JP2022171090A - Production method of carbamic acid ester, in which monosubstituted carbonate salt is used - Google Patents

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 The present invention relates to a method for producing a carbamate using a monosubstituted carbonate salt.

Carbamic acid esters are useful compounds that have a wide range of uses as pharmaceuticals, agricultural chemicals, various fine chemicals, and raw materials for synthesizing these.

Methods for producing carbamic acid esters using carbon dioxide at normal pressure have been proposed so far.
For example, in Non-Patent Document 1, as a method for synthesizing carbamate derivatives, ammonium carbamate synthesized in situ from the reaction of an amine as a carbonyl source with _CO2 , an equivalent amount of triphenylphosphine, an equivalent amount of trichloroisocyanuric acid (TCCA ) has been investigated. [1] uses CO ₂ gas at 1 atm and uses a non-renewable sacrificial reagent.
Non-Patent Document 2 reports a method for synthesizing carbamic acid esters via carbamic acid using 1 atm CO ₂ gas and 1,8-diazabicyclo[5.4.0]undec-7-ene as a catalyst. It is Non-Patent Document 2 uses PBu ₃ and DBAD (di-tert-butyl azodicarboxylate), which are non-renewable sacrificial reagents.
Non-Patent Document 3 reports the synthesis of carbamates from amine and CO ₂ gas using non-renewable sacrificial reagents such as KO ₂ /Et ₄ NBr.
Non-Patent Document 4 reports the synthesis of carbamic acid ester by Mitsunobu reaction using CO ₂ gas at 1 atm and via carbamic acid using Ph ₃ P, DEAD (diethyl azodicarboxylate), which is a sacrificial reagent. It is
(5) discusses _CO2 capture and subsequent conversion techniques by superbase/polyethylene glycol, in the presence of NH4I, _{NH2PEG 150 NH2} captures _CO2 gas and produces _carbamine Formation of cyclic carbamates by reaction of acid salts with aziridines is disclosed.
In Non-Patent Document 6, 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 ₂ reported the synthesis of carbonates from alcohols and aliphatic carbamates from amines.

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 Energy Environ. Sci., 2011, 4, p.3971-3975 New J. Chem., 2018, 42, p.13054-13064

All of the above carbamate syntheses suffer from the drawback that either a sacrificial reagent or high pressure carbon dioxide gas is required.
An object of the present invention is to provide a method for easily producing a carbamate ester without using a sacrificial reagent or high-pressure carbon dioxide gas.

（上記式中、Ｒ^０は置換若しくは無置換のｎ価の炭化水素基であり；Ｒ^１は、それぞれ独立して、置換若しくは無置換の１価の炭化水素基であり；Ｒ^２はそれぞれ独立して、水素原子又は置換若しくは無置換の１価の炭化水素基であり；Ｒ^３は、それぞれ独立して、置換若しくは無置換の炭化水素配位子、アミド配位子、又はハライド配位子であり；Ｍは金属原子であり；Ａ^ｍ＋は、Ａで表される塩基由来のｍ価のカチオンであり；ｎは１又は２であり；ｍは１又は２であり；ｐは、Ｍの形式酸化数を表し、１～６の整数であり；（ｐ－ｑ）は１～６の整数であり；ｑは０以上、（ｐ－１)以下の整数である。）
［３］
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、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］に記載のカルバミン酸エステルの製造方法。
［４］
前記Ｒ^０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価又は２価の基である、［２］又は［３］に記載のカルバミン酸エステルの製造方法。
［５］
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］～［４］のいずれかに記載の一置換カーボネート塩の製造方法。
［６］
前記Ｒ^２が水素原子である、［２］～［５］のいずれかに記載のカルバミン酸エステルの製造方法。
［７］
前記金属アルコキシドがチタンアルコキシド及びアルコキシシランからなる群より選択される１種以上である、［１］～［６］のいずれかに記載のカルバミン酸エステルの製造方
法。
［８］
前記反応工程を非プロトン性極性溶媒の存在下で行う、［１］～［７］のいずれかに記載のカルバミン酸エステルの製造方法。
［９］
前記反応工程の前に、アルコールと、塩基と、二酸化炭素含有ガスと、を接触させることにより、一置換カーボネート塩を生成する工程を含み、前記二酸化炭素含有ガスの全圧をＰ_ｔとし、前記二酸化炭素含有ガス中の二酸化炭素ガスの分圧をＰ_ＣＯ２として、Ｐ_ＣＯ２／Ｐ_ｔが０．０００１以上１以下であり、前記Ｐ_ＣＯ２が０．１ＭＰａ未満である、［１］～［８］のいずれかに記載のカルバミン酸エステルの製造方法。 The present inventors have made intensive studies to solve the above problems, and as a result, have found that a carbamate is produced from a monosubstituted carbonate salt and an alkoxide compound, and have completed the present invention.
The present invention provides the following specific aspects and the like.
[1]
A method for producing a carbamic acid ester, comprising a reaction step of reacting a monosubstituted carbonate salt, a metal alkoxide and an amine compound to produce a carbamic acid ester.
[2]
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), The method for producing a carbamate according to [1], wherein the carbamate is a compound represented by formula (4).

