Process for producing carbamic acid esters using a substituted carbonate salt

Abstract

To provide a simple production method of a carbamic acid ester, in which neither a sacrificial reagent nor a high-pressure carbon dioxide gas is used.SOLUTION: A production method of a carbamic acid ester includes a reaction step to generate the carbamic acid ester by making a monosubstituted carbonate salt, a metal alkoxide, and an amine compound react with one another.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing carbamic acid esters using monosubstituted carbonate salts.

Background Art

[0002] Carbamic acid esters are useful compounds having a wide range of applications as pharmaceuticals, agricultural chemicals, various fine chemicals, and synthetic raw materials thereof.

[0003] Heretofore, methods for producing carbamic acid esters using carbon dioxide at normal pressure have been proposed. For example, Non-Patent Document 1 examines a multi-component synthesis using ammonium carbamate synthesized in situ from the reaction of an amine as a carbonyl source and CO2, an equivalent amount of triphenylphosphine, and an equivalent amount of trichloroisocyanuric acid (TCCA) as a method for synthesizing carbamate derivatives. In Non-Patent Document 1, CO2 gas at 1 atm is used, and non-renewable sacrificial reagents are used. Non-Patent Document 2 reports a method for synthesizing carbamic acid esters via carbamic acid using 1,8-diazabicyclo[5.4.0]undec-7-ene as a catalyst and using CO2 gas at 1 atm. In Non-Patent Document 2, PBu3 and DBAD (di-tert-butyl azodicarboxylate), which are non-renewable sacrificial reagents, are used. Non-Patent Document 3 reports the synthesis of carbamic acid esters using KO2 / Et4NBr or the like, which are non-renewable sacrificial reagents, from amines and CO2 gas. Non-Patent Document 4 reports the synthesis of carbamic acid esters by the Mitsunobu reaction using CO2 gas at 1 atm, via carbamic acid, using Ph3P and DEAD (diethyl azodicarboxylate), which are sacrificial reagents. Non-Patent Document 5 examines CO2 capture by superbase / polyethylene glycol and subsequent conversion technology. In the presence of NH4I, NH2PEG 150The formation of cyclic carbamates by the reaction of carbamates formed by capturing CO2 gas with NH2 and aziridine is disclosed. In Non-Patent Document 6, the synthesis of carbonate salts using CO2 at 1 atm was studied, and transesterification using this as a catalyst and dimethyl carbonate as a reactant was investigated. It has been reported that carbonates were synthesized from alcohols and aliphatic carbamates were synthesized from amines under pressurized (1.0 MPa) CO2.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0005] All of the above methods for synthesizing carbamic acid esters have the problem that either sacrificial reagents or high-pressure carbon dioxide gas is required. An object of the present invention is to provide a method for easily producing carbamic acid esters without using sacrificial reagents or high-pressure carbon dioxide gas. [Means for Solving the Problems]

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that a carbamate is formed from a monosubstituted carbonate salt and an alkoxide compound, and have completed the present invention. The present invention provides the following specific embodiments and the like. [1] A method for producing a carbamate, comprising a reaction step of reacting a monosubstituted carbonate salt, a metal alkoxide, and an amine compound to produce a carbamate. [2] The method for producing a carbamate according to [1], wherein the monosubstituted carbonate salt is a compound represented by formula (1), the amine compound is a compound represented by formula (2), the metal alkoxide is a compound represented by formula (3), and the carbamate is a compound represented by formula (4). [Chemical Formula] (In the above formula, R 0 is a substituted or unsubstituted n-valent hydrocarbon group; R 1 is each independently a substituted or unsubstituted monovalent hydrocarbon group; R 2 is each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; R 3 is each independently a substituted or unsubstituted hydrocarbon ligand, amide ligand, or halide ligand; M is a metal atom; A m+ is an m-valent cation derived from the base represented by A; n is 1 or 2; m is 1 or 2; p represents the formal oxidation number of M and is an integer from 1 to 6; (p - q) is an integer from 1 to 6; q is an integer of 0 or more and (p - 1) or less.) [3] The A m+The method for producing a carbamate according to [2], wherein the cation is selected from the group consisting of an ammonium cation, an amidinium cation, a guanidinium cation, a phosphonium cation, a phosphazenium cation, a carbocation, an alkali metal cation, and an alkaline earth metal cation. [4] Said R 0 The method for producing a carbamate according to [2] or [3], wherein R is a monovalent or divalent group selected from a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms. [5] Said R 1 The method for producing a monosubstituted carbonate salt according to any one of [2] to [4], wherein R is a monovalent group selected from a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms. [6] Said R 2 The method for producing a carbamate according to any one of [2] to [5], wherein R is a hydrogen atom. [7] The method for producing a carbamate according to any one of [1] to [6], wherein the metal alkoxide is at least one selected from the group consisting of a titanium alkoxide and an alkoxysilane. Method. [8] The method for producing a carbamate according to any one of [1] to [7], wherein the reaction step is carried out in the presence of an aprotic polar solvent. [9] Before the reaction step, a step of generating a monosubstituted carbonate salt by bringing an alcohol, a base, and a carbon dioxide-containing gas into contact with each other is included. The total pressure of the carbon dioxide-containing gas is P t and the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas is P CO2 As, P CO2 / P t Is 0.0001 or more and 1 or less, and the P CO2 Is less than 0.1 MPa. The method for producing a carbamate according to any one of [1] to [8].

Advantages of the Invention

[0007] According to the present invention, a method for simply producing a carbamate without using a sacrificial reagent or high-pressure carbon dioxide gas can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] In explaining the details of the present invention, specific examples will be given for explanation. However, it is not limited to the following content as long as it does not deviate from the gist of the present invention, and can be appropriately changed and implemented.

[0010] 1. Method for Producing Carbamate The method for producing a carbamate according to an embodiment of the present invention includes a reaction step (hereinafter, may be abbreviated as "reaction step") of reacting a monosubstituted carbonate salt, a metal alkoxide, and an amine compound to produce a carbamate.

[0011] Examples of the reaction for producing a carbamate from a monosubstituted carbonate salt, a metal alkoxide, and an amine compound include the following reactions.

[0012]

Chemical formula

[0013] According to the present embodiment, a carbamate can be produced without using a sacrificial reagent or a halogenated alkyl that is poor in environmental compatibility. In the present embodiment, high-pressure gas equipment is not required, and a carbamate can be produced at low cost and simply. Further, not only aliphatic carbamates but also aromatic carbamates can be produced. Furthermore, as will be described later, according to the present embodiment, a monosubstituted carbonate salt can be produced using a low-concentration carbon dioxide-containing gas as a raw material, and a carbamate can be produced using the same as a raw material, enabling effective utilization of low-concentration carbon dioxide contained in exhaust gas and the like. So far, no studies have been reported on the synthesis of carbonate salts from low-concentration carbon dioxide gas and the use of the same as a CO2 source in organic synthesis. In the present embodiment, since a metal alkoxide that can be regenerated with alcohol is used, substantially only low-concentration carbon dioxide, an amine compound, and alcohol are consumed, and it is possible to realize the production of a carbamate excellent in environmental compatibility. Hereinafter, the method for producing a carbamate according to the present embodiment will be described in detail.

