KR100493375B1 - Method for preparing n,n'-disubstituted urea using imidazolium alkylselenite catalyst - Google Patents

Abstract

The present invention relates to a method for preparing N, N'-substituted urea using an imidazolium alkyl selenite catalyst. Specifically, an amine in the presence of an imidazolium alkyl selenite compound and a solvent is mixed with an O ₂ / CO mixed gas. The present invention relates to a method for preparing a substituted urea by the reaction according to the present invention, to suppress the formation of by-products, to prepare the urea under mild reaction conditions and high yield, as well as to improve the reactivity to aromatic amines. It is possible to suppress the production of volatile selenium compounds that cause an unpleasant odor, thereby producing urea in mass production and economically.

Description

Method for preparing N, N'-substituted urea using imidazolium alkyl selenite catalyst {METHOD FOR PREPARING N, N'-DISUBSTITUTED UREA USING IMIDAZOLIUM ALKYLSELENITE CATALYST}

The present invention relates to a method for preparing N, N'-substituted urea using a catalyst, and more particularly, to a method for preparing N, N'-substituted urea using an imidazolium alkylselenite catalyst.

In general, urea is a compound that is usefully used as a raw material or intermediate of pesticides, herbicides, insecticides and carbamates, and various preparation methods thereof have been studied.

The conventional method for preparing urea is to react amines with phosgene, and this method has a drawback of not only using toxic and highly corrosive phosgene, but also byproducts of a large amount of HCl, a pollutant.

Therefore, a method of preparing urea without using harmful phosgene has been studied in the United States, Japan, and Europe.

(1) US Pat. No. 2,877,268 discloses a process for preparing urea by reacting an amine with carbonyl sulfide (COS) in the absence of a catalyst, the article " J. Org. Chem. (RA Franz). , 26, p3309, 1961) discloses a process for producing urea by reacting an amine with carbon monoxide (CO) and sulfur (S) using a tertiary amine as a catalyst. However, the manufacturing method has a problem that by-products such as H ₂ S are difficult to produce due to the use of sulfur.

(2) Japanese Laid-Open Patent Publication No. 62-59,253 discloses a method for producing urea from a nitro compound using a catalyst such as rhodium or ruthenium. The method can produce urea with a relatively high conversion and selectivity, but has a disadvantage in that expensive noble metal catalysts are easily decomposed due to high reaction temperature and pressure.

(3) European Patent No. 0 319 111 adds salts, such as copper, iron, manganese, vanadium, chromium, which have redox activity as an activator of palladium, a noble metal catalyst, in the preparation of urea from a mixture of amine and nitrobenzene. To maintain the activity of the palladium catalyst. As described in Example 1, the maximum yield of urea is 73% (return mole per unit time, moles of urea per unit catalyst) when reacted for 20 hours at a reaction temperature of 140 ° C. and 50 atmospheres. There is a problem that the yield is low because it is only <4).

(4) " Chemistry Letter (Koyoshi Kondo, p373, 1972)" describes a method for the synthesis of aliphatic ureas by carbonylating amines under selenium catalysts. Since the method uses the same amount of selenium as the starting material, amine, there is a disadvantage in that the loss of the catalyst is large and the reaction hardly proceeds when the aromatic amine is used as the starting material.

(5) US Pat. No. 4,052,454 also discloses a method for synthesizing urea by reacting a nitro compound with water and carbon monoxide over a selenium metal catalyst. As shown in the patent example 1, the conversion rate of nitrobenzene and urea were reacted for 1 hour at 150 ° C, 53 atm, and a reaction condition of about 1/8 of a molar ratio of the catalyst to nitrobenzene as a starting material. The yield is 66.3% and 33.8%, respectively (turnover frequency: unit time, moles of urea per mole of catalyst <2), which is not an economic method.

As described above, the conventional method for producing urea is an industrial method for producing substituted urea due to by-product formation, reaction conditions of high temperature and high pressure, and low yield. Despite the use of conditions, there are many problems in producing urea with high yields. In addition, in the case of a technique for producing urea using selenium as a catalyst, there is a process problem due to the unpleasant volatile odor peculiar to selenium after the reaction under high temperature and high pressure reaction conditions.

