JP2010215584A - Method of producing carbamate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a carbamate by the reaction of a carbonate and an amine in the presence of an alkaline catalyst comprising a metal, capable of easily separating a reaction product comprising the metal from a reaction mixture resulting from the reaction. <P>SOLUTION: There is provided a method of producing a carbamate by the reaction of a carbonate and an amine in the presence of an alkaline catalyst comprising the metal, with the carbonate and the amine containing moisture in an amount of 0.001 to 50 ppm in total, whereby the carbamate and a reaction product comprising the metal are obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a carbamic acid ester.

  Carbamate esters (urethanes) are industrially very useful compounds widely used for polyurethane foams, surface coatings, elastomers, paints, adhesives and the like. Carbamates are also useful as raw materials for producing isocyanates without using phosgene.

  The main industrial production method of isocyanate is a reaction between an amine and phosgene (phosgene method), and almost all of the world production is produced by the phosgene method. However, the phosgene method has many problems.

  The first is to use a large amount of phosgene as a raw material. Phosgene is extremely toxic and requires special handling in order to prevent exposure to personnel and special equipment to exclude waste.

  Secondly, in the phosgene method, a large amount of highly corrosive hydrogen chloride is by-produced, so that a process for excluding the hydrogen chloride is required, and the produced isocyanate is often hydrolyzable. Chlorine will be contained, and when an isocyanate produced by the phosgene method is used, the weather resistance and heat resistance of the polyurethane product may be adversely affected.

（一般式（ａ）中、Ｒは、ｘ価の有機残基を表し、Ｒ’は、１価の有機残基を表し、ｘは、１以上の整数を表す。） From such a background, a method for producing an isocyanate compound without using phosgene is desired. As one of the methods for producing an isocyanate compound that does not use phosgene, a method by thermal decomposition of a carbamic acid ester has been proposed. It has long been known that isocyanates and hydroxy compounds can be obtained by thermal decomposition of carbamic acid esters (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1). The basic reaction is exemplified by the following general formula.

(In general formula (a), R represents an x-valent organic residue, R ′ represents a monovalent organic residue, and x represents an integer of 1 or more.)

  Thus, carbamic acid esters are industrially useful compounds.

  Various methods have been proposed so far for producing carbamic acid esters.

According to the description in Patent Document 3, an aliphatic diurethane and / or an alicyclic diurethane and / or an aliphatic polyurethane and / or an alicyclic polyurethane is an aliphatic primary diamine and / or an alicyclic primary diamine. And / or aliphatic primary polyamines and / or alicyclic primary polyamines with O-alkyl carbamates and NH ₂ groups of amines in the presence of alcohols: carbamate: alcohol ratio 1: 0.8-10: It is obtained by reacting at 0.25 to 50 at 160 ° C. to 300 ° C. in the presence or absence of a catalyst, and removing the generated ammonia as necessary.

  In addition, according to the description in Patent Document 4, aryl diurethane and / or aryl polyurethane is prepared from aromatic primary amine and / or aromatic primary polyamine in the presence or absence of an O-alkyl carbamate and a catalyst. As well as in the presence or absence of urea and alcohol to produce aryl diurethanes and / or aryl polyurethanes, and the resulting ammonia is optionally removed.

  Other publications include carbonyl-containing compounds such as N-substituted carbamates and / or dialkyl carbonates, or urea and / or diamine moieties with monosubstituted ureas or disubstituted ureas or monosubstituted polyureas or disubstituted polyureas. There is a description relating to physical substitution (see Patent Document 5, Patent Document 6, Patent Document 7, Patent Document 8, and Patent Document 9). Patent Document 10 describes a method for producing an aliphatic O-aryl urethane by reacting a (cyclic) aliphatic polyamine with urea and an aromatic hydroxy compound.

  Patent Document 11 discloses a method for producing a carbamic acid ester from an amine and dimethyl carbonate. In the above method, an amine and dimethyl carbonate are reacted in the presence of a Lewis acid catalyst, lead, titanium or zirconium catalyst, an alkali catalyst, or the like.