[0014] As the present embodiment, a method for producing a carbamate in which the monosubstituted carbonate salt is a compound represented by formula (1), the amine compound is a compound represented by formula (2), the metal alkoxide is a compound represented by formula (3), and the carbamate is a compound represented by formula (4) is preferable.

[0015] [Chemical formula] (In the above formula, R 0 is a substituted or unsubstituted n-valent hydrocarbon group; R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group; R 2 are each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; R 3 are each independently a substituted or unsubstituted hydrocarbon ligand, amide ligand, or halide ligand; M is a metal atom; Am+ is an m-valent cation derived from the base represented by A; n is 1 or 2; m is 1 or 2; p represents the formal oxidation number of M and is an integer from 1 to 6; (p - q) is an integer from 1 to 6; q is an integer greater than or equal to 0 and less than or equal to (p - 1). In the formula (4), R 1 is the R in the formula (1) 1 or the R in the formula (3) 1 and is derived from the R in the formulas (1) and (3). When there are multiple types of R 1 in the formulas (1) and (3), the compound represented by the formula (4) is obtained as a mixture of compounds having each R 1 .)

[0016] 1-1. Monosubstituted carbonate salt The monosubstituted carbonate salt is not particularly limited, but the compound represented by the general formula (1) is preferably mentioned.

Chemical formula

[0017] (R 1 ) R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group. In this specification, the "hydrocarbon group" is not limited to a linear saturated hydrocarbon group, and may have a carbon-carbon unsaturated bond, a branched structure, or a cyclic structure. It may also be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. R 1 The number of carbon atoms of is not particularly limited, but is usually 1 or more, and is usually 30 or less, preferably 24 or less, more preferably 20 or less.

[0018] R 1 Examples of the aliphatic hydrocarbon group represented by include a methyl group, an ethyl group, n-prop Alkyl groups such as methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-docosyl group; cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group; alkenyl groups such as vinyl group, allyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 2-methylallyl group, 1-pentinyl group, 1-hexenyl group, 1-heptenyl group, 1-octenyl group, 2-methyl-1-propenyl group; alkynyl groups such as propargyl group; may be mentioned. Examples of the aromatic hydrocarbon group include phenyl group, 1-naphthyl group, 2-naphthyl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 1-triphenylenyl group, 2-triphenylenyl group.

[0019] R 1When the hydrocarbon group represented by has a substituent, examples of the substituent include a deuterium atom; an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group; a cycloalkyl group having 3 to 4 carbon atoms such as a cyclopropyl group and a cyclobutyl group; an aromatic hydrocarbon group having 6 to 10 carbon atoms such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; a halogeno group such as a fluoro group, a chloro group, a bromo group, and an iodo group; an oxygen-containing functional group such as an alkoxy group, a carboxy group, a carbonyl group, and a hydroxyl group; a nitrogen-containing functional group such as a cyano group; a sulfur-containing functional group such as an alkylthio group; a functional group containing an oxygen atom and a nitrogen atom such as an amide group, an imide group, a urea group, a group containing a urethane structure, a group containing an isocyanuric structure, a nitro group, a nitroso group, a cyanate group, an isocyanate group, and a morpholino group; a heterocyclic group such as an oxygen-containing heterocyclic group such as a furanyl group, a sulfur-containing heterocyclic group such as a thienyl group, and a nitrogen-containing heterocyclic group such as a pyrrolyl group and a pyridyl group; and the like.

[0020] R 1 When the hydrocarbon group represented by has a substituent, R 1 Examples of preferably include an alkyl-substituted phenyl group such as a 2-methylphenyl group, a 3-methylphenyl group, and a 4-methylphenyl group; an alkoxy-substituted phenyl group such as a 2-methoxyphenyl group, a 3-methoxyphenyl group, and a 4-methoxyphenyl group; a halogen-substituted phenyl group such as a 2-chlorophenyl group, a 3-chlorophenyl group, a 4-chlorophenyl group, a 2-bromophenyl group, a 3-bromophenyl group, and a 4-bromophenyl group; a nitro-substituted phenyl group such as a 4-nitrophenyl group and a 2-nitrophenyl group; an aralkyl group such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, and a 2-naphthylmethyl group; a cycloalkylalkyl group such as a cyclohexylmethyl group; a hydrocarbon group having an oxygen-containing heterocyclic ring such as a furfuryl group; a hydrocarbon group having a sulfur-containing heterocyclic ring such as a thienylmethyl group; a hydrocarbon group having a nitrogen-containing heterocyclic ring such as a pyridylmethyl group; and the like. In the case of a hydrocarbon group being a branched alkyl group or the like, the number of carbon atoms in the main chain is defined as the number of carbon atoms in the hydrocarbon group. Further, when the hydrocarbon group has a substituent, the number of carbon atoms means the total number of carbon atoms of the carbon atoms in the substituent and the hydrocarbon group.

[0021] R 1 is preferably a monovalent group selected from a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms. Alternatively, R 1 is, from the viewpoint of easy availability of raw materials, preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 24 carbon atoms; more preferably a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 24 carbon atoms, a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 24 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 24 carbon atoms, or a heterocyclic group such as a substituted or unsubstituted nitrogen-containing heterocyclic ring; still more preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted pyridyl group. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, a cyano group, a halogeno group, or a nitro group is preferable from the viewpoint of the usefulness of the resulting complex. Further, as the substituted phenyl group, an alkyl-substituted phenyl group such as a 2-methylphenyl group, a 4-methylphenyl group, or a 2,4-dimethylphenyl group; an alkoxy-substituted phenyl group such as a 4-methoxyphenyl group or a 2-methoxyphenyl group; a halogen-substituted phenyl group such as a 2-chlorophenyl group, a 4-chlorophenyl group, or a 2,4-dichlorophenyl group; a nitro-substituted phenyl group such as a 4-nitrophenyl group or a 2-nitrophenyl group; is preferable.

[0022] (A m+ , m) A m+ is an m-valent cation derived from the base represented by A. Further, m is 1 or 2, and preferably 1. A m+Although not particularly limited, for example, cations selected from the group consisting of ammonium cations, amidinium cations, guanidinium cations, phosphonium cations, phosphazenium cations, carbocations, alkali metal cations, or alkaline earth metal cations are preferred.

[0023] 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; quaternary ammonium cations such as tetramethylammonium cation, phenyltrimethylammonium cation, tetrabutylammonium cation, etc. Examples of amidinium cations include formamidinium cation, acetamidinium cation, 1,5-diazabicyclo[4.3.0]non-5-ene, and 1,8-diazabicyclo[5.4.0]undec-7-ene, each protonated, 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, as well as derivatives thereof having one or more substituents. Examples of the substituents include hydrocarbon groups such as the alkyl group, cycloalkyl group, and aromatic hydrocarbon group exemplified in the description of item (R 1 ) and the like. Examples of guanidinium cations include 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, each protonated, 1,1,3,3-tetramethylguanidinium cation, 2-tert-butyl-1,1,3,3-tetramethylguanidinium cation, 1,5,7-triaza and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium cation, as well as derivatives thereof having one or more substituents. Examples of the substituents include those described in item (R1 Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, and an aromatic hydrocarbon group, etc., as exemplified in the description of .

