Method for producing carbamates

Abstract

To provide a novel method for manufacturing carbamate from carbon dioxide of a partial pressure lower than atmospheric pressure.SOLUTION: A method for manufacturing carbamate includes bringing a mixed gas containing carbon dioxide in which a partial pressure of the carbon dioxide is 0.001 atm or more but less than 1 atm and an organic compound containing an amino group into contact with each other in the presence of a base in an organic solvent of at least one kind selected from the group consisting of organic solvents whose carbon number is 2 to 8.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Carbamates are useful compounds with a wide range of applications, including as pharmaceuticals, agricultural chemicals, various fine chemicals, and as raw materials for the synthesis of these chemicals.

[0003] Methods for synthesizing carbamates from amines and CO2 have been investigated in the past. For example, Patent Document 1 relates to a method for producing carbamate (ammonium carbamate salt) from CO2 in flue gas, and discloses that exhaust gas containing 5 to 21% by volume of CO2 is introduced (bubbled) into a 0.75 to 1.00 mol / L ethylenediamine / methanol solution under ice bath conditions at 0°C ± 1°C, and the reaction product is separated, washed, and purified to obtain N-(2-aminoethyl)carbamate as white crystals. Patent Document 2 relates to a method for producing a powder of carbamic acid derivative, and discloses a method for obtaining various ammonium carbamates as solids by reacting carbon dioxide with various liquid amines such as ethylenediamine and benzylamine in a solvent at a temperature range of -30 to 500°C and under a pressure range of 0.3 to 100 MPa. Patent Document 3 relates to an absorbent and generator of carbon dioxide derived from air, and discloses a method in which a specific alkylamine substituted with a hydroxy group or an optionally substituted amino group is left in an air atmosphere to absorb carbon dioxide in the air.

[0004] Furthermore, Non-Patent Document 1 reports on the synthesis of ammonium carbamate, a novel carbamic acid-based ionic liquid, by reacting various primary to tertiary amines in the presence of an organic superbase such as diazabicycloundecene (DBU (registered trademark)) or tetramethylguanidine (TMG), in a solvent at a temperature range from room temperature to 40°C and a carbon dioxide atmosphere at a pressure of 5 to 60 bar, and on an investigation of the reaction conditions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] China Patent Publication No. 1821222 [Patent Document 2] International Publication No. 2012 / 111946 [Patent Document 3] JP 2017-031046 A [Non-patent literature]

[0006] [Non-Patent Document 1] Tetrahedron, (Netherlands), 2012, vol.68, p.7408-7413 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a novel method for producing a carbamate from carbon dioxide at a partial pressure lower than atmospheric pressure. [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors have conducted intensive research to solve the above problems, and as a result have found that a carbamate can be efficiently produced by contacting a carbon dioxide-containing mixed gas with an amino group-containing organic compound in a solvent in the presence of a base, thereby completing the present invention. The present invention provides the following specific embodiments. [1] A method for producing a carbamate, comprising contacting a carbon dioxide-containing mixed gas having a carbon dioxide partial pressure of 0.001 atm or more and less than 1 atm with an amino group-containing organic compound in the presence of a base in at least one organic solvent selected from the group consisting of organic solvents having 2 to 8 carbon atoms. [2] A method for producing a carbamate salt according to [1], which is a method for producing a compound represented by the following general formula (a) or a compound represented by the following general formula (b): [ka] (In formula (a), R 1 represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; R 2 represents a hydrocarbon group that is unsubstituted or has, as a substituent, at least one selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; Q represents an n-valent counter cation derived from the base, which is an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation; and n is 1 or 2. [ka] (In formula (b), R 3 each independently represents a hydrogen atom or a hydrocarbon group having at least one selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom as an unsubstituted or substituted group; X represents a divalent hydrocarbon group, which may contain an oxygen atom and / or a nitrogen atom; Q' represents an n'-valent counter cation derived from the base and is an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation; n' is 1 or 2; when n' is 1, q is 2, and when n' is 2, q is 1. [3] The method for producing a carbamate according to [1] or [2], wherein the amino group-containing organic compound is an amino group-containing organic compound represented by the following general formula (B) or an amino group-containing organic compound represented by the following general formula (C): [ka] (In formula (B), R 11 represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; R 21 represents an unsubstituted or substituted hydrocarbon group having at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. [ka] (In formula (C), R 31 each independently represents a hydrogen atom or a hydrocarbon group having, as an unsubstituted or substituted group, at least one selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; and X' represents a divalent hydrocarbon group, which may contain an oxygen atom and / or a nitrogen atom. [4] The method for producing a carbamate according to any one of [1] to [3], wherein the base is at least one selected from the group consisting of an organic base, an alkali metal salt, and an alkaline earth metal salt. [5] The method for producing a carbamate according to any one of [1] to [4], wherein the concentration of the amino group-containing organic compound in the solvent is 0.01 mol / L or more and 10.00 mol / L or less. [6] The method for producing a carbamate according to any one of [1] to [5], wherein the partial pressure of carbon dioxide in the carbon dioxide-containing mixed gas is 0.1 atm or more and 0.5 atm or less. Effect of the Invention

[0009] According to the present invention, there is provided a novel method for producing a carbamate, which can produce a carbamate from carbon dioxide at a partial pressure lower than atmospheric pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In explaining the details of the present invention, specific examples will be given. However, the present invention is not limited to the following contents as long as it does not deviate from the spirit of the present invention, and can be modified as appropriate.

