Method for producing urea compounds

Abstract

To provide a novel technique related to a method for producing an urea compound.SOLUTION: A method for producing an urea compound represented by a following general formula (5) includes a step (a) of bringing a composition comprising an amine compound represented by a following general formula (1) and a carbamic acid compound represented by a following general formula (3) into contact with cerium oxide (IV) under a gas-free condition, a nitrogen atmosphere, or an argon atmosphere, thereby generating the urea compound represented by the following general formula (5). (In the general formulae (1), (3), and (5), R1-R6 each independently represent a hydrogen atom, a phenyl group, or a C1-4 alkyl group; and n is 0 or 1.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a urea compound. [Background technology]

[0002] A urea compound is an organic compound having a urea bond. Known methods for synthesizing a urea compound include, for example, a method of synthesizing a urea compound by reacting carbon dioxide with an amine compound under high temperature and pressure (Non-Patent Document 1), and a method of synthesizing a urea compound by reacting carbon dioxide with a diamine compound in the presence of a solvent and cesium oxide (Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Green Chemistry, 12, 1811-1816(2010) [Non-patent document 2] Green Chemistry, 15, 1567-1577(2013) Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a novel technique relating to a method for producing a urea compound. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have found that a predetermined urea compound can be efficiently obtained by contacting a mixed composition of a predetermined carbamic acid compound and a predetermined amine compound with cerium (IV) oxide under gas-free conditions, in a nitrogen atmosphere, or in an argon atmosphere, and have thus completed the present invention.

[0006] That is, the present invention relates to the following compounds and methods for producing them. [1] A method for producing a urea compound represented by the following general formula (5): A method for producing a urea compound, comprising: a step (a) of contacting a composition comprising an amine compound represented by the following general formula (1) and a carbamic acid compound represented by the following general formula (3) with cerium (IV) oxide under gas-free conditions, in a nitrogen atmosphere, or in an argon atmosphere, to produce a urea compound represented by the following general formula (5): [ka] (In general formulas (1), (3), and (5), R 1 ~R 6 are each independently a hydrogen atom, a phenyl group, or an alkyl group having 1 to 4 carbon atoms, and n is 0 or 1. 1 and R in general formulas (3) and (5) 1 are identical, and R 2 ~R 6 , and similarly for n.) [2] The method according to [1], further comprising a step (b) of contacting the amine compound represented by the general formula (1) with carbon dioxide to obtain the composition. [3] R in the general formulas (1), (3), and (5) 1 and R 2 are each independently a hydrogen atom, a methyl group, or an ethyl group. [4] R in the general formulas (1), (3), and (5) 3 ~R 6 are each independently a hydrogen atom or a methyl group. [5] The method according to any one of [1] to [4], wherein n in the general formulae (1), (3), and (5) is 0. [6] The method according to any one of [1] to [5], wherein the content of the carbamic acid compound in the composition is 5 to 50 mol % based on the total amount of compounds in the composition. [7] The method according to any one of [1] to [6], wherein in the step (a), the composition is contacted with the cerium (IV) oxide at a temperature of 80 to 250°C. [8] The method according to any one of [1] to [7], wherein in the step (a), the composition and the cerium (IV) oxide are brought into contact with each other at a pressure (gauge pressure) of 0 to 5 MPa. [9] A method for producing a urea compound represented by the following general formula (6): A method for producing a urea compound, comprising: a step (a') of contacting a composition comprising an amine compound represented by the following general formula (2) and a carbamic acid compound represented by the following general formula (4) with cerium (IV) oxide under gas-free conditions, in a nitrogen atmosphere, or in an argon atmosphere, to produce a urea compound represented by the following general formula (6): [ka] (In general formulas (2), (4), and (6), R 7 are each independently a hydrogen atom, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. 7 and R in general formulas (4) and (6) 7 are identical.)

[10] The method according to [9], further comprising a step (b') of contacting the amine compound represented by the general formula (2) with carbon dioxide to obtain the composition.

[11] R in the general formulas (2), (4), and (6) 7 is a hydrogen atom, an n-propyl group, or a phenyl group.

[12] The method according to any one of [9] to

[11] , wherein the content of the carbamic acid compound in the composition is 10 to 50 mol % based on the total amount of compounds in the composition.

[13] The method according to any one of [9] to

[12] , wherein in the step (a'), the composition is contacted with the cerium (IV) oxide at a temperature of 80 to 250°C.

[14] The method according to any one of [9] to

[13] , wherein in the step (a'), the composition and the cerium (IV) oxide are brought into contact with each other at a pressure (gauge pressure) of 0 to 5 MPa.

[15] The cerium (IV) oxide has a BET specific surface area of ​​50 m 2 / g or more, [1] to

[14] . [Effects of the Invention]

[0007] According to the present invention, a novel technique relating to a method for producing a urea compound can be provided.

[0008] Furthermore, according to one embodiment of the present invention, a urea compound can be produced without the need for high-pressure carbon dioxide as in Non-Patent Document 1, which enables the effective use of carbon dioxide with low energy consumption and reduces the environmental load. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below.

[0010] The present invention includes a first embodiment for producing a urea compound represented by general formula (5) and a second embodiment for producing a urea compound represented by general formula (6).

[0011] (First embodiment) First, a first embodiment for producing a urea compound represented by general formula (5) will be described.

[0012] The production method of this embodiment is a production method of a urea compound represented by general formula (5), characterized by including step (a).

[0013] Step (a) is a step of contacting a composition consisting of an amine compound represented by the following general formula (1) (hereinafter also referred to as "amine compound (1)") and a carbamic acid compound represented by the following general formula (3) (hereinafter also referred to as "carbamic acid compound (3)") with cerium (IV) oxide under gas-free conditions, a nitrogen atmosphere, or an argon atmosphere to produce a urea compound represented by the general formula (5) (hereinafter also referred to as "urea compound (5)").