[0024] Examples of the phosphonium cation include tertiary phosphonium cations such as a triphenylphosphonium cation and a tri-tert-butylphosphonium cation; quaternary phosphonium cations such as a tetraphenylphosphonium cation, a tetra-p-tolylphosphonium cation, a triphenylbenzylphosphonium cation, a triphenylbutyl cation, a tetraethylphosphonium cation, and a tetrabutylphosphonium cation. Examples of the phosphazenium cation include tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorin, 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)phosphoranilideneamino]-2λ 5 ,4λ 5 -catenadi(phosphazene), which are protonated 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)phosphoranilideneamino]-2λ 5 ,4λ 5- Examples include a - cathenadi (phosphazene) onium cation and derivatives thereof having one or more substituents. Examples of the substituent include hydrocarbon groups such as the alkyl group, cycloalkyl group, and aromatic hydrocarbon group exemplified in the description of item (R 1 ).

[0025] Examples of the carbocation include monovalent carbocations such as triphenylmethyl cation, tropylium cation, and azulenium cation.

[0026] Examples of the alkali metal cation include lithium cation, sodium cation, potassium cation, etc. Examples of the alkaline earth metal cation include magnesium cation, calcium cation, etc.

[0027] From the viewpoints of ease of obtaining raw materials and the yield of the carbamate, it is preferably an ammonium cation, amidinium cation, guanidinium cation, phosphonium cation, phosphazenium cation, or carbocation, more preferably an ammonium cation, amidinium cation, guanidinium cation, phosphonium cation, or phosphazenium cation. Among them, an ammonium cation or an amidinium cation is preferable.

[0028] Specific examples of the compound represented by formula (1) include compounds represented by the following formulas and their counter cations being 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, such as amidinium salts, guanidinium salts, phosphonium salts, phosphazenium salts, carbocation salts, alkali metal salts, or alkaline earth metal salts, but are not limited thereto.

[0029]

Chemical formula

[0030] (Method for producing a monosubstituted carbonate salt) In the present embodiment, a commercially available product may be used as the monosubstituted carbonate salt, or it may be synthesized and used, but it is preferable to synthesize and use the monosubstituted carbonate salt. Specifically, it includes a step of generating a monosubstituted carbonate salt by bringing an alcohol, a base, and a carbon dioxide-containing gas into contact with each other, and the total pressure of the carbon dioxide-containing gas is P t is defined as, and the carbon dioxide partial pressure of carbon dioxide gas in the containing gas is P CO2 is defined as, and P CO2 / P t is 0.0001 or more and 1 or less, and it is preferable to produce it by a method for producing a monosubstituted carbonate salt in which P CO2 is less than 0.1 MPa.

[0031] As the above method for producing a monosubstituted carbonate salt, a method for producing a monosubstituted carbonate salt in which the alcohol is a compound represented by the formula (1') and the monosubstituted carbonate salt is a compound represented by the formula (1) is preferable.

[0032] [Chemical formula] (In the above formula, R 1 is a substituted or unsubstituted monovalent hydrocarbon group, A is a base, A m+ is an m-valent cation derived from the base, and m is 1 or 2.)

[0033] [Alcohol] The alcohol is not particularly limited, but when synthesizing a monosubstituted carbonate salt represented by the formula (1), a compound represented by the formula (1') is used. R 1 OH (1')[[]END] (In the above formula, R 1 is a substituted or unsubstituted monovalent hydrocarbon group.)

[0034] (R1 ) R 1 is a substituted or unsubstituted monovalent hydrocarbon group and is synonymous with R in the monosubstituted carbonate salt represented by formula (1). 1 is synonymous with. Specific examples of the alcohol include, for example, methanol, ethanol, 1-propanol (n-propyl alcohol), 2-propanol (isopropyl alcohol), 1-butanol (n-butyl alcohol), 2-butanol (sec-butyl alcohol), tert-butyl alcohol, isobutyl alcohol (2-methylpropyl alcohol), 1-pentanol (n-pentyl alcohol), 2-pentanol (sec-amyl alcohol), 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol (isoamyl alcohol), 2-methyl-2-butanol (tert-amyl alcohol), 3-methyl-2-butanol, 2,2-dimethyl-1-propanol (neopentyl alcohol), allyl alcohol, crotyl alcohol (2-buten-1-ol), cinnamyl alcohol (3-phenyl-1-propanol), methallyl alcohol (2-methyl-1-propanol), 3-buten-2-ol, 2-cyclohexen-1-ol, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, phenol, and the like.

[0035] The amount of alcohol used (charged amount) is usually preferably m × 1.0 molar equivalent or more with respect to 1.0 molar equivalent of the amount of base used (charged amount) (m is synonymous with m in formula (1)). From the viewpoint of improving the reaction rate, it is more preferably m × 1.3 molar equivalent or more, and still more preferably m × 1.5 molar equivalent or more.

[0036] <Base The base is not particularly limited, but a base represented by A m+ which can be a cation source represented by is preferred. The base represented by A is preferably at least one selected from the group consisting of organic bases, alkali metal salts, and alkaline earth metal salts. is preferably at least one selected from the group consisting of.

[0037] Examples of the organic base include primary amines such as methylamine, ethylamine, isopropylamine, n-butylamine, and 2-hydroxyethylamine; secondary amines such as dimethylamine, diethylamine, and dicyclohexylamine; tertiary amines such as trimethylamine and triethylamine; quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, phenyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, and tetrabutylammonium fluoride; formamidine, acetamidine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,1,3,3-tetramethylguanidine, 2-tert-butyl-1,1,3,3-tetramethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, triphenylphosphine, tri-tert-butylphosphine, tetraphenylphosphine, tetra-p-tolylphosphine, triphenylbenzylphosphine, triphenylbutylphosphine, tetraethylphosphine, tetrabutylphosphine, tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorin, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ 5 ,4λ 5 -catenadi(phosphazene), 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranilideneamino]-2λ 5 ,4λ 5- Organic bases such as catechadi(phosphazene), triphenylmethyl chloride, triphenylmethanol, 1,3,5-cycloheptatriene, azulene, etc. can be mentioned.

[0038] Examples of the alkali metal salts include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, potassium carbonate, lithium methoxide, sodium methoxide, potassium methoxide, lithium ethoxide, sodium ethoxide, potassium ethoxide, etc. Examples of the alkaline earth metal salts include magnesium hydroxide, calcium hydroxide, etc.

[0039] <Carbon dioxide-containing gas> For the production of the monosubstituted carbonate salt, a carbon dioxide-containing gas containing carbon dioxide (gas) as a raw material is used. In the step of producing the monosubstituted carbonate salt, the total pressure of the carbon dioxide-containing gas is P t and the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas is P CO2 such that P CO2 / P t is 0.0001 or more and 1 or less, and the P CO2 is less than 0.1 MPa. The ratio (P CO2 / P t ) of the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas to the total pressure of the carbon dioxide-containing gas is preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.05 or more, particularly preferably 0.10 or more, and is preferably 0.80 or less, more preferably 0.70 or less, still more preferably 0.60 or less, particularly preferably 0.50 or less, and most preferably 0.30 or less. P t The total pressure of the carbon dioxide-containing gas represented by is preferably 0.01 MPa or more, more preferably 0.05 MPa or more, still more preferably 0.08 MPa or more, and is preferably 0.20 MPa or less, more preferably 0.15 MPa or less, still more preferably 0.13 MPa or less, particularly preferably 0.11 MPa or less. P CO2The partial pressure of the carbon dioxide gas represented by is less than 0.1 MPa, preferably . 07 MPa or less, more preferably 0.05 MPa or less, still more preferably 0.03 MPa or less, and particularly preferably 0.02 MPa or less. Also, it is preferably 0.001 MPa or more, more preferably 0.005 MPa or more, and still more preferably 0.01 MPa or more. As the carbon dioxide-containing gas, not only the one prepared as an industrial gas but also the carbon dioxide-containing mixed gas separated and recovered from the exhaust gas from factories, power plants, etc. can be used.