  Thus, various methods for producing carbamic acid esters have been proposed. As a method of using a basic catalyst, Patent Document 12 discloses that an amine and a carbonate ester are alkali metal alcoholate or alkaline earth metal alcoholate. A method for producing a crude reaction solution containing a carbamic acid ester by reacting in the presence is disclosed.

Japanese Patent Application Publication No. 59-48452 Japanese Patent Application Publication No. 2004-262831 U.S. Pat. No. 4,497,963 U.S. Pat. No. 4,290,970 U.S. Pat. No. 4,388,238 US Patent No. 4,430,505 U.S. Pat. No. 4,480,110 U.S. Pat. No. 4,596,678 U.S. Pat. No. 4,596,679 European Patent Application Publication No. 0320235 U.S. Pat. No. 4,395,565 Japanese Patent Application Publication No. 6-72982

Berchte der Deutschen Chemischen Gesellshaft, 3, 653, 1870

  The carbamate produced in the method described in Patent Document 12 is subsequently used for the production of isocyanate. However, since the catalyst contained in the crude reaction liquid often causes a side reaction, the crude reaction liquid is used. It was necessary to go through a process for deactivating the catalyst, such as neutralizing the catalyst contained in the catalyst with an ion exchange resin or the like. However, for example, in the case of neutralization with an ion exchange resin, there is a problem that the work becomes complicated because it is necessary to discard the ion exchange resin broken through the neutralization work or to regenerate it by acid washing or the like. .

  The present invention provides a method for producing a carbamate ester by reacting a carbonate ester with an amine in the presence of a basic catalyst containing a metal, and the reaction product containing the metal is easily obtained from the reaction mixture obtained by the reaction. It is an object of the present invention to provide a method for producing a carbamate that can be separated into two groups.

  The present invention is a method for producing a carbamate by reacting a carbonate and an amine in the presence of a basic catalyst containing a metal, wherein the total amount of water contained in the carbonate and the amine is 0. It is 0.001-50 ppm, The manufacturing method which obtains the reaction product containing the said metal with the said carbamic acid ester by the said reaction is provided.

  In the method for producing a carbamic acid ester of the present invention, the total amount of water contained in the carbonate ester and the amine is 0.001 to 50 ppm, whereby the reaction product is converted into a reaction mixture obtained by the reaction. It becomes insoluble and the reaction product can be easily separated from the reaction mixture.

［式中、Ｒ^１は炭素数１〜１０の脂肪族基を表す。］ The carbonate ester is preferably a compound represented by the following general formula (1).

[Wherein, R ¹ represents an aliphatic group having 1 to 10 carbon atoms. ]

［式中、Ｒ^２は、酸素原子を含んでいてもよい、炭素数１〜２０のｎ価の脂肪族基又は炭素数６〜２０のｎ価の芳香族基であり、ｎは２〜１０の整数を表す。］ The amine is preferably a compound represented by the following general formula (2).

[Wherein, R ² is an n-valent aliphatic group having 1 to 20 carbon atoms or an n-valent aromatic group having 6 to 20 carbon atoms, which may contain an oxygen atom, and n is 2 to 10 Represents an integer. ]

  In the compound represented by the general formula (2), n is preferably 2.

  The basic catalyst containing a metal is preferably an alkali metal or alkaline earth metal alcoholate.

  The reaction product is insoluble in the reaction mixture obtained by the reaction, and the reaction product is preferably separated from the reaction mixture.

  The separation is preferably performed by filtration.

  According to the method for producing a carbamic acid ester of the present invention, in the method for producing a carbamic acid ester by the reaction of a carbonate and an amine in the presence of a basic catalyst containing a metal, Reaction products containing metals can be easily separated.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  First, the carbonate ester in the present embodiment will be described.

［式中、Ｒ^１は炭素数１〜１０の脂肪族基を表す。］ Although there is no restriction | limiting in particular about the carbonate ester used in this Embodiment, The carbonate ester represented with the following general formula (1) is used preferably.