(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 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; each R ³ is independently a substituted or unsubstituted hydrocarbon ligand, an amide ligand, or a halide ligand M is a metal atom; A ^m+ is an m-valent cation derived from a base represented by A; n is 1 or 2; m is 1 or 2; represents a formal oxidation number and is an integer of 1 to 6; (pq) is an integer of 1 to 6; q is an integer of 0 or more and (p-1) or less.)
[3]
The A ^m+ is a cation 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. [2] The method for producing a carbamic acid ester according to [2].
[4]
R ⁰ 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. A method for producing a carbamic acid ester according to [2] or [3].
[5]
[ ² ] The method for producing a monosubstituted carbonate salt according to any one of [4].
[6]
The method for producing a carbamic acid ester according to any one of [2] to [5], wherein R ² is a hydrogen atom.
[7]
The method for producing a carbamic acid ester according to any one of [1] to [6], wherein the metal alkoxide is one or more selected from the group consisting of titanium alkoxide and alkoxysilane.
[8]
The method for producing a carbamic acid ester according to any one of [1] to [7], wherein the reaction step is performed in the presence of an aprotic polar solvent.
[9]
Before the reaction step, a step of contacting an alcohol, a base, and a carbon dioxide-containing gas to produce a monosubstituted carbonate salt, wherein the total pressure of the carbon dioxide-containing gas is _Pt , and the Where P _CO2 is the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas, P _CO2 /P _t is 0.0001 or more and 1 or less, and said P _CO2 is less than 0.1 MPa [1] to [8] A method for producing a carbamic acid ester according to any one of .

ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing a carbamate simply can be provided, without using a sacrificial reagent and high pressure carbon dioxide gas.

FIG. 1 is a schematic diagram of a reactor for synthesizing a monosubstituted carbonate salt.

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. Method for Producing Carbamate Ester A method for producing a carbamate ester according to an embodiment of the present invention includes a reaction step of reacting a monosubstituted carbonate salt, a metal alkoxide, and an amine compound to produce a carbamate ester (hereinafter referred to as may be abbreviated as “reaction step”).

Examples of the reaction for producing a carbamic acid ester from a monosubstituted carbonate salt, a metal alkoxide and an amine compound include the reactions shown below.

According to this embodiment, carbamates can be produced without using sacrificial reagents or environmentally unfriendly alkyl halides. In the present embodiment, high-pressure gas equipment is not required, and carbamic acid ester can be easily produced at low cost. It is also possible to produce not only aliphatic carbamates but also aromatic carbamates. Furthermore, as will be described later, according to the present embodiment, it is also possible to produce a monosubstituted carbonate salt using a low-concentration carbon dioxide-containing gas as a raw material, and to produce a carbamate ester using it as a raw material. It is possible to effectively utilize low-concentration carbon dioxide contained in So far, no studies have been reported on the synthesis of carbonate salts from low-concentration carbon dioxide gas and its utilization as a _CO2 source for organic synthesis. In this embodiment, since a metal alkoxide that can be regenerated with alcohol is used, it is possible to produce a carbamic acid ester excellent in environmental friendliness in which substantially only low-concentration carbon dioxide, an amine compound, and alcohol are consumed.
Hereinafter, the method for producing carbamic acid ester according to the present embodiment will be described in detail.

In this embodiment, the monosubstituted carbonate salt is a compound represented by formula (1), the amine compound is a compound represented by formula (2), and the metal alkoxide is represented by formula (3). and the carbamate is a compound represented by formula (4).