[0040] <Reaction conditions, etc.> The step of bringing the alcohol, the base, and the carbon dioxide-containing gas into contact with each other can be specifically carried out, for example, as follows. First, the raw material alcohol and base are added to the reaction vessel. At this time, it is preferably carried out under an inert gas atmosphere such as nitrogen or argon. After adding the alcohol and base to the reaction vessel, the carbon dioxide-containing gas is continuously supplied into the reactor, and for example, the reaction is carried out at room temperature for 10 to 20 minutes. When using a solvent, it may be added to the reaction vessel before introducing carbon dioxide into the reactor, or it may be added to the reactor simultaneously with the alcohol or the like. Also, during the reaction, stirring is preferably carried out, for example, a magnetic stirrer can be used. After the reaction, it is cooled, the remaining gas is discharged, and then the reaction product is recovered.

[0041] The reaction apparatus used in the reaction process is not particularly limited, but an apparatus capable of continuously supplying a carbon dioxide-containing gas to a mixture of an alcohol and a base is preferred. FIG. 1 is a conceptual diagram (cross-sectional view) of the reaction apparatus used in the present embodiment. The reaction apparatus shown in FIG. 1 mainly comprises a reaction vessel 1, a carbon dioxide-containing gas supply pipe 3 for supplying a carbon dioxide-containing gas, and a discharge pipe 4 for discharging the gas 5 in the reaction vessel. The reaction vessel 1 is not particularly limited as long as it is formed of a material stable against a monosubstituted carbonate salt. The reaction vessel 1 preferably has a volume 1.5 times to 100 times the volume of the reaction mixture 2 containing an alcohol, a base, and, if necessary, a solvent. Further, the reaction apparatus may be provided with a magnetic stirrer for stirring during the reaction.

[0042] (Reaction temperature) The reaction temperature in the monosubstituted carbonate salt formation step is not particularly limited, but is usually 1°C or higher and 50°C or lower, and preferably room temperature from the viewpoint of economy. In the present specification, room temperature means 1°C to 30°C.

[0043] (Reaction time) The reaction time in the monosubstituted carbonate salt formation step is not particularly limited and may be appropriately adjusted according to the reaction temperature, reaction scale, etc. Usually, it is 5 minutes or longer, preferably 10 minutes or longer, and usually 48 hours or shorter, preferably 24 hours or shorter, more preferably 20 hours or shorter, and still more preferably 3 hours or shorter. In the monosubstituted carbonate salt formation step, the "reaction time" is defined as the carbon dioxide-containing gas supply time during which the carbon dioxide-containing gas is continuously supplied into the reaction vessel.

[0044] (Solvent) The monosubstituted carbonate salt formation step may or may not use a solvent. From the viewpoint of achieving monosubstituted carbonate salt formation under milder conditions, for example, enabling shortening of the reaction time, etc., it is preferable not to use a solvent. Note that "not using a solvent" means not using a solvent separate from the reaction reagent. For example, when using a reaction substrate such as an alcohol as a solvent, it is considered a condition of not using a solvent.

[0045] The type of reaction solvent is not particularly limited. For example, aliphatic hydrocarbons such as butane, hexane, octane, cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene; 1,4- ethers such as dioxane, diethyl ether; and other non-polar solvents. Also, protic polar solvents such as carboxylic acids; aprotic polar solvents such as tertiary carboxylic acid amides, sulfoxides, ketones, lactones, lactams, nitriles, urea derivatives, sulfones, carboxylic acid esters, carbonic acid esters; and other polar solvents. As the reaction solvent, a polar solvent is preferred. As the protic polar solvent, for example, carboxylic acids such as formic acid, acetic acid can be mentioned. Also, as the aprotic polar solvent, tertiary carboxylic acid amides; sulfoxides such as dimethyl sulfoxide; ketones such as acetone, isopropyl ketone; lactones such as γ-butyrolactone; lactams such as N-methylpyrrolidone (NMP); nitriles such as acetonitrile, propionitrile, butyronitrile, benzonitrile, 2-cyanopyridine; urea derivatives; sulfones; carboxylic acid esters such as ethyl acetate; carbonic acid esters can be mentioned. Among them, from the viewpoints of improving the reaction rate, ease of availability, and price, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone are preferred, and N-methylpyrrolidone is more preferred. One type of reaction solvent may be used, or two or more types may be used.

[0046] The amount of the reaction solvent used is not particularly limited, but it is usually 0.5 times or more, preferably 1.0 times or more, more preferably 1.5 times or more, based on the volume of the base, and can usually be used up to 20 times, preferably 15 times or less, more preferably 10 times or less.

[0047] (Other steps) In the method for producing a mono-substituted carbonate salt, in addition to the above mono-substituted carbonate salt formation step, optional steps may be included. Examples of the optional steps include a purification step for increasing the purity of the mono-substituted carbonate salt. In the purification step, purification methods commonly used in the field of organic synthesis, such as filtration, adsorption, column chromatography, distillation, etc., can be employed.

[0048] 1-2. Amine compound The amine compound is not particularly limited, but compounds represented by the general formula (2) are preferably mentioned. R 0 (NHR 2 ) n (2) (In the above formula, R 0 is a substituted or unsubstituted n-valent hydrocarbon group; R 2 are each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; n is 1 or 2.)

[0049] (R 0 , n) R 0 is a substituted or unsubstituted n-valent hydrocarbon group, and n is 1 or 2.

[0050] When n is 1, examples of the unsubstituted monovalent hydrocarbon group represented by R 0 include those exemplified by R 1 . When n is 2, R 1Examples of the unsubstituted divalent hydrocarbon group represented by include a methylene group; an ethylene group; a linear, branched or cyclic alkylene group having 3 or more carbon atoms; or an arylene group having 6 or more carbon atoms. Specifically, a methylene group, an ethylene group, a tetramethylethylene group, an n-propylene group (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 (tetramethylene group), a 2-methyl-1,4-butylene group, a 3-methyl-1,4-butylene group, a 2,2-dimethyl-1,4-butylene group, a 2,3-dimethyl-1,4-butylene group, a 2,2,3-trimethyl-1,4-butylene group, an n-pentylene group (pentamethylene group), an n-hexanylene group (hexamethylene group) and other chain hydrocarbon groups; an alicyclic hydrocarbon group such as a 1,4-cyclohexylene group, a 1,4-phenylene group obtained by removing two hydrogen atoms from a benzene ring, a 1,2-phenylene group, a 1,3-phenylene group; a dimethylphenylene group (xylyl group) obtained by removing two hydrogen atoms from the benzene ring of xylene, a methylphenylene group (tolylene group) obtained by removing two hydrogen atoms from the benzene ring of toluene, an aromatic hydrocarbon group such as a naphthanylene group obtained by removing two hydrogen atoms from naphthalene, a divalent group composed of an aliphatic hydrocarbon group and an aromatic hydrocarbon group such as a 1,4-phenylenebis(methylene) group, a 1,4-phenylenebis(ethylene) group, a group obtained by removing one hydrogen atom from each of the two benzene rings of biphenyl, a group obtained by removing one hydrogen atom from each of the two benzene rings of diphenylmethane; a divalent group obtained by removing two hydrogen atoms from a polycyclic aromatic hydrocarbon such as a fluorene ring; and the like.