[Wherein, R ¹ represents an aliphatic group having 1 to 10 carbon atoms. ]

The R ¹ in the general formula (1), preferably an alkyl groups containing 1 to 10 carbon constituting the group, for example, a methyl group, an ethyl group, a propyl group (isomers), butyl group (including Isomer), pentyl group (each isomer), hexyl group (each isomer), heptyl group (each isomer), octyl group (each isomer), nonyl group (each isomer), decyl group (each isomer) Among them, a carbonate ester in which R ¹ is an alkyl group having 2 to 6 carbon atoms, that is, diethyl carbonate, dipropyl carbonate (each isomer), dibutyl carbonate (each isomer), dipentyl carbonate ( Each isomer) and dihexyl carbonate (each isomer) are preferably used.

  As a method for producing the carbonate ester, a known method can be used. Preferably, a carbonate ester is produced by reacting an organic tin compound having a tin-oxygen-carbon bond with carbon dioxide.

  Next, the amine used in the present embodiment will be described.

［式中、Ｒ^２は、酸素原子を含んでいてもよい、炭素数１〜２０のｎ価の脂肪族基又は炭素数６〜２０のｎ価の芳香族基であり、ｎは２〜１０の整数を表す。］ Although there is no restriction | limiting in particular about the amine used in this Embodiment, The amine represented by following General formula (2) is used preferably.

[Wherein, R ² is an n-valent aliphatic group having 1 to 20 carbon atoms or an n-valent aromatic group having 6 to 20 carbon atoms, which may contain an oxygen atom, and n is 2 to 10 Represents an integer. ]

  In the above formula (2), n is preferably a polyamine having 2 or more, and more preferably a diamine in which n is 2.

  Examples of such polyamines include hexamethylenediamine, 4,4′-methylenebis (cyclohexylamine) (each isomer), cyclohexanediamine (each isomer), 3-aminomethyl-3,5,5-trimethylcyclohexyl. Examples include aliphatic diamines such as amines (each isomer); aromatic diamines such as phenylenediamine (each isomer) and toluenediamine (each isomer) 4,4′-methylenedianiline. Among them, hexamethylenediamine, 4,4′-methylenebis (cyclohexylamine) (each isomer), cyclohexanediamine (each isomer), 3-aminomethyl-3,5,5-trimethylcyclohexylamine (each isomer), etc. Aliphatic diamines are preferably used, among which hexamethylenediamine, 4,4′-methylenebis (cyclohexylamine), and 3-aminomethyl-3,5,5-trimethylcyclohexylamine are more preferably used.

  The total amount of water contained in the carbonate ester and the amine is 0.001 to 50 ppm. Surprisingly, when the water content contained in the carbonate ester and the amine is more than 50 ppm, the inventors of the present invention reduce the production amount of a reaction product containing a metal derived from the basic catalyst described later. It has been found that separation from the reaction solution may be difficult. Although the clear correlation between the reaction product of the compound containing a metal derived from the basic catalyst and the amount of water is unknown, the present inventors have determined that the base is determined by the water contained in the carbonate ester and the amine. It is speculated that the reaction product containing the metal derived from the sex catalyst is hydrolyzed. From such a viewpoint, the total amount of water contained in the carbonate ester and the amine is preferably 30 ppm or less, more preferably 10 ppm or less.

  On the other hand, the present inventors have surprisingly found that a small amount of water contained in a carbonate ester and an amine has an effect of improving the activity of the basic catalyst. Although it is not clear about the mechanism that exerts such an effect, the present inventors have found that a small amount of water present in the reaction system acts on the carbonate ester together with the basic catalyst, and the carbonyl carbon of the carbonate ester is reduced. I'm guessing that it might be activated. From such a viewpoint, the total amount of water contained in the carbonate ester and the amine is preferably 0.001 ppm or more, and more preferably 0.003 ppm or more.

The amount of water contained in the carbonate ester and the amine can be quantified by a known method, and for example, methods such as Karl Fischer, ¹ H-NMR, and infrared absorption method can be used.