[0011] <1. Method for producing carbamates> A method for producing a carbamate according to one embodiment of the present invention is characterized in that a carbon dioxide-containing mixed gas having a carbon dioxide partial pressure of 0.001 atm or more and less than 1 atm is contacted with an amino group-containing organic compound in at least one organic solvent selected from the group consisting of organic solvents having 2 to 8 carbon atoms in the presence of a base. According to the present invention, a carbamate can be produced from carbon dioxide at a partial pressure lower than normal pressure. Also, a carbamate can be produced from a low-concentration carbon dioxide mixed gas of about 15% in a relatively short time with high yield. The carbamate obtained by the production method of the present invention can be used to synthesize urea derivatives and carbamic acid esters, and can be a technology for converting low-concentration carbon dioxide contained in exhaust gases, etc., into useful chemical products. Hereinafter, the terms "carbamate", "amino group-containing organic compound", "base", "solvent", "carbon dioxide-containing mixed gas", etc. will be explained. In this specification, the process of producing a carbamate by contacting a carbon dioxide-containing mixed gas with an amino group-containing organic compound in a solvent in the presence of a base is also referred to simply as the "reaction process".

[0012] <1-1. Carbamates> The carbamate produced by the present invention is not particularly limited and may be determined depending on the purpose. According to the method for producing a carbamate according to one embodiment of the present invention, for example, a compound represented by the following general formula (a) or a compound represented by the following general formula (b) can be suitably produced. [ka] (In formula (a), R 1 represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; R2 represents a hydrocarbon group that is unsubstituted or has, as a substituent, at least one selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; Q represents an n-valent counter cation derived from the base, which is an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation; and n is 1 or 2. [ka] (In formula (b), R 3 each independently represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom as a substituent; X represents a divalent hydrocarbon group which may contain an oxygen atom and / or a nitrogen atom; Q' represents an n'-valent counter cation derived from the base and is an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation; n' is 1 or 2; when n' is 1, q is 2, and when n' is 2, q is 1. The compounds represented by the above formula (a) or (b) will be described below.

[0013] <1-1-1. Compound represented by formula (a)> [ka]

[0014] (R 1 ) In formula (a), R 1 represents a hydrogen atom or an unsubstituted or substituted hydrocarbon group having at least one type selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. In this specification, the term "hydrocarbon group" is not limited to a linear saturated hydrocarbon group, but may have a carbon-carbon unsaturated bond, a branched structure, or a cyclic structure. R 1 The number of carbon atoms in the hydrocarbon group is not particularly limited, but is usually 1 or more, and is usually 50 or less, preferably 40 or less, and more preferably 30 or less. R 1 Examples of the unsubstituted hydrocarbon group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an n -Alkyl groups such as n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-docosyl groups; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. groups; aromatic hydrocarbon groups such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-phenanthryl group, a 2-phenanthryl group, a 3-phenanthryl group, a 4-phenanthryl group, a 9-phenanthryl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a 1-pyrenyl group, a 2-pyrenyl group, a 4-pyrenyl group, a 1-triphenylenyl group, and a 2-triphenylenyl group; and the like. The hydrocarbon group as the substituent is not particularly limited, and examples thereof include alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl groups; cycloalkyl groups having 3 to 4 carbon atoms, such as cyclopropyl and cyclobutyl groups; and aromatic hydrocarbon groups having 6 to 10 carbon atoms, such as phenyl, 1-naphthyl, and 2-naphthyl groups. The oxygen-containing functional group may be any functional group containing an oxygen atom, and examples thereof include an alkoxy group, a carboxy group, a carbonyl group, a ketone group, an ether group, and a hydroxyl group. The nitrogen-containing functional group may be any functional group containing a nitrogen atom, but is preferably a nitrogen-containing functional group other than an amino group, such as an ammonium group, an amidino group, a pyrrolyl group, a triazine ring, a triazole ring, a benzotriazolyl group, an imidazolyl group, a benzimidazolyl group, a quinolyl group, a pyridyl group, a pyrimidine group, a pyrazinyl group, a quinazolinyl group, a quinoxalinyl group, a purinyl group, a piperidinyl group, a piperazinyl group, a pyrrolidinyl group, a pyrazolyl group, an aniline group, an azo group, a diazo group, an azide group, and a cyano group. Examples of functional groups containing an oxygen atom and a nitrogen atom include an amide group, an imide group, a urea group, a group containing an isocyanuric structure, a nitro group, a nitroso group, a cyanate group, an isocyanate group, a morpholino group, and a lactam ring. When the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the substituent and the number of carbon atoms of the hydrocarbon group. R 1 When the hydrocarbon group represented by the formula (I) has a substituent, R 1 Preferred examples of the alkyl group include aralkyl groups such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, and a 2-naphthylmethyl group; cycloalkylalkyl groups such as a cyclohexylmethyl group; hydrocarbon groups having an oxygen-containing functional group such as a furfuryl group; and hydrocarbon groups having a nitrogen-containing functional group such as a pyridylmethyl group. R 1 In terms of the usefulness of the carbamate, a hydrogen atom is preferred.