[0014] [ka] In the general formulas (1), (3), and (5), R 1 ~R 6 are each independently a hydrogen atom, a phenyl group, or an alkyl group having 1 to 4 carbon atoms, and n is 0 or 1. 1 and R in general formulas (3) and (5) 1 are identical, and R 2 ~R 6 , and similarly for n.

[0015] The above R 1 ~R 6 The alkyl group having 1 to 4 carbon atoms in the formula (I) is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, and a tert-butyl group.

[0016] The above R 1 ~R 6 Among them, R 1 and R 2 Regarding (a), in terms of superior production efficiency of urea compound (5), it is preferable that they are each independently a hydrogen atom, a methyl group, or an ethyl group; it is more preferable that both of them are hydrogen atoms, a methyl group, or an ethyl group, or one is an ethyl group and the other is a hydrogen atom; it is even more preferable that both of them are hydrogen atoms, or one is an ethyl group and the other is a hydrogen atom; and it is particularly preferable that both of them are hydrogen atoms.

[0017] The above R 1 ~R 6 Among them, R 3 ~R 6 are preferably each independently a hydrogen atom or a methyl group, in terms of superior production efficiency of the urea compound (5), and all of them are preferably hydrogen atoms, methyl groups, or R 3 ~R 6 It is more preferred that one of R is a methyl group and the rest are hydrogen atoms, and all are hydrogen atoms, or R 3 ~R 6 It is even more preferred that one of R is a methyl group and the rest are hydrogen atoms, 3 ~R 6 It is particularly preferred that one of the groups is a methyl group and the rest are hydrogen atoms.

[0018] n is characterized by being 0 or 1, but is preferably 0 in terms of superior production efficiency of the urea compound (5). When n is 0 in the general formula (5), the urea compound (5) can be obtained by the reaction of R 3 Carbon bonded to R 4 The carbon bonded to the carbon atom forms a five-membered ring structure.

[0019] The amine compound (1) and the carbamic acid compound (3) may be commercially available or may be synthesized by a known method, and are not particularly limited.

[0020] The composition consisting of amine compound (1) and carbamic acid compound (3) used in step (a) is a composition consisting essentially of amine compound (1) and carbamic acid compound (3). A composition consisting essentially of amine compound (1) and carbamic acid compound (3) refers to a composition consisting essentially of amine compound (1) and carbamic acid compound (3), excluding impurities unintentionally mixed into the raw materials of the composition. An example of such a composition is a composition having a purity equal to or higher than that of a mixture consisting of only amine compound (1) of commercially available purity and carbamic acid compound (3) of commercially available purity.

[0021] In the composition consisting of amine compound (1) and carbamic acid compound (3), a portion of the carbamic acid compound (3) is assumed to exist as an intramolecular zwitterionic carbamic acid compound (3) represented by the following general formula (3'). In this embodiment, however, carbamic acid compound (3) refers to both the nonionic and intramolecular zwitterionic carbamic acid compound (3). [ka] In general formula (3'), R 1 ~R 6 and n have the same meanings as above.

[0022] In this embodiment, the urea compound (5) is produced by contacting a composition comprising the amine compound (1) and the carbamic acid compound (3) with cerium (IV) oxide under gas-free conditions, a nitrogen atmosphere, or an argon atmosphere (step (a)).

[0023] The cerium (IV) oxide functions as a catalyst to promote the reaction of synthesizing the urea compound (5) from the carbamic acid compound (3) in the presence of the amine compound (1). The cerium (IV) oxide has a BET specific surface area of ​​50 m 2 / g or more is preferred, and 65m 2 / g or more is more preferable, and 80m 2 More preferably, it is / g or more.

[0024] The above-mentioned cerium (IV) oxide is not particularly limited, but is preferably HS grade cerium (IV) oxide manufactured by Daiichi Kigenso Co., Ltd., which is calcined at 600°C for 3 hours according to the method described in a non-patent document (Green Chemistry, 15, 1567-1577 (2013)).

[0025] The contact of the composition comprising the amine compound (1) and the carbamic acid compound (3) with cerium (IV) oxide is carried out under gas-free conditions, a nitrogen atmosphere, or an argon atmosphere.

[0026] "Gas-free conditions" means that the reaction is carried out in the absence of coexisting gas, and is not particularly limited to, for example, a method in which a composition consisting of amine compound (1) and carbamic acid compound (3) is passed through a pipe containing a fixed-bed cerium (IV) oxide catalyst, or a method in which a composition consisting of amine compound (1) and carbamic acid compound (3) and cerium (IV) oxide are introduced into a reaction vessel such as an autoclave, and the vessel is sealed with the composition consisting of amine compound (1) and carbamic acid compound (3) to prevent gas from entering the vessel, thereby contacting the composition. Note that the composition consisting of amine compound (1) and carbamic acid compound (3) is usually a liquid in which carbamic acid compound (3) is dissolved in amine compound (1) at room temperature (15°C).

[0027] The phrase "under a nitrogen atmosphere" or "under an argon atmosphere" refers to the reaction being carried out in an atmosphere in which the gas in the excess space in the reaction system, excluding the composition comprising amine compound (1) and carbamic acid compound (3) and cerium (IV) oxide, has been replaced with nitrogen gas or argon gas. Replacement with nitrogen gas or argon gas can be achieved, for example, by thoroughly flowing nitrogen gas or argon gas through an autoclave containing the composition comprising amine compound (1) and carbamic acid compound (3) and cerium (IV) oxide, or by sufficiently repeatedly pressurizing the reaction vessel with nitrogen gas or argon gas at 1 MPa and depressurizing it. When passing such gas, it is preferable to pass a gas of a volume (under standard conditions) that is at least 50 times the volume of the excess space. When repeating pressurization and depressurization, it is preferable to repeat this process three or more times.