As the basic catalyst used in the reaction between the carbonate ester and the amine, an alkali metal or alkaline earth metal alcoholate is preferably used. Examples of the alkali metal and alkaline earth metal in the basic catalyst include lithium, sodium, potassium, calcium, and barium. On the other hand, as the alkoxy group of the basic catalyst, an alkoxy group in which an oxygen atom is added to an alkyl group having 1 to 10 carbon atoms is preferably used, and a methoxy group, an ethoxy group, a butoxy group (each isomer), a pentyloxy group. (Each isomer), hexyloxy group (each isomer), heptyloxy group (each isomer), octyloxy group (each isomer), nonyloxy group (each isomer), decyloxy group (each isomer) be able to. Among them, the alkoxy group is the same group as the group R ¹ O (R ¹ is a group defined above, and O represents an oxygen atom) constituting the carbonate represented by the above formula (1). Alkoxy groups are preferred.

The reaction conditions under which the carbonate ester reacts with the amine vary depending on the compound to be reacted, but the stoichiometric ratio of the carbonate ester to the amino group of the amine is preferably in the range of 2 to 1000 times. . In order to increase the reaction rate and complete the reaction at an early stage, the carbonic acid diester is preferably in an excess amount with respect to the amino group of the amine. The range is more preferably 2 to 30 times. The reaction temperature is usually in the range of 0 ° C. to 300 ° C., and a high temperature is preferable for increasing the reaction rate. On the other hand, an unfavorable reaction may occur at a high temperature, and preferably 20 ° C. to 150 ° C. Range. In order to keep the reaction temperature constant, a known cooling device or heating device may be installed in the reactor. Moreover, although reaction pressure changes with the kind of compound to be used, and reaction temperature, any of pressure reduction, a normal pressure, and pressurization may be sufficient, and it is performed in the range of 20-1x10 < ⁶ > Pa normally.

  There is no restriction | limiting in particular in reaction time (in the case of a continuous method), Usually, 0.001 to 50 hours, Preferably it is 0.01 to 10 hours, More preferably, it is 0.1 to 5 hours. Alternatively, the reaction solution can be collected, and the reaction can be terminated after confirming that a desired amount of carbamic acid ester has been formed, for example, by liquid chromatography.

  In the present embodiment, it is not always necessary to use a reaction solvent, but an appropriate inert solvent such as hexane (each isomer), heptane (each isomer), for example, for the purpose of facilitating the reaction operation, Alkanes such as octane (each isomer), nonane (each isomer), decane (each isomer), etc .; benzene, toluene, xylene (each isomer), ethylbenzene, diisopropylbenzene (each isomer), dibutylbenzene (each Isomers), aromatic hydrocarbons such as naphthalene and alkyl-substituted aromatic hydrocarbons; chlorobenzene, dichlorobenzene (each isomer), bromobenzene, dibromobenzene (each isomer), chloronaphthalene, bromonaphthalene, nitrobenzene, nitro Aromatic compounds substituted by halogen or nitro groups such as naphthalene; diphenyl, substituted Polycyclic hydrocarbon compounds such as phenyl, diphenylmethane, terphenyl, anthracene, and dibenzyltoluene (each isomer); aliphatic hydrocarbons such as cyclohexane, cyclopentane, cyclooctane, and ethylcyclohexane; ketones such as methyl ethyl ketone and acetophenone Preferred examples of the reaction solvent include esters such as dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, and benzyl butyl phthalate; ethers and thioethers such as diphenyl ether and diphenyl sulfide; and sulfoxides such as dimethyl sulfoxide and diphenyl sulfoxide. These solvents can be used alone or as a mixture of two or more. A carbonate ester used in an excess amount with respect to the amino group of the amine is also suitably used as a solvent in the above reaction.

  As the reactor, a known tank reactor, a column reactor, a distillation column, and a combination of these reactors can be used. The material of the reactor and the line may be any known material as long as it does not adversely affect the starting materials and reactants, but SUS304, SUS316, SUS316L, etc. are inexpensive and can be preferably used.

［式中、Ｒ^１およびＲ^２は、各々、上記一般式（１）及び（２）中で定義した基であり、ｎは、２〜１０の整数である。］ The carbamic acid ester obtained by the method shown above is a compound represented by the following general formula (3).