（上記式中、Ｒ^０は置換若しくは無置換のｎ価の炭化水素基であり；Ｒ^１は、それぞれ独立して、置換若しくは無置換の１価の炭化水素基であり；Ｒ^２はそれぞれ独立して、水素原子又は置換若しくは無置換の１価の炭化水素基であり；Ｒ^３は、それぞれ独立して、置換若しくは無置換の炭化水素配位子、アミド配位子、又はハライド配位子であり；Ｍは金属原子であり；Ａ^ｍ＋は、Ａで表される塩基由来のｍ価のカチオンであり；ｎは１又は２であり；ｍは１又は２であり；ｐは、Ｍの形式酸化数を表し、１～６の整数であり；（ｐ－ｑ）は１～６の整数であり；ｑは０以上、（ｐ－１)以下の整数である。なお、式（４）中のＲ^１は、式（１）中のＲ^１又は式（３）中のＲ^１に由来し、式（１）及び（３）中に複数種のＲ^１が含まれる場合、式（４）で表される化合物は、各Ｒ^１を有する化合物の混合物として得られる。）

(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 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; each R ³ is independently a substituted or unsubstituted hydrocarbon ligand, an amide ligand, or a halide ligand M is a metal atom; A ^m+ is an m-valent cation derived from a base represented by A; n is 1 or 2; m is 1 or 2; represents a formal oxidation number and is an integer of 1 to 6;(p−q) is an integer of 1 to 6;q is an integer of 0 or more and (p−1) or less. R ¹ in is derived from R ¹ in formula (1) or R ¹ in formula (3), and when multiple types of R ¹ are included in formulas (1) and (3), formula (4 ) is obtained as a mixture of compounds having each R ^1. )

（上記式中、Ｒ^１は、それぞれ独立して、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。） 1-1. Monosubstituted Carbonate Salt The monosubstituted carbonate salt is not particularly limited, but preferably includes a compound represented by the general formula (1).

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

( ^R1 )
Each R ¹ is independently 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 carbon atom. -24 alkyl group, substituted or unsubstituted C3-24 cycloalkyl group, substituted or unsubstituted C6-24 monovalent aromatic hydrocarbon group, substituted or unsubstituted C7-24 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 3 to 12 carbon atoms A cycloalkyl 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; groups; 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;

( ^Am+ , 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 cations and derivatives thereof having one or more substituents. 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 and derivatives thereof having one or more substituents; 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 ).

Phosphonium cations include, for example, triphenylphosphonium cation, tertiary phosphonium cations such as tri-tert-butylphosphonium cation; tetraphenylphosphonium cation, tetra-p-tolylphosphonium cation, triphenylbenzylphosphonium cation, triphenylbutyl cation, tetraethyl Examples include quaternary phosphonium cations such as phosphonium cations and tetrabutylphosphonium cations.
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 and derivatives thereof having one or more substituents. 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 viewpoint of availability of raw materials and yield of carbamic acid ester, preferred are ammonium cation, amidinium cation, guanidinium cation, phosphonium cation, phosphazenium cation, or carbocation, and more preferred. ammonium cations, amidinium cations, guanidinium cations, phosphonium cations, or phosphazenium cations. 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.

(Method for producing monosubstituted carbonate salt)
In the present embodiment, the monosubstituted carbonate salt may be a commercially available product or may be synthesized and used, but it is preferable to synthesize and use the monosubstituted carbonate salt. Specifically, it includes a step of producing a monosubstituted carbonate salt by contacting an alcohol, a base, and a carbon dioxide-containing gas, wherein P _t is the total pressure of the carbon dioxide-containing gas, and the carbon dioxide is Where P _CO2 is the partial pressure of carbon dioxide gas in the contained gas, P _CO2 /P _t is 0.0001 or more and 1 or less, and P _CO2 is less than 0.1 MPa. is preferred.

As the above method for producing a monosubstituted carbonate salt, the alcohol is a compound represented by formula (1′), and the monosubstituted carbonate salt is a compound represented by formula (1). A method is preferred.

（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 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. )

<Alcohol>
Alcohol is not particularly limited, but when synthesizing a monosubstituted carbonate salt represented by formula (1), a compound represented by formula (1′) is used.
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 and has the same definition as R ¹ of the monosubstituted carbonate salt represented by formula (1).
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 (1) 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.

<Base>
The base is not particularly limited, but a base represented by A that can serve as a cation source represented by Am ⁺ 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.

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.

<Gas containing carbon dioxide>
A carbon dioxide-containing gas containing carbon dioxide (gas), which is a raw material, is used to produce the monosubstituted carbonate salt.
In the step of producing a monosubstituted carbonate salt, 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. 1 or less, and 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 expressed as P _CO2 is less than 0.1 MPa, preferably 0.1 MPa.
07 MPa or less, more preferably 0.05 MPa or less, more preferably 0.03 MPa or less, particularly preferably 0.02 MPa or less, preferably 0.001 MPa or more, more preferably 0.005 MPa or more, further 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.

<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)
The reaction temperature in the step of producing a monosubstituted carbonate salt is not particularly limited, but 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 of the monosubstituted carbonate salt producing step 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 addition, in the step of producing a monosubstituted carbonate salt, the “reaction time” is the carbon dioxide-containing gas supply time during which the carbon dioxide-containing gas is continuously supplied into the reaction vessel.