[0028] The nitrogen atmosphere or argon atmosphere may be an atmosphere in which the space excluding the composition consisting of amine compound (1) and carbamic acid compound (3) and cerium (IV) oxide is replaced with nitrogen gas or argon gas, respectively, and does not exclude unintentionally remaining gases other than nitrogen gas or argon gas. Examples of unintentionally remaining gases other than nitrogen gas or argon gas include oxygen, nitrogen, and carbon dioxide, but it is preferable that carbon dioxide (carbon dioxide gas) is substantially not contained. "Substantially not containing carbon dioxide gas" means that the carbon dioxide content in the atmosphere is 10 mmol or less per mol of amine compound (1), and the preferred carbon dioxide content is 0 mmol.

[0029] In this embodiment, the composition comprising amine compound (1) and carbamic acid compound (3) is contacted with cerium(IV) oxide under gas-free conditions, nitrogen atmosphere, or argon atmosphere. This is intended to prevent the involvement of carbon dioxide in the catalytic reaction that promotes the synthesis of urea compound (5) from carbamic acid compound (3) in the presence of amine compound (1). As shown in the following reaction formula, in this embodiment, amine compound (1) primarily functions as a solvent, carbamic acid compound (3) serves as a reaction substrate, and urea compound (5) is produced under the catalytic action of cerium(IV) oxide. However, the inventors of the present invention have found that this catalytic reaction proceeds more easily under conditions in which carbon dioxide is blocked. This is thought to be because, when a composition comprising an amine compound (1) and a carbamic acid compound (3) is brought into contact with cerium (IV) oxide in an atmosphere containing an excess of carbon dioxide, the carbamic acid compound (3) reacts with carbon dioxide, as shown in the following reaction formula, to produce a carbamic acid compound represented by the following general formula (α), which cannot be used as a reaction substrate to synthesize the urea compound (5). [ka] In the general formula (α'), R 1 ~R 6 and n have the same meanings as above.

[0030] In the composition comprising the amine compound (1) and the carbamic acid compound (3) in the step (a), the content of the carbamic acid compound (3) in the composition is preferably 5 to 50 mol %, more preferably 7 to 40 mol %, and even more preferably 10 to 30 mol %, relative to 100 mol % of all compounds in the composition, in terms of more excellent production efficiency of the urea compound (5).

[0031] In the above step (a), the temperature at which the composition comprising the amine compound (1) and the carbamic acid compound (3) is brought into contact with cerium (IV) oxide is preferably in the range of 80 to 250°C, more preferably in the range of 90 to 220°C, and still more preferably in the range of 100 to 200°C, in terms of superior production efficiency of the urea compound (5).

[0032] In the above step (a), the pressure (gauge pressure) when the composition comprising the amine compound (1) and the carbamic acid compound (3) is brought into contact with cerium (IV) oxide is preferably in the range of 0 to 5 MPa, more preferably in the range of 0.2 to 4.5 MPa, still more preferably in the range of 0.5 to 4 MPa, and still more preferably in the range of 1 to 3 MPa, in terms of superior production efficiency of the urea compound (5).

[0033] In the above step (a), the amount of cerium (IV) oxide used is not particularly limited, but from the viewpoints of reaction rate and economy, it is usually preferably 0.05 to 0.4 mol, more preferably 0.1 to 0.3 mol, per mol of carbamic acid compound (3). Note that the above ratio is more suitable for a batchwise reaction than for a continuous reaction.

[0034] Regarding cerium (IV) oxide, the above-mentioned cerium (IV) oxide itself (a catalyst made of cerium (IV) oxide) can be used, or it can be mixed with other supports or supported on other supports.

[0035] The carrier is not particularly limited, but examples thereof include activated carbon, silica, alumina, aluminosilicate, zirconia, magnesia, and titania.

[0036] The composition comprising amine compound (1) and carbamic acid compound (3) in step (a) can be obtained by mixing amine compound (1) and carbamic acid compound (3), but it may also be obtained by contacting amine compound (1) with carbon dioxide (step (b)).

[0037] In step (b), when amine compound (1) is brought into contact with carbon dioxide, the amine compound (1) reacts with carbon dioxide to synthesize carbamic acid compound (3), but at this time, a portion of amine compound (1) (a portion of the amine compound) remains without reacting with carbon dioxide, allowing the production of a composition consisting of amine compound (1) and carbamic acid compound (3). The reaction between amine compound (1) and carbon dioxide is affected by the contact conditions (pressure (gauge pressure), temperature, time, etc.) when bringing amine compound (1) into contact with carbon dioxide, so by appropriately adjusting the contact conditions, it is possible to leave a portion of amine compound (1) unreacted with carbon dioxide, while allowing the remaining amine compound to react with carbon dioxide.

[0038] As with the amine compound (1) in step (a), the amine compound (1) in step (b) may be a commercially available product or may be synthesized by a known method.

[0039] In step (b), the carbon dioxide to be contacted with the amine compound (1) may be pure carbon dioxide gas or a mixed gas containing carbon dioxide and a gas other than carbon dioxide. The mixed gas containing carbon dioxide may be a mixture of pure carbon dioxide gas with a gas other than carbon dioxide (e.g., air, nitrogen, argon, etc.), air whose carbon dioxide concentration has been increased by treatment with a separation membrane, or the like, a carbon dioxide-containing exhaust gas emitted from a thermal power plant, or a carbon dioxide-containing gas produced in a carbon dioxide gas production apparatus.

[0040] In step (b), the contact conditions of amine compound (1) and carbon dioxide can be appropriately adjusted so as to obtain a composition consisting of amine compound (1) and carbamic acid compound (3). However, it is preferable to contact amine compound (1) with carbon dioxide in the absence of a metal oxide. When amine compound (1) is contacted with carbon dioxide in the absence of a metal oxide, it is difficult for all of amine compound (1) to be converted to carbamic acid compound (3) regardless of the reaction time (the amine compound (1) tends to remain), making it easier to obtain the desired composition. Examples of metal oxide catalysts include zinc oxide, calcium oxide, lanthanum(III) oxide, titanium(IV) oxide, zirconium(IV) oxide, and cerium(IV) oxide.