[0015] (R 2 ) In formula (a), R 2 represents an unsubstituted or substituted hydrocarbon group having at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. R 2 The number of carbon atoms is not particularly limited, but is usually 1 or more, and is usually 50 or less, preferably 40 or less, and more preferably 30 or less. R 2 As the unsubstituted hydrocarbon group represented by the formula: 1Examples of the groups include those exemplified above. R 2 When the hydrocarbon group represented by the formula (I) has a substituent, the substituent is, for example, R 1 In addition, when the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the substituent and the number of carbon atoms of the hydrocarbon group. 2 When the hydrocarbon group represented by the formula (I) has a substituent, R 2 Preferred examples of the alkyl group include aralkyl groups such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, and a 2-naphthylmethyl group; cycloalkylalkyl groups such as a cyclohexylmethyl group; hydrocarbon groups having an oxygen-containing functional group such as a furfuryl group; and hydrocarbon groups having a nitrogen-containing functional group such as a pyridylmethyl group. R 2 From the viewpoint of availability of raw materials, preferred examples of the alkyl group include an n-hexyl group and the like; a cycloalkyl group and the like; an aromatic hydrocarbon group and the like; and a phenyl group and the like. and preferably an n-hexyl group, a cyclohexyl group, a phenyl group, or a benzyl group.

[0016] (Q) In formula (a), Q is an n-valent counter cation derived from a base, and is an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation. Thus, n is 1 or 2. Examples of ammonium cations include primary ammonium cations such as n-butylammonium cation; secondary ammonium cations such as diethylammonium cation; tertiary ammonium cations such as triethylammonium cation; and quaternary ammonium cations such as tetramethylammonium cation, phenyltrimethylammonium cation, and tetrabutylammonium cation. Examples of the amidinium cation include formamidinium cation, acetamidinium cation, 1,5-diazabicyclo[4.3.0]non-5-enium cation, and 1,8-diazabicyclo[5.4.0]undec-7-enium cation, which are protonated forms of formamidine, acetamidine, 1,5-diazabicyclo[4.3.0]non-5-ene, and 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively, and derivatives thereof having one or more substituents. The substituents include those listed in the item (R 1 Examples of the alkyl group include the alkyl group, the cycloalkyl group, and the aromatic hydrocarbon group exemplified in the description of the alkyl group. The guanidinium cation includes 1,1,3,3-tetramethylguanidine, 2-tert-butyl-1,1,3,3-tetramethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, which are protonated, respectively, 1,1,3,3-tetramethylguanidinium cation, 2-tert-butyl-1,1,3,3-tetramethylguanidinium cation, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, as well as derivatives thereof having one or more substituents. The substituents include those listed in the item (R 1 Examples of the alkyl group include the alkyl group, the cycloalkyl group, and the aromatic hydrocarbon group exemplified in the description of the alkyl group. Examples of the phosphonium cation include tertiary phosphonium cations such as triphenylphosphonium cation and tri-tert-butylphosphonium cation; and quaternary phosphonium cations such as tetraphenylphosphonium cation, tetra-p-tolylphosphonium cation, triphenylbenzylphosphonium cation, triphenylbutyl cation, tetraethylphosphonium cation, and tetrabutylphosphonium cation. Phosphazenium cations include tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ 5 ,4λ 5 -catenadi(phosphazene), and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ 5 ,4λ 5 -catenadi(phosphazene) is protonated, respectively, tert-butylimino-tris(dimethylamino)phosphoranium cation, tert-butylimino-tri(pyrrolidino)phosphoranium cation, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorinium cation, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ 5 ,4λ 5 -catenadi(phosphazene), and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ 5 ,4λ 5 -catenadi(phosphazene)onium cations and their derivatives having one or more substituents. Eyes (R 1 Examples of the alkyl group include the alkyl group, the cycloalkyl group, and the aromatic hydrocarbon group exemplified in the description of the alkyl group. Carbocations include monovalent carbocations such as triphenylmethyl cation, tropylium cation, and azulenium cation. Examples of the alkali metal cation include a lithium cation, a sodium cation, and a potassium cation. Alkaline earth metal cations include magnesium cations and calcium cations. From the viewpoint of easy availability of raw materials, the cation is preferably an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, or a carbocation, more preferably an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, or a phosphazenium cation, and among these, the cation is preferably an ammonium cation or an amidinium cation. In one embodiment of the present invention, the amino group-containing organic compound may be a base, or may be an ammonium cation generated by the amino group-containing organic compound receiving a proton. In another embodiment of the present invention, the amino group-containing organic compound may also serve as a base, or may be a carbamate having a carbamate ion site and an ammonium cation site in one molecule. (n) In formula (a), n is 1 or 2. n represents the number of carbamate anions and is the same value as the valence of Q. Therefore, when Q is a monovalent cation, n is 1, and when Q is a divalent cation, n is 2.

