Method for producing urea compound

Abstract

To provide a novel method for producing a urea compound.SOLUTION: A method for producing a urea compound includes a step of synthesizing a urea compound through reaction of an amine compound and a carbonate. The reaction is, for instance, carried out in the presence of a compound A including a chemical element M. The chemical element M is a metal element or P.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Urea compounds are compounds that can be used as raw materials for various organic compounds such as isocyanate compounds. For example, Patent Document 1 discloses synthesizing a urea compound using carbon dioxide and synthesizing a carbamate compound or an isocyanate compound from the urea compound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-078234 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need for a new method for producing urea compounds. [Means for solving the problem]

[0005] The present invention provides Provided is a method for producing a urea compound, which includes a step of synthesizing a urea compound by reacting an amine compound with a carbonate. [Effects of the Invention]

[0006] According to the present invention, a new method for producing a urea compound can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0007] The method for producing a urea compound according to the first aspect of the present invention comprises the steps of: The method includes a step of synthesizing a urea compound by reacting an amine compound with a carbonate.

[0008] In the second aspect of the present invention, for example, in the production method according to the first aspect, the reaction is carried out in the presence of a compound A containing an element M, and the element M is a metal element or P.

[0009] In a third aspect of the present invention, for example, in the production method according to the second aspect, the element M is V, Fe, Mo, Ta, Nb, Ti, W, or P.

[0010] In a fourth aspect of the present invention, for example, in the production method according to any one of the first to third aspects, the amine compound is represented by the following formula (1). R-NX2(1) In the formula (1), R is a hydrocarbon group which may have a substituent, and X are each independently a hydrogen atom or an arbitrary substituent, provided that at least one of the two Xs is a hydrogen atom or a protecting group.

[0011] In a fifth aspect of the present invention, for example, in the production method according to the fourth aspect, the hydrocarbon group contains at least one selected from the group consisting of an aliphatic ring and an aromatic ring.

[0012] In a sixth aspect of the present invention, for example, in the production method according to any one of the first to fifth aspects, the carbonate salt contains at least one selected from the group consisting of alkali metal cations, alkaline earth metal cations, and ammonium cations.

[0013] In a seventh aspect of the present invention, for example, in the production method according to any one of the first to sixth aspects, in the reaction, the ratio of the carbonate to the amine compound is 400 mol % or less.

[0014] In an eighth aspect of the present invention, for example, in the production method according to any one of the first to eighth aspects, the reaction is carried out in the presence of at least one solvent selected from the group consisting of organic solvents and water.

[0015] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0016] The method for producing a urea compound according to the present embodiment includes a step of synthesizing a urea compound by reacting an amine compound with a carbonate. According to the production method according to the present embodiment, it is not necessary to use gaseous carbon dioxide as a raw material, and therefore the urea compound can be synthesized relatively simply and under mild conditions. In this specification, a urea compound refers to a compound having a urea group (-N-X-CO-N-X-: X is, independently of each other, a hydrogen atom or any substituent).

[0017] (amine compounds) An amine compound is a compound having an amino group. In the amine compound, the amino group is preferably capable of reacting with a carbonate (specifically, a carbonate ion contained in the carbonate), and is preferably a primary amino group or a secondary amino group, and particularly preferably a primary amino group. The amino group may be protected by a protecting group described below. The number of amino groups in the amine compound may be one or two or more.

[0018] The amine compound may contain a cyclic structure. The amine compound may contain one cyclic structure or two or more cyclic structures. The cyclic structure may or may not contain a heteroatom. The cyclic structure may be an aliphatic ring or an aromatic ring.

[0019] Examples of the aliphatic ring include a cyclohexane ring, a cyclopentane ring, an adamantane ring, etc. Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, etc.

[0020] In the amine compound, the nitrogen atom contained in the amino group may or may not be directly bonded to a cyclic structure. In the amine compound, the nitrogen atom contained in the amino group may be directly bonded to an aromatic ring. The amine compound may be a primary amine compound or a secondary amine compound in which the amino group and the aromatic ring are directly bonded.