[0041] In step (b), it is preferable to contact amine compound (1) with carbon dioxide in the absence of a solvent. Contacting amine compound (1) with carbon dioxide in the absence of a solvent makes it difficult for all of amine compound (1) to be converted to carbamic acid compound (3) regardless of the reaction time (the amine compound (1) tends to remain), making it easier to obtain the desired composition. The term "solvent" as used herein refers to a liquid component that does not react with amine compound (1) and carbon dioxide, and examples of such a solvent include water, alcohol (e.g., methanol, ethanol, propanol, isopropanol, butanol, tert-butanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and glycerin), tetrahydrofuran, dioxane, acetonitrile, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, benzene, toluene, xylene, and pyridine.

[0042] In step (b), the method for contacting amine compound (1) with carbon dioxide is not particularly limited, and examples thereof include bubbling contact, atmospheric pressure contact, and pressurized contact, and these may be combined.

[0043] The pressure (gauge pressure) of the pressurized contact may be adjusted so as to obtain a composition comprising the amine compound (1) and the carbamic acid compound (3), and is preferably in the range of 0.01 to 5.0 MPa, more preferably 0.01 to 1.0 MPa.

[0044] In step (b), the time for contacting the amine compound (1) with carbon dioxide may be adjusted so as to obtain a composition comprising the amine compound (1) and the carbamic acid compound (3). The time may be, for example, 0.1 to 24 hours, preferably 1 to 12 hours, and more preferably 1 to 5 hours.

[0045] In step (b), the temperature at which the amine compound (1) is brought into contact with carbon dioxide may be adjusted so as to obtain a composition comprising the amine compound (1) and the carbamic acid compound (3). For example, the temperature may be 10 to 80°C, and preferably 15 to 60°C.

[0046] The amount of carbon dioxide to be contacted with the amine compound (1) is not particularly limited and can be appropriately set taking into consideration the content ratio of the amine compound (1) to the carbamic acid compound (3) in the composition.

[0047] The urea compound (5) produced by the production method of this embodiment can be isolated and purified from the reaction mixture by distillation.

[0048] When purifying by distillation, it is preferable to remove the cerium (IV) oxide catalyst beforehand to prevent deterioration of distillation efficiency. The method for removing the cerium (IV) oxide catalyst beforehand is not particularly limited, but examples include methods of removing the cerium (IV) oxide catalyst by filtering, centrifuging, or the like, the reaction solution after the reaction operation is completed.

[0049] The distillation conditions for the urea compound (5) are not particularly limited, but the distillation is usually carried out at 50°C to 150°C under a pressure of 5 mmHg to 760 mmHg. The amine compound (1) and carbamic acid derivative (3) separated at this stage may be reused as raw materials for producing the urea compound (5).

[0050] According to the production method of this embodiment described above, urea compound (5) can be efficiently produced. Furthermore, according to one aspect of this embodiment, urea compound (5) can be produced without the need for high-pressure carbon dioxide as in Non-Patent Document 1. This enables the effective use of carbon dioxide with low energy consumption, thereby reducing the environmental impact.

[0051] (Second embodiment) Next, a second embodiment for producing the urea compound represented by the general formula (6) will be described.

[0052] The production method of this embodiment differs from the first embodiment in which urea compound (5) is produced, and is a method for producing a urea compound represented by the following general formula (6) (hereinafter also referred to as "urea compound (6)"). The production method of this embodiment in which urea compound (6) is produced is similar to the production method of the first embodiment, except that amine compound (1) is replaced by an amine compound represented by the following general formula (2) (hereinafter also referred to as "amine compound (2)"), and carbamic acid compound (3) is replaced by a carbamic acid compound represented by the following general formula (4) (hereinafter also referred to as "carbamic acid compound (4)"). Therefore, detailed explanations of parts that overlap with the first embodiment will be omitted.

[0053] [ka] (In general formulas (2), (4), and (6), R 7 are each independently a hydrogen atom, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. 7 and R in general formulas (4) and (6) 7 are identical.)

[0054] The above R 7 The alkyl group having 1 to 4 carbon atoms in the formula (I) is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, and a tert-butyl group.

[0055] The above R 7 With regard to , hydrogen, an n-propyl group or a phenyl group is preferred, and an n-propyl group or a phenyl group is more preferred, in terms of excellent production efficiency of the urea compound (6).

[0056] The amine compound (2) and the carbamic acid compound (4) may be commercially available or may be synthesized by a known method, and are not particularly limited.

[0057] The production method of this embodiment is characterized by including step (a'), which corresponds to step (a) of the first embodiment, in which a composition comprising an amine compound (2) and a carbamic acid compound (4) is contacted with cerium (IV) oxide under gas-free conditions, a nitrogen atmosphere, or an argon atmosphere to produce a urea compound (6).

[0058] The composition consisting of amine compound (2) and carbamic acid compound (4) used in step (a') is a composition consisting essentially of amine compound (2) and carbamic acid compound (4). A composition consisting essentially of amine compound (2) and carbamic acid compound (4) refers to a composition consisting essentially of amine compound (2) and carbamic acid compound (4), excluding impurities unintentionally mixed into the raw materials of the composition. An example of such a composition is a composition having a purity equal to or higher than that of a mixture consisting of only amine compound (2) of commercially available purity and carbamic acid compound (4) of commercially available purity.

[0059] In the composition comprising amine compound (2) and carbamic acid compound (4), it is assumed that the carbamic acid compound (4) interacts with amine compound (2) to form a counter ion represented by general formula (4'). In the present embodiment, the carbamic acid compound (4) is a concept that includes not only non-ionic carbamic acid compound (4) but also carbamic acid ions encapsulated in carbamic acid compound (4') that form the counter ion. [ka] In general formula (4'), R 7 is synonymous with the above.

