JP2022171091A - Method for manufacturing monosubstituted carbonate salt - Google Patents

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

The present invention relates to a method for producing monosubstituted carbonate salts.

Carbon dioxide (CO ₂ ) emitted from thermal power generation accounts for 30% of Japan's domestic CO ₂ emissions.Technology development to achieve reduction of carbon dioxide emissions, which is thought to be the cause of global warming. is strongly desired.
In this regard, for example, in Non-Patent Document 1, a technique for CO ₂ capture by superbasic/polyethylene glycol followed by conversion is discussed, in which NH ₂ PEG ₁₅₀ NH ₂ captures CO ₂ in the presence of NH ₄ I. The formation of a cyclic carbamate by the reaction of the carbamate produced by the reaction with aziridine has been reported.
In Non-Patent Document ₂ , a carbonate salt is synthesized using CO at 1 atm, transesterification using this as a catalyst and dimethyl carbonate as a reactant is studied, and pressurized (1.0 MPa) CO Non-Patent Document 3 reports the synthesis of carbonates from alcohols and aliphatic carbamates from amines under _2. Non-Patent Document 3 utilizes 1 atm _CO2 to synthesize carbonate salts from bases such as polyethyleneimine, followed by Techniques for synthesizing formate by hydrogen reduction have been investigated.
Non-Patent Document 4 describes the synthesis of carbonate salts from methanol and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) utilizing CO at room temperature and ₁ atm, followed by hydrogen reduction. discloses a technique for synthesizing methyl formate.
By the way, carbamic acid esters are useful compounds having a wide range of uses as pharmaceuticals, agricultural chemicals, various fine chemicals, and raw materials for synthesizing these. So far, methods for producing carbamic acid esters using carbon dioxide under normal pressure have been investigated (see, for example, Non-Patent Documents 5 to 8).

Energy Environ. Sci., 2011, 4, p.3971-3975 New J. Chem., 2018, 42, p.13054-13064 Green Chem., 2013, 15, p.2825-2829 Inorg. Chem., 2014, 53, p.9849-9854 Phosphorus Sulfur Silicon Relat Elem, 2016, vol.191, p.1-7 Org. Lett., 2010, 12, p.1340-1343 Synth. Commun., 2007, 37, p.2651-2654 Chem., 2007, 138, p.57-60

Both the conventional method for producing a monosubstituted carbonate salt and the method for producing a carbamic acid ester require carbon dioxide gas of 1 atm (0.1 MPa) or more.
The present invention provides a method for easily producing a monosubstituted carbonate salt, which can be used as a raw material for carbamic acid ester, by using a carbon dioxide-containing gas containing carbon dioxide at a partial pressure of less than 0.1 MPa as a raw material. The challenge is to

The present inventors have made intensive studies to solve the above problems, and as a result, have found that a monosubstituted carbonate salt is produced by contacting an alcohol, a base, and a carbon dioxide-containing gas. completed.
The present invention provides the following specific aspects and the like.

（上記式中、Ｒ^１は置換若しくは無置換の１価の炭化水素基であり、Ａは塩基であり、Ａ^ｍ＋は前記塩基由来のｍ価のカチオンであり、ｍは１又は２である。）
［３］
前記Ｒ^１が、置換若しくは無置換の炭素数１～２０の脂肪族炭化水素基及び置換若しくは無置換の炭素数６～２０の芳香族炭化水素基から選ばれる１価の基である、［２］に記載の一置換カーボネート塩の製造方法。
［４］
前記塩基が、有機塩基、アルカリ金属塩、及びアルカリ土類金属塩からなる群より選択される少なくとも１種である、［１］～［３］のいずれかに記載の一置換カーボネート塩の製造方法。
［５］
前記Ａ^ｍ＋が、アンモニウムカチオン、アミジニウムカチオン、グアニジニウムカチオン、ホスホニウムカチオン、ホスファゼニウムカチオン、カルボカチオン、アルカリ金属カチオン、及びアルカリ土類金属カチオンからなる群より選択されるカチオンである、［２］又は［３］に記載の一置換カーボネート塩の製造方法。
［６］
前記Ｐ_ＣＯ２／Ｐ_ｔが、０．０１以上０．５０以下である、［１］～［５］のいずれかに記載の一置換カーボネート塩の製造方法。
［７］
前記Ｐ_ｔが、０．０１ＭＰａ以上０．１５ＭＰａ以下である、［１］～［６］のいずれかに記載の一置換カーボネート塩の製造方法。 [1]
including a step of contacting an alcohol, a base, and a carbon dioxide-containing gas, wherein P _t is the total pressure of the carbon dioxide-containing gas, P _CO is the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas, A method for producing a monosubstituted carbonate salt, wherein P _CO2 /P _t is 0.0001 or more and 1 or less, and the 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).

