KR20110039971A - Method for preparing aliphatic dicarbamates - Google Patents

Abstract

PURPOSE: A method for preparing aliphatic dicarbamates is provided to reduce the production of alkylated amine byproducts and to prepare aliphatic dicarbamates from aliphatic diamine and dialkylcarbonate in high yield. CONSTITUTION: A method for preparing aliphatic dicarbamates by reacting C2-8 aliphatic diamine with dialkylcarbonate comprises the steps of: (i) synthesizing monocarbamate by reacting the aliphatic diamine with dialkylcarbonate at a low temperature using water or C1-6 alcohol solvent as a reaction accelerator; and (ii) converting the monocarbamate into the dicarbamate at a high temperature.

Description

Method for preparing aliphatic dicarbamate {Method for Preparing Aliphatic Dicarbamates}

The present invention relates to a process for preparing aliphatic dicarbamate. More specifically, the present invention reacts aliphatic diamines and dialkylcarbonates in the presence of water in a two-step process at low and high temperatures, thereby increasing the yield of dicarbamate, inhibiting the formation of alkylated amine byproducts and using no catalyst. It relates to a process for producing aliphatic carbamate in an environmentally friendly process.

Isocyanates, which are used as intermediates for polyurethanes, adhesives and pesticides, have been synthesized from amines and phosgene, but this method requires the use of highly toxic phosgene and the disadvantage of the high concentration of pollutant HCl. New environmentally friendly methods have been required that are not used. As a part of this method, a method of preparing carbamate first and pyrolyzing it to prepare an isocyanate is mainly studied.

Methods for preparing carbamate include a method of reacting a nitro compound or an amine with carbon monoxide and an alcohol at a high temperature and high pressure in the presence of a catalyst, a method of synthesizing a carbamate from the reaction of an amine with a dialkyl carbonate, and an amine with ethylene or propylene carbonate. And a reaction method.

U.S. Patent Nos. 3,461,149 and 3,979,427 used metal halide salts such as iron chloride as cocatalysts to increase reaction rates with palladium or rhodium-based catalysts when carbamate was prepared using nitro or amine compounds. Excess promoters are not only difficult to separate after the reaction, but also cause corrosion problems of the device.

U.S. Patent No. 4,178,455 describes that the reaction rate and selectivity can be increased by adding a primary amine when preparing a carbamate from an aromatic nitro compound using a catalyst such as platinum. Since iron chloride is used as the redox active metal halide, this method also has problems with separation and corrosion.

In order to solve this corrosion problem, U.S. Patent Nos. 4,169,269, 4,219,661, 4,262,130, and 4,339,592, etc., add a tertiary amine such as pyridine to the reaction without the use of redox-active metal halides to remove from aromatic nitro compounds. Carbamate was prepared. As the catalyst, palladium, platinum, and other Group VIII elements may be used, and under the same conditions, US Pat. Nos. 3,338,956, 3,993,685, 4,705,883 and the like used a carbonyl compound of rhodium or ruthenium as a catalyst. The pyridine used at this time is in excess of the catalyst used, and sometimes used as a reaction solvent. However, this method is not economically feasible due to the difficulty of using pyridine with inverse smell and recovery of precious metal catalyst.

US Pat. Nos. 4,297,502, 4,304,992 and 4,474,978 use carbamate by reacting a primary amine or urea with an aromatic nitro compound in the presence of CO and alcohol using palladium containing PdCl ₂ and a phosphine ligand as a catalyst. Although there is a method for preparing the catalyst, there is a problem that the catalyst is too expensive and the catalyst recovery after the reaction is not easy.

Japanese Patent Application Laid-Open No. 54-145601 discloses a method of using a transition metal compound such as palladium, a palladium compound as a catalyst, a method of using palladium, ruthenium, rhodium and Lewis acid, and a tertiary amine as a catalyst, but such a method is known. They have a problem that they require low catalyst activity and use expensive precious metal catalysts, as well as by-products of urea compounds and N-alkylated amines in large quantities.