[0060] The amounts of amine compound (2), carbamic acid compound (4), and cerium (IV) oxide used in step (a') of this embodiment are the same as the amounts of amine compound (1), carbamic acid compound (3), and cerium (IV) oxide used in step (a) of the first embodiment, respectively. The treatment conditions in step (a') of this embodiment are the same as the treatment conditions in step (a) of the first embodiment, and therefore detailed explanations thereof will be omitted.

[0061] In the production method of this embodiment, the composition comprising amine compound (2) and carbamic acid compound (4) is contacted with cerium (IV) oxide under gas-free conditions, a nitrogen atmosphere, or an argon atmosphere in order to prevent the involvement of carbon dioxide in the catalytic reaction that promotes the synthesis of urea compound (6) from carbamic acid compound (4) in the presence of amine compound (2). By carrying out the catalytic reaction under gas-free conditions, in the absence of excess carbon dioxide, a nitrogen atmosphere, or an argon atmosphere, the synthesis reaction of urea compound (6) proceeds more easily.

[0062] The composition consisting of amine compound (2) and carbamic acid compound (4) can be obtained by mixing amine compound (2) with carbamic acid compound (4), but it may also be obtained by contacting amine compound (2) with carbon dioxide (step (b')). Step (b') of this embodiment corresponds to step (b) of the first embodiment.

[0063] In step (b'), when the amine compound (2) is brought into contact with carbon dioxide, the amine compound (2) reacts with carbon dioxide to synthesize the carbamic acid compound (4). At this time, a portion of the amine compound (2) (a portion of the amine compound) remains without reacting with carbon dioxide, and a composition consisting of the amine compound (2) and the carbamic acid compound (4) can be produced.

[0064] The amounts of amine compound (2) and carbon dioxide used in step (b') of this embodiment are the same as the amounts of amine compound (1) and carbon dioxide used in step (b) of the first embodiment, and the treatment conditions in step (b') of this embodiment are the same as the treatment conditions in step (b) of the first embodiment, so detailed explanations will be omitted.

[0065] According to the production method of this embodiment described above, urea compound (6) can be efficiently produced. Furthermore, according to one aspect of this embodiment, urea compound (6) can be produced without the need for high-pressure carbon dioxide as in Non-Patent Document 1. This enables the effective use of carbon dioxide with low energy consumption, thereby reducing the environmental impact. [Example]

[0066] The present invention will be described in more detail by the following examples, but the present invention is not limited to these examples.

[0067] [NMR measurement] NMR measurements were carried out using JNM-ECZ400 (1H NMR, 400 MHz) manufactured by JEOL Ltd.

[0068] [Cerium oxide catalyst] In the following examples and comparative examples, cerium (IV) oxide was used as a catalyst. The cerium (IV) oxide used was HS grade cerium (IV) manufactured by Daiichi Kigenso Co., Ltd., which had been calcined at 600°C for 3 hours. The BET specific surface area of ​​the cerium (IV) oxide was 85 m 2 / g.

[0069] Example 1 6.0 g (0.10 mol) of ethylenediamine (manufactured by Tosoh Corporation), which corresponds to the amine compound represented by general formula (1), was placed in a 200 ml autoclave, and the container was pressurized to 2 MPa with carbon dioxide (manufactured by Kansai Shoko Co., Ltd.). While maintaining the carbon dioxide pressure at 2 MPa, the pressurized state was maintained at room temperature (approximately 20°C) for 1 hour. After depressurizing the autoclave, the contents of the container were analyzed by NMR. A composition consisting of 2.06 g (0.020 mol) of ethylenediaminecarbamic acid, which corresponds to the carbamic acid compound represented by general formula (3), and 4.80 g (0.08 mol) of ethylenediamine was obtained (the content of carbamic acid compound (3) relative to all compounds in the composition: 20 mol%).

[0070] 0.34 g (0.002 mol) of the cerium(IV) oxide was added to the autoclave containing the entire composition, and the lid was placed on the autoclave. The atmosphere inside the autoclave was replaced with argon and sealed, after which the autoclave was pressurized to 1 MPa with argon and heated and stirred at 140°C for 16 hours. The atmosphere inside the autoclave was replaced with argon by repeatedly pressurizing the autoclave with 1 MPa argon gas and releasing the pressure five times. The pressure (gauge pressure) inside the autoclave when heated to 140°C was 1.4 MPa. The autoclave was cooled to room temperature, and the resulting autoclave contents (liquid) were analyzed by NMR.

[0071] As a result of NMR analysis, it was confirmed that 1.31 g (0.0164 mol) of 2-imidazolidinone, which corresponds to the urea compound represented by general formula (5), was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the following formula (1) was 82%. JPEG0007796380000008.jpg14170 (in the above formula (1), X represents the yield (%) of urea compound (5), Y represents the number of moles of urea compound (5) produced (0.0164 mol in Example 1), and Z represents the maximum number of moles of urea compound (5) that can be produced from the number of moles of carbamic acid compound (3) contained in the composition (0.020 mol in Example 1) (0.020 mol in Example 1)).

[0072] Regarding Z in the above formula (1) (the maximum number of moles of urea compound (5) that can be produced from the number of moles of carbamic acid compound (3) contained in the composition), since one molecule of the carbamic acid compound represented by general formula (3) undergoes a cyclization reaction to produce one molecule of the urea compound represented by general formula (5), [the maximum number of moles of urea compound (5) that can be produced from the number of moles of carbamic acid compound (3) contained in the composition] = [the number of moles of carbamic acid compound (3) contained in the composition].

[0073] Comparative Example 1 6.0 g of a composition consisting of 0.05 mol of ethylenediamine (manufactured by Tosoh Corporation) and 0.05 mol of isopropanol (solvent), along with 0.34 g (0.012 mol) of the above-mentioned cerium(IV) oxide, were placed in a 200 mL autoclave. After attaching the top lid, the autoclave was purged with carbon dioxide (manufactured by Kansai Shoko Co., Ltd.) (pressurization to 0.9 MPa followed by depressurization was repeated five times). Carbon dioxide was then injected into the autoclave until the pressure reached 0.2 MPa. While maintaining the pressure (0.2 MPa), the autoclave was stirred (mixed) for 10 hours at 25°C. At this time, all of the 0.05 mol of ethylenediamine had been converted to ethylenediaminecarbamic acid.

