TWI858420B - Method for producing 4-hydroxybutyraldehyde, method for producing gamma-butyrolactone, method for producing N-methyl-2-pyrrolidone and compound - Google Patents

Abstract

The method of the present invention is a method for producing 4-hydroxybutyraldehyde, comprising the step of subjecting allyl alcohol to a hydroformylation reaction with carbon monoxide gas and hydrogen in the presence of a catalyst containing a rhodium catalyst and at least one two-seat phosphine ligand selected from formulas (1) to (3) (wherein Ar is an aromatic group which may have a substituent).

Description

Method for producing 4-hydroxybutyraldehyde, method for producing gamma-butyrolactone, method for producing N-methyl-2-pyrrolidone and compound

The present invention relates to a method for producing 4-hydroxybutyraldehyde, a method for producing γ-butyrolactone and a method for producing N-methyl-2-pyrrolidone using the same, and a ligand compound constituting a catalyst applicable to the production of 4-hydroxybutyraldehyde by hydroformylation of allyl alcohol.

4-Hydroxybutyraldehyde (4-HBA) is a useful compound that can be used as a raw material for various compounds. For example, 1,4-butanediol (1,4-BDO) is obtained by subjecting 4-HBA to a hydroreduction reaction. 1,4-BDO is useful as a raw material for polybutylene terephthalate, urethane resins, etc. In addition, gamma-butyrolactone (GBL) can be produced by subjecting 4-HBA or 1,4-BDO to a dehydrogenation reaction. GBL is widely used in industry as a detergent for electronic materials. In addition, N-methyl-2-pyrrolidone (NMP) can be derived by reacting GBL with monomethylamine. NMP has high solubility in various resins called engineering plastics. Therefore, NMP can be widely used in industries such as detergents for electronic materials.

4-HBA can be produced by hydroformylating allyl alcohol. When an olefinic compound is hydroformylated using a rhodium catalyst and a ligand, the selectivity and yield of the linear oxo compound and the branched oxo compound in the reaction product vary greatly depending on the type of olefinic compound and ligand used. This is also true for the hydroformylation of allyl alcohol. When 4-HBA is produced by hydroformylation of allyl alcohol using a rhodium catalyst and a ligand, 4-HBA having a linear structure is generated, and 3-hydroxy-2-methylpropanal (HMPA) having a branched structure is also generated as a by-product, and low-boiling point by-products such as propionaldehyde are further generated.

As a technology for hydroformylating olefinic compounds using a rhodium catalyst and a ligand, there are technologies described in Patent Documents 1 to 3 and Non-Patent Document 1. Patent Document 1 describes a method for synthesizing butanediols by reacting allyl alcohol with carbon monoxide and hydrogen in the presence of a rhodium-containing hydroformylation catalyst to produce hydroxybutyraldehydes, and then hydrogenating the hydroxybutyraldehydes. Specifically, it is described that carbonyltris(triphenylphosphine)rhodium (I) and triphenylphosphine (single-seat ligand) are used as catalysts to react allyl alcohol with carbon monoxide and hydrogen to generate a product containing 4-HBA, and the product is hydrogenated to generate 1,4-BDO.

Patent document 2 describes a method for hydroformylating allyl alcohol in the presence of a rhodium evil compound and a trisubstituted phosphine. Specifically, it describes the method of hydroformylating allyl alcohol using a rhodium evil compound, triphenylphosphine (single-seat ligand) and 1,4-bis(diphenylphosphino)butane (two-seat ligand).

Patent document 3 describes that in the presence of a rhodium complex catalyst, an optically active organic diphosphine compound and a specific organic diphosphine compound are used as ligands in the hydroformylation reaction of allyl alcohol. Example 6 of Patent document 3 describes that rhodium-hydride (carbonyl) tris(triphenylphosphine) is used as a catalyst, and trans-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-difuran (DIOP) and bis(diphenylphosphino)pentane and diphenylmethylphosphine are used as ligands to hydroformylate allyl alcohol. Table 2 of Patent document 3 describes that the selectivity of 4-HBA in Example 6 is 84.8%, and the selectivity of HMPA is 13.8%.

Non-patent document 1 describes the calculation prediction of using a rhodium complex compound and a phosphine ligand having a xanthate skeleton as a catalyst for a hydroformylation reaction. Non-patent document 1 describes the use of 1-octene, a simple olefin, as a model compound for a hydroformylation reaction. Non-patent document 1 describes the use of a phosphine ligand having a xanthate skeleton as a catalyst, and predicts that the formation ratio of a straight chain compound/branched compound will increase. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Publication No. 51-29412 [Patent Document 2] Japanese Patent Publication No. 54-106407 [Patent Document 3] Japanese Patent Publication No. 6-279345 [Non-patent Document]

[Non-patent document 1] Organometallics 2015, 34, 1062-1073

[Problem solved by the invention]

However, when using conventional technology to produce 4-hydroxybutyraldehyde (4-HBA) by hydroformylation of allyl alcohol, it is expected to further increase the amount of 4-HBA produced as the target product and the ratio of the amount of 4-HBA produced to the amount of 3-hydroxy-2-methylpropanal (HMPA) produced as a byproduct (4-HBA/HMPA). HMPA and 4-HBA are similar in physical properties and have similar boiling points. Therefore, in order to separate 4-HBA and HMPA in the reaction product, complicated operations are required. Therefore, in order to establish an industrial process for producing 4-HBA, it is expected to reduce the amount of HMPA produced as a byproduct in the hydroformylation reaction of allyl alcohol and further increase the ratio of the amount of 4-HBA produced to the amount of HMPA produced in the reaction product (4-HBA/HMPA).

Non-patent document 1 states that when a phosphine ligand having a xanthane skeleton is used as a catalyst for the hydroformylation reaction of 1-octene, it is expected that the formation ratio of a linear compound/branched compound can be increased. However, the hydroformylation reaction of a compound having a substituent such as allyl alcohol and the hydroformylation reaction of a simple olefin such as 1-octene have a large difference in the selectivity of a linear compound/branched compound. Non-patent document 1 does not state the prediction of the hydroformylation reaction of allyl alcohol.

The present invention is made in view of the above-mentioned circumstances, and aims to provide a method for producing 4-HBA, which can produce a reaction product with a small amount of HMPA and a large ratio of the amount of 4-HBA to the amount of HMPA (4-HBA/HMPA). The present invention also aims to provide a ligand compound constituting the following catalyst, which can increase the ratio of the amount of 4-HBA to the amount of HMPA (4-HBA/HMPA) in the hydroformylation reaction of allyl alcohol.

Furthermore, the present invention aims to provide a method for producing GBL, wherein the reaction product containing 4-HBA produced in the step of producing 4-HBA can be directly used in the reaction of producing γ-butyrolactone (GBL) without purification, and GBL can be produced at a high yield and high efficiency. Furthermore, the present invention aims to provide a method for producing N-methyl-2-pyrrolidone (NMP), wherein NMP can be efficiently produced by including a step of producing GBL at high efficiency. [Means for Solving the Problem]

That is, the present invention relates to the following matters. The first aspect of the present invention is to provide the following method for producing 4-hydroxybutyraldehyde. [1] A method for producing 4-hydroxybutyraldehyde, which comprises the step of hydroformylating allyl alcohol with carbon monoxide gas and hydrogen in the presence of a catalyst containing a rhodium catalyst and at least one diphosphine ligand selected from the following formulas (1) to (3).

(In formulas (1) to (3), Ar represents an aryl group which may have a substituent.)

The first aspect of the present invention preferably comprises the characteristics described in [2] to [10]. It is also preferred that these characteristics are combined in combination of two or more. [2] A method for producing 4-hydroxybutyraldehyde as described in [1], wherein Ar in the above formulas (1) to (3) is any one of the following formulas (a) to (e).

[3] A method for producing 4-hydroxybutyraldehyde as described in [1] or [2], wherein the difference between the activation energy for 1,2 insertion and the activation energy for 2,1 insertion of allyl alcohol calculated by density functional theory in the hydroformylation reaction in the presence of a rhodium catalyst and the aforementioned two-seat phosphine ligand is 4.2 kcal/mol or more.

[4] The above-mentioned two-phosphine ligand is represented by the above-mentioned formula (1), Ar in the above-mentioned formula (1) is represented by any one of the above-mentioned formulas (a), (b), (c), and the method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [3]. [5] The above-mentioned two-phosphine ligand is represented by the above-mentioned formula (2), Ar in the above-mentioned formula (2) is represented by the above-mentioned formula (a), and the method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [3]. [6] The above-mentioned two-phosphine ligand is represented by the above-mentioned formula (3), Ar in the above-mentioned formula (3) is represented by any one of the above-mentioned formulas (a), (b), (d), (e), and the method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [3].