[0051] From the viewpoints of ease of obtaining raw materials and usefulness of the carbamate, R 0 is preferably a monovalent or divalent group selected from a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms. R 0is more preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent or divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group such as a nitrogen-containing heterocyclic ring, a substituted or unsubstituted phenylene group, a substituted or unsubstituted divalent group having 7 to 20 carbon atoms composed of an aliphatic hydrocarbon group and an aromatic hydrocarbon group; more preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted phenylene group, a substituted or unsubstituted divalent group having 7 to 24 carbon atoms composed of an aliphatic hydrocarbon group and an aromatic hydrocarbon group, a substituted or unsubstituted pyridyl group. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, a cyano group, a halogeno group, or a nitro group is preferable from the viewpoint of the usefulness of the resulting complex. Further, as the substituted phenyl group, an alkyl-substituted phenyl group such as a 2-methylphenyl group, a 4-methylphenyl group, or a 2,4-dimethylphenyl group; an alkoxy-substituted phenyl group such as a 4-methoxyphenyl group or a 2-methoxyphenyl group; a halogen-substituted phenyl group such as a 2-chlorophenyl group, a 4-chlorophenyl group, or a 2,4-dichlorophenyl group; a nitro-substituted phenyl group such as a 4-nitrophenyl group or a 2-nitrophenyl group; is preferable.

[0052] (R 2 ) R 2 is each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. R 2 Examples of the unsubstituted monovalent hydrocarbon group represented by are those exemplified by R 1 . R 2 When the hydrocarbon group represented by has a substituent, examples of the substituent include those exemplified as the substituent of the hydrocarbon group represented by R 1 . Said R 2is preferably a monovalent group selected from a hydrogen atom, a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, and more preferably a hydrogen atom. Also, when n is 2, the two Rs 2 may be the same or different, but are preferably the same.

[0053] The compound represented by the general formula (2) may be a monoamine compound or a diamine compound. Examples of the monoamine compound preferably include aniline or an aniline derivative, 4-aminopyridine, 1-aminohexane, and cyclohexylamine. Examples of the aniline derivative include o-anisidine, m-anisidine, p-anisidine, 4-vinylaniline, 4-nitroaniline, 4-bromoaniline, 4-fluoroaniline, 4- cyanoaniline, 4-cyanoaniline, p-toluidine, 4-chloroaniline, 4-bromoaniline or 4-fluoroaniline are preferably mentioned. Examples of the diamine compound preferably include 4,4'-methylenedianiline, 2,4-tolylenediamine and 1,6-hexyldiamine and derivatives thereof. The usage amount (charged amount) of the amine compound is not particularly limited, but is usually 1 equivalent or more, preferably 1.5 equivalents or more, more preferably 2.5 equivalents or more, still more preferably 3 equivalents or more, and usually 20 equivalents or less, preferably 15 equivalents or less, more preferably 10 equivalents or less, based on 1 equivalent of the monosubstituted carbonate salt.

[0054] 1-3. Metal alkoxide The metal alkoxide is not particularly limited, but a compound represented by the general formula (3) is preferably mentioned. M(OR 1 ) p-q (R 3 ) q (3) (In the above formula, R 1is, independently of each other, a substituted or unsubstituted monovalent hydrocarbon group; R 3 is, independently of each other, a substituted or unsubstituted hydrocarbon ligand, amide ligand, or halide ligand; M is a metal atom; p represents the formal oxidation number of M and is an integer from 1 to 6; (p - q) is an integer from 1 to 6; q is an integer of 0 or more and (p - 1) or less. )

[0055] (R 1 ) R 1 is, independently of each other, a substituted or unsubstituted monovalent hydrocarbon group, and is synonymous with R 1 in the monosubstituted carbonate salt represented by formula (1). Thus, the compound represented by general formula (3) can be a renewable alkoxide source. When (p - q) is from 2 to 6, a plurality of R 1 may be the same or different, but from the viewpoint of ease of obtaining the metal alkoxide, it is preferable that all R 1 are the same.

[0056] (M) M is a metal atom. In the present specification, "metal" shall be a concept including semimetals such as silicon and boron. The type of metal atom is not particularly limited, and examples thereof include metal atoms selected from the group consisting of silicon, titanium, zirconium, germanium, indium, tin, tantalum, zinc, and tungsten. Among them, from the viewpoint of ease of obtaining, silicon or titanium is preferable, and titanium is more preferable.

[0057] (R 3 ) R 3 is, independently of each other, a substituted or unsubstituted hydrocarbon ligand, amide ligand, or halide ligand.

[0058] Examples of hydrocarbon ligands without substitution include alkyl ligands such as methyl ligand and ethyl ligand; cycloalkyl ligands such as cyclohexyl ligand; aryl ligands such as phenyl ligand and naphthyl ligand; aralkyl ligands such as benzyl ligand; unsaturated hydrocarbon ligands such as cyclopentadienyl ligand, cyclohexadienyl ligand, cyclooctadienyl ligand, cyclooctatetraenyl ligand, norbornadienyl ligand, methylcyclopentadienyl ligand, methylcyclohexadienyl ligand, methylcyclooctadienyl ligand, and methylcyclooctatetraenyl ligand; and the like. Examples of substituents that the hydrocarbon ligand may have include, for example, hydroxy group, ester group (-COOR), amide group (-CONRR'), halogen atom, alkylthio group (-SR), amino group (-NRR'), carboxy group, nitro group, sulfonic acid group (-SO3H), oxygen-containing heterocyclic groups such as furanyl group, sulfur-containing heterocyclic groups such as thienyl group, and nitrogen-containing heterocyclic groups such as pyridyl group.

[0059] Examples of amide ligands include unsubstituted amide ligand (NH2), methylamide ligand (NHMe), dimethylamide ligand (NMe2), diethylamide ligand (NEt2), di-n-propylamide ligand (NPr2), isopropylamide ligand, di-n-butylamide ligand, di-t-butylamide ligand, and the like.

[0060] Examples of halide ligands include fluoride ligand, chloride ligand, bromide ligand, iodide ligand, and the like.

[0061] When p is 2 to 5, a plurality of R 3 may be the same or different, but from the viewpoint of ease of obtaining the metal alkoxide, it is preferable that all R 3 are the same.

[0062] (p) p represents the formal oxidation number of M. p is an integer from 1 to 6, preferably from 2 to 4. Also, (p - q) is an integer from 1 to 6.

[0063] (q) q represents an integer of 0 or more and (p - 1) or less. That is, q is an integer from 0 to 5. q is particularly preferably 0.