[0074] Next, the autoclave was heated to 170°C while remaining sealed (i.e., maintaining a carbon dioxide pressure of 0.2 MPa) and stirred for 24 hours. The pressure inside the autoclave when heated to 170°C was 1.4 MPa. After cooling the autoclave to room temperature, the contents (liquid) were analyzed by NMR under the same conditions as in Example 1, confirming that 0.006 mol of 2-imidazolidinone had been produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 12%.

[0075] Comparative Example 2 The reaction was carried out under the same conditions as in Comparative Example 1, except that the carbon dioxide pressure applied inside the autoclave was maintained at 0.4 MPa. The amount of ethylenediaminecarbamic acid converted from ethylenediamine was 0.05 mol. The pressure inside the autoclave when heated to 170°C was 1.5 MPa. NMR analysis of the contents (liquid) confirmed that 0.0055 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 11%.

[0076] Comparative Example 3 The reaction was carried out under the same conditions as in Comparative Example 1, except that the carbon dioxide pressure applied inside the autoclave was maintained at 0.6 MPa. The amount of ethylenediaminecarbamic acid converted from ethylenediamine was 0.05 mol. The pressure inside the autoclave when heated to 170°C was 1.6 MPa. NMR analysis of the contents (liquid) confirmed that 0.005 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 10%.

[0077] Comparative Example 4 The reaction was carried out under the same conditions as in Comparative Example 1, except that the carbon dioxide pressure applied to the autoclave was maintained at 1.0 MPa. The amount of ethylenediaminecarbamic acid converted from ethylenediamine was 0.05 mol. The pressure inside the autoclave when heated to 170°C was 2.0 MPa. NMR analysis of the contents (liquid) confirmed that 0.005 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 10%.

[0078] Comparative Example 5 The reaction was carried out under the same conditions as in Comparative Example 1, except that the carbon dioxide pressure applied inside the autoclave was maintained at 4.5 MPa. The amount of ethylenediaminecarbamic acid converted from ethylenediamine was 0.05 mol. The pressure inside the autoclave when heated to 170°C was 5.0 MPa. NMR analysis of the contents (liquid) confirmed that 0.0045 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 9%.

[0079] Comparative Example 6 A composition consisting of 2.06 g (0.020 mol) of ethylenediaminecarbamic acid and 4.80 g (0.08 mol) of ethylenediamine obtained during the procedure of Example 1 was washed with ethanol to isolate 2.06 g (0.020 mol) of ethylenediaminecarbamic acid.

[0080] 2.06 g (0.020 mol) of the isolated ethylenediaminecarbamic acid, 1.0 mL of isopropanol, and 2.06 g (0.012 mol) of cerium(IV) oxide were placed in a 200 mL autoclave, the autoclave's internal atmosphere was replaced with argon, and the autoclave was sealed. The autoclave was then pressurized with argon to 1 MPa and heated and stirred at 140°C for 16 hours. The atmosphere inside the autoclave was replaced with argon in the same manner as in Example 1. The pressure inside the autoclave when heated to 140°C was 1.4 MPa. After cooling the autoclave to room temperature, NMR analysis of the contents (liquid) under the same conditions as in Example 1 confirmed the formation of 0.004 mol of 2-imidazolidinone. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 20%.

[0081] Comparative Example 7 The same operation conditions as in Comparative Example 6 were used, except that the amount of isopropanol was changed from 1.0 ml to 5 ml. The pressure inside the autoclave when heated to 140°C was 1.6 MPa. Analysis of the contents (liquid) by NMR confirmed that 0.009 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 45%.

[0082] Comparative Example 8 The same operation conditions as in Comparative Example 6 were used, except that the amount of isopropanol was changed from 1.0 ml to 10 ml. The pressure inside the autoclave when heated to 140°C was 1.8 MPa. Analysis of the contents (liquid) by NMR confirmed that 0.012 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 60%.

[0083] Comparative Example 9 The same operation conditions as in Comparative Example 6 were used, except that the amount of isopropanol was changed from 1.0 ml to 15 ml. The pressure inside the autoclave when heated to 140°C was 1.9 MPa. NMR analysis of the contents (liquid) confirmed that 0.014 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 70%.

[0084] Comparative Example 10 The same operation conditions as in Comparative Example 6 were used, except that the amount of isopropanol was changed from 1.0 ml to 20 ml. The pressure inside the autoclave when heated to 140°C was 2.0 MPa. Analysis of the contents (liquid) by NMR confirmed that 0.014 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 70%.

[0085] Comparative Example 11 The same operation conditions as in Comparative Example 6 were used, except that the amount of isopropanol was changed from 1.0 ml to 20 ml, and further, argon substitution was changed to carbon dioxide substitution, and argon pressure of 1 MPa was changed to carbon dioxide pressure of 1 MPa. The pressure inside the autoclave when heated to 140°C was 2.0 MPa. NMR analysis of the contents (liquid) confirmed that 0.012 mol of 2-imidazolidinone was produced. The yield of urea compound (5) (2-imidazolidinone) calculated from the above formula (1) was 60%.