Chemistry Letters (1972) 373-374 describe a method for synthesizing carbamate by carbonylating an amine on a selenium catalyst, but using an equivalent amount of selenium leads to a high loss of catalyst and an aromatic amine as a raw material. There is a drawback that little reaction proceeds.

As a method for solving this problem, a method of reacting dialkyl carbonate and amine under relatively mild conditions has been proposed. For example, Japanese Patent Laid-Open No. 51-33095 describes a method of using Lewis acids such as uranyl acetate and antimony trichloride as a catalyst. However, these catalysts promote the alkylation reaction of amines by diester carbonate in addition to the carbamate formation reaction, resulting in increased by-products of N-alkylated amines. In addition, the uranium compound gives a relatively good result, but the handling of the radioactive element is difficult, so there is no practical use.

Japanese Laid-Open Patent Publication No. 57-82361 discloses a method using a neutral or basic compound of zinc, titanium or zirconium as a catalyst. This method has high yield of carbamate, but requires high temperature and long reaction, and it is not industrially preferable because of difficulty in separating catalyst after reaction.

Lewis acids such as aluminum chloride, tin chloride, iron chloride, zinc chloride, rhodium chloride, and the like are used as catalysts by Gazz. Ital 115, 275. According to this document, reactions using these catalysts give good results, but the reaction is carried out in the presence of an excess of amines for dialkyl carbonates, which requires a lot of energy for recycling amines when it is necessary to use high boiling amines. There is a problem.

On the other hand, Japanese Patent Laid-Open No. 2-311452 discloses a method of using an alcohol of an alkali metal and an alkaline earth metal as a method of using a base as a catalyst, but a base may remain in the carbamate obtained in this method. Residual base should be removed by neutralization with acid as it may cause polymerization or coloring when converting carbamate to isocyanate.

JP-A-3-275662 discloses a method of adding 1 mol% or more of water to diester carbonate in the reaction of ammonia or monoamine and diester carbonate to synthesize monocarbamate. However, in the above-mentioned patent document, not only is there no mention of producing dicarbamate from diamine, but there is a lot of difficulty in separating and purifying the product because an excess amine is used together with water.

Japanese Unexamined Patent Application Publication No. 5-85854 shows that the use of excess amine for dialkyl carbonate allows the reaction to proceed rapidly even in the absence of a catalyst and to prepare carbamate with high selectivity in high yield. This method has the advantage that it is not necessary to add materials other than the reaction raw materials to the reaction system and carbamate can be obtained in a high yield in a short time, but in the case of diamine, the yield is low and the difficulty of purifying the amine used excessively is difficult. have.

Korean Patent Publication No. 1999-0079326 discloses a method for preparing carbamate in a high yield by reacting an amine with an alcohol and a mixed CO / O ₂ gas in the presence of a selenium catalyst system. There is a problem that the catalyst must be recovered.

The present inventors have studied diligently to solve the above-mentioned various problems of the prior art, and as a result, the yield of dicarbamate is increased by reacting aliphatic diamine and dialkyl carbonate in the presence of water in a two-step process at low temperature and high temperature. The present invention was completed by discovering that aliphatic dicarbamate can be produced in an environmentally friendly process that does not require a catalyst separation process after the reaction by suppressing the production of alkylated amine by-products and not using a catalyst.

Accordingly, it is an object of the present invention to provide a process for producing environmentally friendly aliphatic dicarbamate from aliphatic diamines and dialkylcarbonates with greatly reduced production of alkylated amine by-products.

The present invention is a method for producing an aliphatic dicarbamate by reacting an aliphatic diamine having 2 to 8 carbon atoms with dialkyl carbonate, using water or an alcohol solvent having 1 to 6 carbon atoms as a reaction accelerator, (i) the aliphatic diamine Reacting a dialkyl carbonate at low temperature to synthesize aliphatic monocarbamate, and (ii) a second step of converting the monocarbamate to the dicarbamate at a high temperature. It is about.

Hereinafter, the manufacturing method of the present invention will be described in more detail.

