably, it is 0-50 degreeC, Most preferably, it is 0 or more and less than 10 degreeC. The reaction pressure at that time is preferably a normal pressure to 20 MPa, more preferably 0.2 to 15 MPa as a hydrogen partial pressure. By making reaction temperature and reaction pressure into the above-mentioned range, the production | generation of a by-product is fully suppressed and reaction rate can be enlarged further. Thereby, the yield and selectivity of tetrahydrofuran can be further increased. The reduction step and the reaction step may be performed continuously, or the reaction step may be performed after once isolating the catalyst obtained in the reduction step.

  The target tetrahydrofuran compound can be obtained by the above steps. After completion of the reaction, the tetrahydrofuran compound can be isolated and purified from the obtained reaction solution by general operations such as filtration, concentration, extraction, distillation, sublimation, recrystallization, column chromatography and the like.

  In the method for producing a tetrahydrofuran compound of the present embodiment, in the reaction step, a mixture containing a palladium compound and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element is reduced. A hydrogenation catalyst having palladium and the above metal is obtained. This hydrogenation catalyst is a hydrogenation catalyst suitable for the synthesis of the tetrahydrofuran compound represented by the general formula (2). Such a hydrogenation catalyst can be manufactured by the mixing step and the reduction step described above. The mixing step and the reduction step may be performed separately in this order, or may be performed by a method in which the reduction proceeds simultaneously while mixing.

(Second Embodiment)
The method for producing a tetrahydrofuran compound according to the present embodiment includes a reduction step of reducing a palladium compound to obtain a catalyst having palladium, and the furan compound of formula (1) and hydrogen in the presence of the catalyst at a temperature of less than 10 ° C. And a reaction step of obtaining a tetrahydrofuran compound of the above general formula (2) by contacting in a temperature range.

  The reduction step is a step of obtaining a catalyst having palladium by reducing the palladium compound. This reduction step can be performed in the same manner as in the first embodiment except that a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table is not used as a constituent element. As the palladium compound, the same one as in the first embodiment is used. That is, for example, palladium halides such as palladium chloride, palladium bromide and palladium iodide; palladium acid salts such as palladium acetate, palladium nitrate and palladium sulfate; palladium oxide and the like. You may use 1 type of these palladium compounds individually or in combination of 2 or more types. Among these palladium compounds, palladium halide is preferably used, and palladium chloride is more preferably used from the viewpoint of efficiently immobilizing palladium on a carrier and reducing the production cost. You may use a palladium compound in the state dissolved in the hydrate or aqueous solution. Similarly to the first embodiment, the reduction step may be performed after mixing the support and the palladium compound, or the catalyst precursor having the palladium compound immobilized on the support may be reduced.

  The palladium compound is preferably supported on a carrier in order to facilitate separation from the reaction solution containing the tetrahydrofuran compound obtained in the reaction step. The carrier is preferably a porous carrier, for example, silica, alumina, silica-alumina, ceria, magnesia, calcia, titania, silica-titania, zirconia and activated carbon (carbon), zeolite, mesoporous material (mesoporous alumina, female). Porous silica, female porous carbon) and the like. Of these, silica, alumina, and activated carbon (carbon) are more preferably used. In addition, you may use these support | carriers individually by 1 type or in combination of 2 or more types. A commercially available product on which a palladium compound is already supported may be used as it is or after appropriate treatment, or may be prepared separately and used.

  There is no particular limitation on the method for supporting the palladium compound on the carrier, and general methods such as impregnation, precipitation, water absorption and the like can be appropriately selected and employed. As an example of this preparation method, there is a method in which a solution containing a palladium compound is added to a carrier powder and prepared by a co-precipitation method. The firing atmosphere is usually a gas containing oxygen (for example, air). Further, an inert gas such as nitrogen may be used. The firing temperature can be appropriately selected in consideration of the decomposition temperature of the palladium compound used, the firing atmosphere, and the like. The firing time can be appropriately selected between 0.5 hour and 24 hours.

  A catalyst can be obtained by reducing the above-described palladium compound or a catalyst precursor having a palladium compound supported on a carrier in the same manner as in the reduction step of the first embodiment. The palladium content (supported amount) in the catalyst is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass with respect to the support, from the viewpoint of sufficiently increasing the reaction rate in the reaction step. It is. In addition, you may use a commercial item as such a catalyst.