[0021] The amine compound may be a compound represented by the following formula (1): R-NX2(1)

[0022] In formula (1), R is a hydrocarbon group which may have a substituent, and X are each independently a hydrogen atom or an arbitrary substituent, provided that at least one of the two Xs is a hydrogen atom or a protecting group.

[0023] In X of formula (1), the optional substituent includes a hydrocarbon group which may have a substituent, a protecting group, etc. Examples of the hydrocarbon group include those described below for R. Examples of the protecting group include a silyl protecting group and a carbamate protecting group. Examples of the silyl protecting group include a trimethylsilyl group (TMS group), a triethylsilyl group (TES group), a triisopropylsilyl group (TIPS group), a tert-butyldimethylsilyl group (TBDMS group), and a tert-butyldiphenylsilyl group (TBDPS group). Examples of the carbamate protecting group include a tert-butoxycarbonyl group (Boc group) and a benzyloxycarbonyl group (Cbz group).

[0024] In formula (1), X is preferably a hydrogen atom.

[0025] In R of formula (1), the number of carbon atoms in the hydrocarbon group is not particularly limited as long as it is at least 1. The number of carbon atoms in the hydrocarbon group may be, for example, 20 or less, 15 or less, 12 or less, or 10 or less.

[0026] In a preferred embodiment of the present invention, the hydrocarbon group in formula (1) contains a cyclic structure. In formula (1), the hydrocarbon group may contain at least one ring selected from the group consisting of an aliphatic ring and an aromatic ring.

[0027] The hydrocarbon group containing a cyclic structure is, for example, an alicyclic hydrocarbon group or an aromatic cyclic hydrocarbon group. In this specification, the term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an aliphatic ring as a cyclic structure and does not contain an aromatic ring, and may be a monocyclic alicyclic hydrocarbon group or a polycyclic alicyclic hydrocarbon group. Here, the alicyclic hydrocarbon group does not need to be composed only of an aliphatic ring, and may contain a chain structure as part of it. The term "aromatic cyclic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring as a cyclic structure. Here, the aromatic cyclic hydrocarbon group does not need to be composed only of an aromatic ring, and may contain an aliphatic ring or a chain structure as part of it.

[0028] Examples of the alicyclic hydrocarbon group include a cyclohexyl group, a cyclopentyl group, an adamantyl group, etc. The alicyclic hydrocarbon group is preferably a cyclohexyl group.

[0029] The aromatic hydrocarbon group may contain a benzene ring. Examples of the aromatic hydrocarbon group include a phenyl group, a methylphenyl group, a naphthyl group, a benzyl group, and a phenethyl group.

[0030] In another preferred embodiment of the present invention, the hydrocarbon group in formula (1) is a linear or branched chain hydrocarbon group. The chain hydrocarbon group may be an alkyl group, an alkenyl group, or an alkynyl group.

[0031] Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, sec-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. Examples of alkenyl groups include vinyl and allyl groups. Examples of alkynyl groups include ethynyl groups.

[0032] Examples of the substituent on the hydrocarbon group include halogen, an alkoxy group, an alkyl ester group, a carboxyl group, and a hydroxyl group.

[0033] Examples of halogen include fluorine, chlorine, bromine, and iodine. Examples of alkoxy groups include methoxy, ethoxy, and isopropoxy groups.

[0034] Specific examples of the amine compound include ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, cyclohexylamine, cyclopentylamine, phenylmethylamine, 2-phenylethylamine (phenethylamine), 1-phenylethylamine, 2-phenylpropylamine, 3-phenylpropylamine, 3,3-diphenylpropylamine, 2-(4-methylphenyl)ethylamine, 2-(4-bromophenyl)ethylamine, 2-(4-trifluoromethylphenyl)ethylamine, 3-ethoxypropylamine, 1-adamantanamine, 4-methoxyaniline (p-anisidine), tetrahydrofuran-2-methaneamine, hexamethylenediamine, 1,5-pentamethylenediamine, toluenediamine, 4,4'-methylenedianiline, tetrahydrofuranamine, etc. When structural isomers exist in the compounds exemplified above, the structural isomers are also included in the examples. The amine compound is preferably p-anisidine, phenethylamine, or the like.

