Method for producing a substituted carbonate salt

Abstract

To provide a method by which it is easy to manufacture a monosubstituted carbonate.SOLUTION: A method for manufacturing a monosubstituted carbonate salt includes the step of causing alcohol, base and carbon dioxide containing gas to come into contact with each other. PCO2 / Pt is 0.0001-1, and PCO2 is less than 0.1 MPa in which a total pressure of the carbon dioxide containing gas is taken as Pt, and a partial pressure of carbon dioxide gas in the carbon dioxide containing gas is taken as PCO2.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a monosubstituted carbonate salt.

Background Art

[0002] Carbon dioxide (CO2) emitted from thermal power generation accounts for 30% of Japan's domestic CO2 emissions, and there is a strong demand for the development of technologies to achieve a reduction in the emissions of carbon dioxide, which is the cause of global warming. Regarding this, for example, in Non-Patent Document 1, CO2 capture using superbase / polyethylene glycol and subsequent conversion technology have been studied. In the presence of NH4I, NH2PEG 150 The formation of cyclic carbamate by the reaction of carbamate formed by NH2 capturing CO2 with aziridine has been reported. In Non-Patent Document 2, the synthesis of carbonate salts using CO2 at 1 atm and the subsequent transesterification using these as catalysts and dimethyl carbonate as a reactant have been studied, and it has been reported that carbonates were synthesized from alcohols and aliphatic carbamates were synthesized from amines under pressurized (1.0 MPa) CO2. In Non-Patent Document 3, the technology of synthesizing carbonate salts from bases such as polyethyleneimine using CO2 at 1 atm and then synthesizing formate salts by subsequent hydrogen reduction has been studied. Non-Patent Document 4 discloses a technology for synthesizing carbonate salts from methanol and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) using CO2 at 1 atm at room temperature and then synthesizing methyl formate by subsequent hydrogen reduction. By the way, carbamic acid esters are useful compounds having a wide range of uses as pharmaceuticals, agricultural chemicals, various fine chemicals, and synthetic raw materials thereof. So far, methods for producing carbamic acid esters using carbon dioxide at normal pressure have been studied (see, for example, Non-Patent Documents 5 to 8).

Prior Art Documents

Non-Patent Documents

[0003] [Non-Patent Document 1] Energy Environ. Sci., 2011, 4, p.3971-3975 [Non-Patent Document 2] New J. Chem., 2018, 42, p.13054-13064 [Non-Patent Document 3] Green Chem., 2013, 15, p.2825-2829 [Non-Patent Document 4] Inorg. Chem., 2014, 53, p.9849-9854 [Non-Patent Document 5] Phosphorus Sulfur Silicon Relat Elem, 2016, vol.191, p.1-7 [Non-Patent Document 6] Org. Lett., 2010, 12, p.1340-1343 [Non-Patent Document 7] Synth. Commun., 2007, 37, p.2651-2654 [Non-Patent Document 8] Monatsh. Chem., 2007, 138, p.57-60 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] Conventional methods for producing monosubstituted carbonate salts and methods for producing carbamic acid esters both require carbon dioxide gas at 1 atm (0.1 MPa) or more. An object of the present invention is to provide a method for easily producing a monosubstituted carbonate salt using a carbon dioxide-containing gas containing carbon dioxide at a partial pressure of less than 0.1 MPa as a raw material for the monosubstituted carbonate salt that can be a raw material for a carbamic acid ester. [Means for Solving the Problems]

[0005] As a result of intensive studies to solve the above problems, the present inventors have found that a monosubstituted carbonate salt is formed by bringing an alcohol, a base, and a carbon dioxide-containing gas into contact with each other, and have completed the present invention. The present invention provides the following specific embodiments and the like.

[0006] [1] A method for producing a monosubstituted carbonate salt, comprising a step of bringing an alcohol, a base, and a carbon dioxide-containing gas into contact with each other, wherein 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 P CO2 is less than 0.1 MPa. [2] The method for producing a monosubstituted carbonate salt according to [1], wherein the alcohol is a compound represented by formula (1) and the monosubstituted carbonate salt is a compound represented by formula (2).

Chemical formula

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a method for simply producing a monosubstituted carbonate salt that can be used as a raw material for carbamic acid esters, using a carbon dioxide-containing gas containing carbon dioxide at a partial pressure of less than 0.1 MPa as a raw material.