(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. )
[3]
[ ² ] The manufacturing method of the monosubstituted carbonate salt as described in ].
[4]
The method for producing a monosubstituted carbonate salt according to any one of [1] to [3], wherein the base is at least one selected from the group consisting of organic bases, alkali metal salts, and alkaline earth metal salts. .
[5]
The Am ⁺ is a cation selected from the group consisting of ammonium cations, amidinium cations, guanidinium cations, phosphonium cations, phosphazenium cations, carbocations, alkali metal cations, and alkaline earth metal cations. , [2] or a method for producing a monosubstituted carbonate salt according to [3].
[6]
The method for producing a monosubstituted carbonate salt according to any one of [1] to [5], wherein P _CO2 /P _t is 0.01 or more and 0.50 or less.
[7]
The method for producing a _{monosubstituted} carbonate salt according to any one of [1] to [6], wherein the Pt is 0.01 MPa or more and 0.15 MPa or less.

According to the present invention, there is provided a method for easily producing a monosubstituted carbonate salt that can be used as a raw material for a carbamic acid ester, using a carbon dioxide-containing gas containing carbon dioxide at a partial pressure of less than 0.1 MPa as a raw material. can provide.

FIG. 1 is a conceptual diagram of a reactor used in one embodiment of the present invention.

In describing the details of the present invention, specific examples will be given, but the present invention is not limited to the following contents as long as they do not deviate from the gist of the present invention, and can be implemented with appropriate modifications.

1. A method for producing a monosubstituted carbonate salt A method for producing a monosubstituted carbonate salt according to one embodiment of the present invention includes a step of contacting an alcohol, a base, and a carbon dioxide-containing gas, and P _CO2 /P _t is 0.0001 or more and 1 or less, and P _CO2 is less than 0.1 MPa, where P _t is the pressure and P _CO2 is the partial pressure of the carbon dioxide gas in the carbon dioxide-containing gas. characterized by

As a reaction for producing a monosubstituted carbonate salt by contacting an alcohol, a base and a carbon dioxide-containing gas, for example, 1,8-diazabicyclo[5.4.0]undec-7-ene and n -Bubbling a carbon dioxide/nitrogen gas mixture through butanol to form a monosubstituted carbonate salt.

The reaction mechanism in this case is presumed as follows.

According to the present embodiment, a monosubstituted carbonate salt is produced in a relatively short time and at a high yield from a low-concentration carbon dioxide-containing gas containing about 0.15 (15% by volume) of carbon dioxide gas. be able to. The monosubstituted carbonate salt obtained by the production method according to the present embodiment can be used for synthesizing carbamic acid esters, and can be a technique for converting low-concentration carbon dioxide contained in exhaust gas and the like into useful chemical products.
Hereinafter, "alcohol", "base", "carbon dioxide-containing gas", "monosubstituted carbonate salt" and the like will be explained. In this specification, the step of contacting the alcohol, the base and the carbon dioxide-containing gas is also simply referred to as the "reaction step".

（上記式中、Ｒ^１は置換若しくは無置換の１価の炭化水素基であり、Ａは塩基であり、Ａ^ｍ＋は前記塩基由来のｍ価のカチオンであり、ｍは１又は２である。） In the present embodiment, it is preferable that the alcohol is a compound represented by formula (1) and the monosubstituted carbonate salt is a compound represented by formula (2).