[0035] In the production method of this embodiment, various types of urea compounds can be produced by selecting the amine compound.

[0036] (carbonate) In this specification, carbonate refers to a salt formed by substituting at least a portion of the hydrogen atoms of carbonic acid (H2CO3). That is, in this specification, "carbonate" also includes hydrogen carbonate. The carbonate preferably contains a metal cation or an ammonium cation. The carbonate preferably contains at least one selected from the group consisting of an alkali metal cation, an alkaline earth metal cation, and an ammonium cation, and particularly preferably contains an alkali metal cation.

[0037] Examples of carbonates containing alkali metal cations include lithium carbonate, sodium carbonate, potassium carbonate, potassium sodium carbonate, sodium sesquicarbonate, etc. Examples of carbonates containing alkaline earth metal cations include calcium carbonate, barium carbonate, etc. Examples of carbonates containing ammonium cations include ammonium carbonate.

[0038] In the reaction between an amine compound and a carbonate, typically, 1 mole of carbonate reacts with 2 moles of the amine compound to produce a urea compound. However, according to the studies of the present inventors, using a carbonate in a greater amount than the stoichiometric amount tends to improve the yield of the urea compound. In the above reaction, the ratio P1 of the carbonate to the amine compound is, for example, 50 mol% or more, 80 mol% or more, 100 mol% or more, 150 mol% or more, 200 mol% or more, 250 mol% or more, or even 300 mol% or more. However, if the ratio P1 is too high, the yield of the urea compound may actually decrease. The upper limit of the ratio P1 is preferably 1000 mol% or less, and may be 800 mol% or less, 700 mol% or less, 600 mol% or less, 500 mol% or less, or even 400 mol% or less. In this specification, the ratio of compounds refers to the molar ratio of the compounds at the stage of charging into a reactor (before the reaction).

[0039] In recent years, research has been conducted into technologies for producing carbonates from carbon dioxide in order to reuse carbon dioxide contained in off-gas from chemical plants and thermal power plants. Carbonates can be mainly used in cement production and steelmaking. According to the present embodiment, a new method for utilizing carbonates can be provided.

[0040] (Compound A containing element M) The reaction between the amine compound and the carbonate is preferably carried out in the presence of a compound A containing an element M. In the compound A, the element M is a metal element or P. The compound A is a compound that promotes the reaction between the amine compound and the carbonate, and is preferably a catalyst having catalytic activity for the reaction.

[0041] Compound A preferably has an element M-oxygen double bond. The number of element M-oxygen double bonds in one molecule of compound A may be 1 or more, for example, 1 to 5. The number of element M-oxygen double bonds in one molecule of compound A is preferably 1. However, in some cases, the number of element M-oxygen double bonds in one molecule of compound A may be 2 or more.

[0042] As described above, the element M is a metal element or P. The element M is preferably a metal element. The element M may be V, Fe, Mo, Ta, Nb, Ti, W, or P, or may be V, Fe, Mo, Ta, Nb, Ti, or W, or may be V, Fe, Mo, or Nb, or may be V. As an example, it is preferable that the element M is V and the compound A has a vanadium-oxygen double bond.

[0043] In one preferred embodiment of the present invention, compound A may be a complex having a ligand that coordinates with element M.

[0044] Examples of the ligand include a hydrocarbon group which may have a substituent, an oxyhydrocarbon group which may have a substituent, and a halogen.

[0045] The number of carbon atoms in the hydrocarbon group is not particularly limited as long as it is at least 1. The number of carbon atoms in the hydrocarbon group may be, for example, 20 or less, 15 or less, 10 or less, 5 or less, or 3 or less.

[0046] The hydrocarbon group may be a linear or branched chain hydrocarbon group. The chain hydrocarbon group may be an alkyl group, an alkenyl group, or an alkynyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and a sec-butyl group. Examples of the alkenyl group include a vinyl group and an allyl group. Examples of the alkynyl group include an ethynyl group.