[0017] Specific examples of the compound represented by formula (a) include, but are not limited to, methylammonium N-methylcarbamate, ethylammonium N-ethylcarbamate, propylammonium N-propylcarbamate, butylammonium N-butylcarbamate, pentylammonium N-pentylcarbamate, hexylammonium N-hexylcarbamate, benzylammonium N-benzylcarbamate, phenylammonium N-phenylcarbamate, compounds represented by the following formulas, and amidinium salts, guanidinium salts, phosphonium salts, phosphazenium salts, carbocation salts, alkali metal salts, or alkaline earth metal salts in which the counter cation is an amidinium cation, guanidinium cation, phosphonium cation, phosphazenium cation, carbocation, alkali metal cation, or alkaline earth metal cation other than 1,8-diazabicyclo[5.4.0]undec-7-enium cation. [ka]

[0018] <1-1-2. Compound represented by formula (b)> [ka]

[0019] (R 3 ) In formula (b), R 3 each independently represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. R 3 The unsubstituted hydrocarbon group represented by the formula (a) is R 1 Examples of the groups include those exemplified above. R 3 In the case where the hydrocarbon group represented by the formula (a) has a substituent, the substituent is, for example, R 1 In addition, when the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the substituent and the number of carbon atoms of the hydrocarbon group. 3 When the hydrocarbon group represented by the formula (I) has a substituent, R 3 A preferred example of the alkyl group is a benzyl group. The Two R's 3 may be the same or different, but are preferably the same from the viewpoints of ease of synthesis and economy. In addition, from the viewpoint of usefulness of the carbamate, at least one R 3 is preferably a hydrogen atom or a methyl group, and two R 3 More preferably, is a hydrogen atom or a methyl group.

[0020] (X) In formula (b), X represents a divalent hydrocarbon group and may contain an oxygen atom and / or a nitrogen atom. X "may contain an oxygen atom or a nitrogen atom" means that X may contain a functional group containing an oxygen atom and / or a nitrogen atom, such as a nitro group (-NO2), an epoxy group, a hydroxyl group (-OH), a carbonyl group (-C(=O)-), or an azide group (-N3), as a substituent, or may contain a linking group containing an oxygen atom or a nitrogen atom, such as an ether group (-O-), inside the carbon skeleton. That is, the carbon atom constituting the skeleton of the divalent hydrocarbon group may be substituted with an oxygen atom or a nitrogen atom. Therefore, for example, the hydrocarbon group having 2 carbon atoms as X includes a hydrocarbon group having 2 carbon atoms containing a hydroxyl group, such as -CH2-CH(OH)-, and a hydrocarbon group having 2 carbon atoms containing an ether group, such as -CH2-O-CH2-, inside the carbon skeleton. When X has a substituent, the carbon number of X includes the number of carbon atoms contained in the substituent. The divalent hydrocarbon group includes a hydrocarbon group containing at least one of an aliphatic hydrocarbon group and an aromatic hydrocarbon group; preferably, a group containing at least one selected from an aliphatic hydrocarbon group having 1 to 20 carbon atoms and an aromatic hydrocarbon group having 6 to 20 carbon atoms; more preferably, a group selected from an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, and a group consisting of an aliphatic hydrocarbon group having 1 to 20 carbon atoms and an aromatic hydrocarbon group having 6 to 20 carbon atoms; and even more preferably, a group selected from an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, and a group consisting of an aliphatic hydrocarbon group and an aromatic hydrocarbon group having 7 to 20 carbon atoms. Specific examples of divalent aliphatic hydrocarbon groups include a methylene group, an ethylene group, a tetramethylethylene group, an n-propylene group (a trimethylene group), a 1-methylpropylene group, a 1,1-dimethylpropylene group, a 2-methylpropylene group, a 1,2-dimethylpropylene group, a 2,2-dimethylpropylene group, a 1,1,2-trimethylpropylene group, a 1,1,3-trimethylpropylene group, an n-butylene group (a tetramethylethylene group), a chain hydrocarbon groups such as 1,4-cyclohexylene group, 2-methyl-1,4-butylene group, 3-methyl-1,4-butylene group, 2,2-dimethyl-1,4-butylene group, 2,3-dimethyl-1,4-butylene group, 2,2,3-trimethyl-1,4-butylene group, n-pentylene group (pentamethylene group), and n-hexanylene group (hexamethylene group); and alicyclic hydrocarbon groups such as 1,4-cyclohexylene group. Specific examples of divalent aromatic hydrocarbon groups include 1,4-phenylene, 1,2-phenylene, and 1,3-phenylene groups obtained by removing two hydrogen atoms from a benzene ring; dimethylphenylene (xylyl) groups obtained by removing two hydrogen atoms from the benzene ring of xylene; methylphenylene (tolylene) groups obtained by removing two hydrogen atoms from the benzene ring of toluene; and naphthalene groups obtained by removing two hydrogen atoms from naphthalene. Specific examples of groups consisting of aliphatic hydrocarbon groups and aromatic hydrocarbon groups include Examples of such groups include a 1,4-phenylenebis(methylene) group, a 1,4-phenylenebis(ethylene) group, a group in which one hydrogen atom has been removed from each of the two benzene rings of biphenyl, and a group in which one hydrogen atom has been removed from each of the two benzene rings of diphenylmethane. From the viewpoint of the usefulness of the carbamate, X is particularly preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a group having 7 to 20 carbon atoms composed of an aliphatic hydrocarbon group and an aromatic hydrocarbon group; and most preferably an aliphatic hydrocarbon group having 2 to 20 carbon atoms, and among these, a hexamethylene group having 6 carbon atoms is preferred.