(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. )

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

( ^R1 )
R ¹ is a substituted or unsubstituted monovalent hydrocarbon group. As used herein, the term "hydrocarbon group" is not limited to a linear saturated hydrocarbon group, and may have a carbon-carbon unsaturated bond, or may have a branched structure. , may have a cyclic structure. Also, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.
The number of carbon atoms in 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.

Aliphatic hydrocarbon groups represented by R ¹ include, for example, 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, Alkyl groups such as n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-docosyl group; cyclopropyl group, cyclobutyl group , cyclopentyl group, cycloalkyl group such as cyclohexyl group; vinyl group, allyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 2-methylallyl group, 1-peptynyl group, 1-hexenyl alkenyl groups such as groups, 1-heptenyl group, 1-octenyl group and 2-methyl-1-propenyl group; alkynyl groups such as propargyl group;
Examples of aromatic hydrocarbon groups include phenyl, 1-naphthyl, 2-naphthyl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, 9-phenanthryl, 1- anthryl group, 2-anthryl group, 9-anthryl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 1-triphenylenyl group and 2-triphenylenyl group.

When the hydrocarbon group represented by R ¹ has a substituent, examples of the substituent include deuterium atom; methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl Alkyl groups having 1 to 4 carbon atoms such as group, isobutyl group and tert-butyl group; Cycloalkyl groups having 3 to 4 carbon atoms such as cyclopropyl group and cyclobutyl group; Phenyl group, 1-naphthyl group and 2-naphthyl group aromatic hydrocarbon groups having 6 to 10 carbon atoms such as; halogeno groups such as fluoro group, chloro group, bromo group and iodo group; oxygen-containing functional groups such as alkoxy group, carboxy group, carbonyl group and hydroxyl group; Nitrogen-containing functional groups; sulfur-containing functional groups such as alkylthio groups; a functional group containing an oxygen atom and a nitrogen atom such as; an oxygen-containing heterocyclic group such as a furanyl group; a sulfur-containing heterocyclic group such as a thienyl group; a pyrrolyl group; mentioned.

When the hydrocarbon group represented by R ¹ has a substituent, examples of R ¹ include alkyl-substituted phenyl groups such as 2-methylphenyl group, 3-methylphenyl group and 4-methylphenyl group; Phenyl group, 3-methoxyphenyl group, alkoxy-substituted phenyl group such as 4-methoxyphenyl group; 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 3-bromophenyl group, 4- Halogen-substituted phenyl groups such as bromophenyl group; Nitro-substituted phenyl groups such as 4-nitrophenyl group and 2-nitrophenyl group; Aralkyl groups such as benzyl group, phenethyl group, 1-naphthylmethyl group and 2-naphthylmethyl group; Cycloalkylalkyl groups such as a cyclohexylmethyl group; hydrocarbon groups having an oxygen-containing heterocycle such as a furfuryl group; hydrocarbon groups having a sulfur-containing heterocycle such as a thienylmethyl group; nitrogen-containing heterocycles such as a pyridylmethyl group Hydrocarbon group; and the like can be mentioned preferably.
When the hydrocarbon group is a branched alkyl group or the like, the number of carbon atoms in the main chain is 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 substituent and the carbon number of the hydrocarbon group.

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 availability of raw materials; more preferably a substituted or unsubstituted 1 to 24 carbon atoms. 24 alkyl group, substituted or unsubstituted C3-24 cycloalkyl group, substituted or unsubstituted C6-24 monovalent aromatic hydrocarbon group, substituted or unsubstituted C7-24 an aralkyl group or a heterocyclic group such as a substituted or unsubstituted nitrogen-containing heterocyclic ring; more preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted cyclo They are an alkyl group, a substituted or unsubstituted phenyl group, and a substituted or unsubstituted pyridyl group. The substituent is preferably an alkyl group, an alkenyl group, an alkoxy group, a cyano group, a halogeno group, or a nitro group in view of the usefulness of the resulting complex. Examples of substituted phenyl groups include alkyl-substituted phenyl groups such as 2-methylphenyl group, 4-methylphenyl group and 2,4-dimethylphenyl group; alkoxy-substituted phenyl groups such as 4-methoxyphenyl group and 2-methoxyphenyl group; Group; Halogen-substituted phenyl groups such as 2-chlorophenyl group, 4-chlorophenyl group and 2,4-dichlorophenyl group, and nitro-substituted phenyl groups such as 4-nitrophenyl group and 2-nitrophenyl group are preferable.