An object of the present invention is to solve a variety of problems caused by the prior art, specifically by suppressing the production of by-products, by producing a urea in a mild reaction conditions and high yield, industrial mass production is possible, It is to provide a method for producing N, N'-substituted urea capable of inhibiting the production of volatile selenium compounds that cause reactivity and unpleasant odor.

In order to achieve the above object, the present invention is to prepare a substituted urea represented by the formula (2) by reacting an amine with O ₂ / CO mixed gas in the presence of an imidazolium alkyl selenite compound represented by the formula (1) and a solvent Provide a method.

(In the above formula,

R ¹ and R ² are each independently a C ₁ to C ₈ alkyl, phenyl, benzyl or fluorinated alkyl group,

R ³ is a C ₁ to C ₆ alkyl, phenyl, fluorinated alkyl, cycloalkyl, phenyl or benzyl group.)

(In the formula, R ⁴ is a C ₁ to C ₁₈ alkyl group, cycloalkyl group or phenyl group.)

That is, the present invention uses the imidazolium alkyl selenite compound as a catalyst,

(1) can produce urea substituted in high yield under mild conditions, and no by-products are generated;

(2) can also solve low reactivity to aromatic amines,

(3) Finally, there is provided a method for producing a substituted urea capable of inhibiting the production of volatile selenium compounds that cause an unpleasant odor.

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

The present invention is characterized by using an imidazolium alkylselenite compound, which is an ionizing liquid, as a catalyst in the method for producing a substituted urea, as shown in Scheme 1 below.

(Wherein R ⁴ is as shown in Formula 2)

The imidazolium alkyl selenite compound is composed of an imidazolium cation and a selenite anion, preferably [1-n-butyl-3-methylimidazolium] [SeO ₂ (OCH ₃ )] ([1- n- butyl-3-methylimidazolium] [SeO ₂ (OCH ₃ )]; [bmim] [SeO ₂ (OCH ₃ )]), [1-ethyl-3-methylimidazolium] [SeO ₂ (OCH ₃ )] ([1-ethyl-3-methylimidazolium] [SeO ₂ (OCH ₃ )]; [emim] [SeO ₂ (OCH ₃ )]), [1,3-dimethylimidazolium] [SeO ₂ (OCH ₃ )] ([1,3-dimethylimidazolium] [SeO ₂ (OCH ₃ )]; [dmim] [SeO ₂ (OCH ₃ )]), [1-n-butyl-3-methylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )] ([1- n -butyl-3-methylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )]; bmim] [SeO ₂ (OCH ₂ CF ₃ )]), [1-ethyl-3-methyl Midazolium] [SeO ₂ (OCH ₂ CF ₃ )] ([1-ethyl-3-methylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )]; [emim] [SeO ₂ (OCH ₂ CF ₃ )]), [ 1,3-dimethylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )] ([1,3-dimethylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )]; [dmim] [SeO ₂ (OCH ₂ CF ₃ ) ]).

The use amount is 1 / 12800-1 / 100 mol with respect to 1 mol of amine which is a starting material, Preferably it is 1 / 3200-1 / 400 mol. If the amount of the catalyst used is less than the above range, the reaction proceeds too slowly, and if it exceeds the above range, the use of the catalyst more than necessary is uneconomical.

In preparing the substituted urea in the present invention, by using the imidazolium alkyl selenite compound, urea can be produced in high yield under mild reaction conditions, and the loss of the catalyst is caused by using the equivalent amount of selenium in the prior art. Esau can be manufactured economically by reducing its usage. It can also improve the reactivity to aromatic amines and inhibit the production of volatile selenium compounds that cause an unpleasant odor.