[0086] Example 2 The same procedure as in Example 1 was carried out, except that 6.0 g (0.10 mol) of ethylenediamine was replaced with 8.9 g (0.12 mol) of 1,2-propanediamine (Tokyo Chemical Industry Co., Ltd.), which corresponds to amine compound (1), and the heating and stirring time in the catalytic reaction using cerium (IV) oxide was changed from 16 hours to 48 hours. During this procedure, the composition obtained by contacting 1,2-propanediamine with carbon dioxide consisted of 1.84 g (0.020 mol) of 1,2-propanediaminecarbamic acid, which corresponds to carbamic acid compound (3), and 7.4 g (0.1 mol) of 1,2-propanediamine (the proportion of carbamic acid compound (3) relative to all compounds in the composition: 16.7 mol%). The pressure inside the autoclave when heated to 140°C was 1.4 MPa. The autoclave contents obtained as the reaction product were analyzed by NMR, and it was confirmed that 0.018 mol of 4-methyl-2-imidazolidinone, a urea compound represented by general formula (5), was produced. The yield of urea compound (5) (4-methyl-2-imidazolidinone) calculated from the above formula (1) was 90%.

[0087] Example 3 The same procedure as in Example 1 was carried out, except that 6.0 g (0.10 mol) of ethylenediamine was replaced with 10.6 g (0.12 mol) of N-ethylethylenediamine (Tokyo Chemical Industry Co., Ltd.), which corresponds to amine compound (1), and the heating and stirring time in the catalytic reaction using cerium (IV) oxide was changed from 16 hours to 72 hours. During this procedure, the composition obtained by contacting N-ethylethylenediamine with carbon dioxide consisted of 2.1 g (0.020 mol) of N-ethylethylenediamine carbamic acid, which corresponds to carbamic acid compound (3), and 8.8 g (0.1 mol) of N-ethylethylenediamine (the proportion of carbamic acid compound (3) relative to all compounds in the composition: 16.7 mol%). The pressure inside the autoclave when heated to 140°C was 1.7 MPa. The autoclave contents obtained as the reaction product were analyzed by NMR, and it was confirmed that 0.0163 mol of N-ethyl-2-imidazolidinone, a urea compound represented by general formula (5), was produced. The yield of urea compound (5) (N-ethyl-2-imidazolidinone) calculated from the above formula (1) was 82%.

[0088] Example 4 The same procedure as in Example 1 was carried out, except that 6.0 g (0.1 mol) of ethylenediamine was replaced with 10.6 g (0.12 mol) of N,N'-dimethylethylenediamine (Tokyo Chemical Industry Co., Ltd.), which corresponds to amine compound (1), and the heating and stirring time in the catalytic reaction using cerium (IV) oxide was changed from 16 hours to 96 hours. During this procedure, the composition obtained by contacting N,N'-dimethylethylenediamine with carbon dioxide consisted of 2.1 g (0.020 mol) of N,N'-dimethylethylenediaminecarbamic acid, which corresponds to carbamic acid compound (3), and 8.5 g (0.1 mol) of N,N'-dimethylethylenediamine (the proportion of carbamic acid compound (3) relative to all compounds in the composition: 16.7 mol%). The pressure inside the autoclave when heated to 140°C was 1.8 MPa. The autoclave contents obtained as the reaction product were analyzed by NMR, and it was confirmed that 0.0145 mol of N,N'-dimethyl-2-imidazolidinone, a urea compound represented by general formula (5), was produced. The yield of urea compound (5) (N,N'-dimethyl-2-imidazolidinone) calculated from the above formula (1) was 73%.

[0089] Example 5 The same procedure as in Example 1 was carried out, except that 6.0 g (0.10 mol) of ethylenediamine was replaced with 8.9 g (0.12 mol) of 1,3-propanediamine (Tokyo Chemical Industry Co., Ltd.), which corresponds to amine compound (1), and the heating and stirring time in the catalytic reaction using cerium (IV) oxide was changed from 16 hours to 48 hours. During this procedure, the composition obtained by contacting 1,3-propanediamine with carbon dioxide consisted of 1.8 g (0.020 mol) of 1,3-propanediaminecarbamic acid, which corresponds to carbamic acid compound (3), and 7.4 g (0.1 mol) of 1,3-propanediamine (the proportion of carbamic acid compound (3) relative to all compounds in the composition: 16.7 mol%). The pressure inside the autoclave when heated to 140°C was 1.4 MPa. The autoclave contents obtained as the reaction product were analyzed by NMR, and it was confirmed that 0.0172 mol of 1,3-diazan-2-one, a urea compound represented by general formula (5), was produced. The yield of urea compound (5) (1,3-diazan-2-one) calculated from formula (1) above was 86%.

[0090] Example 6 The same procedure as in Example 1 was carried out, except that 6.0 g (0.10 mol) of ethylenediamine in Example 1 was replaced with 8.8 g (1.2 mol) of butylamine (Tokyo Chemical Industry Co., Ltd.), which corresponds to amine compound (2), and the heating and stirring time in the catalytic reaction using cerium (IV) oxide was changed from 16 hours to 72 hours. During this procedure, the composition obtained by contacting butylamine with carbon dioxide consisted of 1.82 g (0.020 mol) of butylamine carbamic acid, which corresponds to carbamic acid compound (4), and 7.3 g (0.10 mol) of butylamine (16.7 mol%) (the content of carbamic acid compound (4) relative to all compounds in the composition). The pressure inside the autoclave when heated to 140°C was 2.1 MPa.

[0091] The autoclave contents obtained as the reaction product were analyzed by NMR, and it was confirmed that 0.0074 mol of N,N'-dibutylurea, a urea compound represented by general formula (6), was produced. The yield of urea compound (6) (N,N'-dibutylurea) calculated from the following formula (2) was 74%. JPEG0007796380000009.jpg14170 (in the above formula (2), A represents the yield (%) of urea compound (6), B represents the number of moles of urea compound (6) produced (0.0074 mol in Example 6), and C represents the maximum number of moles of urea compound (6) that can be produced from the number of moles of carbamic acid compound (4) contained in the composition (0.020 mol in Example 1) (0.010 mol in Example 1).)

[0092] Regarding C in the above formula (2) (the maximum number of moles of urea compound (6) that can be produced from the number of moles of carbamic acid compound (4) contained in the composition), since two molecules of carbamic acid compound (4) undergo a condensation reaction to produce one molecule of urea compound (6), [the maximum number of moles of urea compound (6) that can be produced from the number of moles of carbamic acid compound (4) contained in the composition] = [the number of moles of carbamic acid compound (4) contained in the composition] ÷ 2.