[0064] Specific examples of the metal alkoxide represented by formula (3) include tetramethoxysilane, tetraethoxysilane, tetra(n-propoxy)silane, tetra(iso-propoxy)silane, tetra(n-butoxy)silane, tetra(2-butoxy)silane, tetra(t-butoxy)silane, trimethoxy(iso-propoxy)silane, trimethoxy(n-butoxy)silane, trimethoxy(2-butoxy)silane, trimethoxy(t-butoxy)silane, trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, cyclohexyltripropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, dimethoxydiethylsilane, diethoxydiethylsilane, dimethoxymethylvinylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane and other alkoxysilanes; Tetramethoxytitanium (titanium tetramethoxide), tetraethoxytitanium, tetraallyloxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium (titanium tetra-iso-propoxide), tetra-n-butoxytitanium (titanium tetra-n-butoxide), tetraisobutoxytitanium, tetra-sec-butoxytitanium, tetra-t-butoxytitanium (titanium tetra-t-butoxide), tetra-n-pentyloxytitanium, tetracyclopentyloxytitanium, tetrahexyloxytitanium, tetracyclohexyloxytitanium, tetrabenzyloxytitanium, tetraoctyloxytitanium, tetrakis(2-ethylhexyloxy)titanium, tetradecyloxytitanium, tetradodecyloxytitanium, tetrastearyloxytitanium, tetrakis(8-hydroxyoctyloxy)titanium, diisopropoxybis(2-ethyl-1,3-hexanediolato)titanium, bis(2-ethylhexyloxy)bis(2-ethyl-1,3-hexanediolato)titanium, tetrakis(2-chloroethoxy)titanium, tetrakis(2-bromoethoxy)titanium, tetrakis(2-methoxyethoxy)titanium, tetrakis(2-ethoxyethoxy)titanium, butoxytrimethoxytitanium, dibutoxydimethoxytitanium, butoxytriethoxytitanium, dibutoxydiethoxytitanium, butoxytrisopropoxytitanium, dibutoxydiisopropoxytitanium, tetraphenoxytitanium, tetrakis(o-chlorophenoxy)titanium, tetrakis(m-nitrophenoxy)titanium, tetrakis(p-methylphenoxy)titanium, tetrakis(trimethylsilyloxy)titanium, triethoxytitanium, trimethoxytitanium, triisopropoxytitanium, tributoxytitanium, methyldimethoxytitanium, ethyltriethoxytitanium, methyltriisopropoxytitanium, tetradimethylaminotitanium, dimethyltitanium diacetylacetonate, ethyltitanium triacetylacetonate and other titanium alkoxides; Alkoxyzirconiums such as tetramethoxyzirconium, tetraethoxyzirconium, tetraallyloxyzirconium, tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetraisobutoxyzirconium, tetra-sec-butoxyzirconium, tetra-t-butoxyzirconium, tetra-n-pentyloxyzirconium, tetracyclopentyloxyzirconium, tetrahexyloxyzirconium, tetracyclohexyloxyzirconium, tetrabenzyloxyzirconium, tetraoctyloxyzirconium, tetrakis(2-ethylhexyloxy)zirconium, tetradecyloxyzirconium, tetradodecyloxyzirconium, tetrastearyloxyzirconium, tetrakis(8-hydroxyoctyloxy)zirconium, diisopropoxybis(2-ethyl-1,3-hexanedionato)zirconium, bis(2-ethylhexyloxy)bis(2-ethyl-1,3-hexanedionato)zirconium, tetrakis(2-chloroethoxy)zirconium, tetrakis(2-bromoethoxy)zirconium, tetrakis(2-methoxyethoxy)zirconium, tetrakis(2-ethoxyethoxy)zirconium, butoxytrimethoxyzirconium, dibutoxydimethoxyzirconium, butoxytriethoxyzirconium, dibutoxydiethoxyzirconium, butoxytrisopropoxyzirconium, dibutoxydisisopropoxyzirconium, tetraphenoxyzirconium, tetrakis(o-chlorophenoxy)zirconium, tetrakis(m-nitrophenoxy)zirconium, tetrakis(p-methylphenoxy)zirconium; Alkoxygermaniums such as tetraethoxygermanium, tetrapropoxygermanium, tetraisopropoxygermanium, tetra(n-butoxy)germanium, tetra(2-butoxy)germanium, tetra(t-butoxy)germanium; Alkoxy indiums such as tetra(n-butoxy)indium, tetra(2-butoxy)indium, tetra(t-butoxy)indium, trimethoxyindium, triethoxyindium, tri(n-propoxy)indium, triisopropoxyindium, tri(n-butoxy)indium, triisobutoxyindium, tri(t-butoxy)indium, tri(s-butoxy)indium; Alkoxy tins such as dibutyldimethoxysn, dibutyldiethoxysn, dibutyldipropoxysn; Alkoxy tantalums such as tetramethoxytantalum, tetraethoxytantalum, tetra(n-propoxy)tantalum, tetraisopropoxytantalum, tetra(n-butoxy)tantalum, tetra(2-butoxy)tantalum, tetra(t-butoxy)tantalum, pentaethoxytantalum; Alkoxy zincs such as isopropoxy zinc, tetra(n-butoxy)zinc, tetra(2-butoxy)zinc, tetra(t-butoxy)zinc; Alkoxy tungstens such as pentamethoxytungsten, pentaethoxytungsten, pentaisopropoxytungsten, tungsten(V) pentabutoxytungsten, triisobutoxytungsten, tri(t-butoxy)tungsten; may be mentioned.

[0065] As the metal alkoxide represented by the formula (3), from the viewpoint of easy availability, it is preferably at least one selected from the group consisting of titanium alkoxide and alkoxysilane, more preferably titanium tetramethoxide, titanium tetra-iso-propoxide, titanium tet ra-n-butoxide, titanium tetra-t-butoxide, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, and still more preferably titanium tetramethoxide, titanium tetra-iso-propoxide, titanium tetra-n-butoxide, titanium tetra-t-butoxide, tetramethoxysilane.

[0066] In this embodiment, a metal alkoxide may be introduced into the reaction system, or a metal alkoxide may be generated and used in the reaction system. For example, a method of reacting zirconium tetrachloride (ZrCl4) with sodium ethoxide to generate tetraethoxyzirconium can be mentioned. Further, a method of reacting zirconocene dichloride (Cp2ZrCl2) with sodium ethoxide to generate zirconocene diethoxide can be mentioned. Further, a method of reacting dibutyltin dichloride (Bu2SnCl2) with sodium ethoxide to generate dibutyltin diethoxide can be mentioned.

[0067] (Catalyst) In this embodiment, the reaction step may be carried out in the presence of a catalyst. In particular, when an alkoxysilane is used as the metal alkoxide, the reaction step is preferably carried out in the presence of a catalyst. Examples of the catalyst preferably include organic base carboxylates, alkali metal salts, zinc compounds, titanium(IV) compounds, and zirconium(IV) compounds (however, compounds corresponding to the above metal alkoxides are excluded).

[0068] Examples of the organic base carboxylate include acetate of 1,8-diazabicyclo[5.4.0]undec-7-ene, acetate of 1,5-diazabicyclo[4.3.0]non-5-ene, nitrate of 1,1,3,3-tetramethylguanidine, and the like. Examples of the alkali metal salt 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. Examples of zinc compounds include zinc halides such as zinc chloride and zinc bromide; zinc sulfate; zinc sulfonates such as zinc p-toluenesulfonate and zinc trifluoromethanesulfonate; zinc formate, zinc acetate, zinc propionate, zinc octanoate, zinc salicylate, zinc pivalate, zinc acrylate, p-chlorobenzoic acid, zinc phenolate, zinc chloroacetate, zinc acetylacetonate, zinc oxalate, and zinc trifluoroacetate, and carboxylic acid zinc derivatives such as zinc(II)-1,10-phenanthroline complex. Examples of titanium(IV) compounds include titanium(IV)oxysulfate·n hydrate, TiCl4, TiBr4, etc. Examples of zirconium(IV) compounds include zirconium(IV) chloride and zirconium(IV)oxychloride·octahydrate.