In the present invention, amine is used as a starting material. Amines are available in both an aromatic amine or aliphatic amine, and preferably uses the amine substituted with an alkyl group, a cycloalkyl group or a phenyl group of the C ₁ ~C _18. More preferably methylamine, ethylamine, isopropylamine, butylamine, isobutylamine, hexylamine, dodecylamine, hexadecylamine, octadecylamine, benzylamine, phenylamine, cyclobutylamine, cyclohexylamine, 1,3-toluenediamine, 1,4-phenylenediamine, 1,3-phenylene diamine, 4,4-aminophenol or 4,4'-methylenedianiline is used.

In the present invention, it is also characterized by using an aromatic amine that is conventionally less reactive and can be used only at high temperature and high pressure. By using the above catalyst, a high yield of urea can be obtained using aromatic amine as a starting material even under mild conditions.

Although the preparation method of the present invention can proceed in the absence of a solvent, it is more effective to use a solvent in consideration of agitation, separation of the catalyst and efficiency. The solvent may be a C ₁ to C ₆ alcohol or a polar solvent such as THF, DMF, DMSO, benzotrifluoride, etc., but in consideration of reactivity and catalyst separation problem after the reaction, a C ₁ to C ₃ alcohol may be used. Preferably, methanol, ethanol, n-propanol or iso-propanol are used.

The present invention uses imidazolium alkyl selenite as a catalyst to obtain substituted urea under mild reaction temperature and pressure.

The reaction temperature may be selected in the range of 40 to 250 ℃ depending on the type of the amine as the starting material, it is preferable to select in the range of 60 to 120 ℃ considering the reaction rate and selectivity to urea.

In addition, the pressure may be selected in the range of 5 to 200 atm, but preferably in the range of 10 to 50 atm in consideration of the reaction rate and selectivity to urea.

The present invention reacts a mixed gas of O ₂ / CO with the amine during the reaction. The mixed gas serves as a starting material in the method of preparing a substituted urea, and the molar ratio of the mixed gas added at this time is determined in consideration of reactivity and explosiveness of the mixed gas. Specifically, the O ₂ / CO mixed gas is preferably composed of O ₂ : CO = 5 to 45:55 to 95 (mol / mol).

In addition, after the reaction is completed by the present invention to obtain a substituted urea, insoluble urea can be easily separated by filtration and drying.

 The present invention will be described in more detail with reference to the following Examples, but the scope of the present invention is not limited to these Examples.

Preparation Example 1 Preparation of Catalyst of the Invention

(1) catalyst KSeO ₂ (OCH ₃ ) Produce

SeO ₂ (3.3 g, 30 mL) was dissolved in 50 mL methanol. Then K ₂ CO ₃ (2.0 g, 15 mmol) was added to the solution, followed by stirring at room temperature for 1 hour. After adding THF to the solution, the resulting white solid was separated using a fritted glass funnel and dried in vacuo to obtain KSeO ₂ (OCH ₃ ).

(2) catalyst [bmim] [SeO ₂ (OCH ₃ )] Produce

KSeO ₂ (OCH ₃ ) (3.6 g, 19.8 mmol) obtained in (1) of Preparation Example 1 was dissolved in 50 mL of methanol, and [bmim] Cl (3.1 g, 18 mmol) was added to the solution. Stir at room temperature for hours. After stirring, the produced white solid (KCl) was separated and removed using a fritted glass funnel. The solvent of the solution obtained above was removed in vacuo, and then CH ₂ Cl ₂ was added thereto to separate unreacted KSeO ₂ (OCH ₃ ) and KCl using a fritted glass funnel. The solvent of the remaining filtrate was completely removed in vacuo to give [bmim] [SeO ₂ (OCH ₃ )] as a yellow liquid.

Example 1 Preparation of Urea 1

To 300 ㎖ high pressure reactor equipped with a stirrer aniline (29.76 g, 320 mmol), [bmim] [SeO 2 (OCH 3)] ([ a 1-n- butyl-3-methyl imidazolium] [SeO ₂ (OCH ₃ 0.22 g, 0.8 mmol) and 14 cc, O ₂ / CO mixed gas pressure molar ratio after filling 40 cc of CH ₃ OH (O ₂ / CO) = 20/80), and the reaction was carried out for 2 hours under conditions of a temperature of 60 ° C. The mixture obtained after the reaction was cooled to room temperature, the solid product was separated and weighed, and the filtrate was analyzed by gas-liquid chromatography.