[7] A method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [6], wherein the amount of the rhodium catalyst used is such that the ratio of rhodium atoms to the allyl alcohol is 0.01 mol% to 5 mol%. [8] A method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [7], wherein the amount of the diphosphine ligand used is such that the ratio of the rhodium atoms to the allyl alcohol is 0.01 mol% to 5 mol%.

[9] A method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [8], wherein the pressure of the mixed gas containing carbon monoxide gas and hydrogen in the reaction vessel for carrying out the hydroformylation reaction is in the range of 0.1 to 10 MPaG (gauge pressure), and the partial pressure ratio of carbon monoxide gas to hydrogen in the reaction vessel (hydrogen gas/carbon monoxide gas) is in the range of 1/10 to 10/1. [10] A method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [9], wherein the carbon monoxide gas and the hydrogen are produced by thermal decomposition of waste plastics and/or biomass.

The second aspect of the present invention is to provide the following method for producing γ-butyrolactone. [11] A method for producing γ-butyrolactone comprising the steps of producing 4-hydroxybutyraldehyde by the method for producing 4-hydroxybutyraldehyde as described in any one of [1] to [10], and contacting the produced 4-hydroxybutyraldehyde with a catalyst containing copper. The second aspect of the present invention is preferably characterized by the following [11]. [12] A method for producing γ-butyrolactone as described in [11], wherein the catalyst containing copper further contains an oxide of at least one metal element selected from the group consisting of zinc, zirconium and aluminum.

The third aspect of the present invention is to provide the following method for producing N-methyl-2-pyrrolidone. [13] A method for producing N-methyl-2-pyrrolidone comprising the steps of producing γ-butyrolactone by the method for producing γ-butyrolactone as described in [11] or [12], and reacting the produced γ-butyrolactone with monomethylamine.

The fourth aspect of the present invention is to provide the following compound. [14] A compound represented by the following formula (10).

The above compounds can be preferably used as catalysts in the above production methods.

The fourth aspect of the present invention is to provide the following compound. [15] A compound represented by the following formula (8).

The above compound can be preferably used as a catalyst in the above production method. [Effects of the Invention]

According to the method for producing 4-HBA of the present invention, the amount of HMPA generated by the hydroformylation reaction is small, and a reaction product having a large ratio of the amount of 4-HBA generated to the amount of HMPA generated (4-HBA/HMPA) can be obtained.

The compound of the present invention is a compound represented by formula (10) or a compound represented by formula (8). Therefore, when used as a ligand of a catalyst in the hydroformylation reaction of allyl alcohol, 4-HBA can be produced at a high yield, and a reaction product having a large ratio of the amount of 4-HBA generated to the amount of HMPA generated (4-HBA/HMPA) can be obtained.

The method for producing GBL of the present invention includes a step of producing 4-HBA by the method for producing 4-HBA of the present invention, and a step of bringing the produced 4-HBA into contact with a catalyst containing copper. Therefore, the reaction product containing 4-HBA produced in the step of producing 4-HBA has a large ratio of the amount of 4-HBA produced to the amount of HMPA produced (4-HBA/HMPA). Therefore, the reaction product containing 4-HBA does not need to be purified, and even if it is directly used in the reaction for producing GBL, GBL can be produced at a high yield and efficiently.

Furthermore, the method for producing NMP of the present invention comprises a step of producing GBL by the method for producing GBL of the present invention, and a step of reacting the produced GBL with monomethylamine. Therefore, GBL can be produced efficiently, and NMP, which is a useful compound, can be produced efficiently industrially using the produced GBL.

[Type of implementation of the invention]

The inventors of the present invention intend to solve the above-mentioned problems and obtain a reaction product having a larger ratio of the amount of 4-HBA generated to the amount of HMPA generated (4-HBA/HMPA). When allyl alcohol is hydroformylated with carbon monoxide gas and hydrogen gas, they focus on the phosphine ligand used together with the rhodium catalyst and conduct detailed examination. As a result, they found that the catalyst contains a rhodium catalyst and at least one two-seat phosphine ligand selected from the above formulas (1) to (3).

As described later, the hydroformylation reaction of allyl alcohol by carbon monoxide gas and hydrogen gas is composed of a stage in which carbon monoxide and hydrogen atoms are inserted into the allyl alcohol through the coordinated rhodium complex catalyst to form an intermediate (olefin insertion), and a stage in which the rhodium complex catalyst is reductively removed from the intermediate to generate a hydroxy aldehyde (reductive removal stage). The two-seat phosphine ligands shown in formulas (1) to (3) all have a Xantphos skeleton and are rich in electrons. It can be seen from this that when the aforementioned two-seat phosphine ligand is coordinated to the rhodium complex catalyst, the olefin insertion becomes the rate-controlling stage. Therefore, it is presumed that the generation of 4-HBA in the hydroformylation reaction is promoted while the generation of HMPA is also suppressed. After further repeated examinations, the inventors of the present invention confirmed that a reaction product with a large 4-HBA/HMPA ratio can be obtained by subjecting allyl alcohol to a hydroformylation reaction with carbon monoxide gas and hydrogen gas in the presence of the above-mentioned catalyst, thereby completing the present invention.

The following is a detailed description of the method for producing 4-hydroxybutyraldehyde, the method for producing γ-butyrolactone, the method for producing N-methyl-2-pyrrolidone, and preferred examples of the compounds provided by the present invention. In addition, the present invention is not limited to the embodiments shown below. In the present invention, for example, addition, omission, substitution, and modification may be performed on the number, type, position, amount, ratio, material, and composition without departing from the scope of the present invention.

[Method for producing 4-hydroxybutyraldehyde] The method for producing 4-hydroxybutyraldehyde (4-HBA) of this embodiment comprises the step of hydroformylating allyl alcohol with carbon monoxide gas and hydrogen gas in the presence of a catalyst containing a rhodium catalyst and at least one diphosphine ligand selected from the following formulas (1) to (3).

(In formulas (1) to (3), Ar represents an aryl group which may have a substituent.)

(Hydrogen, carbon monoxide gas) In the method for producing 4-HBA of this embodiment, allyl alcohol is subjected to a hydroformylation reaction with carbon monoxide gas and hydrogen. In this embodiment, allyl alcohol and a catalyst are added to a reaction container selected arbitrarily such as a general container or a pressure-resistant container used in this field. In this embodiment, it is preferred to supply a gas containing carbon monoxide gas and a gas containing hydrogen to the reaction container in which allyl alcohol is subjected to a hydroformylation reaction. The gas containing carbon monoxide gas and the gas containing hydrogen can be supplied to the reaction container separately, or they can be supplied to the reaction container in a mixed gas state of the gas containing carbon monoxide gas and the gas containing hydrogen.

The gas containing carbon monoxide supplied to the reaction vessel may be only carbon monoxide gas, or may contain inert gases such as nitrogen and argon in addition to carbon monoxide gas. The gas containing hydrogen supplied to the reaction vessel may be only hydrogen gas, or may contain inert gases such as nitrogen and argon in addition to hydrogen gas. It is preferred that the gas containing carbon monoxide gas and the gas containing hydrogen do not contain oxidizing gases such as air and oxygen.

In the present embodiment, as the carbon monoxide gas and hydrogen gas used in the hydroformylation reaction of allyl alcohol, those produced by thermal decomposition of waste plastics and/or biomass can be used.

The pressure of the mixed gas containing carbon monoxide gas and hydrogen in the reaction vessel for carrying out the hydroformylation reaction is not particularly limited, but is preferably in the range of 0.1 to 10 MPaG (gauge pressure), more preferably in the range of 0.1 to 5.0 MPaG (gauge pressure), and even more preferably in the range of 0.5 to 2.5 MPaG (gauge pressure). The pressure of the mixed gas in the reaction vessel is preferably maintained in the range of 0.5 to 2.5 MPaG from the start to the end of the hydroformylation reaction, and it is particularly preferred that the reaction is carried out while replenishing the carbon monoxide gas and hydrogen consumed by the hydroformylation reaction.