  The catalyst obtained by the above-described reduction step has a hydrogenation action, and since it has a reduction action, it can also be referred to as a reduction catalyst or a hydrogenation catalyst. When this catalyst is used, the formyl group bonded to the furan ring is reduced together with the internal olefin of the furan compound in a low temperature region of less than 10 ° C., preferably in a low temperature region of less than 5 ° C. It can be produced in high yield.

  A reaction process can be performed like 1st Embodiment except using the above-mentioned catalyst (reduction catalyst) which does not have the metal which belongs to periodic table group 5-9. Here, the overlapping description is omitted. The amount of the catalyst used in the reaction step is preferably 0.0001 to 0.1 mol, more preferably 0.0005 to 0.08 mol with respect to 1 mol of the furan compound, in terms of palladium atom. . By setting the amount within this range, the tetrahydrofuran compound can be obtained with a higher yield and selectivity while sufficiently increasing the reaction rate. In addition, you may use a catalyst combining the multiple types of catalyst containing the different component prepared separately.

  The temperature range when the furan compound and hydrogen are brought into contact with each other in the presence of a catalyst is preferably -5 to 8 ° C from the viewpoint of obtaining a sufficient reaction rate while simplifying production equipment on an industrial scale, preferably It is 0-5 degreeC, More preferably, it is 0-3 degreeC. Other conditions can be the same as in the first embodiment.

  The method for producing a tetrahydrofuran compound of the present embodiment uses a hydrogenation catalyst having palladium, which is obtained by reducing a palladium compound in the reaction step. This hydrogenation catalyst is a hydrogenation catalyst suitable for the synthesis of the tetrahydrofuran compound represented by the general formula (2). Such a hydrogenation catalyst can be produced by the above-described reduction step. The reduction step and the reaction step may be performed separately in this order, or may be performed by a method in which the reaction proceeds simultaneously while reducing.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
[Manufacture of catalyst]
A first aqueous solution was prepared by dissolving 33.3 mg (0.188 mmol) of palladium dichloride in 0.7 g of 1N hydrochloric acid. This first aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6) and dried at 110 ° C. for 7 hours in an air atmosphere. Next, 16.6 mg of ammonium tetracosaoxoheptamolybdate (VI) tetrahydrate (0.0940 mmol in terms of molybdenum) was dissolved in 0.7 g of water to prepare a second aqueous solution. After impregnating the first aqueous solution, the dried silica was impregnated with the second aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the molybdenum compound. Thus, a solid catalyst in which palladium and molybdenum are supported by 2% by mass and 0.9% by mass, respectively, with respect to silica (hereinafter also referred to as “Pd—Mo / SiO ₂ catalyst (1)”). 10 g was obtained. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2-hydroxymethyltetrahydrofuran]
100 mg of the Pd—Mo / SiO ₂ catalyst (1) obtained by the above procedure and 10 ml of 0.5 M aqueous furfural solution were placed in an autoclave having an internal volume of 50 ml equipped with a glass inner tube. The inside of the autoclave was pressurized with hydrogen and stirred at 2 ° C. for 4 hours in an 8 MPa hydrogen atmosphere. Thereby, the reduction reaction shown in the following reaction formula (3) was performed. After completion of the reaction, the obtained reaction solution was filtered with a syringe equipped with a membrane filter (0.45 μm) to obtain a filtrate. When this filtrate was analyzed by gas chromatography (manufactured by Shimadzu Corporation, apparatus name: GC-2014, the same applies to the following examples), the conversion of furfural was 99.6%, and 2-hydroxymethyl The yield of tetrahydrofuran was 93.6%.

(Example 2)
[Synthesis of 2-hydroxymethyltetrahydrofuran]
40.0 mg of a commercially available catalyst (5% by mass Pd / activated carbon, manufactured by Wako Pure Chemical Industries, Ltd.) on which 5% by mass of palladium is supported with respect to the activated carbon and 10.0 mL of a 0.5M aqueous furfural solution, It was introduced into an autoclave with an internal volume of 50 ml equipped with a tube. The inside of the autoclave was pressurized with hydrogen and stirred at 2 ° C. for 2 hours in an 8 MPa hydrogen atmosphere. After completion of the reaction, the obtained reaction solution was filtered with a syringe equipped with a membrane filter (0.45 μm) to obtain a filtrate. When this filtrate was analyzed by gas chromatography, the conversion of furfural was 99.6% and the yield of 2-hydroxymethyltetrahydrofuran was 91.9%.