The conversion rate of aniline, the selectivity of diphenylurea, and turnover frequency were calculated using the analysis results and the following equations (1) to (3).

The analysis results and the results according to Equations 1 to 3 are as follows.

(1) conversion rate of aniline: 98.4%;

(2) selectivity for diphenylurea: 100%;

(3) turnover frequency: 205 h ^-1 .

<Examples 2-9> Preparation of Urea 2-9

In order to measure the change according to the type of imidazolium alkyl selenite catalyst in the present invention, the reaction was carried out by changing the imidazolium alkyl selenite catalyst as shown in Table 1 under the same conditions as in Example 1. In this case, 1.2 mmol of the added catalyst was used.

The conversion rate and diphenylurea selectivity of the prepared urea are shown in Table 1 below.

Example catalyst % Conversion Diphenylurea Selectivity (%) 2 [bmim] [SeO ₂ (OCH ₃ )] 98.4 100 3 [emim] [SeO ₂ (OCH ₃ )] 98.2 100 4 [dmim] [SeO ₂ (OCH ₃ )] 97.4 100 5 [bmim] [SeO ₂ (OCH ₂ CF ₃ )] 98.6 100 6 [emim] [SeO ₂ (OCH ₂ CF ₃ )] 97.4 100 7 [dmim] [SeO ₂ (OCH ₂ CF ₃ )] 98.6 100 8 [bmim] [SeO ₂ (OPh)] 98.6 100 9 [emim] [SeO ₂ (OPh)] 97.1 100  In the above, [bmim] is [1-n-butyl-3-methylimidazolium]; [emim] is [1-ethyl-3-methylimidazolium]; [dmim] represents [1,3-dimethylimidazolium].

As shown in Table 1 , it can be seen that when the catalyst according to the present invention is used, the conversion rate is 97.1 to 98.6%, and the diphenylurea selectivity is 100%, thereby producing a high yield of urea.

<Examples 10-15> Preparation of Urea 10-15

In order to measure the change according to the molar ratio of the starting material aniline in the present invention, the reaction was carried out by fixing the amount of catalyst and changing the molar ratio of starting material aniline to the catalyst under the same conditions as in Example 1.

The conversion rate and diphenylurea selectivity of the prepared urea are shown in Table 2 below.

Example Aniline / catalyst (molar ratio) % Conversion Diphenylurea Selectivity (%) 10 12800 5.3 100 11 6400 16.2 100 12 3200 33.6 100 13 800 97.0 100 14 400 98.4 100 15 200 99.6 100

As shown in Table 2 , when the molar ratio of aniline / catalyst is 200 to 800, the conversion rate is 97.0 to 96.9%, and the diphenylurea selectivity is 100%, indicating that a high yield of urea can be prepared. In addition, when the molar ratio of aniline / catalyst was 3200 to 12800, the conversion was low as 5.2 to 33.6%, but the diphenylurea selectivity was excellent at 100%.

<Examples 16-20> Preparation of Urea 16-20

The reaction was carried out under the same conditions as in Example 1 while varying the temperature, pressure and O ₂ / CO molar ratio. The conversion and selectivity of diphenylurea for the above examples are shown in Table 3 below.

Example Temperature (℃) Pressure (atmospheric pressure) O ₂ / CO molar ratio % Conversion Diphenylurea Selectivity (%) 16 40 120 45/55 48.6 100 17 60 90 30/70 97.8 100 18 80 60 20/80 98.1 92.1 19 100 30 10/90 97.5 85.1 20 120 10 5/95 95.4 75.6

As shown in Table 3 , the conversion was 97.5 to 98.1%, and in Example 16, the conversion was low as 48.6%, but it can be seen that the diphenylurea selectivity was excellent as 100%. In addition, the diphenyl urea selectivity is 75.6 to 100%, it can be seen that the reactivity is excellent.