[0069] The catalyst may be formed from and used with, for example, two or more compounds. For example, zinc acetate and 1,10-phenanthroline may be introduced into a reaction vessel to form a zinc(II)-1,10-phenanthroline (phen) complex and used as a catalyst. Among them, zinc compounds such as zinc acetate, zinc pivalate, zinc(II)-1,10-phenanthroline (phen) complex, zinc p-toluenesulfonate, and zinc trifluoromethanesulfonate are preferred, and zinc acetate and zinc(II)-1,10-phenanthroline (phen) complex are more preferred.

[0070] The amount of the catalyst used (charged amount) in the reaction step is not particularly limited and should be appropriately selected according to, for example, the monosubstituted carbonate salt, etc., but is preferably 1 mol% or more and 70 mol% or less, more preferably 50 mol% or less, based on the amount of substance of the monosubstituted carbonate salt. Also, one type of catalyst may be used, or two or more types may be used.

[0071] 1-4. Carbamic acid ester The carbamic acid ester produced according to this embodiment is not particularly limited and may be determined according to the purpose. In the production method according to this embodiment, when a compound represented by the formula (1) is used as the monosubstituted carbonate salt, a compound represented by the formula (2) is used as the amine compound, and a compound represented by the formula (3) is used as the metal alkoxide, a carbamate represented by the general formula (4) can be produced.

[0072]

Chemical formula

[0073] (In the above formula, R 0 is a substituted or unsubstituted n-valent hydrocarbon group; R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group; R 2 are each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; n is 1 or 2.) In the formula (4), R 0 is synonymous with R 0 in the formula (2). In the formula (4), R 1 is synonymous with R 1 in the formulas (1) and (3). In the formula (4), R 2 is synonymous with R 2 in the formula (2). In the formula (4), R 3 is synonymous with R 3 in the formula (3). In the formula (4), n is synonymous with n in the formula (2).

[0074] Examples of the carbamate represented by the formula (4) include the following compounds.

Chemical formula

[0075] 1-5. Production of Carbamate (Reaction step) In the reaction process, a monosubstituted carbonate salt, a metal alkoxide, and an amine compound are reacted to produce a carbamic acid ester. Specifically, first, a solution containing a monosubstituted carbonate salt is prepared, and an amine compound and a metal alkoxide may be added thereto. During the reaction, stirring is preferably performed. For example, a magnetic stirrer can be used.

[0076] (Solvent) The reaction process may or may not use a solvent. It is considered that the reaction rate is improved by using a reaction solvent. The type of the reaction solvent is not particularly limited. For example, aliphatic hydrocarbons such as butane, hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as 1,4-dioxane and diethyl ether; and other nonpolar solvents can be mentioned. In addition, protic polar solvents such as alcohols and carboxylic acids; aprotic polar solvents such as tertiary carboxylic acid amides, sulfoxides, ketones, lactones, lactams, nitriles, urea derivatives, sulfones, carboxylic acid esters, and carbonic acid esters; and other polar solvents can be mentioned. As the reaction solvent, a polar solvent is preferred, and an aprotic polar solvent is more preferred. Examples of the protic polar solvent 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; carboxylic acids such as formic acid and acetic acid. In addition, examples of the aprotic polar solvent include tertiary carboxylic acid amides; sulfoxides such as dimethyl sulfoxide; ketones such as acetone and isopropyl ketone; lactones such as γ-butyrolactone; lactams such as N-methylpyrrolidone (NMP); nitriles such as acetonitrile, propionitrile, butyronitrile, benzonitrile, and 2-cyanopyridine; urea derivatives; sulfones; carboxylic acid esters such as ethyl acetate; carbonic acid esters; and the like. Among them, from the viewpoints of improving the reaction rate and yield, N-methylpyrrolidone, acetonitrile, or 1-butanol is preferable, and N-methylpyrrolidone is more preferable. One kind of reaction solvent may be used, or two or more kinds may be used.

[0077] The amount of the reaction solvent used is not particularly limited, but is usually 1 equivalent or more, preferably 1.5 equivalents or more, more preferably 2.5 equivalents or more, still more preferably 4 equivalents or more, and usually 20 equivalents or less, preferably 15 equivalents or less, more preferably 10 equivalents or less, relative to 1 equivalent of the monosubstituted carbonate salt.

[0078] (Reaction temperature) The reaction temperature is not particularly limited, but is usually 100°C or higher, preferably 120°C or higher, more preferably 140°C or higher, and usually 250°C or lower, preferably 230°C or lower, more preferably 200°C or lower. When the reaction temperature is within this range, the carbamic acid ester can be efficiently produced.

[0079] (Reaction time) The reaction time is not particularly limited and may be appropriately adjusted according to the reaction temperature, the amount of catalyst, the reaction scale, etc. Usually, it is 30 minutes or more, preferably 1 hour or more, more preferably 2 hours or more, and usually 120 hours or less, preferably 100 hours or less, more preferably 80 hours or less. Still more preferably, it is 50 hours or less. In this specification, the "reaction time" means the time from when the temperature in the reactor reaches the predetermined reaction temperature until it is maintained at the predetermined reaction temperature.

[0080] (Reaction atmosphere) The atmosphere in the reaction step may be an air atmosphere, or an inert gas atmosphere such as nitrogen or argon. Further, the reaction step may be carried out under either pressurized or reduced pressure conditions, and is usually 0.01 atm or higher, preferably 0.05 atm or higher, more preferably 0.1 atm or higher, and usually 10 atm or lower, preferably 5 atm or lower, more preferably 2 atm or lower.

[0081] (Reaction vessel) The reaction vessel is not particularly limited as long as it is made of a material stable to carbamic acid esters, and is appropriately selected according to a continuous process or a batch process. In this embodiment, a continuous process or a batch process may be used. In the case of a batch process, it is preferably a sealed reaction vessel (sealed reaction container), more preferably a sealed pressure-resistant container having a volume 10 to 100 times the volume of a mixture of a monosubstituted carbonate salt, a metal alkoxide, and an amine compound, and if necessary, a reaction solvent, and still more preferably an autoclave made of stainless steel.

[0082] (Other steps) In the method for producing a carbamic acid ester according to this embodiment, any steps may be included in addition to the above reaction step. Examples of the optional steps include the monosubstituted carbonate salt formation step described in the section (method for producing a monosubstituted carbonate salt), the step of regenerating a metal alkoxide with an alcohol, and the purification step for increasing the purity of the carbamic acid ester. In the purification step, purification methods commonly performed in the field of organic synthesis such as filtration, adsorption, column chromatography, and distillation can be employed.