[0047] Examples of the substituent on the hydrocarbon group include halogen, amino, alkoxy, alkyl ester, carboxyl, and hydroxyl groups.

[0048] Examples of hydrocarbon groups contained in the oxyhydrocarbon group include those described above. The oxyhydrocarbon group may be an alkoxy group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and an isopropoxy group. Examples of the substituent of the oxyhydrocarbon group include those described above for the hydrocarbon group. Examples of the oxyhydrocarbon group having a substituent include a group derived from triethanolamine (TEA).

[0049] Examples of halogen include fluorine, chlorine, bromine, and iodine, and an example is chlorine.

[0050] The ligand is preferably an isopropoxy group, an ethyl group, an ethoxy group, chlorine, or TEA.

[0051] The number of ligands can be adjusted appropriately depending on the type of element M. The number of ligands may be 1 or more, for example, 1 to 5. The number of ligands may be 3 or 4. The number of ligands is preferably 3.

[0052] Compound A may be a compound represented by the following formula (2): L n VO (2)

[0053] In formula (2), L's are each independently a hydrocarbon group which may have a substituent, an oxyhydrocarbon group which may have a substituent, or a halogen, and n is a natural number of 1 to 5. At least two selected from the plurality of L's may be linked to each other.

[0054] Examples of the hydrocarbon group which may have a substituent and the oxyhydrocarbon group which may have a substituent are those mentioned above.

[0055] In formula (2), n may be 3 or 4. n is preferably 3.

[0056] In formula (2), L is preferably an alkoxy group, more preferably an isopropoxy group.

[0057] A specific example of compound A is vanadium(V) oxytriisopropoxide (VO(O i Pr)3), VO(OEt)3, VO(OEt)Cl2, VOCl3, VO(TEA), etc.

[0058] Compound A is not limited to the above-mentioned complexes. In another preferred embodiment of the present invention, compound A may be an oxide of element M or an inorganic salt containing element M. Examples of compound A include V2O5, NH4VO3, Na3VO4, TiO2, WO3, FeO, Fe2O3, NbO2, Nb2O5, (NH4)2MoO4, etc.

[0059] In the reaction between the amine compound and the carbonate, the ratio P2 of the compound A to the amine compound is, for example, 150 mol% or less, and may be 100 mol% or less, 80 mol% or less, 50 mol% or less, 30 mol% or less, 20 mol% or less, or even 15 mol% or less. The lower limit of the ratio P2 is not particularly limited, and is, for example, 1 mol% or more.

[0060] (solvent) The reaction between the amine compound and the carbonate may be carried out in the presence of at least one solvent selected from the group consisting of an organic solvent and water. The solvent is preferably an organic solvent. The solvent may be a mixed solvent of an organic solvent and water. The solvent may be a polar solvent or a nonpolar solvent. In this specification, a nonpolar solvent is a solvent having a relative dielectric constant of 8.0 or less at 25°C. A polar solvent is a solvent having a relative dielectric constant of more than 8.0 at 25°C.

[0061] Examples of non-polar solvents include toluene, benzene, xylene, hexane, 1,4-dioxane, tetrahydrofuran, ethyl acetate, cyclopentyl methyl ether, and mixed solvents thereof.

[0062] Examples of polar solvents include acetonitrile, dimethyl sulfoxide, dichloromethane, propylene carbonate, methanol, ethanol, dimethylacetamide, and mixed solvents thereof, with dimethylacetamide (DMA) being preferred.

[0063] (Other ingredients) In the reaction between an amine compound and a carbonate, other components may be present in addition to compound A and a solvent, such as a base, a dehydrating agent, and a phase transfer catalyst (PTC).

[0064] The base may be an inorganic base or an organic base. Examples of inorganic bases include hydride salts such as sodium hydride and lithium hydride; hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and barium hydroxide; and ammonia. Examples of organic bases include nitrogen-containing compounds such as N,N-diisopropylethylamine (DIEA), diazabicycloundecene (DBU), 1,8-bis(dimethylamino)naphthalene, and N-ethyldiisopropylamine.