[Wherein, R ¹ and R ² are groups defined in the general formulas (1) and (2), respectively, and n is an integer of 2 to 10. ]

  Examples of such carbamic acid esters include N, N′-hexanediyl-dicarbamic acid-dimethyl ester, N, N′-hexanediyl-dicarbamic acid-diethyl ester, N, N′-hexanediyl-dicarbamic acid— Dibutyl ester (each isomer), N, N′-hexanediyl-dicarbamic acid-dipentyl ester (each isomer), N, N′-hexanediyl-dicarbamic acid-dihexyl ester (each isomer), N, N ′ -Hexanediyl-dicarbamic acid-dioctyl ester (each isomer), dimethyl-4,4'-methylene-dicyclohexyl carbamate, diethyl-4,4'-methylene-dicyclohexyl carbamate, dipropyl-4,4'-methylene-dicyclohexyl carbamate (Each isomer), dibutyl- , 4'-methylene-dicyclohexyl carbamate (each isomer), dipentyl-4,4'-methylene-dicyclohexyl carbamate (each isomer), dihexyl-4,4'-methylene-dicyclohexyl carbamate (each isomer), diheptyl- 4,4′-methylene-dicyclohexyl carbamate (each isomer), dioctyl-4,4′-methylene-dicyclohexyl carbamate (each isomer), 3- (methoxycarbonylamino-methyl) -3,5,5-trimethylcyclohexyl Carbamic acid methyl ester, 3- (ethoxycarbonylamino-methyl) -3,5,5-trimethylcyclohexylcarbamic acid ethyl ester, 3- (propyloxycarbonylamino-methyl) -3,5,5-trimethylcyclohexylcarbamic acid Lopyl ester (each isomer), 3- (butyloxycarbonylamino-methyl) -3,5,5-trimethylcyclohexylcarbamic acid butyl ester (each isomer), 3- (pentyloxycarbonylamino-methyl) -3,5 , 5-Trimethylcyclohexylcarbamic acid pentyl ester (each isomer), 3- (hexyloxycarbonylamino-methyl) -3,5,5-trimethylcyclohexylcarbamic acid hexyl ester (each isomer), 3- (heptyloxycarbonyl) Amino-methyl) -3,5,5-trimethylcyclohexylcarbamic acid heptyl ester (each isomer), 3- (octyloxycarbonylamino-methyl) -3,5,5-trimethylcyclohexylcarbamic acid octyl ester (each isomer) ), Toluene di Carbamic acid-dimethyl ester (each isomer), toluene-dicarbamic acid-diethyl ester (each isomer), toluene-dicarbamic acid-dipropyl ester (each isomer), toluene-dicarbamic acid-dibutyl ester (each isomer) , Toluene-dicarbamic acid-dipentyl ester (each isomer), toluene-dicarbamic acid-dihexyl ester (each isomer), toluene-dicarbamic acid-diheptyl ester (each isomer), toluene-dicarbamic acid-dioctyl ester (each Isomer), N, N ′-(4,4′-methanediyl-diphenyl) -dicarbamic acid-dimethyl ester, N, N ′-(4,4′-methanediyl-diphenyl) -dicarbamic acid-diethyl ester, N, N ′-(4,4′-methanediyl-diphenyl) -di Rubamic acid-dipropyl ester, N, N ′-(4,4′-methanediyl-diphenyl) -dicarbamic acid-dibutyl ester, N, N ′-(4,4′-methanediyl-diphenyl) -dicarbamic acid-dipentyl ester N, N ′-(4,4′-methanediyl-diphenyl) -dicarbamic acid-dihexyl ester, N, N ′-(4,4′-methanediyl-diphenyl) -dicarbamic acid-diheptyl ester, N, N ′ Mention may be made of carbamic acid esters such as-(4,4'-methanediyl-diphenyl) -dicarbamic acid-dioctyl ester.

On the other hand, although the structure of the reaction product containing the metal derived from the basic catalyst produced by the above method is not clear, the present inventors have conducted structural analysis and ICP (induction by ¹ H-NMR). From the result of quantification of the metal content by the combined plasma emission analysis), it is presumed that it is a complex of a carbamate and a metal derived from the basic catalyst.