Specific examples of alcohols include 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-butene-2- ol, 2-cyclohexen-1-ol, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, phenol and the like.

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

1-2. Base The base used in the present embodiment is not particularly limited, but a base represented by A that can serve as a cation source represented by Am ⁺ , which will be described later, is preferable. 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.

Organic bases 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 and 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, triphenylbutyl phosphine, tetraethylphosphine, tetrabutylphosphine, tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1, 3,2-diazaphosphorine, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ ⁵ ,4λ ⁵ -catenadi(phosphazene), 1-tert-butyl-4,4,4 -tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ ⁵ ,4λ ⁵ -catenadi(phosphazene), triphenylmethyl chloride, triphenylmethanol, 1,3,5- organic bases such as cycloheptatriene and azulene;

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 and the like. mentioned.
Alkaline earth metal salts include magnesium hydroxide, calcium hydroxide and the like.

1-3. Carbon Dioxide-Containing Gas In the reaction step, a carbon dioxide-containing gas containing carbon dioxide (gas), which is a raw material for the monosubstituted carbonate salt, is used.
In the present embodiment, P _t is the total pressure of the carbon dioxide-containing gas, P _CO2 is the partial pressure of the carbon dioxide gas in the carbon dioxide-containing gas, and P _CO2 /P _t is 0.0001 or more and 1 or less. , the P _CO2 is less than 0.1 MPa.
The ratio of the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas to the total pressure of the carbon dioxide-containing gas (P _CO2 /P _t ) is preferably 0.001 or more, more preferably 0.01 or more, and still more preferably 0 0.05 or more, particularly preferably 0.10 or more, 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.
The total pressure of the carbon dioxide-containing gas represented by _Pt is preferably 0.01 MPa or more, more preferably 0.05 MPa or more, still more preferably 0.08 MPa or more, and more preferably 0.20 MPa or less, more preferably It is 0.15 MPa or less, more preferably 0.13 MPa or less, and particularly preferably 0.11 MPa or less.
The partial pressure of carbon dioxide gas represented by P _CO2 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. and 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 those prepared as industrial gases but also carbon dioxide-containing mixed gases separated and recovered from exhaust gases from factories, power plants, and the like can be used.

1-4. Monosubstituted Carbonate Salt The monosubstituted carbonate salt produced in the present embodiment is not particularly limited, and may be determined depending on the purpose.
In the production method according to the present 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. .

（上記式中、Ｒ^１は置換若しくは無置換の１価の炭化水素基であり、Ａ^ｍ＋はＡで表される塩基由来のｍ価のカチオンであり、ｍは１又は２である。）

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

In formula (2), R ¹ has the same definition as R ¹ in formula (1).

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

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 butylammonium cation;
Amidinium cations include, for example, formamidine, acetamidine, 1,5-diazabicyclo[4.3.0]non-5-ene, and 1,8-diazabicyclo[5.4.0]undec-7- 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, derivatives thereof having one or more substituents, and the like. Examples of the substituents include hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aromatic hydrocarbon groups exemplified in the description of item (R ¹ ).
Guanidinium cations include, for example, 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 were protonated, respectively, 1,1,3, 3-tetramethylguanidinium cation, 2-tert-butyl-1,1,3,3-tetramethylguanidinium cation, 1,5,7-triazabisi and 7-methyl-1,5,7-triaza bicyclo[4.4.0]dec-5-enium cations, derivatives thereof having one or more substituents, and the like. Examples of the substituents include hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aromatic hydrocarbon groups exemplified in the description of item (R ¹ ).