[0021] (Q') In formula (b), Q' is a counter cation of n' valency derived from a base, and is an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation. Therefore, n' is 1 or 2. Specific examples of Q' include the cations exemplified in <1-1-1. Compound represented by formula (a)>. In addition, from the viewpoint of ease of synthesis, it is preferably an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation, and more preferably an ammonium cation, an amidinium cation, a guanidinium cation, or a phosphazenium cation. Among them, it is preferably a tert-butylimino-tri(pyrrolidino)phosphoranium cation or a 1,8-diazabicyclo[5.4.0]undec-7-enium cation. (q) In formula (b), q represents the number of cations Q', and when Q' is a monovalent cation, i.e., when n' is 1, q is 2, and when Q' is a divalent cation, i.e., when n' is 2, q is 1.

[0022] Specific examples of the compound represented by formula (b) include compounds represented by the following formula and amidinium salts, guanidinium salts, phosphonium salts, phosphazenium salts, carbocation salts, alkali metal salts, or alkaline earth metal salts, in which the counter cation is an amidinium cation, guanidinium cation, phosphonium cation, phosphazenium cation, carbocation, alkali metal cation, or alkaline earth metal cation other than 1,8-diazabicyclo[5.4.0]undec-7-enium cation, but are not limited to these. [ka] Specific examples of the compound represented by formula (b) include compounds represented by the following formulas and and the like, in which the counter cation is an amidinium salt, a guanidinium salt, a phosphonium salt, a phosphazenium salt, a carbocation salt, an alkali metal salt, or an alkaline earth metal salt other than an amidinium cation, a guanidinium cation, a phosphonium cation, or a phosphazenium cation other than tert-butylimino-tri(pyrrolidino)phosphoranium cation, a carbocation, an alkali metal cation, or an alkaline earth metal cation, but is not limited to these. [ka]

[0023] <1-2. Amino group-containing organic compounds> The amino group-containing organic compound used in one embodiment of the present invention is not particularly limited, and may be appropriately selected from those that produce the desired carbamate. The amino group-containing organic compound is preferably an amino group-containing organic compound represented by formula (B) or (C).

[0024] <1-2-1. Amino group-containing organic compound represented by formula (B)> [ka] (In formula (B), R11 represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; R 21 represents an unsubstituted or substituted hydrocarbon group having at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom.

[0025] (R 11 ) R 11 represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. R 11 As the unsubstituted hydrocarbon group represented by the formula: 1 Examples of the groups include those exemplified above. R 11 When the hydrocarbon group represented by the formula (I) has a substituent, the substituent is, for example, R 1 In addition, when the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the substituent and the number of carbon atoms of the hydrocarbon group. 11 When the hydrocarbon group represented by the formula (I) has a substituent, R 11 A preferred example of the alkyl group is a benzyl group. R 11 From the viewpoint of the usefulness of the carbamate, a hydrogen atom is preferred as the alkyl group.

[0026] (R 21 ) R 21 represents an unsubstituted or substituted hydrocarbon group having at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. R 21 As the unsubstituted hydrocarbon group represented by the formula: 1 Examples of the groups include those exemplified above. R 21When the hydrocarbon group represented by the formula (I) has a substituent, the substituent is, for example, R 1 In addition, when the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the substituent and the number of carbon atoms of the hydrocarbon group. 21 When the hydrocarbon group represented by the formula (I) has a substituent, R 21 For example, R 2 Of these, a benzyl group is more preferred. R 21 From the viewpoint of ease of availability of raw materials, the alkyl group is preferably an alkyl group such as an n-hexyl group; a cycloalkyl group such as a cyclohexyl group; an aromatic hydrocarbon group such as a phenyl group; or an aralkyl group such as a benzyl group; and more preferably an n-hexyl group, a cyclohexyl group, a phenyl group, or a benzyl group.

[0027] Examples of the amino group-containing organic compound represented by formula (B) include monoamine compounds such as benzylamine, hexylamine, dimethylamine, diethylamine, ethylmethylamine, cyclohexylamine, and aniline.

[0028] <1-2-2. Amino group-containing organic compound represented by formula (C)> [ka] (In formula (C), R 31 each independently represents a hydrogen atom or a hydrocarbon group having, as an unsubstituted or substituted group, at least one selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom; and X' represents a divalent hydrocarbon group, which may contain an oxygen atom and / or a nitrogen atom.

[0029] (R 31 ) R 31 each independently represents a hydrogen atom or a hydrocarbon group which is unsubstituted or has at least one substituent selected from a hydrocarbon group, an oxygen-containing functional group, a nitrogen-containing functional group, and a functional group containing an oxygen atom and a nitrogen atom. R31 As the unsubstituted hydrocarbon group represented by the formula: 1 Examples of the groups include those exemplified above. R 31 When the hydrocarbon group represented by the formula (I) has a substituent, the substituent is, for example, R 1 In addition, when the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the substituent and the number of carbon atoms of the hydrocarbon group. 31 When the hydrocarbon group represented by the formula (I) has a substituent, R 31 A preferred example of the alkyl group is a benzyl group. The Two R's 31 may be the same or different, but are preferably the same from the viewpoints of ease of synthesis and economy. In addition, from the viewpoint of usefulness of the carbamate, at least one R 31 is preferably a hydrogen atom or a methyl group, and two R 31 More preferably, is a hydrogen atom or a methyl group.