The present invention relates to a process for preparing aliphatic dicarbamate by reacting aliphatic diamine having 2 to 8 carbon atoms with dialkyl carbonate, wherein water or an alcohol solvent having 1 to 6 carbon atoms is used as a reaction accelerator, and the reaction is carried out at low temperature and high temperature. It is characterized by proceeding by dividing into steps. In the first low temperature reaction, monocarbamate is mainly synthesized, and in the second high temperature reaction, monocarbamate is converted to dicarbamate, thereby increasing the yield of dicarbamate and suppressing the production of byproduct alkylated amine. In the second stage reaction, it is preferable to use the reactor to which the Dean-Stark apparatus is attached to remove the by-produced alcohol in an azeotropic mixture with the dialkyl carbonate.

Aliphatic diamines having 2 to 8 carbon atoms used in the preparation method of the present invention include cycloaliphatic diamines having 2 to 8 carbon atoms, for example 1,2-ethanediamine (EDA), 1,3-propanediamine (PDA) , 1,4-butanediamine (BDA), 1,6-hexanediamine (HDA), 1,8-octanediamine (ODA), 1,2-cyclohexanediamine (1,2-CHDA), 1,3- Cyclohexane diamine (1,3-CHDA), 1,4-cyclohexane diamine (1,4-CHDA), 1,3-cyclohexane bismethylamine (1,3-CHBMA), 1,4-cyclohexane bis Methylamine (1,4-CHBMA) and the like, but are not limited thereto.

In addition, the dialkyl carbonate used in the production method of the present invention includes dimethyl carbonate (DMC), diethyl carbonate (DEC), diisopropyl carbonate (DIPC), dipropyl carbonate (DPC), dibutyl carbonate (DBC) and the like. Including but not limited to.

The amount of the dialkyl carbonate used is preferably 2 to 20 mol, more preferably 5 to 10 mol based on 1 mol of the aliphatic diamine as a starting material. If the amount of dialkyl carbonate is less than 2 moles, the yield of dicarbamate is significantly decreased. If the amount of dialkyl carbonate is more than 20 moles, the amount of dialkyl carbonate to be recovered after the reaction will result in using more dialkyl carbonate than necessary. This will be a lot.

In the production method of the present invention, water or an alcohol solvent having 1 to 6 carbon atoms may be used as the reaction accelerator, and water is more preferably used in consideration of separation efficiency of the product and the unreacted product.

The amount of water used is preferably 0.1 to 20 moles, more preferably 2 to 8 moles, per 1 mole of aliphatic diamine as a starting material. When the amount of water used is less than 0.1 mole, the reaction proceeds too slowly, resulting in diamine conversion and dicarbamate yield, and increase in the formation of alkylated amine by-products. This results in a large amount of water to be removed after the reaction, which is uneconomical.

The reaction temperature may be selected in the range of 10 to 60 ℃, the second stage of the reaction 60 to 100 ℃ depending on the type of aliphatic diamine as a starting material, the reaction rate, yield of dicarbamate, by-products, etc. In consideration of the first step, the reaction is preferably selected in the range of 20 to 50 ℃, the second stage of the reaction 70 to 90 ℃. When the temperature of the first stage reaction exceeds 60 ℃, the alkylation process of the amine by the dialkyl carbonate is promoted to increase the by-products, and when the temperature of the second stage reaction is less than 60 ℃, by-produced alcohol at azeotropy It becomes difficult to remove by this, and the yield of dicarbamate becomes low.

In addition, the reaction time may be selected in the range of 0.5 to 6 hours for the first stage reaction and 0.5 to 12 hours for the second stage reaction, but considering the yield of dicarbamate and the economics of the reaction, the first stage reaction is 1 to 4 hours, the second stage reaction is preferably selected in the range of 2 to 6 hours.

According to the process for preparing aliphatic dicarbamate of the present invention, by using water or an alcohol solvent having 1 to 6 carbon atoms as a reaction accelerator and proceeding the reaction in two stages of low temperature and high temperature, it is possible to achieve high yield and high selectivity under mild conditions. Not only can dicarbamate be prepared, but also the production of alkylated amine by-products can be greatly reduced. In addition, since it is not necessary to use toxic phosgene or expensive metal catalysts, it is possible to produce aliphatic dicarbamate economically and environmentally.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, it is obvious to those skilled in the art that the scope of the present invention is not limited to these examples.