(Example 3)
[Synthesis of 2-hydroxymethyltetrahydrofuran]
The reaction and analysis were performed in the same manner as in Example 2 except that the reaction time was changed from 2 hours to 4 hours. As a result, the conversion rate of furfural was 99.6%, and the yield of 2-hydroxymethyltetrahydrofuran was 97.1%.

Example 4
[Production of reduction catalyst]
Commercially available catalyst (5% by mass Pd / activated carbon, manufactured by Wako Pure Chemical Industries, Ltd.) on which 5% by mass of palladium is supported on activated carbon was added to 1.00 g of ammonium tetracosaoxoheptamolybdate (VI) 41 An aqueous solution obtained by dissolving 0.3 mg (0.23 mmol of molybdenum) in 0.7 g of water was impregnated and dried at 300 ° C. for 3 hours in a nitrogen atmosphere. In this way, palladium and molybdenum are solid catalysts in which 5% by mass and 2.2% by mass of molybdenum are supported with respect to the activated carbon, respectively (hereinafter also referred to as “Pd—Mo / C catalyst”) 1 .05 g was obtained.

(Synthesis of 2-hydroxymethyltetrahydrofuran)
40.0 mg of the “Pd—Mo / C catalyst” obtained by the above procedure and 10.0 ml of a 0.5 M aqueous furfural solution were placed in an autoclave having an internal volume of 50 ml equipped with a glass inner tube. The inside of the autoclave was pressurized with hydrogen and stirred at 2 ° C. for 2 hours in an 8 MPa hydrogen atmosphere. After completion of the reaction, the obtained reaction solution was filtered with a syringe equipped with a membrane filter (0.45 μm) to obtain a filtrate. When this filtration was analyzed by gas chromatography, the conversion of furfural was 99.6% and the yield of 2-hydroxymethyltetrahydrofuran was 90.4%.

  Table 1 summarizes the types of catalysts used in Examples 1 to 4, the mixing ratio of raw materials, the amount of supported metal, and reaction conditions. Data related to the synthesis reactions of Examples 1 to 4 are summarized in Table 2. In Table 2, THFA represents 2-hydroxymethyltetrahydrofuran, FOL represents furfural alcohol, and THFAL represents tetrahydrofurfural. Others indicates the total of components other than THFA, FOL, and THF. The conversion rate is a molar ratio of the raw material consumed with respect to the raw material (furfural) charged. Selectivity is the molar ratio of each product to the total reaction product. The yield is the molar ratio of the produced target product (2-hydroxymethyltetrahydrofuran) to the charged raw material.

(Example 5)
[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
100 mg of the “Pd—Mo / SiO ₂ catalyst (1)” obtained in Example 1 and 10 ml of a 0.5 M aqueous solution of 5-hydroxymethylfurfural were placed in an autoclave having an inner volume of 50 ml equipped with a glass inner tube. It was. The inside of the autoclave was pressurized with hydrogen and stirred at 2 ° C. for 6 hours in an 8 MPa hydrogen atmosphere. Thereby, the reduction reaction shown in the following reaction formula (4) was performed. After completion of the reduction reaction, the obtained reaction solution was filtered with a syringe equipped with a membrane filter (0.45 μm) to obtain a filtrate. When this filtrate was analyzed by gas chromatography, the conversion of 5-hydroxymethylfurfural was 99.7% and the yield of 2,5-dihydroxymethyltetrahydrofuran was 93.5%.

(Example 6)
[Production of reduction catalyst]
A first aqueous solution was prepared in the same manner as in Example 1. This first aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6) and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 100 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound. As a result, 1.10 g of a solid catalyst (hereinafter also referred to as “Pd / SiO ₂ catalyst”) in which 2% by mass of palladium was supported on silica was obtained.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
Other than using the Pd / SiO ₂ catalyst obtained in Example 6 in place of the “Pd—Mo / SiO ₂ catalyst (1)” used in Example 5, and changing the reaction time from 6 hours to 4 hours. Was reacted in the same manner as in Example 5. As a result, the conversion of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 90.7%.