Examples of phosphonium cations include tertiary phosphonium cations such as triphenylphosphonium cations and tri-tert-butylphosphonium cations; tetraphenylphosphonium cations, tetra-p-tolylphosphonium cations, triphenylbenzylphosphonium cations and triphenylbutylphosphonium cations. , tetraethylphosphonium cation, and tetrabutylphosphonium cation.
Phosphazenium cations include, for example, tert-butylimino-tris(dimethylamino)phosphorane, tert-butylimino-tri(pyrrolidino)phosphorane, 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1 ,3,2-diazaphosphorine, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ ⁵ ,4λ ⁵ -catenadi(phosphazene), and 1-tert-butyl-4,4 tert ^- butylimino ^- tris(dimethyl amino)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(dimethyl amino)-2,2-bis[tris(dimethylamino)phosphoranylideneamino]-2λ ⁵ ,4λ ⁵ -catenadi(phosphazene)onium cations, derivatives thereof having one or more substituents, and the like. Examples of the substituents include hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aromatic hydrocarbon groups exemplified in the description of item (R ¹ ).

Examples of carbocations include monovalent carbocations such as triphenylmethyl cation, tropylium cation, and azulenium cation.

Alkali metal cations include lithium cations, sodium cations, potassium cations, and the like.
Examples of alkaline earth metal cations include magnesium cations and calcium cations.

From the standpoint of availability of raw materials, ammonium cation, amidinium cation, guanidinium cation, phosphonium cation, phosphazenium cation, or carbocation are preferred, and ammonium cation and amidinium are more preferred. cation, guanidinium cation, phosphonium cation, or phosphazenium cation. Among them, ammonium cations or amidinium cations are preferred.

Specific examples of the compound represented by formula (1) include compounds represented by the following formula and counter cations thereof other than 1,8-diazabicyclo[5.4.0]undec-7-enium cations amidinium salts, guanidinium salts, phosphonium salts, phosphazenium salts, carbocation salts that are amidinium cations, guanidinium cations, phosphonium cations, phosphazenium cations, carbocations, alkali metal cations, or alkaline earth metal cations , alkali metal salts, or alkaline earth metal salts.

1-5. Reaction conditions, etc. Specifically, the step of contacting the alcohol, the base, and the carbon dioxide-containing gas can be performed, for example, as follows.
First, the raw material alcohol and base are added to the reaction vessel. At this time, it is preferable to carry out in an inert gas atmosphere such as nitrogen or argon. After the alcohol and base are added to the reaction vessel, a carbon dioxide-containing gas is continuously supplied into the reactor and reacted at room temperature for 10 to 20 minutes, for example. When using a solvent, it may be added to the reaction vessel before introducing carbon dioxide into the reactor, or may be added to the reactor simultaneously with alcohol and the like. Moreover, it is preferable to stir during the reaction, and for example, a magnetic stirrer can be used. After the reaction, it is cooled, the remaining gas is discharged, and the reaction product is recovered.

A reaction apparatus used in the reaction step is not particularly limited, but an apparatus capable of continuously supplying a mixture of alcohol and a base with a carbon dioxide-containing gas is preferable. FIG. 1 is a conceptual diagram (cross-sectional view) of a reactor used in this embodiment. The reactor shown in FIG. 1 is mainly composed of a reaction vessel 1, a carbon dioxide-containing gas supply pipe 3 for supplying carbon dioxide-containing gas, and a discharge pipe 4 for discharging gas 5 in the reaction vessel. The reaction vessel 1 is not particularly limited as long as it is made of a material that is stable with respect to the monosubstituted carbonate salt. The reaction vessel 1 preferably has a volume of 1.5 to 100 times the volume of the reaction mixture 2, which preferably comprises alcohol, base and optionally solvent. The reactor may also be equipped with a magnetic stir bar for stirring during the reaction.

(reaction temperature)
Although the reaction temperature is not particularly limited, it is usually 1° C. or higher and 50° C. or lower, preferably room temperature from the viewpoint of economy. In this specification, room temperature is 1°C to 30°C.