Examples

[0083] Examples are given below to more specifically explain the present invention, but it can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0084] [Example 1-1]

Chemical formula

[0085] To a mixture of 1,8-diazabicyclo[5.4.0]undec-7-ene (1.52 g, 10.0 mmol), n-butanol (1.5 mL), and N-methylpyrrolidone (1.5 mL), a carbon dioxide / nitrogen mixed gas (v:v = 15:85, P t= 0.1 MPa, P CO2 = 0.015 MPa, P CO2 / P t A mixed solution containing a monosubstituted carbonate salt prepared by bubbling (v:v = 0.15) at room temperature (25 °C) at a flow rate of 0.1 L / min for 10 minutes was placed in a sealed reaction vessel with a volume of 5 mL, and aniline (186 mg, 2.0 mmol), titanium tetrabutoxide (680 mg, 2.0 mmol), and acetonitrile (1.5 mL) were added, followed by reaction at 180 °C for 16 hours. The yield of butyl-N-phenylcarbamate was 30%. The yield was determined by 1 1H NMR.

[0086] [Example 1-2] Butyl-N-phenylcarbamate was obtained in the same manner as in Example 1-1, except that N-methylpyrrolidone (1.5 mL) was used instead of acetonitrile and the reaction time was set to 1 hour. The yield was 47%. The yield was determined by 1 1H NMR.

[0087] [Example 1-3] Butyl-N-phenylcarbamate was obtained in the same manner as in Example 1-2, except that the reaction temperature was 160 °C and the reaction time was 5 hours. The yield was 61%. The yield was determined by 1 1H NMR.

[0088] [Example 2-1] [Chemical formula]

[0089] For a mixture of 1,8-diazabicyclo[5.4.0]undec-7-ene (912 mg, 6.0 mmol) and n-butanol (2.0 mL), a carbon dioxide / nitrogen mixed gas (v:v = 15:85, P t = 0.1 MPa, P CO2 = 0.015 MPa, P CO2 / Pt A mixed solution containing a monosubstituted carbonate salt prepared by bubbling a carbon dioxide / nitrogen mixed gas (v:v = 0.15) at a flow rate of 0.1 L / min for 10 minutes at room temperature (25 °C) was placed in a 5 mL sealed reaction vessel, and hexamethylenediamine (116 mg, 1.0 mmol), titanium tetrabutoxide (680 mg, 2.0 mmol), and n-butanol (1.5 mL) were added, followed by reaction at 180 °C for 3 hours. The yield of N,N'-hexamethylenebis(dibutylcarbamate) was 71%. The yield was determined by 1H NMR using mesitylene (50 mg) as an internal standard. 1 Determined by 1H NMR.

[0090] [Example 3-1] [Chemical formula]

[0091] To a mixture of 1,8-diazabicyclo[5.4.0]undec-7-ene (912 mg, 6.0 mmol), n-butanol (0.6 mL), and N-methylpyrrolidone (0.5 mL), a mixed solution containing a monosubstituted carbonate salt prepared by bubbling a carbon dioxide / nitrogen mixed gas (v:v = 15:85, P t = 0.1 MPa, P CO2 = 0.015 MPa, P CO2 / P t = 0.15) at a flow rate of 0.1 L / min for 20 minutes at room temperature (25 °C) was placed in a 5 mL sealed reaction vessel, and hexylamine (202 mg, 2.0 mmol), titanium tetrabutoxide (680 mg, 2.0 mmol), and N-methylpyrrolidone (2.5 mL) were added, followed by reaction at 150 °C for 5 hours. The yield of butyl-N-hexylcarbamate was 57%. The yield was determined by 1H NMR using mesitylene (50 mg) as an internal standard. 1 Determined by 1H NMR. [Industrial Applicability]

[0092] According to the present invention, a carbamate can be produced using a monosubstituted carbonate salt, a metal alkoxide, and an amine compound as raw materials. Further, the present invention can also produce a monosubstituted carbonate salt using a low-concentration carbon dioxide mixed gas as a raw material and then produce a carbamate, which is a reaction enabling effective utilization of low-concentration carbon dioxide contained in exhaust gas and the like. Furthermore, since the metal alkoxide used in the present invention can be recovered after the reaction and then regenerated using alcohol, substantially only low-concentration carbon dioxide, an amine compound, and alcohol are consumed, and it is a reaction excellent in environmental compatibility.

Explanation of Signs

[0093] 1 Reaction vessel 2 Reaction mixture 3 Carbon dioxide-containing gas supply pipe 4 Discharge pipe 5 Gas

Claims

1. A method for producing a carbamate, comprising a reaction step of reacting a monosubstituted carbonate salt represented by formula (1) with a metal alkoxide and an amine compound to produce a carbamate. 【Chemical Formula 1】 (In the above formula, each R1 is independently a monovalent hydrocarbon group which is unsubstituted or has an alkyl group, an alkenyl group, an alkoxy group, a cyano group, a halogeno group or a nitro group as a substituent; Am+ is an m-valent ammonium cation, amidinium cation, guanidinium cation, phosphonium cation, phosphazenium cation or carbocation derived from the base represented by A; m is 1 or 2.)

2. The method for producing a carbamate according to claim 1, wherein the amine compound is a compound represented by formula (2), the metal alkoxide is a compound represented by formula (3), and the carbamate is a compound represented by formula (4). 【Chemical Formula 2】 (In the above formula, R ０ is a substituted or unsubstituted n-valent hydrocarbon group; R １ is as defined above; R ２ are each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; R ３ are each independently a substituted or unsubstituted hydrocarbon ligand, amide ligand or halide ligand; M is a metal atom; A ｍ＋ is as defined above; n is 1 or 2; m is as defined above; p represents the formal oxidation number of M and is an integer from 1 to 6; (p - q) is an integer from 1 to 6; q is an integer of 0 or more and (p - 1) or less .)

3. The A ｍ＋ is an m-valent ammonium cation or amidinium cation derived from the base represented by A, and the method for producing a carbamate according to claim 2.

4. The R ０The method for producing a carbamate according to claim 2 or 3, wherein the group is a monovalent or divalent group selected from a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms.

5. Said R １ is a monovalent group selected from an unsubstituted or substituted aliphatic hydrocarbon group having 1 to 20 carbon atoms having an alkyl group, alkenyl group, alkoxy group, cyano group, halogeno group or nitro group as a substituent and an unsubstituted or substituted aromatic hydrocarbon group having 6 to 20 carbon atoms having an alkyl group, alkenyl group, alkoxy group, cyano group, halogeno group or nitro group as a substituent, and the method for producing a monosubstituted carbonate salt according to any one of claims 2 to 4.

6. Said R ２ is a hydrogen atom, and the method for producing a carbamate according to any one of claims 2 to 5.

7. The method for producing a carbamate according to any one of claims 1 to 6, wherein the metal alkoxide is at least one selected from the group consisting of titanium alkoxide and alkoxysilane.

8. The method for producing a carbamate according to any one of claims 1 to 7, wherein the reaction step is carried out in the presence of an aprotic polar solvent.

9. Before the reaction step, a step of generating a monosubstituted carbonate salt by bringing an alcohol, the base, and a carbon dioxide-containing gas into contact with each other is included, and the total pressure of the carbon dioxide-containing gas is P ｔ and the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas is P ＣＯ２ and P ＣＯ２ / P ｔ is 0.0001 or more and 1 or less, and P ＣＯ２ is less than 0.1 MPa, and the method for producing a carbamate according to any one of claims 1 to 8.

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