(solvent)
The monosubstituted carbonate salt formation 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;
non-polar solvents such as dioxane, ethers such as diethyl ether; 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, and 2-cyanopyridine; urea derivatives; sulfones; carboxylic acid esters such as ethyl acetate;
Among them, N-methylpyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferred, and N-methylpyrrolidone is more preferred, from the viewpoints of improved reaction rate, availability and price.
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 may include an optional step in addition to the step of producing a monosubstituted carbonate salt. 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.

1-2. Amine Compound The amine compound is not particularly limited, but preferably includes a compound represented by the general formula (2).
^R0 (NHR2) _n ( ² )
(In the above formula, R ⁰ is a substituted or unsubstituted n-valent hydrocarbon group; R ² is each independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; n is 1 or 2.)

(R ⁰ , n)
R ⁰ is a substituted or unsubstituted n-valent hydrocarbon group, where n is 1 or 2;

When n is 1, the unsubstituted monovalent hydrocarbon group represented by R ⁰ includes those exemplified for R ¹ .
When n is 2, the unsubstituted divalent hydrocarbon group represented by R ¹ includes, for example, a methylene group; an ethylene group; and a linear, branched or cyclic alkylene group having 3 or more carbon atoms. or an arylene group having 6 or more carbon atoms. Specifically, methylene group, ethylene group, tetramethylethylene group, n-propylene group (trimethylene group), 1-methylpropylene group, 1,1-dimethylpropylene group, 2-methylpropylene group, 1,2-dimethyl Propylene group, 2,2-dimethylpropylene group, 1,1,2-trimethylpropylene group, 1,1,3-trimethylpropylene group, n-butylene group (tetramethylene group), 2-methyl-1,4-butylene group, 3-methyl-1,4-butylene group, 2,2-dimethyl-1,4-butylene group, 2,3-dimethyl-1,4-butylene group, 2,2,3-trimethyl-1,4 Chain hydrocarbon groups such as -butylene group, n-pentylene group (pentamethylene group), n-hexanylene group (hexamethylene group); alicyclic hydrocarbon groups such as 1,4-cyclohexylene group, benzene ring 1,4-phenylene group, 1,2-phenylene group, 1,3-phenylene group obtained by removing two hydrogen atoms from dimethylphenylene group (xylyl group) obtained by removing two hydrogen atoms from the benzene ring of xylene, toluene Aromatic hydrocarbon groups such as a methylphenylene group (tolylene group) obtained by removing two hydrogen atoms from the benzene ring of, a naphthalene group obtained by removing two hydrogen atoms from naphthalene, 1,4-phenylenebis (methylene) group, 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, and other aliphatic hydrocarbon groups and an aromatic hydrocarbon group; and a divalent group obtained by removing two hydrogen atoms from a polycyclic aromatic hydrocarbon such as a fluorene ring.

From the viewpoint of the availability of raw materials and the usefulness of carbamic acid esters, R ⁰ is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms and a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms. It is preferably a monovalent or divalent group selected from group hydrocarbon groups.
R ⁰ is 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 an 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 aliphatic hydrocarbon group and a divalent group having 7 to 20 carbon atoms consisting of an aromatic hydrocarbon group; more preferably a substituted or unsubstituted carbon number 1 to 12 alkyl groups, substituted or unsubstituted C3 to C12 cycloalkyl groups, substituted or unsubstituted C1 to C12 alkylene groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted phenylene a divalent group having 7 to 24 carbon atoms consisting of a substituted or unsubstituted aliphatic hydrocarbon group and an aromatic hydrocarbon 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; groups; 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;

( ^R2 )
Each R ² is independently a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group.
Examples of the unsubstituted monovalent hydrocarbon group represented by R ² include those exemplified for R ¹ .
Examples of the substituent when the hydrocarbon group represented by R ² has a substituent include those exemplified as the substituent of the hydrocarbon group represented by R ¹ .
R ² is a hydrogen atom or 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. is preferred, and a hydrogen atom is more preferred.
When n is 2, two R ² may be the same or different, but are preferably the same.

The compound represented by the general formula (2) may be a monoamine compound or a diamine compound.
Preferred monoamine compounds include, for example, aniline or aniline derivatives, 4-aminopyridine, 1-aminohexane, and cyclohexylamine. Examples of aniline derivatives 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 preferred.
Preferred diamine compounds include, for example, 4,4′-methylenedianiline, 2,4-tolylenediamine, 1,6-hexyldiamine, and derivatives thereof.
The amount of the amine compound used (amount to be charged) is not particularly limited, but is usually 1 equivalent or more, preferably 1.5 equivalent or more, more preferably 2.5 equivalent or more, and still more preferably 1 equivalent of the monosubstituted carbonate salt. is 3 equivalents or more, and usually 20 equivalents or less, preferably 15 equivalents or less, more preferably 10 equivalents or less.