When the pressure of the mixed gas in the reaction vessel during the hydroformylation reaction is 0.1 MPaG or more, the hydroformylation reaction is easy to proceed. When the pressure of the mixed gas in the reaction vessel is to be promoted, it is better to be higher. However, if the pressure of the mixed gas in the reaction vessel during the hydroformylation reaction is set to more than 10 MPaG, expensive equipment must be used. By setting the pressure of the mixed gas in the hydroformylation reaction to less than 10 MPaG, 4-HBA can be produced using industrially applicable equipment and methods. In this embodiment, since the hydroformylation reaction can be promoted by the catalyst, even if the pressure of the mixed gas is set below 10 MPaG, a sufficient reaction rate can be obtained, and 4-HBA can be produced at a sufficient yield.

The partial pressure ratio of carbon monoxide gas to hydrogen (hydrogen/carbon monoxide gas) in the reaction vessel for the hydroformylation reaction is preferably set in the range of 1/10 to 10/1, more preferably in the range of 1/5 to 5/1, and even more preferably in the range of 1/2 to 2/1. When the partial pressure ratio of carbon monoxide gas to hydrogen (hydrogen/carbon monoxide gas) in the reaction vessel during the hydroformylation reaction is in the range of 1/10 to 10/1, a sufficient reaction rate can be obtained by supplying hydrogen and carbon monoxide gases necessary for the hydroformylation reaction. If the partial pressure ratio (hydrogen gas/carbon monoxide gas) is set to 2/1 or less, the hydrogen reduction reaction proceeds, and the decrease in the yield of 4-HBA can be suppressed.

(Rhodium catalyst) The rhodium catalyst used in the method for producing 4-HBA of this embodiment can be any catalyst used for hydroformylation of olefins. Only one rhodium catalyst may be used, or two or more rhodium catalysts may be used.

Specific examples of rhodium catalysts include rhodium oxides such as RhO, Rh ₂ O ₃ , and RhO _{2 ,} rhodium salts such as rhodium nitrate, rhodium sulfate, rhodium chloride, rhodium bromide, rhodium iodide, and rhodium acetate, and rhodium complexes such as dicarbonylrhodium acetylacetonate, carbonyl(triphenylphosphine)rhodium acetylacetonate, and hydride carbonyltris(triphenylphosphine)rhodium (I), and rhodium carbonyl clusters such as Rh ₄ (CO) ₁₂ and Rh ₆ (CO) ₁₆ . Among these rhodium catalysts, rhodium complexes are preferred in terms of catalytic activity, solubility in solvents and ease of handling as a catalyst, and hydride carbonyltris(triphenylphosphine)rhodium (I) is particularly preferred.

The amount of the rhodium catalyst used is not particularly limited. The ratio of rhodium atoms to allyl alcohol is preferably 0.01 mol% to 5 mol%, more preferably 0.05 mol% to 2 mol%, and even more preferably 0.1 mol% to 1 mol%. When the ratio of rhodium atoms is 0.01 mol% or more, sufficient hydroformylation activity can be obtained. When the ratio of rhodium atoms is 5 mol% or less, the loss during the recovery of the rhodium catalyst can be suppressed and has economic value.

(Two-seat phosphine ligand) The two-seat phosphine ligand used in the method for producing 4-HBA of this embodiment is at least one selected from the above formulas (1) to (3). Only one type of two-seat phosphine ligand may be used, or two or more types may be used.

The two-seat phosphine ligands shown in formulas (1) to (3) all have a Xantphos skeleton. When these two-seat phosphine ligands are used, olefin insertion in the hydroformylation reaction of allyl alcohol becomes the rate-controlling stage. Although this situation has not yet been clarified, it can be inferred that it has a great influence on the selectivity of 4-HBA and HMPA in the hydroformylation reaction of allyl alcohol. As a result, it is inferred that the formation of 4-HBA is promoted, while the formation of HMPA is also inhibited, the selectivity of 4-HBA becomes higher, and the reaction product with a larger 4-HBA/HMPA ratio is obtained. And the value (ratio) of 4-HBA/HMPA can be arbitrarily selected as necessary. Examples may be 10.0 or more, 11.0 or more, 12.0 or more, 13.0 or more, 14.0 or more, or 15.0 or more, but the present invention is not limited to these examples.

In contrast, for example, when trans-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-difuran (DIOP) which does not have a two-seat phosphine ligand of the Xantphos skeleton is used in the hydroformylation reaction of allyl alcohol, the reductive dissociation of the rhodium catalyst in the hydroformylation reaction becomes the rate-determining stage.

Ar in formula (1) to (3) is an aromatic group which may have a substituent. The aromatic group which may have a substituent is not particularly limited as long as it is an aromatic hydrocarbon group. Therefore, the aromatic group which may have a substituent may be a monocyclic aromatic group or a polycyclic aromatic group. The aromatic groups which may have four substituents contained in one molecule of the two-seat phosphine ligand may be different from each other, or may be partially or entirely the same. From the perspective of easy production, it is preferred that all of them are the same.

The aryl group which may have a substituent may have one substituent or may have two or more substituents. When the aryl group has two or more substituents, these substituents may be all different or partly or completely the same. When the aryl group which may have a substituent has a substituent, the bonding position of the substituent in the aryl group is not particularly limited.

Examples of the substituents of the aryl group which may have a substituent include a linear or branched alkyl group, a dialkylamino group, a cyano group, a nitro group, an amino group, a hydroxyl group, a halogenated alkyl group, etc. As the substituent, a linear or branched alkyl group and/or a dialkylamino group are particularly preferred in order to provide an electron donor group and to provide a good stability of the aryl group which may have a substituent.

The linear or branched alkyl group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples of the linear or branched alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, etc., and methyl is preferred from the viewpoint of easy production.

The dialkylamino group preferably has 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples of the dialkylamino group include dimethylamino, diethylamino, and methylethylamino. From the viewpoint of easy production, dimethylamino is preferred.

The aromatic group which may have a substituent is preferably a phenyl group or a phenyl group having a substituent. In formulas (1) to (3), Ar is preferably any of the following formulas (a) to (e) in order to obtain a reaction product having a larger ratio of the amount of 4-HBA produced to the amount of HMPA produced (4-HBA/HMPA). In order to produce 4-HBA at a high yield, formula (b) is more preferred. In addition, "---" in each formula means a bond with a P atom.

When the two-phosphine ligand is represented by formula (1), it is preferred that Ar in formula (1) is any one of the above formulas (a), (b), and (c) in order to obtain a reaction product having a large 4-HBA/HMPA ratio. In particular, from the viewpoint of being able to produce 4-HBA at a high yield and obtaining a reaction product having a large 4-HBA/HMPA ratio, it is preferred that Ar in formula (1) is represented by formula (b) and a compound represented by the following formula (10).

When the two-phosphine ligand is represented by formula (2), it is preferred that Ar in formula (2) is the above-mentioned formula (a) in order to obtain a reaction product with a larger 4-HBA/HMPA. When the two-phosphine ligand is represented by formula (3), it is preferred that Ar in formula (3) is any one of the above-mentioned formulas (a), (b), (d), and (e) in order to obtain a better reaction product of 4-HBA/HMPA. In particular, when 4-HBA is to be produced at a high yield, it is preferred that Ar in formula (3) is a compound represented by formula (a), or Ar in formula (3) is a compound represented by the following formula (8) in which Ar is formula (b).

The difference in activation energy between 1,2 insertion and 2,1 insertion in the hydroformylation reaction calculated by the density functional method described later (hereinafter sometimes simply referred to as "activation energy difference") of the two-phosphine ligand is preferably 4.2 kcal/mol or more, more preferably 4.5 kcal/mol or more, and even more preferably 5.0 kcal/mol or more, and the larger the better. When the difference in activation energy of the two-phosphine ligand is 4.2 kcal/mol or more, the selectivity of 4-HBA becomes higher, and a reaction product having a larger ratio of the amount of 4-HBA generated to the amount of HMPA generated (4-HBA/HMPA) can be obtained. Therefore, the yield and selectivity of 4-HBA in the method for producing 4-HBA of this embodiment can be further improved.

[Difference in activation energy between 1,2 insertion and 2,1 insertion] When allyl alcohol is subjected to a hydroformylation reaction using the manufacturing method of this embodiment, the target product 4-HBA can be produced, and HMPA can be produced as a by-product. 4-HBA is a linear compound with a linear structure. HMPA is a branched compound with a branched structure. When a catalyst having an Rh-H bond is used as a rhodium catalyst, the so-called 1,2 insertion in the hydroformylation reaction of allyl alcohol means a reaction in which allyl alcohol (olefin) is inserted between the Rh-H bonds of the rhodium catalyst to form a linear rhodium complex, as shown in the following reaction formula, which is a reaction pathway for producing 4-HBA. The so-called 2,1 insertion refers to the reaction of inserting allyl alcohol into the Rh-H bond of the rhodium catalyst to form a branched rhodium complex. As shown in the following reaction formula, it is a reaction pathway for generating HMPA.