Brief Description of the Drawings

[0008]

Figure 1

Modes for Carrying Out the Invention

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

[0010] 1. Method for Producing Monosubstituted Carbonate Salt The method for producing a monosubstituted carbonate salt according to one embodiment of the present invention includes a step of 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 twherein the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas is P CO2 where P CO2 / P t is 0.0001 or more and 1 or less, and the P CO2 is less than 0.1 MPa.

[0011] Examples of the reaction for producing a monosubstituted carbonate salt by contacting an alcohol, a base, and a carbon dioxide-containing gas include, for example, the reaction of passing a carbon dioxide / nitrogen mixed gas through 1,8-diazabicyclo[5.4.0]undec-7-ene and n-butanol to produce a monosubstituted carbonate salt.

[0012]

Chemical formula

[0013] The reaction mechanism in this case is presumed as follows.

Chemical formula

[0014] According to the present embodiment, a monosubstituted carbonate salt can be produced from a low-concentration carbon dioxide-containing gas having a carbon dioxide gas content of about 0.15 (15% by volume) in a relatively short time and with a high yield. The monosubstituted carbonate salt obtained by the production method according to the present embodiment can be used for the synthesis of carbamic acid esters, and can be a technology for converting low-concentration carbon dioxide contained in exhaust gas or the like into a useful product. Hereinafter, “alcohol”, “base”, “carbon dioxide-containing gas”, “monosubstituted carbonate salt”, etc. will be described. In this specification, the step of contacting an alcohol, a base, and a carbon dioxide-containing gas is also simply referred to as the “reaction step”.

[0015] In the present embodiment, it is preferable that the alcohol is a compound represented by the formula (1), and the monosubstituted carbonate salt is a compound represented by the formula (2).

Chemical formula

[0016] 1-1. Alcohol The alcohol used in this embodiment is not particularly limited, but is preferably a compound represented by the formula (1). R 1 OH (1) (In the above formula, R 1 is a substituted or unsubstituted monovalent hydrocarbon group.)

[0017] (R 1 ) R 1 is a substituted or unsubstituted monovalent hydrocarbon group. In the present 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. Further, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The carbon number of R 1 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 1Examples of the aliphatic hydrocarbon group represented by include 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; and alkynyl groups such as propargyl group. 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.

[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 such as a branched alkyl group, the number of carbon atoms in the main chain is defined as the number of carbon atoms in the hydrocarbon group. 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 carbon atoms in 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 preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 24 carbon atoms from the viewpoint of easy availability of raw materials; 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 heterocycle; 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 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; and a nitro-substituted phenyl group such as a 4-nitrophenyl group or a 2-nitrophenyl group are preferable.

[0022] 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.

[0023] The amount of alcohol used (charged amount) is usually preferably m × 1.0 molar equivalents or more with respect to 1.0 molar equivalent of the amount of base used (charged amount) (m has the same meaning as m in formula (2)). From the viewpoint of improving the reaction rate, it is more preferably m × 1.3 molar equivalents or more, and still more preferably m × 1.5 molar equivalents or more.

[0024] 1-2. Base The base used in this embodiment 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.

[0025] Examples of the organic base include primary amines such as methylamine, ethylamine, isopropylamine, n-butylamine, and 2-hydroxyethylamine; Secondary amines such as dimethylamine, diethylamine, dicyclohexylamine; Tertiary amines such as trimethylamine, triethylamine; Quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, phenyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, 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 -catena-di(phosphazene), 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranilideneamino]-2λ 5 ,4λ 5 -catena-di(phosphazene), organic bases such as triphenylmethyl chloride, triphenylmethanol, 1,3,5-cycloheptatriene, azulene; are included.

[0026] Examples of the alkali metal salt include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, potassium carbonate, lithium methoxide, sodium methoxide, potassium methoxide, lithium ethoxide, sodium ethoxide, potassium ethoxide, and the like. Examples of the alkaline earth metal salt include magnesium hydroxide, calcium hydroxide, and the like.

[0027] 1-3. Carbon dioxide-containing gas In the reaction step, a carbon dioxide-containing gas containing carbon dioxide (gas), which is a raw material of the monosubstituted carbonate salt, is used. In the present embodiment, 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 carbon dioxide gas represented by is less than 0.1 MPa, preferably 0.07 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.