(Example 7)
[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
40.0 mg of a commercially available catalyst (5% by mass Pd / activated carbon, manufactured by Wako Pure Chemical Industries, Ltd.) on which 5% by mass of palladium is supported with respect to the activated carbon and 10 mL of a 0.5M aqueous solution of 5-hydroxymethylfurfural was made of glass. It put into the autoclave of the internal volume 50ml provided with the inner cylinder pipe | tube. The inside of the autoclave was pressurized with hydrogen and stirred at 2 ° C. for 4 hours in an 8 MPa hydrogen atmosphere. The obtained reaction solution was filtered with a syringe equipped with a membrane filter (0.45 μm) to obtain a filtrate. When this filtrate was analyzed by gas chromatography, the conversion of 5-hydroxymethylfurfural was 99.8%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 94.8%.

(Example 8)
[Manufacture of catalyst]
A third aqueous solution was prepared by dissolving 20.0 mg (0.113 mmol) of palladium dichloride in 0.7 g of 1N hydrochloric acid. This third aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6), and dried at 110 ° C. for 7 hours in an air atmosphere. Next, 26.1 mg (0.0991 mmol) of rhodium trichloride trihydrate was dissolved in 0.7 g of water to prepare a fourth aqueous solution. After impregnating the third aqueous solution, the dried silica was impregnated with the fourth aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the rhodium compound. As a result, 1.07 g of a solid catalyst (hereinafter also referred to as “Pd—Rh / SiO ₂ catalyst”) in which palladium and rhodium are supported by 1.2% by mass and 1.0% by mass, respectively, with respect to silica. Got. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
Instead of the Pd / SiO ₂ catalyst used in Example 6, the Pd—Rh / SiO ₂ catalyst obtained in Example 8 was used, the reaction temperature was changed from 2 ° C. to 40 ° C., and the reaction time was changed from 4 hours to 1 hour. The reaction was performed in the same manner as in Example 6 except that the changes were made. As a result, the conversion of 5-hydroxymethylfurfural was 99.4%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 62.6%.

Example 9
[Manufacture of catalyst]
A third aqueous solution was prepared in the same manner as in Example 8. This third aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6), and dried at 110 ° C. for 7 hours in an air atmosphere. Next, ruthenium trichloride n-hydrate (ruthenium content: 41.5% by mass) 24.1 mg (ruthenium content: 0.0991 mmol) was dissolved in 0.7 g of water to prepare a fifth aqueous solution. After impregnating with the third aqueous solution, the dried silica was impregnated with the fifth aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the ruthenium compound. Thus, 1.07 g of a solid catalyst (hereinafter also referred to as “Pd—Ru / SiO ₂ catalyst”) in which palladium and ruthenium are supported by 1.2% by mass and 1.0% by mass, respectively, with respect to silica. Got. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
The reaction was performed in the same manner as in Example 8, except that the Pd—Ru / SiO ₂ catalyst obtained in Example 9 was used instead of the Pd—Rh / SiO ₂ catalyst used in Example 8. As a result, the conversion of 5-hydroxymethylfurfural was 99.9%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 65.6%.

(Example 10)
[Manufacture of catalyst]
A third aqueous solution was prepared in the same manner as in Example 8. This third aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6), and dried at 110 ° C. for 7 hours in an air atmosphere. Next, 51.5 mg (iridium content: 0.0991 mmol) of iridium chloride n-hydrate (iridium content: 37.0 mass%) was dissolved in 0.7 g of water to prepare a sixth aqueous solution. After impregnating the third aqueous solution, the dried silica was impregnated with the sixth aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the iridium compound. Thereby, 1.08 g of a solid catalyst (hereinafter also referred to as “Pd—Ir / SiO ₂ catalyst”) in which 1.2% by mass and 1.9% by mass of palladium and iridium are supported with respect to silica, respectively. Got. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
The reaction was performed in the same manner as in Example 8 except that the Pd—Ir / SiO ₂ catalyst obtained in Example 10 was used instead of the Pd—Rh / SiO ₂ catalyst used in Example 8. As a result, the conversion of 5-hydroxymethylfurfural was 100%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 65.7%.