  The reaction product containing the metal derived from the basic catalyst produced by the above-mentioned method is often dispersed as a powder in the reaction system, such as filtration, membrane separation, decantation, and centrifugal separation. It can be separated and recovered from the reaction system by a known method. The separation operation is preferably carried out under an inert atmosphere such as nitrogen, helium, argon, neon or the like. By this operation, the amount of metal contained in the reaction solution containing the carbamate ester produced by the above-described method can be reduced, so work for separating the carbamate ester and the metal derived from the catalyst.・ The load can be reduced.

  The carbamic acid ester obtained by the method shown above is a compound useful for the production of isocyanate, and the isocyanate produced from the carbamic acid ester is suitably used as a raw material for producing polyurethane foam, paints, adhesives and the like. be able to. In addition, the above-described method can easily separate the carbamate and the compound containing the metal derived from the basic catalyst, and the amount of metal contained in the carbamate can be reduced. The present invention is extremely important in industry.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, the scope of the present invention is not limited to these Examples.

<Analysis method>
1) Water analysis method apparatus: manufactured by Mitsubishi Chemical, Japan, CA-05 micro moisture meter (1) Quantitative analysis method After collecting about 1 g of an analytical sample using a syringe in a dry nitrogen atmosphere and measuring the weight Then, it was poured into a moisture meter as it was, and water was quantified. Thereafter, the syringe was again weighed, the sample injection amount was calculated, and the water content in the sample was calculated.

2) Liquid chromatography analysis method Apparatus: LC-10AT system manufactured by Shimadzu Corporation, Japan Column: Silica-60 columns manufactured by Tosoh Corporation, Japan Connected in series Developing solvent: Hexane / tetrahydrofuran = 80/20 (volume ratio) Liquid mixture of solvent: 2 mL / min Column temperature: 35 ° C.
Detector: R.I. I. (Refractometer)

(1) Sample for liquid chromatography analysis About 0.1 g of sample was weighed, about 1 g of tetrahydrofuran (made by Wako Pure Chemical Industries, Japan, dehydration) and bisphenol A (Japan, Wako Pure Chemical Industries, Ltd.) as an internal standard substance. A solution obtained by adding about 0.02 g of (manufactured, first grade) and mixing uniformly was used as a sample for liquid chromatography analysis.

(2) Quantitative analysis method Each standard substance was analyzed, and based on the prepared calibration curve, quantitative analysis of the analysis sample solution was performed.

3) Gas chromatography analysis method Apparatus: GC-2010 manufactured by Shimadzu Corporation, Japan
Column: DB-1 manufactured by Agilent Technologies, USA
Length 30m, inner diameter 0.250mm, film thickness 1.00μm
Column temperature: After holding at 50 ° C. for 5 minutes, the temperature is raised to 200 ° C. at a heating rate of 10 ° C./min.
After holding at 200 ° C. for 5 minutes, the temperature is raised to 300 ° C. at a temperature rising rate of 10 ° C./min. Detector: FID

(1) Sample for gas chromatography analysis About 0.05 g of the sample was weighed, about 1 g of toluene (made by Wako Pure Chemical Industries, Japan, dehydration) and diphenyl ether (made by Wako Pure Chemical Industries, Japan) as an internal standard substance. A solution obtained by adding about 0.02 g of special grade) and mixing them uniformly was used as a sample for gas chromatography analysis.

(2) Quantitative analysis method Each standard substance was analyzed, and based on the prepared calibration curve, quantitative analysis of the analysis sample solution was performed.

4) ICP mass spectrometry apparatus: Seiko Electronics Co., Ltd., SPQ-8000

(1) Quantitative analysis method After 0.1 g of sample was incinerated with dilute sulfuric acid, it was dissolved in dilute nitric acid. The amount of sodium element in this sample was quantified with an ICP mass spectrometer.