<Examples 21-27> Preparation of Urea 21-27

Under the same conditions as in Example 1, the reaction was carried out while changing the kinds of starting amine and alcohol. The conversion and selectivity of diphenylurea for the above examples are shown in Table 4 below.

Example Amine Alcohol % Conversion Diphenylurea Selectivity (%) 21 Butylamine Methanol 99.8 100 22 Cyclohexylamine Methanol 99.7 100 23 aniline ethanol 99.3 100 24 Benzylamine iso -propanol 91.6 100 25 4,4'-methylenedianiline Methanol 82.0 100 26 2,4-dimethylaniline Methanol 95.4 100 27 2,4,6-trimethylaniline Methanol 92.1 100

As shown in Table 4 , when the amine and the alcohol according to the present invention were used, the conversion was 82.0 to 99.9%, and the diphenylurea selectivity was 100%, indicating that the reactivity was excellent. The reactivity can be seen.

As described above, the present invention relates to a method for preparing N, N'-substituted urea using an imidazolium alkyl selenite catalyst, which inhibits by-product generation through the preparation method according to the present invention, Urea can be produced in high yield, and the production of volatile selenium compounds that cause reactivity and unpleasant odors to aromatic amines can be suppressed, thereby producing a large amount of substituted urea, and avoiding the use of expensive precious metal catalysts. It can be produced economically substituted urea.

Claims (10)

N, N'-substituted by reacting the amine with O ₂ / CO mixed gas in the presence of an imidazolium alkyl selenite compound represented by the formula (1) and a solvent to produce a substituted urea represented by the formula (2) Method for preparing urea.  Formula 1 (In the above formula, R ¹ and R ² are each independently a C ₁ to C ₈ alkyl, phenyl, benzyl or fluorinated alkyl group, R ³ is a C ₁ to C ₆ alkyl, phenyl, fluorinated alkyl, cycloalkyl, phenyl or benzyl group.) Formula 2 (In the formula, R ⁴ is a C ₁ to C ₁₈ alkyl group, cycloalkyl group or phenyl group.) The method of claim 1, wherein the imidazolium alkyl selenite compound is [1-n-butyl-3-methylimidazolium] [SeO ₂ (OCH ₃ )], [1-ethyl-3-methylimidazolium] [SeO ₂ (OCH ₃ )], [1,3-dimethylimidazolium] [SeO ₂ (OCH ₃ )], [1-n-butyl-3-methylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )], [1-ethyl-3-methylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )] and [1,3-dimethylimidazolium] [SeO ₂ (OCH ₂ CF ₃ )]. Manufacturing method characterized in that the selected. The method according to claim 1, wherein the imidazolium alkyl selenite compound is added in an amount of 1/12800 to 1/100 mol based on 1 mol of the amine. The method according to claim 3, wherein the imidazolium alkyl selenite compound is added in 1/3200 to 1/400 moles with respect to 1 mole of the amine. The method of claim 1, wherein the amine is methylamine, ethylamine, isopropylamine, butylamine, isobutylamine, hexylamine, dodecylamine, hexadecylamine, octadecylamine, benzylamine, phenylamine, cyclobutylamine , Cyclohexylamine, 1,3-toluenediamine, 1,4-phenylenediamine, 1,3-phenylene diamine, 4,4-aminophenol and 4,4'-methylenedianiline. The manufacturing method to make. The method according to claim 1, wherein the solvent is a C ₁ to C ₆ alcohol. 7. A process according to claim 6 wherein the solvent is methanol, ethanol, n -propanol or iso -propanol. The method according to claim 1, wherein the production method is performed at a reaction temperature of 40 to 250 ° C and a pressure of 5 to 200 atmospheres. The method according to claim 8, wherein the production method is performed at a reaction temperature of 40 to 100 DEG C and a pressure of 10 to 50 atmospheres. The method according to claim 1, wherein the O ₂ / CO mixed gas is made of O ₂ : CO = 5 to 45 mol: 55 to 95 mol.