The difference between the activation energy of 1,2 insertion and the activation energy of 2,1 insertion (2,1 insertion - 1,2 insertion) is correlated with the ratio of the amount of 4-HBA generated to the amount of HMPA generated (4-HBA/HMPA). Specifically, 4-HBA/HMPA tends to increase as the activation energy of 1,2 insertion is small and the activation energy of 2,1 insertion is large. Therefore, by obtaining the value calculated by the density functional method, 4-HBA/HMPA can be predicted from the difference in activation energy between 1,2 insertion and 2,1 insertion in the hydroformylation reaction of allyl alcohol. However, the above activation energy difference is a value that does not take into account the side reactions accompanying the isomerization of allyl alcohol. The ratio of the amount of 4-HBA produced to the amount of HMPA produced (4-HBA/HMPA) is sometimes slightly affected by the side reactions accompanying the isomerization of allyl alcohol.

Depending on the type of the diphosphine ligand, the activation energy of 1,2 insertion and the activation energy of 2,1 insertion in the hydroformylation reaction of allylic alcohol when using a ligand with Rh-H bond as a rhodium catalyst will change. Therefore, the difference in activation energy can be used as an indicator for selecting the diphosphine ligand used in the hydroformylation reaction of allylic alcohol.

The amount of the diphosphine ligand used is in the range of 0.5 mol to 50 mol, preferably in the range of 1.5 mol to 20 mol, and more preferably in the range of 2.0 mol to 10 mol, relative to 1 mol of rhodium atoms contained in the rhodium catalyst. When the amount of the diphosphine ligand used is 50 mol or less, the reaction rate of the hydroformylation reaction can be fully improved, which is beneficial from the economic aspect. When the amount of the diphosphine ligand used is 0.5 mol or more, the selectivity of 4-HBA becomes higher, and a reaction product with a higher ratio of the generated amount of 4-HBA to the generated amount of HMPA (4-HBA/HMPA) can be obtained.

The two-phosphine ligand used in the method for producing 4-HBA of this embodiment can be produced by a known method using an appropriate organization. The two-phosphine ligand can be purchased and used.

(Solvent) In the method for producing 4-HBA of this embodiment, it is preferred to carry out the hydroformylation reaction of allyl alcohol in a solvent. As a solvent, it is preferred to use a solvent that is inert to the allyl alcohol of the raw material and the reaction product. Specifically, as a solvent, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, cyclohexanone, ethyl acetate, n-propyl acetate, n-butyl acetate, n-heptane, acetonitrile, benzene, toluene, xylene, N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, etc. can be cited. Among these solvents, aromatic compounds such as benzene, toluene, and xylene that have good separation properties from water are particularly preferred. By using these aromatic compounds as solvents and performing a separation operation by adding water to the reaction solution after the hydroformylation reaction of allyl alcohol, the reaction product containing 4-HBA as the target can be efficiently extracted on the water layer side.

The amount of solvent used is preferably 1 to 50 times, more preferably 5 to 30 times, and even more preferably 5 to 20 times the weight of allyl alcohol in order to improve the separation of the organic layer and the aqueous layer when water is added to the reaction solution after the hydroformylation reaction to perform the separation operation.

(Reaction conditions) The reaction temperature in the hydroformylation reaction of allyl alcohol is preferably 40~100℃, more preferably 40~80℃, and even more preferably 50~70℃. If the reaction temperature is above 40℃, the reaction rate will not become extremely slow, and 4-HBA can be produced efficiently. In addition, if the reaction temperature is below 100℃, the selectivity of 4-HBA will not be reduced due to excessively high reaction rate, and the stability of the catalyst will not be damaged.

If the reaction time in the hydroformylation reaction of allyl alcohol is too short, the conversion rate of allyl alcohol may become insufficient. In addition, if the reaction time is too long, the reaction product may decompose. Therefore, the reaction time is preferably set to 0.5 to 10 hours, preferably 0.5 to 5 hours, and more preferably 1 to 3 hours. If the reaction time is 0.5 to 10 hours, a high yield can be ensured and good productivity can be obtained. As the reaction apparatus used in the method for producing 4-HBA of this embodiment, a pressure-resistant reaction apparatus such as a high-pressure and high-temperature reactor can be used. In addition, the 4-HBA obtained in the step of performing the hydroformylation reaction can be further purified. Or it can be directly stored without purification, or directly used as a raw material in other manufacturing. For example, the obtained 4-HBA can be directly used in the manufacturing method of γ-butyrolactone without purification. Moreover, the so-called high yield can be, for example, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 97% or more, but it is not limited to these examples.

[Method for producing γ-butyrolactone] The method for producing γ-butyrolactone (GBL) of this embodiment includes a step of producing 4-HBA by the method for producing 4-HBA of this embodiment, and a step of bringing the produced 4-HBA into contact with a catalyst containing copper. In the method for producing GBL of this embodiment, 4-HBA is brought into contact with a catalyst containing copper, and GBL is generated by performing a dehydrogenation reaction of 4-HBA.

The method for producing GBL of the present embodiment includes a step of producing 4-HBA by the method for producing 4-HBA of the present embodiment. Therefore, the HMPA content of the reaction product containing 4-HBA produced in the step of producing 4-HBA is small, and the ratio of the amount of 4-HBA produced to the amount of HMPA produced (4-HBA/HMPA) is large. Therefore, there is no need to purify the reaction product containing 4-HBA, and even if it is directly used in the reaction of producing GBL, GBL can be produced at a high yield, and GBL can be produced efficiently. The so-called high yield can be, for example, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 97% or more, and is not limited to these examples.

In addition, in the method for producing GBL of the present embodiment, the reaction product containing 4-HBA produced by the method for producing 4-HBA of the present embodiment can be further purified to obtain high-purity 4-HBA, which can be used in the reaction for producing GBL. In this case, the reaction product containing 4-HBA produced in the step of producing 4-HBA is easy to purify because the ratio of 4-HBA/HMPA is large. As a method for purifying the reaction product containing 4-HBA, for example, a known method such as a method of separating the components by distillation using the difference in boiling points of the components contained in the reaction product can be used.

(Copper-containing catalyst) In this embodiment, the copper-containing catalyst that can be in contact with 4-HBA contains copper as an active metal. The copper-containing catalyst can preferably further contain an oxide of at least one metal element selected from the group consisting of zinc, zirconium and aluminum. The copper-containing catalyst can further contain other metal oxides in addition to the oxide of at least one metal element selected from the group consisting of zinc, zirconium and aluminum and copper.

As other metal oxides, chromium oxide is preferred. The copper-containing catalyst may further contain chromium oxide in addition to the oxide of at least one metal element selected from the group consisting of zinc, zirconium and aluminum, and metallic copper, and it is expected that the active barrier of the dehydrogenation reaction of 4-HBA can be reduced and the reaction of generating GBL can be activated. In addition, the copper-containing catalyst can suppress the side reactions of generating 1,4-butanediol and other impurities by containing chromium oxide, and it is expected that the selectivity of GBL can be improved. It can be seen from this that the copper-containing catalyst used in the dehydrogenation reaction of 4-HBA is better than the one containing chromium oxide.

The catalyst containing copper is preferably composed of copper, at least one selected from the group consisting of zinc, zirconium and aluminum, chromium and oxygen. Specific examples of the case where the catalyst containing copper is an oxide containing chromium include oxides containing zinc and chromium, and a catalyst containing metallic copper (CuZnCrOx); oxides containing zirconium and chromium, and a catalyst containing metallic copper (CuZrCrOx); oxides containing aluminum and chromium, and a catalyst containing metallic copper (CuAlCrOx); oxides containing zinc, zirconium and chromium, and a catalyst containing metallic copper (CuAlCrOx). , and a catalyst containing metallic copper (CuZnZrCrOx); oxides containing zinc, aluminum and chromium, and a catalyst containing metallic copper (CuZnAlCrOx); oxides containing zirconium, aluminum and chromium, and a catalyst containing metallic copper (CuZrAlCrOx); oxides containing zinc, zirconium, aluminum and chromium, and a catalyst containing metallic copper (CuZnZrAlCrOx), etc. In the above formula, x representing the proportion of oxygen atoms is an arbitrarily selected number. In the formula, x can be, for example, 0.025~13.5, 0.045~10.5, 0.065~6.5, or 0.085~2.25.