1-3. Metal Alkoxide Although the metal alkoxide is not particularly limited, a compound represented by the general formula (3) is preferable.
M(OR ¹ ) _pq (R ³ ) _q (3)
(In the above formula, R ¹ is each independently a substituted or unsubstituted monovalent hydrocarbon group; R ³ is each independently a substituted or unsubstituted hydrocarbon ligand, an amide ligand is a ligand, or a halide ligand; M is a metal atom; p represents the formal oxidation number of M and is an integer from 1 to 6; (pq) is an integer from 1 to 6 ; q is an integer of 0 or more and (p-1) or less.)

( ^R1 )
Each R ¹ is independently a substituted or unsubstituted monovalent hydrocarbon group and has the same definition as R ¹ in the monosubstituted carbonate salt represented by formula (1). As a result, the compound represented by general formula (3) can serve as a renewable alkoxide source. When (pq) is 2 to 6, ^a plurality of R ¹ may be the same or different. preferable.

(M)
M is a metal atom. In this specification, the term “metal” is a concept including metalloids such as silicon and boron.
Although the type of metal atom is not particularly limited, examples thereof include metal atoms selected from the group consisting of silicon, titanium, zirconium, germanium, indium, tin, tantalum, zinc and tungsten. Among them, silicon or titanium is preferable, and titanium is more preferable, in terms of availability.

⁽ R3)
Each R ³ is independently a substituted or unsubstituted hydrocarbon ligand, amide ligand, or halide ligand.

Examples of unsubstituted hydrocarbon ligands include alkyl ligands such as methyl ligands and ethyl ligands; cycloalkyl ligands such as cyclohexyl ligands; phenyl ligands and naphthyl ligands; Aryl ligand; aralkyl ligand such as benzyl ligand; cyclopentadienyl ligand, cyclohexadienyl ligand, cyclooctadienyl ligand, cyclooctatetraenyl ligand, norbonadienyl ligand unsaturated hydrocarbon ligands such as ligands, methylcyclopentadienyl ligands, methylcyclohexadienyl ligands, methylcyclooctadienyl ligands, and methylcyclooctatetraenyl ligands; . Substituents that the hydrocarbon ligand may have include, for example, a hydroxy group, an ester group (-COOR), an amide group (-CONRR'), a halogen atom, an alkylthio group (-SR), an amino group (- NRR′), a carboxy group, a nitro group, a sulfonic acid group (—SO ₃ H), 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 pyridyl group. mentioned.

Amide ligands include unsubstituted amide ligand (NH ₂ ), methylamide ligand (NHMe), dimethylamide ligand (NMe ₂ ), diethylamide ligand (NEt ₂ ), di-n-propylamide ligand (NPr ₂ ), isopropylamide ligand, di-n-butylamide ligand, di-t-butylamide ligand and the like.

Examples of halide ligands include fluorine ligands, chlorine ligands, bromine ligands, iodine ligands, and the like.

When p is 2 to 5, a plurality of R ³ may be the same or different, but from the viewpoint of easy availability of metal alkoxide, it is preferred that all R ³ are the same.

(p)
p represents the formal oxidation number of M; p is an integer of 1-6, preferably 2-4. (pq) is an integer of 1-6.

(q)
q represents an integer of 0 or more and (p-1) or less. That is, q is an integer from 0 to 5. As for q, 0 is especially preferable.