(Example 11)
[Manufacture of catalyst]
A third aqueous solution was prepared in the same manner as in Example 8. This third aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6), and dried at 110 ° C. for 7 hours in an air atmosphere. Next, 25.9 mg (tungsten content: 0.0991 mmol) of hentetracontoxooxotungsten (VI) ammonium pentahydrate was dissolved in 0.7 g of water to prepare a seventh aqueous solution. After impregnating with the third aqueous solution, the dried silica was impregnated with the seventh aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the tungsten compound. As a result, 1.07 g of a solid catalyst (hereinafter also referred to as “Pd—W / SiO ₂ catalyst”) in which palladium and tungstenene are supported by 1.2% by mass and 1.8% by mass, respectively, with respect to silica. Got. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
The reaction was conducted in the same manner as in Example 8 except that the Pd—W / SiO ₂ catalyst obtained in Example 11 was used instead of the Pd—Rh / SiO ₂ catalyst used in Example 8. As a result, the conversion of 5-hydroxymethylfurfural was 98.2%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 48.6%.

(Example 12)
[Manufacture of catalyst]
A third aqueous solution was prepared in the same manner as in Example 8. This third aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6), and dried at 110 ° C. for 7 hours in an air atmosphere. Next, 26.6 mg (rhenium content: 0.0991 mmol) of ammonium tetraoxorhenate (VII) was dissolved in 0.7 g of water to prepare an eighth aqueous solution. After impregnating the third aqueous solution, the dried silica was impregnated with the eighth aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the rhenium compound. As a result, 1.08 g of a solid catalyst (hereinafter also referred to as “Pd—Re / SiO ₂ catalyst”) in which palladium and rhenium are supported on 1.2% by mass and 1.8% by mass, respectively, with respect to silica. Got. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
The reaction was conducted in the same manner as in Example 8 except that the Pd—Rh / SiO ₂ catalyst used in Example 8 was used and the Pd—Re / SiO ₂ catalyst obtained in Example 12 was used. As a result, the conversion of 5-hydroxymethylfurfural was 99.4%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 53.8%.

(Example 13)
[Manufacture of catalyst]
A third aqueous solution was prepared in the same manner as in Example 8. This third aqueous solution was impregnated with 1.00 g of silica (SiO ₂ ; manufactured by Fuji Silysia Chemical Ltd., trade name: CARiACT G-6), and dried at 110 ° C. for 7 hours in an air atmosphere. Next, 17.5 mg of ammonium tetracosaoxoheptamolybdate (VI) tetrahydrate (molybdenum content: 0.0997 mmol) was dissolved in 0.7 g of water to prepare a ninth aqueous solution. After impregnating the third aqueous solution, the dried silica was impregnated with the ninth aqueous solution and dried at 110 ° C. for 7 hours in an air atmosphere. Thereafter, it was fired at 500 ° C. for 3 hours in an air atmosphere to obtain a powder. The obtained powder was heated at 500 ° C. for 0.5 hours under a hydrogen stream to reduce the palladium compound and the molybdenum compound. Thus, a solid catalyst in which palladium and molybdenum are supported by 1.2% by mass and 1.0% by mass, respectively, with respect to silica (hereinafter also referred to as “Pd—Mo / SiO ₂ catalyst (2)”). 1.08 g was obtained. The catalyst loading is a calculated value based on the charged amount.

[Synthesis of 2,5-dihydroxymethyltetrahydrofuran]
Instead of the Pd—Rh / SiO ₂ catalyst used in Example 8, the “Pd—Mo / SiO ₂ catalyst (2)” obtained in Example 13 was used. Reaction was performed. As a result, the conversion of 5-hydroxymethylfurfural was 98.0%, and the yield of 2,5-dihydroxymethyltetrahydrofuran was 34.7%.

  Table 3 summarizes the types of catalysts used in Examples 5 to 13, the mixing ratio of raw materials, and the amount of supported metal. Moreover, the data regarding the synthesis reaction of Examples 5-13 are collectively shown in Table 4. In Table 3, HMF is 5-hydroxymethylfurfural, BHTF is 2,5-dihydroxymethyltetrahydrofuran, BHF is 2,5-dihydroxymethylfuran, and HTF is 5-hydroxymethyltetrahydro-2-furaldehyde. Show. Others indicates the total of components other than BHTF, BHF, and HTF. M represents a second metal. The conversion rate is a molar ratio of the raw material consumed with respect to the raw material (furfural) charged. Selectivity is the molar ratio of each product to the total reaction product. The yield is the molar ratio of the produced target product (2,5-dihydroxymethyltetrahydrofuran) to the charged raw material.