[0030] (X') X' represents a divalent hydrocarbon group and may contain an oxygen atom and / or a nitrogen atom. For X' to "may contain an oxygen atom or a nitrogen atom", the explanation in <1-1-2. Compound represented by formula (b)> applies. X' is preferably a group containing at least one selected from an aliphatic hydrocarbon group having 1 to 20 carbon atoms and an aromatic hydrocarbon group having 6 to 20 carbon atoms; more preferably a group selected from an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, and a group consisting of an aliphatic hydrocarbon group having 1 to 20 carbon atoms and an aromatic hydrocarbon group having 6 to 20 carbon atoms; even more preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, It is a group selected from a hydrocarbon group and a group having 7 to 20 carbon atoms consisting of an aliphatic hydrocarbon group and an aromatic hydrocarbon group; particularly preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a group having 7 to 20 carbon atoms consisting of an aliphatic hydrocarbon group and an aromatic hydrocarbon group; most preferably an aliphatic hydrocarbon group having 2 to 20 carbon atoms, and among these, a hexamethylene group having 6 carbon atoms is preferred. Specific examples of the aliphatic hydrocarbon group and the aromatic hydrocarbon group include the groups mentioned above in <1-1-2. Compound represented by formula (b)>.

[0031] Specific examples of the amino group-containing organic compound represented by formula (C) include, but are not limited to, methylenediamine, ethylenediamine, propylenediamine, hexyldiamine (hexamethylenediamine), phenylenediamine, and 4,4'-diaminodiphenylmethane. When an amino group-containing organic compound represented by formula (C) is used, from the viewpoints of ease of synthesis and economic efficiency, an embodiment in which a basic compound other than an amino group-containing organic compound is used as the base is also preferred.

[0032] <1-2-3. Amount of Amino Group-Containing Organic Compound Used> The amount of the amino group-containing organic compound used (charged amount) is not particularly limited, but from the viewpoint of the yield of the carbamate, the concentration in the solvent is preferably 0.01 mol / L or more and 10.00 mol / L or less. In one embodiment of the present invention, the amino group-containing organic compound is a monoamine compound, which is also used as a base, and the concentration of the monoamine compound in the solvent is preferably 0.01 mol / L or more, more preferably 0.1 mol / L or more, and is preferably 1.00 mol / L or less, more preferably 0.6 mol / L or less. In another embodiment of the present invention, the amino group-containing organic compound is a monoamine compound, a strong organic base other than the monoamine compound is used as the base, and the concentration of the monoamine compound in the solvent is preferably 0.01 mol / L or more, more preferably 0.1 mol / L or more, and preferably 1.00 mol / L or less, more preferably 0.7 mol / L or less, and even more preferably 0.6 mol / L or less. In another embodiment of the present invention, the amino group-containing organic compound is a diamine compound, which is also used as a base, and the concentration of the diamine compound in the solvent is preferably 1.1 mol / L or more and 10.0 mol / L or less, more preferably 4.0 mol / L or less. In another embodiment of the present invention, the amino group-containing organic compound is a diamine compound, a strong organic base other than the diamine compound is used as the base, and the concentration of the diamine compound in the solvent is preferably 0.01 mol / L or more, more preferably 0.1 mol / L or more, and preferably 10.0 mol / L or less, more preferably 4.0 mol / L or less.

[0033] <1-3. Bases> The reaction step is carried out in the presence of a base. Since an amino group-containing organic compound is usually a basic compound, in one embodiment of the present invention, an amino group-containing organic compound may be used as the base. In another embodiment of the present invention, a basic compound other than an amino group-containing organic compound may be used as the base. In one embodiment of the present invention, the reacting step is carried out in the presence of at least one base, preferably selected from the group consisting of organic bases, alkali metal salts, and alkaline earth metal salts. Examples of organic bases include amino group-containing organic compounds and basic compounds other than amino group-containing organic compounds. Examples of basic compounds other than amino group-containing organic compounds include 1,1,3,3-tetramethylguanidine, 2-tert-butyl-1,1,3,3-tetramethylguanidine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1, 5-diazabicyclo[4.3.0]non-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ 5 ,4λ 5 -Catenazi(phosphazene), 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ 5 ,4λ 5 -catenadi(phosphazene), pyridine, triethylamine, etc. Among them, preferred are strong organic bases, and more preferred is 1,8-diazabicyclo[5.4.0]undec-7-ene. Examples of alkali metal salts include alkali metal acetates such as lithium acetate, sodium acetate, potassium acetate, rubidium acetate, and cesium acetate; alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide; and alkali metal alkoxides such as lithium alkoxide, sodium alkoxide, potassium alkoxide, rubidium alkoxide, and cesium alkoxide. Examples of alkaline earth metal salts include alkaline earth metal acetates such as calcium acetate, strontium acetate, barium acetate, etc.; alkaline earth metal carbonates such as calcium carbonate, strontium carbonate, barium carbonate, etc.; alkaline earth metal hydroxides such as calcium hydroxide, strontium hydroxide, barium hydroxide, etc.; and alkaline earth metal alkoxides such as calcium alkoxide, strontium alkoxide, barium alkoxide, etc. When a basic compound other than an amino group-containing organic compound is used as the base, the amount of the base used is The (feed amount) is usually 1 equivalent or more and usually 15 equivalents or less, preferably 10 equivalents or less, more preferably 5 equivalents or less, and even more preferably 3 equivalents or less, relative to 1 equivalent of the amino group of the amino group-containing organic compound.