Specifically, the metal alkoxide represented by formula (3) is
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, methyltri Propoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, cyclohexyltripropoxysilane, phenyltriethoxysilane methoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, dimethoxydiethylsilane, diethoxydiethylsilane, dimethoxymethylvinylsilane, Alkoxysilanes such as dimethoxydiphenylsilane, dimethoxymethylphenylsilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane;
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, di isopropoxybis(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, Butoxytri isopropoxy titanium,
Dibutoxydiisopropoxytitanium, tetraphenoxytitanium, tetrakis(o-chlorophenoxy)titanium, tetrakis(m-nitrophenoxy)titanium, tetrakis(p-methylphenoxy)titanium, tetrakis(trimethylsilyloxy)titanium, triethoxytitanium, tri Titanium alkoxides such as methoxytitanium, triisopropoxytitanium, tributoxytitanium, methyldimethoxytitanium, ethyltriethoxytitanium, methyltriisopropoxytitanium, tetradimethylaminotitanium, dimethyltitanium diacetylacetonate, ethyltitanium triacetylacetonate;
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, tetradodecyl oxyzirconium, tetrastearyloxyzirconium, tetrakis(8-hydroxyoctyloxy)zirconium, diisopropoxybis(2-ethyl-1,3-hexanediolat)zirconium, bis(2-ethylhexyloxy)bis(2-ethyl- 1,3-hexanediolato)zirconium, tetrakis(2-chloroethoxy)zirconium, tetrakis(2-bromoethoxy)zirconium, tetrakis(2-methoxyethoxy)zirconium, tetrakis(2-ethoxyethoxy)zirconium, butoxytrimethoxyzirconium , dibutoxydimethoxyzirconium, butoxytriethoxyzirconium, dibutoxydiethoxyzirconium, butoxytriisopropoxyzirconium, dibutoxydiisopropoxyzirconium, tetraphenoxyzirconium, tetrakis(o-chlorophenoxy)zirconium, tetrakis(m-nitrophenoxy) alkoxyzirconium such as zirconium and tetrakis(p-methylphenoxy)zirconium;
alkoxygermanium such as tetraethoxygermanium, tetrapropoxygermanium, tetraisopropoxygermanium, tetra(n-butoxy)germanium, tetra(2-butoxy)germanium, tetra(t-butoxy)germanium;
Tetra(n-butoxy)indium, Tetra(2-butoxy)indium, Tetra(t-butoxy)indium, Trimethoxyindium, Triethoxyindium, Tri(n-propoxy)indium, Triisopropoxyindium, Tri(n-butoxy) ) alkoxyindium such as indium, triisobutoxyindium, tri(t-butoxy)indium, tri(s-butoxy)indium;
Alkoxytins such as dibutyldimethoxytin, dibutyldiethoxytin, dibutyldipropoxytin;
Tetramethoxytantalum, tetraethoxytantalum, tetra(n-propoxy)tantalum, tetraisopropoxytantalum, tetra(n-butoxy)tantalum, tetra(2-butoxy)tantalum, tetra(t-butoxy)tantalum, pentaethoxytantalum, etc. alkoxy tantalum;
Alkoxyzinc such as isopropoxyzinc, tetra(n-butoxy)zinc, tetra(2-butoxy)zinc, tetra(t-butoxy)zinc;
Alkoxy tungsten such as pentamethoxytungsten, pentaethoxytungsten, pentaisopropoxytungsten, tungsten (V) pentabutoxytungsten, triisobutoxytungsten, and tri(t-butoxy)tungsten;
is mentioned.

From the standpoint of availability, the metal alkoxide represented by formula (3) is preferably one or more selected from the group consisting of titanium alkoxide and alkoxysilane, more preferably titanium tetramethoxide and titanium tetra-iso-propoxide, titanium tetra-n-butoxide, titanium tetra-t-butoxide, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, more preferably titanium tetra- methoxide, titanium tetra-iso-propoxide, titanium tetra-n-butoxide, titanium tetra-t-butoxide, tetramethoxysilane.

In this embodiment, a metal alkoxide may be added to the reaction system, or a metal alkoxide may be generated in the reaction system and used. For example, zirconium tetrachloride (ZrCl ₄ ) and sodium ethoxide are reacted to generate tetraethoxyzirconium. Also, a method of reacting zirconocene dichloride (Cp ₂ ZrCl ₂ ) with sodium ethoxide to generate zirconocene diethoxide can be mentioned. Another example is a method of reacting dibutyldichlorotin (Bu ₂ SnCl ₂ ) and sodium ethoxide to generate dibutyldiethoxytin.

(catalyst)
In this embodiment, the reaction step may be performed in the presence of a catalyst. In particular, when alkoxysilane is used as the metal alkoxide, the reaction step is preferably carried out in the presence of a catalyst. Preferred examples of catalysts include organic base carboxylates, alkali metal salts, zinc compounds, titanium (IV) compounds, and zirconium (IV) compounds (excluding compounds corresponding to the above metal alkoxides).

Organic base carboxylates include 1,8-diazabicyclo[5.4.0]undec-7-ene acetate, 1,5-diazabicyclo[4.3.0]non-5-ene acetate, Nitrate of 1,1,3,3-tetramethylguanidine and the like can be mentioned.
Alkali metal salts include alkali metal acetates such as lithium acetate, sodium acetate, potassium acetate, rubidium acetate and cesium acetate; alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate; alkali metal hydroxides such as lithium, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide;
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, and octanoic acid. Zinc, zinc salicylate, zinc pivalate, zinc acrylate, p-chlorobenzoic acid, zinc phenolate, zinc chloroacetate, zinc acetylacetonate, zinc oxalate, and zinc trifluoroacetate, zinc(II)-1,10- Examples include zinc carboxylate derivatives such as phenanthroline complexes.
Examples of titanium (IV) compounds include titanium (IV) oxysulfate.n-hydrate, TiCl ₄ and TiBr ₄ .
Zirconium (IV) compounds include zirconium (IV) chloride and zirconium (IV) oxychloride octahydrate.