[0093] Example 7 The same procedure was carried out as in Example 1, except that 6.0 g (0.10 mol) of ethylenediamine was replaced with 15.0 g (0.14 mol) of benzylamine (Tokyo Chemical Industry Co., Ltd.), corresponding to amine compound (2), and the heating and stirring time in the catalytic reaction using cerium (IV) oxide was changed from 16 hours to 72 hours. During this procedure, the composition obtained by contacting benzylamine with carbon dioxide consisted of 2.50 g (0.020 mol) of benzylamine carbamic acid, corresponding to carbamic acid compound (4), and 10.72 g (0.12 mol) of benzylamine (0.14 mol) (the content of carbamic acid compound (4) relative to all compounds in the composition: 14.3 mol%). The pressure inside the autoclave when heated to 140°C was 1.5 MPa. NMR analysis of the contents of the autoclave obtained as the reaction product confirmed the formation of 0.0073 mol of N,N'-dibenzylurea, a urea compound represented by general formula (6). The yield of the urea compound (6) (N,N'-dibenzylurea) calculated from the above formula (2) was 73%.

[0094] [Table 1] JPEG0007796380000011.jpg164169

[0095] As shown in Table 1 above, the yields of the urea compounds produced in Examples 1 to 7 were higher than the yields of the urea compounds produced in Comparative Examples 1 to 11. From these results, it was understood that the urea compound production methods of Examples 1 to 7 could efficiently produce urea compounds.

[0096] In particular, as can be seen from the results of Comparative Examples 1 to 5, when carbamic acid compound (3) is produced from amine compound (1) and carbon dioxide under a carbon dioxide atmosphere and urea compound (5) is produced from carbamic acid compound (3), the yield of urea compound (5) increases as the carbon dioxide pressure decreases, but even in Comparative Example 1, where the carbon dioxide pressure was the lowest, the yield was 12%. This was lower than the yields (73 to 90%) of urea compound (5) in Examples 1 to 5, where urea compound (5) was produced from carbamic acid compound (3) under an argon atmosphere.

[0097] Furthermore, as can be seen from the results of Comparative Examples 6 to 10, when urea compound (5) was produced from carbamic acid compound (3) under an argon atmosphere, the yield of urea compound (5) increased as the amount of isopropanol (solvent) containing carbamic acid compound (3) increased, but the yield plateaued at 70% (Comparative Examples 9 and 10). This was lower than the yield of urea compound (5) (73 to 90%) in Examples 1 to 5, in which amine compound (1) was used as the solvent.

Claims

1. A method for producing a urea compound represented by the following general formula (5): The method includes a step (a) of contacting a composition comprising an amine compound represented by the following general formula (1) and a carbamic acid compound represented by the following general formula (3) with cerium (IV) oxide under a gas-free condition, a nitrogen atmosphere, or an argon atmosphere to produce a urea compound represented by the following general formula (5): The method for producing a urea compound, wherein the content of the carbamic acid compound in the composition is 5 to 50 mol % based on all compounds contained in the composition. 【Chemistry 1】 (In general formulas (1), (3), and (5), R １ ~R ６ are each independently a hydrogen atom, a phenyl group, or an alkyl group having 1 to 4 carbon atoms, and n is 0 or 1. １ and R in general formulas (3) and (5) １ are identical, and R ２ ~R ６ , and similarly for n.)

2. The method according to claim 1 , further comprising a step (b) of contacting the amine compound represented by the general formula (1) with carbon dioxide to obtain the composition.

3. R in the general formulas (1), (3), and (5) １ and R ２ The method according to claim 1 or 2, wherein each of the groups independently represents a hydrogen atom, a methyl group, or an ethyl group.

4. R in the general formulas (1), (3), and (5) ３ ~R ６ The method according to claim 1 , wherein each of the groups independently represents a hydrogen atom or a methyl group.

5. The method according to claim 1 , wherein n in the general formulae (1), (3), and (5) is 0.

6. 6. The method according to claim 1, wherein in step (a), the composition and the cerium (IV) oxide are contacted at a temperature of 80 to 250°C.

7. 7. The method according to claim 1, wherein in the step (a), the composition and the cerium (IV) oxide are contacted at a pressure (gauge pressure) of 0 to 5 MPa.

8. A method for producing a urea compound represented by the following general formula (6): A method for producing a urea compound, comprising: a step (a') of contacting a composition comprising an amine compound represented by the following general formula (2) and a carbamic acid compound represented by the following general formula (4) with cerium (IV) oxide under a gas-free condition, a nitrogen atmosphere, or an argon atmosphere to produce a urea compound represented by the following general formula (6): 【Chemistry 2】 (In general formulas (2), (4), and (6), R ７ are each independently a hydrogen atom, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. ７ and R in general formulas (4) and (6) ７ are identical.)

9. The method according to claim 8, further comprising a step (b') of contacting the amine compound represented by the general formula (2) with carbon dioxide to obtain the composition.

10. R in the general formulas (2), (4), and (6) ７ The method according to claim 8 or 9, wherein is a hydrogen atom, an n-propyl group, or a phenyl group.

11. The method according to any one of claims 8 to 10, wherein the content of the carbamic acid compound in the composition is 5 to 50 mol% based on all compounds in the composition.

12. The method according to any one of claims 8 to 11, wherein in step (a'), the composition is contacted with the cerium (IV) oxide at a temperature of 80 to 250°C.

13. The method according to any one of claims 8 to 12, wherein in the step (a'), the composition and the cerium (IV) oxide are contacted at a pressure (gauge pressure) of 0 to 5 MPa.

14. The cerium (IV) oxide has a BET specific surface area of ​​50 m ２ The method according to any one of claims 1 to 13, wherein the SiO2 content is 1 / g or more.

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