[0028] 1-4. Monosubstituted carbonate salt The monosubstituted carbonate salt produced in this embodiment is not particularly limited and may be determined according to the purpose. In the production method according to this embodiment, when the compound represented by the formula (1) is used as the alcohol and the base represented by A is used, the compound represented by the general formula (2) can be produced.

[0029]

Chemical formula

[0030] In the formula (2), R 1 is synonymous with R 1 in the formula (1).

[0031] (The cation represented by A m+ ) A m+ is an m-valent cation derived from the base represented by A. Also, 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.

[0032] Examples of the ammonium cation 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. 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 ). Examples of the guanidinium cation include 1,1,3,3-tetramethylguanidinium cation, 2-tert-butyl-1,1,3,3-tetramethylguanidinium cation, 1,5,7-triazabicyclo[4.4.0]dec-5-enium cation, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium cation, which are protonated forms of 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, respectively. Clo[4.4.0]deca-5-enium cationand 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium cation, and derivatives thereof having one or more substituents, etc. are mentioned. Examples of the said substituents include hydrocarbon groups such as the alkyl group, cycloalkyl group, aromatic hydrocarbon group, etc. exemplified in the description of item (R 1 ).

[0033] Examples of the phosphonium cation include tertiary phosphonium cations such as triphenylphosphonium cation and tri-tert-butylphosphonium cation; quaternary phosphonium cations such as tetraphenylphosphonium cation, tetra-p-tolylphosphonium cation, triphenylbenzylphosphonium cation, triphenylbutylphosphonium cation, tetraethylphosphonium cation, and 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 -catendia(phosphazene), and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranilideneamino]-2λ 5 ,4λ 5 -catendia(phosphazene) each 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-Catena-di(phosphazene), and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranilidenamino]-2λ 5 ,4λ 5 -Catena-di(phosphazene)onium cation, and derivatives thereof having one or more substituents, etc. are exemplified. Examples of the said substituent include hydrocarbon groups such as the alkyl group, cycloalkyl group, aromatic hydrocarbon group, etc. exemplified in the description of item (R 1 ).

[0034] Examples of the carbocation include monovalent carbocations such as triphenylmethyl cation, tropylium cation, azulenium cation, etc.

[0035] 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.

[0036] Preferably, from the viewpoint of easy availability of raw materials, it is 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, preferably an ammonium cation or an amidinium cation.

[0037] Specific examples of the compound represented by formula (1) include compounds represented by the following formula and their counter cations being amidinium cations, guanidinium cations, phosphonium cations, phosphazenium cations, carbocations, alkali metal cations, or alkaline earth metal cations other than 1,8-diazabicyclo[5.4.0]undec-7-enium cation Examples include, but are not limited to, onium salts, guanidinium salts, phosphonium salts, phosphazenium salts, carbocations, alkali metal salts, or alkaline earth metal salts.

[0038] [Chemical formula]

[0039] 1 - 5. Reaction conditions, etc. The step of bringing an alcohol, a base, and a carbon dioxide-containing gas into contact can be specifically carried out, for example, as follows. First, the raw material alcohol and base are added to a 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, a 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.

[0040] The reaction apparatus used in the reaction step 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. Figure 1 is a conceptual diagram (cross-sectional view) of the reaction apparatus used in this embodiment. The reaction apparatus shown in Figure 1 mainly consists of 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 to the 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. Also, the reaction apparatus may be equipped with a magnetic stirrer for stirring during the reaction.

[0041] (Reaction temperature) The reaction temperature is not particularly limited, but is usually 1°C or higher and 50°C or lower, and from the perspective of economy, it is preferably room temperature. In this specification, room temperature means 1°C to 30°C.

[0042] (Reaction time) The reaction time 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 even more preferably 3 hours or shorter. In this specification, the "reaction time" refers to the carbon dioxide-containing gas supply time during which the carbon dioxide-containing gas is continuously supplied into the reaction vessel.

[0043] (Solvent) The reaction step may or may not use a solvent. From the perspective of achieving the formation of mono-substituted carbonate salts under milder conditions, for example, from the perspective of shortening 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 alcohol as a solvent, it is considered a condition of not using a solvent.