Example 1:

1,6-hexanediamine (HAD; 9.28 g, 0.08 mol), dimethyl carbonate (43.2 g, 0.48 mol) and water (in a 100 mL three-necked flask with reflux unit, Dean-Stark unit and thermometer) 8.64 g, 0.48 mol) was charged and reacted at 25 ° C. for 2 hours, and then heated to 80 ° C. for 3 hours. The precipitate obtained by cooling the reaction mixture to room temperature was filtered, dried, and weighed and analyzed by gas chromatography. As a result, the conversion of 1,6-hexanediamine was 100%, and mono and dicarbonate were 0.2% and 99.1%, respectively. What was obtained by the yield of was confirmed.

The diamine conversion and mono and dicarbamate yields were calculated as follows.

% Conversion of diamine = (reaction amount of amine / amount of amine used) x 100

Yield of monocarbamate (%) = (Production amount of monocarbamate / amount of amine) × 100

Yield (%) of dicarbamate = (production amount of dicarbamate / consumption of amine) × 100

Examples 2-11:

In order to determine the effect of water in the same conditions as in Example 1 fixed the molar ratio of dimethyl carbonate and HDA to 6, the reaction was carried out while changing the molar ratio of water and HDA, the results are shown in Table 1.

TABLE 1

Example Molar ratio
(H ₂ O: HDA) HDA conversion rate
(%) yield(%) Monocarbamate Dicarbamate by-product 2 0: 1 73.2 31.3 29.2 12.7 3 0.1: 1 77.8 29.6 38.7 9.5 4 0.5: 1 88.5 35.1 47.0 6.4 5 1: 1 95.1 16.0 74.9 4.2 6 2: 1 100 6.4 91.5 2.1 7 3: 1 100 5.2 93.0 1.8 8 4: 1 100 2.3 96.3 1.4 9 5: 1 100 1.3 97.5 1.2 10 8: 1 100 0.1 99.3 0.6 11 12: 1 100 0.1 99.4 0.5

Examples 12-16:

Under the same conditions as in Example 1, the molar ratio of water and HDA was fixed at 6, and the reaction was performed while changing the molar ratio of dimethyl carbamate and HDA, and the results are shown in Table 2.

TABLE 2

Example Molar ratio (DMC / HDA) HDA conversion rate (%) Yield (%) Monocarbamate Dicarbamate by-product 12 2 100 11.3 88.4 0.3 13 4 100 3.6 95.9 0.5 14 8 100 0.1 98.2 1.7 15 10 100 0 96.3 3.7 16 20 100 0 94.8 5.2

Examples 17-21:

Under the same conditions as in Example 1, the reaction was carried out while fixing the second reaction temperature to 80 ° C. and changing the first reaction temperature, and the results are shown in Table 3.

[Table 3]

Example Reaction temperature ( ^o C) HDA conversion rate (%) Yield (%) Monocarbamate Dicarbamate by-product 17 20 97.8 3.0 94.7 0.1 18 30 100 0.1 98.0 1.9 19 40 100 0.1 97.5 2.5 20 50 100 0 91.5 8.5 21 60 100 0 88.7 11.3

Examples 22-25:

Under the same conditions as in Example 1, the first stage reaction temperature was fixed at 25 ^° C. and the reaction was performed while changing the second stage reaction temperature, and the results are shown in Table 4.

[Table 4]

Example Reaction temperature ( ^o C) HDA conversion rate (%) Yield (%) Monocarbamate Dicarbamate by-product 22 60 88.6 23.9 76.0 0.1 23 70 95.7 6.5 93.4 0.1 24 90 100 0.1 98.5 1.4 25 100 100 0 97.6 2.4

Examples 26-29:

Under the same conditions as in Example 1, the second stage reaction time was fixed at 3 hours and the reaction was performed while changing the first stage reaction time, and the results are shown in Table 5.