[0065] The base may also function as a dehydrating agent. For example, when sodium hydride is used as the base, it may be converted to sodium hydroxide by reaction and function as a dehydrating agent.

[0066] In the reaction between an amine compound and a carbonate, the ratio P3 of the base to the amine compound is not particularly limited and is, for example, 10 to 500 mol %, or 40 to 300 mol %. In the reaction between an amine compound and a carbonate, a base does not necessarily have to be used.

[0067] The dehydrating agent may be a molecular sieve.

[0068] The amount of the dehydrating agent used is not particularly limited, and is, for example, 1 g to 1 kg per 1 L of solvent. In the reaction between an amine compound and a carbonate, a dehydrating agent does not necessarily have to be used.

[0069] The phase transfer catalyst tends to promote the dissolution of the carbonate in the solvent, and examples of the phase transfer catalyst include quaternary ammonium salts, quaternary phosphates, macrocyclic polyethers such as crown ethers, nitrogen-containing macrocyclic polyethers such as cryptands, nitrogen-containing linear polyethers, polyethylene glycols and their alkyl ethers.

[0070] Examples of quaternary ammonium salts include tetrabutylammonium fluoride (TBAF), tetrabutylammonium chloride, methyltrioctylammonium chloride, benzyltrimethylammonium chloride, trimethylphenylammonium bromide, tributylammonium tribromide, tetrahexylammonium hydrogensulfate, decyltrimethylammonium bromide, diallyldimethylammonium chloride, dodecyltrimethylammonium bromide, dimethyldioctadecylammonium bromide, tetraethylammonium tetrafluoroborate, ethyltrimethylammonium iodide, tris(2-hydroxyethyl)methylammonium hydroxide, tetramethylammonium acetate, tetramethylammonium bromide, and tetraethylammonium iodide.

[0071] The amount of the phase transfer catalyst used is not particularly limited, and is, for example, 0.1 mmol to 1 mol per 1 L of solvent. In the reaction between an amine compound and a carbonate, a phase transfer catalyst does not necessarily have to be used.

[0072] (Reaction conditions) The reaction between the amine compound and the carbonate may be carried out in an air atmosphere or an inert atmosphere, preferably an argon atmosphere or a nitrogen atmosphere.

[0073] In the reaction between an amine compound and a carbonate, the reaction temperature is, for example, 50° C. or higher, and may be 80° C. or higher, 100° C. or higher, or even 130° C. or higher. The reaction temperature is, for example, the boiling point of the solvent used or lower, and may be 160° C. or lower, or even 150° C. or lower.

[0074] The reaction time for the reaction between the amine compound and the carbonate is not particularly limited and may be, for example, 10 minutes or more, 1 hour or more, 3 hours or more, 5 hours or more, 10 hours or more, 15 hours or more, or even 24 hours or more. The upper limit of the reaction time is, for example, 48 hours or less.

[0075] The reaction between the amine compound and the carbonate may be carried out using a batch reactor or a flow reactor (for example, a plug flow reactor (PFR) or a continuous stirred tank reactor (CSTR)).

[0076] (Urea compounds) As described above, in the production method of this embodiment, a urea compound can be synthesized by reacting an amine compound with a carbonate. In this reaction, typically, one mole of carbonate reacts with two moles of an amine compound to produce the urea compound. In the urea group (-NX-CO-NX-) contained in the urea compound, the carbonyl moiety (-CO-) is derived from the carbonate, and the amine moiety (-NX-NX-) is derived from the amine compound.

[0077] The urea compound may be a compound represented by the following formula (3). R-NX-CO-NX-R (3)

[0078] In formula (3), X's are each independently a hydrogen atom or an arbitrary substituent. The arbitrary substituent is preferably a hydrocarbon group which may have a substituent. Examples of the hydrocarbon group include those described above for formula (1). In formula (3), the two X's may be the same or different.

[0079] In formula (3), R are each independently a hydrocarbon group which may have a substituent. Examples of the hydrocarbon group include those described above for formula (1). In formula (3), the two R may be the same or different.