[0044] The type of reaction solvent is not particularly limited, and examples include non-polar solvents such as aliphatic hydrocarbons such as butane, hexane, octane, cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene; ethers such as 1,4-dioxane, diethyl ether; etc. 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; etc. As the reaction solvent, a polar solvent is preferred. Examples of protic polar solvents include carboxylic acids such as formic acid and acetic acid. Examples of aprotic polar solvents 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; carbonate esters; and the like. Among them, from the viewpoints of improving the reaction rate and the solubility of the product, N-methylpyrrolidone or 1,3-dimethyl-2-imidazolidinone is preferred, and N-methylpyrrolidone is more preferred. One kind of reaction solvent may be used, or two or more kinds may be used.

[0045] 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 usually 20 times or less, preferably 15 times or less, more preferably 10 times or less.

[0046] (Other steps) In the method for producing a monosubstituted carbonate salt according to this embodiment, in addition to the above reaction step, an arbitrary step may be included. Examples of the arbitrary step include a purification step for increasing the purity of the monosubstituted carbonate salt. In the purification step, purification methods commonly used in the field of organic synthesis, such as filtration, adsorption, column chromatography, and distillation, can be employed.

Examples

[0047] The present invention will be described in more detail with reference to the following examples, but it can be appropriately modified 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.

[0048] [Example 1]

Chemical formula

[0049] 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 = 0.15) was bubbled at room temperature (25 °C) at a flow rate of 0.1 L / min for 10 minutes. Ten minutes after the start of bubbling, 1 it was confirmed by 1H NMR that 1,8-diazabicyclo[5.4.0]undec-7-ene was completely consumed and a monosubstituted carbonate salt was quantitatively formed.

[0050] [Example 2] [Chemical formula]

[0051] To 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 / P t = 0.15) was bubbled at room temperature (25 °C) at a flow rate of 0.1 L / min for 10 minutes. Ten minutes after the start of bubbling, 1 it was confirmed by 1H NMR that 1,8-diazabicyclo[5.4.0]undec-7-ene was completely consumed and a monosubstituted carbonate salt was quantitatively formed.

[0052] [Example 3] [Chemical formula]

[0053] 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 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) was bubbled at room temperature (25 °C) at a flow rate of 0.1 L / min for 20 minutes. Twenty minutes after the start of bubbling, 1 It was confirmed by 1H NMR that 1,8-diazabicyclo[5.4.0]undec-7-ene was completely consumed and a monosubstituted carbonate salt was quantitatively formed.

Industrial Applicability

[0054] According to the present invention, a monosubstituted carbonate salt can be easily produced using an alcohol, a base, and a carbon dioxide-containing gas containing carbon dioxide at a low concentration as raw materials. The monosubstituted carbonate salt obtained by the production method of the present invention can be used for the synthesis of carbamic acid esters and is useful as a technology for converting low-concentration carbon dioxide contained in exhaust gas and the like into useful products.

Explanation of Symbols

[0055] 1 Reaction vessel 2 Reaction mixture 3 Carbon dioxide-containing gas supply pipe 4 Discharge pipe 5 Gas

Claims

1. A process comprising contacting an alcohol, a base, and a carbon dioxide-containing gas, wherein the base is 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, and the total pressure of the carbon dioxide-containing gas is P ｔ , 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 a method for producing a monosubstituted carbonate salt.

2. The method for producing a monosubstituted carbonate salt according to claim 1, wherein the alcohol is a compound represented by formula (1) and the monosubstituted carbonate salt is a compound represented by formula (2). 【Chemical 1】 (In the above formula, R １ is a substituted or unsubstituted monovalent hydrocarbon group, A is the base, and A ｍ＋ is 1,5-diazabicyclo[4.3.0]non-5-enium cation, 1,8-diazabicyclo[5.4.0]undec-7-enium cation, 1,5,7-triazabicyclo[4.4.0]dec-5-enium cation or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium cation, and m is 1.)

3. Said R １ is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and substituted or The method for producing a monosubstituted carbonate salt according to claim 2, which is a monovalent group selected from unsubstituted aromatic hydrocarbon groups having 6 to 20 carbon atoms.

4. The foregoing P ＣＯ２ / P ｔ is from 0.01 to 0.50, and the method for producing a monosubstituted carbonate salt according to any one of claims 1 to 3.

5. The above-mentioned P ｔ is from 0.01 MPa to 0.15 MPa, and the method for producing a monosubstituted carbonate salt according to any one of claims 1 to 4.

6. The method for producing a monosubstituted carbonate salt according to any one of claims 1 to 5, wherein the PCO2 is 0.001 MPa or more and 0.07 MPa or less.

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