The content of each metal of copper, zinc, zirconium, aluminum, and chromium in the copper-containing catalyst can be arbitrarily selected. The content of each metal in the copper-containing catalyst can further promote the reaction of generating GBL, so it is preferably 1 mol of copper, 1.0 mol or less of zinc, 5.0 mol or less of zirconium, 5.0 mol or less of aluminum, and 0.5 mol or less of chromium.

The zinc content in the catalyst containing copper is preferably 1.0 mol or less, more preferably 0.005-0.4 mol, more preferably 0.01-0.3 mol, even more preferably 0.01-0.2 mol, and particularly preferably 0.05-0.1 mol, relative to 1 mol of copper.

The zirconium content in the catalyst containing copper is preferably 5.0 mol or less, more preferably 0.01-1.0 mol, more preferably 0.05-0.4 mol, even more preferably 0.05-0.3 mol, and particularly preferably 0.1-0.2 mol, relative to 1 mol of copper.

Relative to 1 mol of copper, the aluminum content in the catalyst containing copper is preferably 5.0 mol or less, more preferably 0.01-3.0 mol, more preferably 0.05-1.0 mol, even more preferably 0.1-0.8 mol, and particularly preferably 0.2-0.6 mol.

The chromium content in the catalyst containing copper is preferably 0.5 mol or less, preferably 0.01-0.4 mol, more preferably 0.03-0.3 mol, more preferably 0.05-0.2 mol, and more preferably 0.07-0.15 mol, relative to 1 mol of copper.

As a method for producing a catalyst containing copper, for example, a known method such as a coprecipitation method, a pore filling method, a hydrothermal synthesis method, etc. can be used.

(Step of producing γ-butyrolactone) In the step of producing GBL by bringing 4-HBA into contact with a catalyst containing copper in the method for producing GBL of the present embodiment (hereinafter sometimes referred to as the "GBL producing step"), it is preferred to vaporize an aqueous solution of 4-HBA and bring the vaporized 4-HBA into contact with a catalyst containing copper. As the aqueous solution of 4-HBA, an aqueous solution containing 1 to 30% by mass of 4-HBA is preferably used, more preferably 5 to 25% by mass, and more preferably 10 to 20% by mass. By vaporizing an aqueous solution containing 1 to 30% by mass of 4-HBA and bringing 4-HBA into contact with a catalyst containing copper in the gas phase, the formation reaction of GBL can be further promoted. This step may also include preparing an aqueous solution of 4-HBA of a preferred concentration as described above, or adjusting the solution.

In the GBL production step, when an aqueous solution containing 30% by mass or more of 4-HBA is used as the aqueous solution of 4-HBA, it is preferred to adjust the liquid space velocity (LHSV) calculated on the basis of the raw material. For example, when an aqueous solution containing 30 to 50% by mass of 4-HBA is used, in order to maintain the yield of GBL, it is preferred to set the liquid space velocity (LHSV) calculated on the basis of the raw material to 1.6 hr ^-1 or less, and more preferably to 0.4 hr ^-1 or less. The lower limit of the liquid space velocity (LHSV) can be selected as necessary, for example, it can also be 0.1 hr ^-1 or more, but it is not limited thereto.

In the GBL production step, it is preferred to contact 4-HBA with a catalyst containing copper in a gas phase at a reaction temperature exceeding 200°C. If the reaction temperature exceeds 200°C, 4-HBA in the reaction exists in the gas phase, the formation reaction of GBL is promoted, and GBL can be produced at a higher yield. In order to further improve the safety of the formation reaction of GBL, the reaction temperature is preferably set below 400°C. The reaction temperature is preferably 210~370°C, more preferably 230~360°C, and particularly preferably 260~350°C.

The GBL production step can be carried out, for example, using a fixed bed gas phase reaction apparatus having a reaction container filled with a catalyst containing copper. The GBL obtained in the GBL production step can also be purified by a general method such as reduced pressure distillation. The GBL obtained in the GBL production step can preferably be used as a raw material for N-methyl-2-pyrrolidone.

[Method for producing N-methyl-2-pyrrolidone] The method for producing N-methyl-2-pyrrolidone (NMP) of this embodiment includes a step of producing GBL by the method for producing GBL of this embodiment, and a step of reacting the produced GBL with monomethylamine.

In the method for producing NMP of the present embodiment, the step of reacting GBL with monomethylamine is, for example, a step of generating NMP by adding GBL, monomethylamine and a solvent into a reaction vessel to react in a liquid phase. As the reaction vessel, a stainless steel reaction vessel is preferably used. As the solvent, alcohol or water can be used, preferably water.

In the step of reacting GBL with monomethylamine, the molar ratio of monomethylamine to 1 mole of GBL used as a raw material is preferably in the range of 1 to 10, more preferably in the range of 1 to 5, and more preferably in the range of 1 to 1.5. When the molar ratio of monomethylamine to 1 mole of GBL is in the range of 1 to 10, NMP can be produced at a high yield.

The reaction of GBL and monomethylamine can be carried out in the atmosphere, or in an inert gas environment such as a nitrogen environment or an argon environment, and is preferably carried out in a nitrogen environment. The reaction of GBL and monomethylamine is preferably carried out at a reaction temperature of 100-400°C, preferably 150-350°C, and more preferably 200-300°C. When the reaction temperature is 100-400°C, the formation reaction of NMP can be promoted, and NMP can be produced at a higher yield. The reaction time of GBL and monomethylamine is preferably 0.1-10 hours, preferably 0.5-7 hours, and more preferably 1-5 hours. When the reaction time is 0.1-10 hours, a high yield can be ensured and good productivity can be obtained. The so-called high yield may be, for example, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 97% or more, but is not limited to these examples.

The reaction solution containing NMP generated in the step of reacting GBL with monomethylamine can be purified by a general method such as reduced pressure distillation. The method for producing NMP of this embodiment includes a step of producing GBL by the method for producing GBL of this embodiment. Therefore, GBL can be produced efficiently, and NMP, an industrially useful compound, can be efficiently produced using the produced GBL. [Example]

The present invention is described in more detail below by way of embodiments and comparative examples. The present invention is not limited to the following embodiments.

[Analysis method] In the following production methods of 4-hydroxybutyraldehyde (4-HBA), γ-butyrolactone (GBL), and N-methyl-2-pyrrolidone (NMP), the conversion rate and yield of the produced compounds were obtained. Specifically, the raw materials and reaction products in the reaction solution were analyzed using high-performance liquid chromatography (HPLC) under the following analysis conditions, and the absolute standard curve method was used for quantification, and the values were calculated using the results.

<Analysis conditions: 4-HBA manufacturing method> Column: Shodex SUGAR SH-1011 (Showa Denko Co., Ltd.) Column size: 8.0mm×300mm Column temperature: 40℃ Solvent: 0.01N sulfuric acid aqueous solution Solvent flow rate: 0.5ml/min Detector: UV (ultraviolet) 210nm, RI (differential refractive index)

<Analysis conditions: GBL manufacturing method, NMP manufacturing method> Column: Shodex RSpak KS-801 (Showa Denko Co., Ltd.) Column size: 8.0mm×250mm Column temperature: 40℃ Solvent: pure water Flow rate of solvent: 0.6ml/min Detector: UV (ultraviolet) 210nm, RI (differential refractive index)

[Production method of 4-hydroxybutyraldehyde (4-HBA)] (Example 1) In a 100 mL stainless steel high pressure and high temperature reaction vessel, there were placed 1.89 g of allyl alcohol (AAL), 30 g of toluene as a solvent, 0.0536 g of carbonyltris(triphenylphosphine)rhodium(I) hydride (RhH(CO)( _PPh3 ) ₃ (manufactured by Tokyo Chemical Industry Co., Ltd.) as a catalyst (0.18 mol % relative to allyl alcohol), and 0.129 g of 4,6-bis(diphenylphosphine)phenoxazine (Nixantphos, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) as a diphophosphine ligand (4 mol relative to 1 mol of rhodium atom contained in the rhodium catalyst).

Then, the pressure of the mixed gas of carbon monoxide gas and hydrogen gas was set to 2.0 MPaG (gauge pressure) (partial pressure of carbon monoxide gas 1.0 MPaG (gauge pressure), partial pressure of hydrogen gas 1.0 MPaG (gauge pressure)) in the reaction container, and the reaction was carried out at a reaction temperature of 65° C. for 3 hours while stirring the reaction container. 30 g of water was added to the reaction solution after the reaction, and extraction was performed, and the aqueous layer was recovered by liquid separation operation to obtain an aqueous solution containing a reaction product having 4-HBA.