The catalyst may be used, for example, generated from two or more compounds. For example, zinc acetate and 1,10-phenanthroline may be charged into a reaction vessel to form a zinc (II)-1,10-phenanthroline (phen) complex, which may be 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 is more preferred. , zinc(II)-1,10-phenanthroline (phen) complex.

The amount (charged amount) of the catalyst used in the reaction step is not particularly limited, and should be appropriately selected according to the monosubstituted carbonate salt and the like. Above, it is 70 mol % or less, more preferably 50 mol % or less. In addition, one type of catalyst may be used, or two or more types may be used.

1-4. Carbamate Ester The carbamate produced according to the present embodiment is not particularly limited, and may be determined according to the purpose.
In the production method according to the present embodiment, a compound represented by formula (1) as a monosubstituted carbonate salt, a compound represented by formula (2) as an amine compound, and a metal alkoxide represented by formula (3) When each compound is used, a carbamate represented by general formula (4) can be produced.

(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 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; n is 1 or 2.)
In formula (4), R ⁰ has the same meaning as R ⁰ in formula (2).
In formula (4), R ¹ has the same definition as R ¹ in formulas (1) and (3).
In formula (4), R ² has the same definition as R ² in formula (2).
In formula ( ⁴ ), R3 has the same definition as R3 in formula ( ³ ).
In formula (4), n has the same meaning as n in formula (2).

Examples of carbamic acid esters represented by formula (4) include the following compounds.

1-5. Production of carbamic acid ester (reaction process)
In the reaction step, 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 are added thereto.
Stirring is preferred during the reaction, for example, a magnetic stirrer can be used.

(solvent)
The reaction step may or may not use a solvent. It is believed that the use of a reaction solvent improves the reaction rate.
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 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 carbonate esters; polar solvents.
As the reaction solvent, a polar solvent is preferred, and an aprotic polar solvent is more preferred. Examples of protic polar solvents include ethanol, propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, t-butanol, allyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, alcohols such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol and glycerin; and 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, acetonitrile, or 1-butanol is preferred, and N-methylpyrrolidone is more preferred, from the viewpoint of improving the reaction rate and yield.
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 1 equivalent or more, preferably 1.5 equivalents or more, more preferably 2.5 equivalents or more, and still more preferably 4 equivalents or more, relative to 1 equivalent of the monosubstituted carbonate salt. and is usually 20 equivalents or less, preferably 15 equivalents or less, more preferably 10 equivalents or less.

(reaction temperature)
Although the reaction temperature is not particularly limited, it is generally 100°C or higher, preferably 120°C or higher, more preferably 140°C or higher, and generally 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 produced efficiently.

(reaction time)
The reaction time is not particularly limited, and may be appropriately adjusted depending on the reaction temperature, amount of catalyst, reaction scale, and the like. Usually 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. More preferably, it is 50 hours or less. As used herein, the term “reaction time” refers to the time during which the temperature inside the reactor reaches a predetermined reaction temperature and is maintained at the predetermined reaction temperature.

(reaction atmosphere)
The atmosphere of the reaction step may be an air atmosphere or an inert gas atmosphere such as nitrogen or argon. In addition, the reaction step may be carried out under pressure or under reduced pressure, usually 0.01 atm or more, preferably 0.05 atm or more, more preferably 0.1 atm or more, and usually 10 atm or less, preferably is 5 atm or less, more preferably 2 atm or less.

(reaction vessel)
The reaction vessel is not particularly limited as long as it is made of a material that is stable with respect to the carbamate, and is appropriately selected according to the continuous process or batch process. In this embodiment, it may be a continuous process or a batch process. In the case of a batch process, it is preferably a closed reaction vessel (closed reaction vessel), more preferably a monosubstituted carbonate salt, a metal alkoxide and an amine compound, and if necessary, 10 times to 100 times the volume of the mixture of the reaction solvent. It is a sealed pressure-resistant container having double the volume, more preferably a stainless steel autoclave.