[0034] <1-4. Solvent> The reaction step is carried out in a solvent, which is at least one selected from the group consisting of organic solvents having from 2 to 8 carbon atoms, and two or more of which may be used in combination. Examples of organic solvents having 2 to 8 carbon atoms include alcohols such as ethanol, propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, t-butanol, allyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and glycerin; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; hydrocarbon solvents such as n-hexane, cyclohexane, n-octane, benzene, toluene, and xylene; nitriles such as acetonitrile, propionitrile, butyronitrile, and isobutyronitrile; and aprotic polar solvents such as dimethylacetamide, N,N-dimethylformamide, N,N'-dimethylpropyleneurea, 1,3-dimethyl-2-imidazolidinone, and N-methylpyrrolidone. Preferably, the reaction solvent is an alcohol, an ether, a hydrocarbon solvent, or an aprotic polar solvent, and more preferably, ethanol, hexane, 1,4-dioxane, or N-methylpyrrolidone. The reaction solvent can be used to produce the carbamate more efficiently. The amount of the solvent used is not particularly limited and can be appropriately adjusted according to the reaction scale, and is preferably within the range described in <1-2. Amino group-containing organic compound>.

[0035] <1-5. Carbon dioxide-containing mixed gas> The carbon dioxide-containing mixed gas used in the reaction step has a partial pressure of carbon dioxide in the carbon dioxide-containing mixed gas of 0.001 atm or more and less than 1 atm. The partial pressure of carbon dioxide in the carbon dioxide-containing mixed gas is preferably 0.01 atm or more, more preferably 0.05 atm or more, even more preferably 0.10 atm or more, particularly preferably 0.15 atm or more, most preferably 0.20 atm or more, and preferably 0.50 atm or less. Examples of gases other than carbon dioxide that can be contained in the carbon dioxide-containing mixed gas include inert gases such as nitrogen and argon; oxygen, etc. In addition, the pressure of the reaction step is usually 0.01 atm or more, preferably 0.05 atm or more, more preferably 0.5 atm or more, and usually 10 atm or less, preferably 5 atm or less, more preferably 2 atm or less, even more preferably 1.2 atm or less, and particularly preferably 1±0.1 atm. Exhaust gas, etc. can be used as the carbon dioxide-containing mixed gas, and the production of carbamate salt by the production method of the present invention is effective in reducing greenhouse gas emissions, and low-concentration carbon dioxide can be effectively utilized.

[0036] <1-6. Other reaction conditions, etc.> In the reaction step, for example, an amino group-containing organic compound and a solvent are placed in a sealed reaction vessel, and a carbon dioxide-containing gas is blown in to generate a carbamate. As an embodiment of the present invention, for example, when the volume of carbon dioxide in the carbon dioxide-containing mixed gas in the solvent is 15%, a carbamate can be synthesized with a yield of 80% or more by reacting 1 mmol of an amino group-containing organic compound as a raw material for 5 to 10 minutes. In addition, when 40 mmol of an amino group-containing organic compound is used, a yield of 90 minutes or more can be achieved with a reaction time of about 180 minutes. The generated carbamate can be easily isolated by filtration. The temperature of the reaction step is not particularly limited, but is usually 5°C to 45°C, and from the viewpoint of economy, it is preferable to carry out the reaction at around room temperature of 15°C to 25°C.

[0037] (Reaction time) The reaction time is not particularly limited, and may be appropriately adjusted depending on the reaction temperature, reaction scale, etc. It is usually 5 minutes or more, preferably 10 minutes or more, and usually 48 hours or less, preferably 24 hours or less, more preferably 20 hours or less, and even more preferably 3 hours or less. In particular, when a diamine compound is used as the amino group-containing organic compound and an alcohol is used as the solvent, a carbamate can be synthesized in high yield even in a reaction time of 30 minutes or less under room temperature conditions using a low-concentration carbon dioxide gas containing about 15 volume % of carbon dioxide.

[0038] (Reaction vessel) The reaction vessel is not particularly limited and should be appropriately selected depending on whether the process is a continuous process or a batch process. In one embodiment of the present invention, the process may be a continuous process or a batch process. In the case of a batch process, the reaction vessel is preferably a sealed reaction vessel (sealed reaction vessel), and more preferably a sealed reaction vessel having a volume 10 to 100 times the volume of the mixture of the amino group-containing organic compound, the solvent, and the base.

[0039] (Other processes) The method for producing a carbamate according to the present embodiment may include any other step in addition to the reaction step. The optional step may include a purification step for increasing the purity of the carbamate. In the purification step, a purification method usually performed in the field of organic synthesis, such as filtration, adsorption, column chromatography, distillation, etc., may be adopted. Specifically, when the target carbamate is solid, after the reaction step, for example, the product is recovered by filtration, washed with the same type of solvent as that used in the reaction, and then vacuum dried. EXAMPLES

[0040] The present invention will be described in more detail below with reference to examples, but the examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited to the specific examples shown below.