(Example 2) ＜Preparation of two-seat phosphine ligand＞ In a nitrogen-substituted 200 mL two-necked flask, 4,6-bis(diphenylphosphino)phenoxazine (1 g, 1.81 mmol) and 20 mL of dehydrated tetrahydrofuran were placed, 0.1 g of sodium hydroxide was added, and the mixture was refluxed at 40°C for 1 hour. A mixed solution of 0.62 g of benzyl chloride and 5 mL of tetrahydrofuran was further added, and the mixture was refluxed at 70°C for 16 hours to react. Thereafter, the reaction solution was cooled to room temperature, and benzene and sodium chloride aqueous solution were added to separate the liquids. Then, the organic layer was washed with water and dried with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was washed with hexane. After that, 0.9 g of a light gray solid of the compound represented by the following formula (4) was obtained by recrystallization with dichloromethane and ethanol. The yield of the compound represented by formula (4) was 78%.

The obtained compound represented by formula (4) was subjected to ¹ H-NMR and ³¹ P-NMR measurements, and its structure was identified based on the following results. ¹ H-NMR (400 MHz, CDCl ₃ ): δ7.33 (m, 5H), 7.24 (m, 20H), 6.59 (t, J=9.6Hz, 2H), 6.31 (dd, J=7.9, 1.3Hz, 2H), 6.04 (dq, J=7.8, 1.6, 1.6Hz, 2H), 4.80 (s, 2H) ³¹ P-NMR (162 MHz, CDCl ₃ ): δ-18.4

As the diphophosphine ligand, 0.1496 g (4 mol relative to 1 mol of rhodium atom contained in the rhodium catalyst) of the diphophosphine ligand of formula (4) was used, and the reaction time was set to 2 hours. In the same manner as in Example 1, an aqueous solution containing a reaction product having 4-HBA was obtained.

(Example 3) ＜Preparation of two-seat phosphine ligand＞ In a 200 mL two-necked flask substituted with nitrogen, cesium carbonate (18.07 g, 55.5 mol) was placed, and after vacuum drying at 150°C for 2 hours, palladium acetate (II) (0.15 g, 0.70 mmol), triphenylphosphine (0.73 g, 2.77 mmol), 1-naphthol (2 g, 13.87 mmol), 1,2-dibromobenzene (2 mL, 16.6 mmol) and 80 mL of N,N-dimethylformamide were added, and the mixture was refluxed at 140°C for 72 hours to react. Thereafter, the temperature of the reaction solution was lowered to room temperature, and diethyl ether and water were added to separate the liquids. Then, the organic layer was washed with water and dried with anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure, and the residue was purified by chromatography. Thus, 2.5 g of the compound represented by the following formula (5) was obtained as a white solid. The yield of the compound represented by formula (5) was 83%.

In a nitrogen-substituted 200 mL three-necked flask, the compound represented by formula (5) (2 g, 9.13 mmol), N,N,N',N'-tetramethylethylenediamine (4.11 ml, 27.49 mmol) and 100 ml of dehydrated diethyl ether were placed, and n-butyl lithium solution (2.5 M hexane solution, 11 ml, 27.49 mmol) was added dropwise over 20 minutes while maintaining the temperature at 0°C. After the addition was completed, the mixture was stirred at room temperature for 16 hours. Chlorodiphenylphosphine (4.93 ml, 27.4 mmol) was further added while maintaining the temperature at 0°C. Thereafter, the mixture was stirred and reacted at room temperature for more than 3 hours. Dichloromethane and water were added to the reaction solution and the mixture was separated. Then, the organic layer was washed with water and dried with anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure, and the residue was washed with hexane. After recrystallization with dichloromethane and hexane, 2.5 g of a light yellow solid of the compound represented by the following formula (6) was obtained. The yield of the compound represented by formula (6) was 47%.

The obtained compound represented by formula (6) was subjected to ¹ H-NMR and ³¹ P-NMR measurements, and its structure was identified based on the following results. ¹ H-NMR (400MHz, CDCl ₃ ): δ7.85 (d, J=7.8Hz, 1H), 7.67(d, J=6.4Hz, 1H), 7.53(d, J=7.8Hz, 1H), 7.45(t, J=7.7Hz, 1H), 7.23(m, 21H), 7.01(t, J=7 .7Hz, 1H), 6.80 (dd, J=8.5, 3.6Hz, 1H), 6.66 (ddd, J=7.5, 3.6, 1.4Hz, 1H). ³¹ P-NMR (162MHz, CDCl ₃ ): δ-17.4 (d, J=21.9Hz, 1P), -20.5 (d, J=21.9Hz, 1 P)

An aqueous solution containing a reaction product having 4-HBA was obtained in the same manner as in Example 2 except that 0.1369 g (4 mol per 1 mol of rhodium atom contained in the rhodium catalyst) of the diphosphine ligand represented by formula (6) was used as the diphosphine ligand.

(Example 4) ＜Preparation of two-seat phosphine ligand＞ In a nitrogen-substituted three-necked flask with a capacity of 500 mL, phosphorus trichloride (4.3 mL, 50 mmol) and dehydrated diethyl ether 300 mL were placed, and diethylamine (10.4 mL, 100 mmol) was dripped in at -78°C for 30 minutes. After the dripping was completed, the reaction solution was stirred and reacted at room temperature for 16 hours, and then filtered. The obtained filtrate was distilled to remove the solvent, and the residue was distilled under reduced pressure to obtain 6.5 g of dichlorodiethylaminophosphine as a colorless liquid. The yield of dichlorodiethylaminophosphine was 75%.

In a 500 mL three-necked flask substituted with nitrogen, 5-bromo-m-xylene (25 g, 135.09 mmol) and 250 mL of dehydrated diethyl ether were placed, and n-butyl lithium solution (2.5 M hexane solution, 88.4 mL, 141.5 mmol) was dripped in over 20 minutes while maintaining the temperature at 0°C. After the dripping was completed, the mixture was stirred at 0°C for 4 hours. Dichlorodiethylaminophosphine (11.19 g, 64.33 mmol) was further added and stirred at 0°C for 4 hours to synthesize [bis-(3,5-dimethylphenyl)](diethylamino)phosphine. Subsequently, 33 mL of hydrogen chloride solution was added to the reaction solution for synthesizing [bis-(3,5-dimethylphenyl)](diethylamino)phosphine while maintaining the temperature at 0°C, and the mixture was stirred and reacted at room temperature for 1 hour. The reaction solution was filtered through diatomaceous earth, and the solvent was removed by drying the obtained filtrate under reduced pressure. The residue was dried under reduced pressure for 1 day to obtain bis(3,5-dimethylphenyl)chlorophosphine represented by the following formula (7). The obtained bis(3,5-dimethylphenyl)chlorophosphine can be used in the following reaction without purification.

In a nitrogen-substituted 200 mL three-necked flask, place the compound represented by formula (5) (2 g, 9.13 mmol), N,N,N',N'-tetramethylethylenediamine (4.11 ml, 27.49 mmol) and 100 mL of dehydrated diethyl ether, and drip n-butyl lithium solution (2.5 M hexane solution, 11 mL, 27.49 mmol) over 20 minutes while maintaining the temperature at 0°C. After the dripping is completed, stir at room temperature for 16 hours. Further, add bis(3,5-dimethylphenyl)chlorophosphine represented by formula (7) (excess amount) while maintaining the temperature at 0°C. Then, stir and react at room temperature for more than 3 hours. Add dichloromethane and water to the reaction solution and separate the liquids. Then, the organic layer was washed with water and dried with anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure, and the residue was washed with hexane. After recrystallization with dichloromethane and hexane, 1.9 g of a light yellow solid of the compound represented by the following formula (8) was obtained. The yield of the compound represented by formula (8) was 30%.

The obtained compound represented by formula (8) was subjected to ¹ H-NMR and ³¹ P-NMR measurements, and its structure was identified based on the following results. ¹ H-NMR (400MHz, CDCl ₃ ): δ7.81 (d, J=7.4Hz, 1H), 7.64(d, J=6.9Hz, 1H), 7.51(d, J=7.4Hz, 1H), 7.47(t, J=7.4Hz, 1H), 7.17(d, J=8.2Hz, 1H), 7.00 (t, J=7.4Hz, 1H), 6.86-6.82. (m, 9H), 6.80(d, J=7.4Hz, 4H), 6.66(ddd, J=7.3, 3.4, 1.4Hz, 1H), 2.18(d, J=4.6Hz, 24H). ³¹ P-NMR(162MHz, CDCl ₃ ): δ-17.5(d, J=21.9Hz, 1P), -21.2(d, J=21.9Hz, 1P)

An aqueous solution containing a reaction product having 4-HBA was obtained in the same manner as in Example 2 except that 0.1631 g (4 mol per 1 mol of rhodium atom contained in the rhodium catalyst) of the diphosphine ligand represented by formula (8) was used as the diphosphine ligand.