[0080] (Other processes) In the production method of the present embodiment, a mixed solution containing a urea compound is usually obtained by reacting an amine compound with a carbonate. The production method of the present embodiment may further include a step of separating the urea compound from the mixed solution containing the urea compound.

[0081] The method for separating the urea compound from the mixed solution is not particularly limited, and known methods such as column chromatography can be used.

[0082] As described above, the urea compound can be used as a raw material for various organic compounds. The production method of the present embodiment may further include a step of converting the urea compound into an organic compound other than the urea compound.

[0083] Examples of other organic compounds include isocyanate compounds, carbodiimide compounds, isocyanurate compounds, and urethane compounds. [Example]

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0085] Example 1 First, 0.24 mmol of p-anisidine as an amine compound, 0.72 mmol of potassium carbonate as a carbonate, 0.24 mmol of vanadium(V)oxytriisopropoxide as compound A, 0.72 mmol of diazabicycloundecene as a base, and 2 mL of dimethylacetamide as a solvent were placed in a reaction vessel. These were stirred at 130°C for 4 hours under an argon atmosphere. This caused the reaction between the amine compound and the carbonate to proceed, producing a urea compound.

[0086] After the reaction was completed, the reaction solution in the reaction vessel was subjected to a separation operation using ethyl acetate. The obtained extract was dehydrated with sodium sulfate, and then the solvent was removed using an evaporator to obtain a reaction mixture. 1 Analysis was carried out using H-NMR, and the amount of the urea compound produced was identified based on the analysis results. 1 In H-NMR, trimethoxybenzene was used as an internal standard and deuterated dimethyl sulfoxide (DMSO) was used as a solvent. Furthermore, the yield of the urea compound was calculated based on the amount of the amine compound added to the reaction vessel.

[0087] Examples 2 to 8 The reactions in Examples 2 to 8 were carried out in the same manner as in Example 1, except that the types and amounts of materials used and the reaction conditions were changed as shown in Tables 1 and 2. In Examples 5 to 8, a separation operation was carried out using dichloromethane. In Examples 5 to 8, triphenylmethane was used as the internal standard substance, and deuterated chloroform was used as the solvent. 1 H-NMR analysis was carried out.

[0088] [Table 1]

[0089] [Table 2]

[0090] The abbreviations in Tables 1 and 2 are as follows: VO(O i Pr)3: Vanadium(V) oxytriisopropoxide DBU: Diazabicycloundecene DIEA: N,N-diisopropylethylamine MS3A: Molecular sieve TBAF·3H2O: Tetrabutylammonium fluoride trihydrate (NBu4)Cl: Tetrabutylammonium chloride DMA: Dimethylacetamide [Industrial Applicability]

[0091] According to the production method of this embodiment, a urea compound can be produced relatively simply and under mild conditions.

Claims

1. A method for producing a urea compound, comprising a step of synthesizing a urea compound by reacting an amine compound with a carbonate.

2. The reaction is carried out in the presence of a compound A containing an element M, The method according to claim 1 , wherein the element M is a metal element or P.

3. The method according to claim 2 , wherein the element M is V, Fe, Mo, Ta, Nb, Ti, W, or P.

4. The method according to claim 1 , wherein the amine compound is represented by the following formula (1): R-NX 2 (1) In the formula (1), R is a hydrocarbon group which may have a substituent, and X are each independently a hydrogen atom or an arbitrary substituent, provided that at least one of the two Xs is a hydrogen atom or a protecting group.

5. The method according to claim 4 , wherein the hydrocarbon group includes at least one selected from the group consisting of an aliphatic ring and an aromatic ring.

6. The method according to claim 1 , wherein the carbonate salt contains at least one cation selected from the group consisting of alkali metal cations, alkaline earth metal cations, and ammonium cations.

7. 2. The method according to claim 1, wherein the ratio of the carbonate to the amine compound in the reaction is 400 mol % or less.

8. The method according to claim 1, wherein the reaction is carried out in the presence of at least one solvent selected from the group consisting of an organic solvent and water.

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