[0041] <Example 1> [ka] Benzylamine (40 g, 373 mmol) and hexane (1 L) were added to the reaction vessel, and a carbon dioxide / nitrogen mixed gas (1 atm, v:v = 15:85) was passed through at a flow rate of 0.5 L / min for 3 hours. After the reaction was completed, the white precipitate was filtered off, washed with hexane, and then vacuum dried to obtain benzylammonium N-benzylcarbamate in a yield of 93%.

[0042] <Example 2> [ka] Benzylamine (229 mg, 2.2 mmol), 1,8-diazabicyclo[5.4.0]undec-7-ene (338 mg, 2.2 mmol), and 1,4-dioxane (5 ml) were added to the reaction vessel, and a carbon dioxide / nitrogen mixed gas (1 atm, v:v=15:85) was passed through at a flow rate of 0.3 L / min for 15 minutes. After the reaction was completed, a portion of the solution was 1 1 H NMR measurement confirmed that the carbamate was produced quantitatively.

[0043] <Example 3> [ka] Hexyldiamine (232 mg, 2.0 mmol), 1,8-diazabicyclo[5.4.0]undec-7-ene (609 mg, 4.0 mmol), and 1,4-dioxane (5 ml) were added to the reaction vessel, and a carbon dioxide / nitrogen mixed gas (1 atm, v:v=15:85) was passed through at a flow rate of 0.3 L / min for 10 minutes. After the reaction was completed, the solution and some of the precipitated semi-solid were 1 1 H NMR measurement confirmed that the dicarbamate was produced quantitatively.

[0044] <Example 4> [ka] Aniline (186 mg, 2.0 mmol), 1,8-diazabicyclo[5.4.0]undec-7-ene (1.52 g, 10.0 mmol), and N-methylpyrrolidone (1.5 ml) were added to a reaction vessel, and a carbon dioxide / nitrogen mixed gas (1 atm, v:v=15:85) was added. The mixture was aerated at a flow rate of 0.1 L / min for 20 minutes. After the reaction was completed, a part of the solution was 1 1 H NMR measurement confirmed that the carbamate was produced quantitatively.

[0045] <Example 5> [ka] Hexyldiamine (116 mg, 1.0 mmol), tert-butylimino-tri(pyrrolidino)phosphorane (1250 mg, 4.0 mmol), and N-methylpyrrolidone (2 ml) were added to the reaction vessel, and a carbon dioxide / nitrogen mixed gas (1 atm, v:v=15:85) was passed through at a flow rate of 0.3 L / min for 20 minutes. After the reaction was completed, a portion of the solution was 1 1 H NMR measurement confirmed that the dicarbamate was produced quantitatively. [Industrial Applicability]

[0046] According to the present invention, a carbamate can be produced from carbon dioxide at a partial pressure lower than normal pressure. The carbamate obtained by the production method of the present invention can be used to synthesize urea derivatives and carbamic acid esters, and can be a technology for converting low-concentration carbon dioxide contained in exhaust gases and the like into useful chemical products.

Claims

1. The method includes a reaction step of contacting a carbon dioxide-containing mixed gas having a carbon dioxide partial pressure of 0.10 atm or more and 0.50 atm or less with an amino group-containing organic compound in at least one organic solvent selected from the group consisting of organic solvents having 2 to 8 carbon atoms in the presence of a base, the base is 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, or 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine; The method for producing a carbamate, wherein the amino group-containing organic compound is an amino group-containing organic compound represented by the following general formula (B) or an amino group-containing organic compound represented by the following general formula (C): 【Chemistry 1】 (In formula (B), R 11 represents a hydrogen atom; R 21 represents an unsubstituted or substituted hydrocarbon group.) 【Chemistry 2】 (In formula (C), R 31 represents a hydrogen atom; and X′ represents a divalent hydrocarbon group.)

2. The method for producing a carbamate according to claim 1, which is a method for producing a compound represented by the following general formula (a) or a compound represented by the following general formula (b): 【Chemistry 3】 (In formula (a), R １ represents a hydrogen atom; R ２ represents a hydrocarbon group that is unsubstituted or has a hydrocarbon group as a substituent; Q represents a 1,8-diazabicyclo[5.4.0]undec-7-enium cation, a 1,5-diazabicyclo[4.3.0]non-5-enium cation, a tert-butylimino-tris(dimethylamino)phosphoranium cation, a tert-butylimino-tri(pyrrolidino)phosphoranium cation, or a 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorinium cation; and n is 1. 【Chemistry 4】 (In formula (b), R ３ represents a hydrogen atom; X represents a divalent hydrocarbon group; Q' represents a 1,8-diazabicyclo[5.4.0]undec-7-enium cation, a 1,5-diazabicyclo[4.3.0]non-5-enium cation, a tert-butylimino-tris(dimethylamino)phosphoranium cation, a tert-butylimino-tri(pyrrolidino)phosphoranium cation, or a 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorinium cation; and q is 2.

3. 3. The method for producing a carbamate according to claim 1, wherein the concentration of the amino group-containing organic compound in the solvent is 0.01 mol / L or more and 10.00 mol / L or less.

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