(Example 5) ＜Preparation of two-seat phosphine ligand＞ Put phenoxazine (5g, 1.81mmol) and 80mL of dehydrated tetrahydrofuran in a two-necked flask substituted with nitrogen and having a capacity of 200mL, add 1.65g of sodium hydride, and reflux at 40°C for 1 hour. Then, lower the solution temperature to room temperature, add a mixed solution of 6.17g of tert-butyldimethylsilyl chloride and 10mL of tetrahydrofuran, and reflux at 70°C for more than 3 hours to react. Next, after lowering the temperature of the reaction solution to room temperature, add ice water to the reaction solution to stop the reaction. Thereafter, ethyl acetate was added to the reaction solution, the organic layer was washed with water and dried with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by chromatography. Thus, 2.5 g of the compound represented by the following formula (9) was obtained as a white solid. The yield of the compound represented by formula (9) was 60%.

In a nitrogen-substituted 200 mL three-necked flask, the compound represented by formula (9) (2 g, 6.73 mmol), N,N,N',N'-tetramethylethylenediamine (1.64 ml, 14.12 mmol) and 100 mL of dehydrated diethyl ether were placed, and n-butyl lithium solution (2.5 M hexane solution, 8.82 mL, 14.12 mmol) was added dropwise over 10 minutes while maintaining the temperature at 0°C. After the addition was completed, the mixture was stirred at room temperature for 16 hours. Further, bis(3,5-dimethylphenyl)chlorophosphine represented by formula (7) (excess amount) was added while maintaining the temperature at 0°C. Thereafter, the mixture was stirred at room temperature for 16 hours to react. Dichloromethane and water were added to the reaction solution to separate the liquids. Then, the organic layer was washed with water and dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to obtain a solid reaction product.

The solid reaction product obtained was dried, and after adding 50 mL of tetrahydrofuran, tetrabutylammonium fluoride trihydrate (3.4 g, 10.76 mmol) was added, and the mixture was stirred and reacted at room temperature for 48 hours. The solvent was then distilled off under reduced pressure, and dichloromethane and water were added to separate the liquids. Then, the organic layer was washed with water and dried with anhydrous sodium sulfate, and the residue was washed with hexane and ethanol. Thereafter, 2.3 g of the compound represented by the following formula (10) was obtained as a light gray solid by recrystallization with dichloromethane and ethanol. The yield of the compound represented by formula (10) was 50%.

The obtained compound represented by formula (10) was subjected to ¹ H-NMR and ³¹ P-NMR measurements, and its structure was identified based on the following results. ¹ H-NMR (400 MHz, C ₆ D ₆ ): δ7.18 (m, 8H), 6.66 (s, 4H), 6.46 (m, 4H), 5.74 (dd, J=6.9, 2.8Hz, 2H), 4.01 (s, 2H), 1.96 (s, 24H) ³¹ P-NMR (162 MHz, CDCl ₃ ): δ-18.0

An aqueous solution containing a reaction product having 4-HBA was obtained in the same manner as in Example 1 except that 0.1549 g (4 mol per 1 mol of rhodium atom contained in the rhodium catalyst) of the diphosphine ligand represented by formula (10) was used as the diphosphine ligand.

(Comparative Example 1) An aqueous solution containing a reaction product having 4-HBA was obtained in the same manner as in Example 1 except that 0.0612 g (4 mol per 1 mol of rhodium atom contained in the rhodium catalyst) of triphenylphosphine (PPh ₃ ) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as a monophosphine ligand instead of the diphosphine ligand.

(Comparative Example 2) Except that 0.116 g (4 mol per 1 mol of rhodium atom contained in the rhodium catalyst) of trans-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-difuran (DIOP) (manufactured by Fuji Film Co., Ltd.) was used as the diphophosphine ligand, an aqueous solution containing a reaction product having 4-HBA was obtained in the same manner as in Example 2.

The conditions for the hydroformylation reaction of allyl alcohol in the methods for producing 4-HBA in Examples 1 to 5, Comparative Example 1, and Comparative Example 2 (partial pressure (gauge pressure) of carbon monoxide gas, partial pressure (gauge pressure) of hydrogen gas in the reaction vessel), reaction temperature, reaction time) are shown in Table 1.

In the methods for producing 4-HBA of Examples 1 to 5 and Comparative Example 2, the difference in activation energy between 1,2 insertion and 2,1 insertion in the hydroformylation reaction of each allyl alcohol was calculated by the following method. The results are shown in Table 1.

[Calculation method of the difference in activation energy between 1,2 insertion and 2,1 insertion] Using Gaussian16, a quantum chemical calculation software, the migration state calculation of the 1,2 insertion process and the 2,1 insertion process was performed according to the density functional theory (DFT) method wB97XD/6-31+G* method, and the Gibbs free energy in each migration state was obtained by vibration analysis in the state.

Then, the difference between (1) the Gibbs free energy (activation energy) of the migration state of 1,2 insertion and (2) the Gibbs free energy (activation energy) of the migration state of 2,1 insertion ((2) - (1)) is calculated as the activation energy difference.

The calculation time of the activation energy of 1,2 insertion and the activation energy of 2,1 insertion differs depending on the type of two-seat phosphine ligand and the size of the molecule. Therefore, sometimes the calculation cost is inflated depending on the type of two-seat phosphine ligand and the size of the molecule. Therefore, in the present invention, the following calculation technique is used to achieve a balance between calculation time and calculation accuracy, and the Gibbs free energy of the migration state is calculated.

That is, for a relatively small molecular weight of 2-seat phosphine ligand of 700 or less, the above-mentioned migration state calculation is performed under toluene solvent conditions by the continuous dielectric model (hereinafter sometimes referred to as "PCM model") to obtain the Gibbs free energy. Also, for a relatively large molecular weight of 2-seat phosphine ligand of more than 700, the above-mentioned migration state calculation or structural optimization is performed under gas phase conditions. Thereafter, for the optimized structure, vibration analysis is performed under toluene solvent conditions by the PCM model to calculate the Gibbs free energy (activation energy).

Furthermore, for the two-seat phosphine ligand in Calculation Example 1 described later, even if the molecular weight exceeds 700, the calculation time of the Gibbs free energy does not become extended, so the above method used for the molecular weight below 700 is applied to obtain the Gibbs free energy.

In addition, the convergence of numerical calculations may be poor depending on the type of aryl group in the aryl group that can be substituted by the second phosphine ligand, the bonding position of the substituent on the aryl group, etc. Specifically, it may happen that the four thresholds used as convergence conditions in Gaussian 16 cannot be completed in real time at the same time. In this case, the integration accuracy is improved by using the int (grid=ultrafine) option to obtain the molecular structure necessary for the calculation of activation energy.

In addition, 4-HBA, HMPA, and other by-products (propionaldehyde, 1-propyl alcohol (PrOH), GBL) obtained in the 4-HBA production methods of Examples 1 to 5 and Comparative Examples 1 and 2 were analyzed by liquid chromatography under the above-mentioned analysis conditions to obtain the conversion rate of allyl alcohol (AAL), the yield of 4-HBA, the yield of HMPA, the yield of other by-products, and the ratio of the amount of 4-HBA generated to the amount of HMPA generated (4-HBA/HMPA). The results are shown in Table 1.

The yield of 4-HBA shown in Table 1 is the total value of the yield of 4-HBA and the yield of 2-hydroxytetrahydrofuran. Since 4-HBA in the aqueous solution is in equilibrium with 2-hydroxytetrahydrofuran, the yield of 2-hydroxytetrahydrofuran contained in the aqueous solution containing the reaction product is also converted as the yield of 4-HBA.

As shown in Table 1, the reaction products obtained by the methods for producing 4-HBA in Examples 1 to 5 using at least one selected from Formulas (1) to (3) as a two-seat phosphine ligand are all compared with the reaction products obtained by the methods for producing 4-HBA in Comparative Examples 1 and 2. The amount of HMPA produced is small, and the 4-HBA/HMPA is larger than 10.0. In particular, in Examples 4 and 5 in which the compound represented by Formula (8) or the compound represented by Formula (10) which may have an aromatic group having a substituent is used as a two-seat phosphine ligand, the yield of 4-HBA is more than 90%, and it is confirmed that 4-HBA can be produced at a high yield.