[Example 1]
Into a 5 L four-necked flask of the inner solution was placed 1537 g (7.6 mol) of bis (3-methylbutyl) carbonate and 220.8 g (1.9 mol) of hexamethylenediamine (Aldrich, USA), and a stir bar. A fractionation head with a reflux condenser connected to a liquid receiver and a thermometer were attached, and the inside of the flask was replaced with vacuum-nitrogen. About 1 g of the solution in the flask was collected, and the water content was measured with a Karl Fischer moisture meter. As a result, about 10 ppm of water was contained. The flask was immersed in an oil bath heated to 80 ° C., and 10 g of sodium methoxide (manufactured by Aldrich, USA, 25% methanol solution) was added with a syringe. After 6 hours, a white precipitate was visually confirmed. When the reaction solution was sampled and analyzed by gas chromatography, hexamethylenediamine was not detected.

  The above reaction solution was put in a stainless steel holder with a tank (Japan, Toyo Seisakusho KST-90) equipped with a PTFE membrane filter (Japan, Toyo Roshi Kaisha, pore size 0.25 μm) under a nitrogen atmosphere. Then, filtration was performed by introducing 0.4 MPa of nitrogen into the tank. On the filter, 16.5 g of a white solid was obtained, which contained about 5 wt% sodium.

  The filtrate was analyzed by liquid chromatography and found to contain N, N'-hexanediyl-bis-carbamic acid bis (3-methylbutyl) ester. Further, sodium contained in the filtrate was about 20 ppm.

[Comparative Example 1]
Refrigeration cooling connected to a distillate receiver with 1245 g (6.2 mol) of bis (3-methylbutyl carbonate) and 179 g (1.5 mol) of hexamethylenediamine in a 4 L flask with 5 L of inner solution, and a stir bar. A fractionation head with a vessel and a thermometer were attached, and the inside of the flask was replaced with vacuum-nitrogen. About 1 g of the solution in the flask was collected and the water content was measured with a Karl Fischer moisture meter. As a result, about 120 ppm of water was contained. The flask was immersed in an oil bath heated to 80 ° C., and 10 g of sodium methoxide (25% methanol solution) was added by a syringe to react. After 6 hours, no white precipitate was observed in the reaction solution. When the reaction solution was sampled and analyzed by gas chromatography, hexamethylenediamine was not detected.

  The above reaction solution was put in a stainless steel holder with a tank (Japan, Toyo Seisakusho KST-90) equipped with a PTFE membrane filter (Japan, Toyo Roshi Kaisha, pore size 0.25 μm) under a nitrogen atmosphere. Then, filtration was performed by introducing 0.4 MPa of nitrogen into the tank. No solid matter was obtained on the filter.

  As a result of analyzing the filtrate by liquid chromatography, it contained 35.7 wt% of N, N′-hexanediyl-bis-carbamic acid bis (3-methylbutyl) ester. Moreover, the sodium contained in a filtrate was about 700 ppm.

  In the method for producing a carbamic acid ester of the present invention, a reaction product produced in the production of a carbamic acid ester and containing a metal derived from the basic catalyst can be easily separated from the carbamic acid ester. Therefore, the present invention is extremely important in industry.

Claims (7)

A process for producing a carbamate by reacting a carbonate with an amine in the presence of a basic catalyst containing a metal,
The total amount of water contained in the carbonate ester and the amine is 0.001 to 50 ppm,
The manufacturing method of obtaining the reaction product containing the said metal with the said carbamic acid ester by the said reaction. The production method according to claim 1, wherein the carbonate ester is a compound represented by the following general formula (1).

[Wherein, R ¹ represents an aliphatic group having 1 to 10 carbon atoms. ] The production method according to claim 1 or 2, wherein the amine is a compound represented by the following general formula (2).

[Wherein, R ² is an n-valent aliphatic group having 1 to 20 carbon atoms or an n-valent aromatic group having 6 to 20 carbon atoms, which may contain an oxygen atom, and n is 2 to 10 Represents an integer. ]   The manufacturing method of Claim 3 whose n in the compound represented by the said General formula (2) is 2.   The production method according to any one of claims 1 to 4, wherein the basic catalyst containing a metal is an alkali metal or alkaline earth metal alcoholate.   The production method according to any one of claims 1 to 5, wherein the reaction product is insoluble in the reaction mixture obtained by the reaction, and the reaction product is separated from the reaction mixture. The production method according to claim 6, wherein the separation is performed by filtration.