(reaction time)
The reaction time is not particularly limited, and may be appropriately adjusted depending on the reaction temperature, reaction scale, and the like. It is usually 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 this specification, 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.

(solvent)
The reaction step may or may not use a solvent. From the viewpoint of achieving the formation of the monosubstituted carbonate salt under milder conditions, for example, from the viewpoint of shortening the reaction time, it is preferable not to use a solvent. The term "without solvent" means that no solvent is used separately from the reaction reagent. .

The type of reaction solvent is not particularly limited, and examples include 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; Non-polar solvents such as In addition, protic polar solvents such as carboxylic acids; tertiary carboxylic acid amides, sulfoxides, ketones, lactones, lactams, nitriles, urea derivatives, sulfones, carboxylic acid esters, carbonate esters and other aprotic polar solvents; Solvents can be mentioned.
As the reaction solvent, a polar solvent is preferable, and 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 dimethylsulfoxide; ketones such as acetone and isopropyl ketone; lactones such as γ-butyrolactone; lactams such as N-methylpyrrolidone (NMP); , propionitrile, butyronitrile, benzonitrile, nitriles such as 2-cyanopyridine; urea derivatives; sulfones; carboxylic acid esters such as ethyl acetate;
Among them, N-methylpyrrolidone or 1,3-dimethyl-2-imidazolidinone is preferred, and N-methylpyrrolidone is more preferred, from the viewpoint of improving the reaction rate and the solubility of the product.
One type of reaction solvent may be used, or two or more types may be used.

The amount of the reaction solvent used is not particularly limited, but is usually 0.5 times or more, preferably 1.0 times or more, more preferably 1.5 times or more, and usually 20 times or less, relative to the volume of the base. It can be used preferably at 15 times or less, more preferably at 10 times or less.

(Other processes)
The method for producing a monosubstituted carbonate salt according to the present embodiment may include optional steps in addition to the reaction steps described above. Optional steps include purification steps to increase 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.

The present invention will be described in more detail with reference to examples below, but modifications can be made as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

[Example 1]

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) and 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 room temperature (25° C.). Aeration was performed for 10 minutes at a flow rate of 1 L/min. 10 minutes after the start of aeration, it was confirmed by ¹ H NMR that 1,8-diazabicyclo[5.4.0]undec-7-ene was completely consumed and a monosubstituted carbonate salt was produced quantitatively. .

[Example 2]

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

[Example 3]

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

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 synthesizing carbamic acid esters, and is useful as a technique for converting low-concentration carbon dioxide contained in exhaust gas and the like into useful chemical products.

REFERENCE SIGNS LIST 1 reaction vessel 2 reaction mixture 3 carbon dioxide-containing gas supply pipe 4 discharge pipe 5 gas

Claims (7)

including a step of contacting an alcohol, a base, and a carbon dioxide-containing gas, wherein P _t is the total pressure of the carbon dioxide-containing gas, P _CO is the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas, A method for producing a monosubstituted carbonate salt, wherein P _CO2 /P _t is 0.0001 or more and 1 or less, and the P _CO2 is less than 0.1 MPa. 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).

(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. ) wherein said R ¹ 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; 3. A method for producing a monosubstituted carbonate salt according to 2. The method for producing a monosubstituted carbonate salt according to any one of claims 1 to 3, wherein the base is at least one selected from the group consisting of organic bases, alkali metal salts, and alkaline earth metal salts. . The Am ⁺ is a cation selected from the group consisting of ammonium cations, amidinium cations, guanidinium cations, phosphonium cations, phosphazenium cations, carbocations, alkali metal cations, and alkaline earth metal cations. A method for producing a monosubstituted carbonate salt according to claim 2 or 3. The method for producing a monosubstituted carbonate salt according to any one of claims 1 to 5, wherein the P _CO2 /P _t is 0.01 or more and 0.50 or less. The method for producing a _{monosubstituted} carbonate salt according to any one of claims 1 to 6, wherein the Pt is 0.01 MPa or more and 0.15 MPa or less.

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