(Other processes)
The method for producing a carbamic acid ester according to the present embodiment may include optional steps in addition to the reaction steps described above. Optional steps include the monosubstituted carbonate salt production step described in the section (Manufacturing method of monosubstituted carbonate salt), the step of regenerating the metal alkoxide with alcohol, and the purification step for increasing the purity of the carbamic acid ester. mentioned. 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 1-1]

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.). A mixed solution containing a monosubstituted carbonate salt prepared by aeration for 10 minutes at a flow rate of 1 L/min was placed in a closed reaction vessel with a volume of 5 mL, and aniline (186 mg, 2.0 mmol) and titanium tetrabutoxide (680 mg, 2.0 mmol) were added. ) and acetonitrile (1.5 mL) were added and reacted at 180° C. for 16 hours. The yield of butyl-N-phenylcarbamate was 30%. Yields were determined by ¹ H NMR using mesitylene (50 mg) as an internal standard.

[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 1 hour. Yield was 47%. Yields are ¹ H using mesitylene (50 mg) as an internal standard.
Determined by NMR.

[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. Yield was 61%. Yields were determined by ¹ H NMR using mesitylene (50 mg) as an internal standard.

[Example 2-1]

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.) at a flow rate of 0.1 L/min for 10 minutes. A mixed solution containing the monosubstituted carbonate salt obtained was placed in a closed reaction vessel with a volume of 5 mL, and hexamethylenediamine (116 mg, 1.0 mmol), titanium tetrabutoxide (680 mg, 2.0 mmol), and n-butanol (1.5 mL) were added. and reacted at 180° C. for 3 hours. The yield of N,N'-hexamethylenebis(dibutylcarbamate) was 71%. Yields were determined by ¹ H NMR using mesitylene (50 mg) as an internal standard.

[Example 3-1]

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 / A mixed solution containing a monosubstituted carbonate salt prepared by aeration for 20 minutes at a flow rate of min was placed in a 5 mL sealed reaction vessel, and hexylamine (202 mg, 2.0 mmol) and titanium tetrabutoxide (680 mg, 2.0 mmol) were added. , and N-methylpyrrolidone (2.5 mL) were added and reacted at 150° C. for 5 hours. Yield of butyl-N-hexylcarbamate was 57%. Yields were determined by ¹ H NMR using mesitylene (50 mg) as an internal standard.

According to the present invention, a carbamic acid ester can be produced using a monosubstituted carbonate salt, a metal alkoxide, and an amine compound as raw materials. In addition, the present invention makes it possible to produce a monosubstituted carbonate salt using a low-concentration carbon dioxide mixed gas as a raw material to produce a carbamic acid ester, enabling effective utilization of low-concentration carbon dioxide contained in exhaust gas and the like. It is a reaction to Furthermore, since the metal alkoxide used in the present invention can be recovered after the reaction and then regenerated using alcohol, it is a highly environmentally friendly reaction in which substantially only low-concentration carbon dioxide, amine compounds, and alcohol are consumed. be.

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

Claims (9)

A method for producing a carbamic acid ester, comprising a reaction step of reacting a monosubstituted carbonate salt, a metal alkoxide and an amine compound to produce a carbamic acid ester. 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), The method for producing a carbamate according to claim 1, wherein the carbamate is a compound represented by formula (4).

(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 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; each R ³ is independently a substituted or unsubstituted hydrocarbon ligand, an amide ligand, or a halide ligand M is a metal atom; A ^m+ is an m-valent cation derived from a base represented by A; n is 1 or 2; m is 1 or 2; represents a formal oxidation number and is an integer of 1 to 6; (pq) is an integer of 1 to 6; q is an integer of 0 or more and (p-1) or less.) The A ^m+ is a cation 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. The method for producing a carbamic acid ester according to claim 2. R ⁰ 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. The method for producing a carbamic acid ester according to claim 2 or 3. 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; A method for producing a monosubstituted carbonate salt according to any one of 2 to 4. The method for producing a carbamic acid ester according to any one of claims 2 to 5, wherein said R ² is a hydrogen atom. The method for producing a carbamic acid ester according to any one of claims 1 to 6, wherein the metal alkoxide is one or more selected from the group consisting of titanium alkoxide and alkoxysilane. The method for producing a carbamic acid ester according to any one of claims 1 to 7, wherein the reaction step is performed in the presence of an aprotic polar solvent. Before the reaction step, a step of contacting an alcohol, a base, and a carbon dioxide-containing gas to produce a monosubstituted carbonate salt, wherein the total pressure of the carbon dioxide-containing gas is _Pt , and the Any one of claims 1 to 8, wherein P _CO2 /P _t is 0.0001 or more and 1 or less, and the P _CO2 is less than 0.1 MPa, where P _CO2 is the partial pressure of carbon dioxide gas in the carbon dioxide-containing gas. 1. A method for producing a carbamic acid ester according to claim 1.

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