  In each of the above examples, it was confirmed that a tetrahydrofuran compound can be produced in a high yield and a high selectivity at a high reaction rate at a low temperature by hydrogen reduction of a furan compound in the presence of a catalyst.

  According to the present invention, a tetrahydrofuran compound corresponding to the furan compound can be produced by hydrogen reduction of the furan compound using a catalyst. Tetrahydrofuran compounds are useful as, for example, polymer raw materials such as polyester, polycarbonate, and polyurethane, resin additives, intermediate materials for medical and agricultural chemicals, various solvents, and the like.

Claims (9)

A furan compound of the general formula (1) in the presence of a catalyst obtained by mixing and reducing a palladium compound and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element. A method for producing a tetrahydrofuran compound, comprising the step of bringing hydrogen into contact with hydrogen to obtain a tetrahydrofuran compound of the general formula (2).

(In the formula, R represents a formyl group or a hydroxymethyl group, R ^1a represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a formyl group, or a hydroxymethyl group, and R ² and R ³ are each independently selected. to a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ^1a and R ² and R ² and R ³ are attached to adjacent carbon each may be bonded to each other to form a ring .)

(In the formula, R ^1b represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, and R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. . R ^1b and R ² and R ² and R ³ are attached to adjacent carbon each may be bonded to each other to form a ring.)   The method for producing a tetrahydrofuran compound according to claim 1, wherein in the step, the furan compound and hydrogen are brought into contact with each other in a temperature range of 0 to 50 ° C to obtain the tetrahydrofuran compound. A process for producing a tetrahydrofuran compound, comprising a step of contacting a furan compound of the general formula (1) with hydrogen in a temperature range of less than 10 ° C. to obtain a tetrahydrofuran compound of the general formula (2) in the presence of a catalyst containing palladium. .

(In the formula, R represents a formyl group or a hydroxymethyl group, R ^1a represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a formyl group, or a hydroxymethyl group, and R ² and R ³ are each independently selected. to a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ^1a and R ² and R ² and R ³ are attached to adjacent carbon each may be bonded to each other to form a ring .)

(In the formula, R ^1b represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, and R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. . R ^1b and R ² and R ² and R ³ are attached to adjacent carbon each may be bonded to each other to form a ring.)   The method for producing a tetrahydrofuran compound according to claim 3, wherein the catalyst is obtained by reducing a palladium compound.   The tetrahydrofuran compound according to any one of claims 1 to 4, wherein the furan compound includes at least one selected from the group consisting of furfural, 5-methylfurfural, 5-hydroxymethylfurfural, and 5-formylfurfural. Production method.   The catalyst comprises (A) a support and palladium supported on the support, or (B) a support and palladium supported on the support and a metal belonging to Groups 5 to 9 of the periodic table. The manufacturing method of the tetrahydrofuran compound as described in any one of -5.   The method for producing a tetrahydrofuran compound according to claim 6, wherein the carrier includes at least one selected from the group consisting of carbon, alumina, silica-alumina, zeolite, and silica. A method for producing a hydrogenation catalyst for synthesizing a tetrahydrofuran compound represented by the general formula (2),
A step of mixing a palladium compound and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element and reducing the mixture to obtain a hydrogenation catalyst having palladium and the metal; A method for producing a hydrogenation catalyst.

(In the formula, R ^1b represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, and R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. . R ^1b and R ² and R ² and R ³ are attached to adjacent carbon each may be bonded to each other to form a ring.) A hydrogenation catalyst for synthesizing a tetrahydrofuran compound represented by the general formula (2),
A hydrogenation catalyst comprising palladium and the metal obtained by mixing and reducing a palladium compound and a metal compound having at least one metal belonging to Groups 5 to 9 of the periodic table as a constituent element.

(In the formula, R ^1b represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, and R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. . R ^1b and R ² and R ² and R ³ are attached to adjacent carbon each may be bonded to each other to form a ring.)