Furthermore, as shown in Table 1, in the methods for producing 4-HBA of Examples 1 to 5, the difference between the activation energy of 1,2 insertion and the activation energy of 2,1 insertion calculated by the density functional method is 4.2 kcal/mol or more. In contrast, in the method for producing 4-HBA of Comparative Example 2, the difference in activation energy is less than 4.2 kcal/mol regardless of the use of a two-seat phosphine ligand. Therefore, the magnitude relationship of the calculated values of the difference in activation energy in the methods for producing 4-HBA of Examples 1 to 5 and Comparative Example 2 is consistent with the magnitude relationship of the experimental results of 4-HBA/HMPA in the methods for producing 4-HBA of Examples 1 to 5 and Comparative Example 2. It can be seen from this that the greater the difference in activation energy between 1,2 insertion and 2,1 insertion calculated by the density functional method, the greater the tendency of 4-HBA/HMPA is confirmed, and the validity of the above calculation method is confirmed.

(Calculation Example 1 to Calculation Example 3) When the compounds shown in Table 2 are used as the two-seat phosphine ligands, the difference in activation energy between 1,2 insertion and 2,1 insertion in the hydroformylation reaction of each allylic alcohol is calculated using the above calculation method. The results are shown in Table 2.

As shown in Table 2, when using the two-seat phosphine ligands shown in Table 2 in Calculation Examples 1 to Calculation Examples 3, the difference between the activation energy of 1,2 insertion and the activation energy of 2,1 insertion calculated by the density functional method is 4.2 kcal/mol or more, similarly to the 4-HBA production methods of Examples 1 to 5. Thus, when using the two-seat phosphine ligands shown in Table 2 instead of the two-seat phosphine ligands used in the 4-HBA production methods of Examples 1 to 5, it is expected that a reaction product with a larger 4-HBA/HMPA ratio can be obtained.

[Method for producing γ-butyrolactone (GBL)] As a fixed bed gas phase reaction device, a cylindrical reaction vessel with a diameter of 4.5 mm and a height of 50 mm is used, a vaporizer is provided at the top of the reaction vessel, a carrier gas inlet and a raw material inlet are provided at the top of the vaporizer, and a reaction liquid collection vessel (cooling) with a degassing port is provided at the bottom of the reaction vessel. CuZnZrAlCrOx (molar ratio Cu:Zn:Zr:Al:Cr=1.0:0.1:0.1:0.45:0.1) is produced by coprecipitation method as a catalyst containing copper.

0.8 g of the copper-containing catalyst was filled in a reaction vessel of a fixed bed gas phase reaction device, and hydrogen gas at 300°C was circulated in the reaction vessel at a flow rate of 30 mL/min for 1 hour to perform hydrogen reduction of the copper-containing catalyst. Thereafter, a 20 mass % aqueous solution containing the reaction product of 4-HBA produced in Example 1 was sent to a vaporizer at 0.1 ml/min and vaporized, and nitrogen gas as a carrier gas was simultaneously supplied from the upper part of the reaction vessel at 10 ml/min, and the copper-containing catalyst was contacted and reacted at 300°C to produce GBL. At this time, the GHSV (gas space velocity) was 8707 hr ^-1 , and the LHSV (liquid space velocity calculated on the basis of the raw material) was 1.5 hr ^-1 . The reaction product containing 4-HBA produced in Example 1 can be used directly without purification.

The obtained GBL was analyzed by HPLC, and the conversion rate of 4-HBA was 98.5%, the yield of GBL was 97.5%, and the selectivity of GBL was 99.0%. From this, it can be seen that the reaction product containing 4-HBA produced in Example 1 does not need to be purified, and even if it is directly used in the reaction of producing GBL, GBL can be produced at a high yield, and it is confirmed that GBL can be produced efficiently. This is because the 4-HBA/HMPA ratio of the reaction product containing 4-HBA produced in Example 1 is larger.

[Production method of N-methyl-2-pyrrolidone (NMP)] In a 100 mL stainless steel high pressure and high temperature reactor, 12.92 g of GBL produced by the above production method using the reaction product containing 4-HBA produced in Example 1, 12.89 g of a 40% monomethylamine aqueous solution (produced by Fujifilm Wako Pure Chemical Industries, Ltd.) (molar ratio of monomethylamine to 1 mol of GBL: 1.1), and 51.66 g of water as a solvent were placed. Then, in a nitrogen environment, the reaction starting pressure was set at 101.3 kPa, and the reaction was allowed to proceed at 240°C for 3 hours while stirring to produce NMP.

The reaction solution containing the obtained NMP was analyzed by HPLC to obtain the conversion rate of GBL and the yield of NMP. As a result, the conversion rate of GBL was 98.4% and the yield of NMP was 97.9%. It can be confirmed that GBL produced using the reaction product containing 4-HBA produced in Example 1 as a raw material can produce NMP with high yield and efficiency. [Industrial Applicability]

The present invention provides a method for producing 4-HBA, which can obtain a reaction product with a small amount of HMPA produced and a large 4-HBA/HMPA ratio.

Claims (14)

A method for producing 4-hydroxybutyraldehyde comprises the step of subjecting allyl alcohol to a hydroformylation reaction with carbon monoxide gas and hydrogen in the presence of a catalyst containing a rhodium catalyst and at least one diphosphine ligand selected from the group consisting of the following formulas (1) to (3), wherein in the hydroformylation reaction in the presence of the catalyst containing the rhodium catalyst and the diphosphine ligand, the difference between the activation energy of 1,2 insertion and the activation energy of 2,1 insertion of the allyl alcohol calculated by density functional theory is 4.2 kcal/mol or more and 6.9 kcal/mol or less,

(In formulas (1) to (3), Ar represents an aryl group which may have a substituent). The method for producing 4-hydroxybutyraldehyde of claim 1, wherein Ar in the aforementioned formulas (1) to (3) is any one of the following formulas (a) to (e),

The method for producing 4-hydroxybutyraldehyde as claimed in claim 1, wherein the two-seat phosphine ligand is represented by the aforementioned formula (1), and Ar in the aforementioned formula (1) is represented by any one of the aforementioned formulas (a), (b), and (c). As in the method for producing 4-hydroxybutyraldehyde of claim 1, the aforementioned two-seat phosphine ligand is represented by the aforementioned formula (2), and Ar in the aforementioned formula (2) is represented by the aforementioned formula (a). The method for producing 4-hydroxybutyraldehyde as claimed in claim 1, wherein the two-seat phosphine ligand is represented by the aforementioned formula (3), and Ar in the aforementioned formula (3) is represented by any one of the aforementioned formulas (a), (b), (d), and (e). As in the method for producing 4-hydroxybutyraldehyde of claim 1, the amount of the aforementioned rhodium catalyst used is such that the ratio of rhodium atoms to the aforementioned allyl alcohol is 0.01 mol% to 5 mol%. As in the method for producing 4-hydroxybutyraldehyde of claim 1, the amount of the aforementioned two-seat phosphine ligand used is in the range of 0.5 mol to 50 mol relative to 1 mol of rhodium atoms contained in the aforementioned rhodium catalyst. As in the method for producing 4-hydroxybutyraldehyde of claim 1, the pressure of the mixed gas containing carbon monoxide gas and hydrogen in the reaction vessel for the aforementioned hydroformylation reaction is in the range of 0.1~10MPaG (gauge pressure), and the partial pressure ratio of carbon monoxide gas to hydrogen in the aforementioned reaction vessel (hydrogen/carbon monoxide gas) is in the range of 1/10~10/1. The method for producing 4-hydroxybutyraldehyde as in claim 1, wherein the carbon monoxide gas and the hydrogen gas are produced by thermal decomposition of waste plastics and/or biomass. A method for producing gamma-butyrolactone, comprising a step of producing 4-hydroxybutyraldehyde by the method for producing 4-hydroxybutyraldehyde as described in claim 1, and a step of bringing the produced 4-hydroxybutyraldehyde into contact with a catalyst containing copper. The method for producing gamma-butyrolactone as claimed in claim 10, wherein the copper-containing catalyst further contains an oxide of at least one metal element selected from the group consisting of zinc, zirconium and aluminum. A method for producing N-methyl-2-pyrrolidone, comprising the steps of producing γ-butyrolactone by the method for producing γ-butyrolactone as claimed in claim 10, and reacting the produced γ-butyrolactone with monomethylamine. A compound represented by the following formula (10),

A compound represented by the following formula (8),