TABLE 5

Example Reaction time (h) HDA conversion rate (%) Yield (%) Monocarbamate Dicarbamate by-product 26 0.5 75.8 35.7 76.0 0 27 One 89.3 15.3 84.7 0 28 4 100 0 99.5 0.5 29 6 100 0 99.8 0.2

Examples 30 to 35:

Under the same conditions as in Example 1, the first stage reaction time was fixed at 2 hours and the reaction was performed while changing the second stage reaction time, and the results are shown in Table 6.

TABLE 6

Example Reaction time (h) HDA conversion rate (%) Yield (%) Monocarbamate Dicarbamate by-product 30 0.5 100 64.5 35.4 0.1 31 One 100 24.4 75.5 0.1 32 2 100 6.4 93.1 0.5 33 6 100 0.1 97.5 2.4 34 8 100 0 96.9 3.1 35 12 100 0 95.7 4.3

Examples 36 to 40:

The reaction was carried out under different conditions of the diamine under the same conditions as in Example 1, and the results are shown in Table 7.

TABLE 7

Example Diamine Diamine Conversion (%) Yield (%) Monocarbamate Dicarbamate by-product 36 EDA 100 0 99.9 0.1 37 BDA 100 0 99.9 0.1 38 ODA 97.1 4.6 92.6 2.8 39 1,2-CHDA 93.1 10.5 87.1 2.4 40 1,3-CHBMA 90.3 11.3 86.2 2.5

Examples 41-44:

The reaction was carried out under different conditions of the dialkyl carbonate under the same conditions as in Example 1, and the results are shown in Table 8.

[Table 8]

Example Diamine Diamine Conversion (%) Yield (%) Monocarbamate Dicarbamate by-product 41 DEC 100 5.6 92.6 1.8 42 DPC 100 7.3 91.6 1.1 43 DIPC 96.2 8.7 87.2 0.3 44 DBC 91.4 14.6 76.6 0.2

Claims (10)

 In the process for producing aliphatic dicarbamate by reacting aliphatic diamine having 2 to 8 carbon atoms with dialkyl carbonate, water or an alcohol solvent having 1 to 6 carbon atoms is used as a reaction accelerator, and (i) the aliphatic diamine is dialkyl. And a second step of synthesizing aliphatic monocarbamate by reacting the carbonate at low temperature and (ii) converting the monocarbamate to the dicarbamate at high temperature. The process according to claim 1, wherein a reactor with a Dean-Stark device is used. The aliphatic diamine of claim 1, wherein the aliphatic diamine having 2 to 8 carbon atoms is 1,2-ethanediamine (EDA), 1,3-propanediamine (PDA), 1,4-butanediamine (BDA), 1,6-hexanediamine (HDA), 1,8-octanediamine (ODA), 1,2-cyclohexane diamine (1,2-CHDA), 1,3-cyclohexane diamine (1,3-CHDA), 1,4-cyclohexane Diamine (1,4-CHDA), 1,3-cyclohexane bismethylamine (1,3-CHBMA) or 1,4-cyclohexane bismethylamine (1,4-CHBMA). A process according to claim 1 wherein the dialkyl carbonate is dimethyl carbonate (DMC), diethyl carbonate (DEC), diisopropyl carbonate (DIPC), dipropyl carbonate (DPC) or dibutyl carbonate (DBC). Way. The method according to claim 1, wherein the amount of dialkyl carbonate used is 2 to 20 moles per 1 mole of aliphatic diamine. The method according to claim 1, wherein water is used as a reaction accelerator. The production method according to claim 6, wherein the amount of water used is 0.1 to 20 moles per 1 mole of aliphatic diamine. 8. The process according to claim 1, wherein the reaction temperature is from 10 to 60 ° C. for the first stage reaction and from 60 to 100 ° C. for the second stage reaction. 9. The method of claim 8, wherein the reaction temperature is 20 to 50 ° C. for the first step reaction and 70 to 90 ° C. for the second step reaction. The method according to any one of claims 1 to 7, wherein the reaction time is 0.5 to 6 hours for the first stage reaction and 0.5 to 12 hours for the second stage reaction.