JPH07590B2 - Method for producing urea - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a method for producing ureas.

[Prior Art] As a method of producing ureas, a method of reacting an amine with carbon monoxide using a catalyst such as cobalt carbonyl, silver acetate, sulfur, selenium, or a platinum group metal has been proposed.

Further, it is known that when nitrobenzene and carbon monoxide are reacted in the presence of hydrogen in the presence of a ruthenium complex catalyst, N, N′-diphenylurea and aniline are produced.

In the above-mentioned method for producing ureas with amine and carbon monoxide, the method using cobalt carbonyl or silver acetate is described in Can. J. Chem., 40 1718 (1962), J. Org.
m., 37 2670 (1972), but the yield and selectivity of ureas are not very high. The method using sulfur or selenium is described in J. Org. Chem., 26 3309 (1961), J.
Amer. Chem. Soc., 93 6344 (1971). These generally have high yield and selectivity, but require a complicated operation for separating and recovering the catalyst component. Methods using platinum group metals are described, for example, in Japanese Examined Patent Publication No. 53-41123 and J. Or.
g. Chem., 40 2819 (1975), and JP-A-58-144363. The former one has a low yield of about 60%. Further, in the latter, in addition to palladium, which is the main metal catalyst, the catalyst system is a complicated one containing oxygen gas together with a halogen compound and carbon monoxide, and a complicated operation is required to recover the catalyst, A problem with the reactor is that expensive materials with excellent corrosion resistance must be used.

On the other hand, in Inorg. Chem., 9 342 (1970), N, N′-diphenylurea was obtained by reacting nitrobenzene and carbon monoxide in the presence of hydrogen with a ruthenium complex catalyst. The reaction has a low reaction rate, and a large amount of aniline by-product cannot be avoided.

Further, in JP-A Nos. 62-111960 and 62-111958, N, N'-diphenylurea is obtained by reacting nitrobenzene and carbon monoxide as an aniline solvent with a ruthenium complex catalyst. However, in this reaction, the ruthenium complex catalyst may be precipitated during the post-treatment process, and may go out of the system together with the product crystal of the urea compound.

Further, in Japanese Patent Application No. 63-012018, the precipitation of the catalyst is suppressed by the added solvent, but the increase in the reaction rate due to the addition of the solvent is not observed.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to easily separate a reaction product and a catalyst component from each other and further to provide urea. By using a compound having a high yield of compounds and having a coordinating power to the catalyst metal as a part of the solvent, the reaction rate can be further increased and the catalyst can be recycled efficiently. It is to provide a manufacturing method.

[Means for Solving the Problems] The present invention comprises reacting an aromatic primary amine, an aromatic nitro compound, and carbon monoxide, using a catalyst mainly containing a compound containing a platinum group metal, In addition, it is a method for producing ureas in which a compound having a coordinating power to a metal is used as a part of a solvent.

It is considered that this method proceeds according to the following reaction formula.

[H]: Means MH (M: catalytic metal) Examples of aromatic primary amines include anilines, aminonaphthalenes, aminoanthracenes, and aminobiphenyls, and specific compounds include aniline. , O-, m
-And p-toluidine, o-, m- and p-chloroaniline, α and β naphthylamine, 2-methyl-1-aminonaphthalene, diaminobenzene isomers, triaminobenzene isomers, aminotoluene isomers, Examples include diaminotoluene isomers, aminonaphthalene isomers, and mixtures thereof.

Examples of the aromatic nitro compound include nitrobenzenes, nitronaphthalenes, nitroanthracenes, nitrobiphenyls or at least one hydrogen atom as another substituent, for example, a halogen atom, a cyano group, an alicyclic group, an aromatic group, an alkyl group. , Nitro compounds substituted by an alkoxy group, a sulfone group, a sulfoxide group, a carbonyl group, an ester group, an amide group and the like. Specific compounds include nitrobenzene, o-, m- and p-nitrotoluene, o- Nitro-p-xylene, 2-methyl-1-
Nitronaphthalene, dinitrobenzene isomers, trinitrobenzene isomers, dinitrotoluene isomers, nitronaphthalene isomers, o-, m-chloronitrobenzene, 1-bromo-4-nitrobenzene, and mixtures thereof. To be However, it is preferable to use a nitro compound corresponding to the aromatic primary amine.

Examples of the coordinating amide compound to be added include amides, specifically N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidinone, and the like. A substituted urea compound represented by (R ¹ , R ² , R ³ and R ⁴ are alkylene containing 3 to 5 carbon atoms linked by an alkyl group and a carbon chain), specifically N, N, N ′, In the method of the present invention, only N′-tetramethylurea, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyltetrahydro-2 (1H) -pyrimidinone, etc. are added to have a coordinating force. It can be used as it is as a solvent, but it is also a preferable method to perform it in a mixed solvent with another suitable solvent. Examples of such other suitable solvent include aromatic hydrocarbons such as benzene, toluene, xylene and mesitylene, halogenated aliphatic hydrocarbons such as chlorohexane and chlorocyclohexane, chlorobenzene, bromobenzene and dichlorobenzene. And halogenated aromatic hydrocarbons such as trichlorobenzene are used.

Carbon monoxide may be pure or may contain nitrogen, argon, helium, carbon dioxide gas, halogenated hydrocarbon and the like.

A compound containing a platinum group metal is a compound such as ruthenium, rhodium, palladium, a platinum group element such as platinum, carbon monoxide, a ligand such as phosphines, or an organometallic compound having an organic group. Those containing no halogen element are preferable. Specifically, Ru ₃ (CO) ₁₂ , H ₄ Ru ₄ (CO)
₁₂ , [Ru ₂ (CO) ₄ (HCOO) ₂ ] n, Ru (CO) ₃ (dppe), Ru (CO) ₃ (PPh
Ruthenium complex compounds such as ₃ ) ₂ and Ru (acac) ₃ , Rh ₆ (C
O) ₁₆ , RhH (CO) (PPh ₃ ) ₃ , Rh (acac) (CO) (PPh ₃ ), Rh (acac)
Examples include rhodium complex compounds such as (CO) ₂ and Rh (acac) ₃ . However, PPh ₃ is triphenylphosphine, dppe
Indicates diphenylphosphinoethane, and acac indicates acetylacetonate.

In addition to these complex compounds, it is also possible to use an inorganic platinum group metal compound that changes into an active species in the reaction system. Specific examples include RuO ₂ · nH ₂ O, Ru-black, Ru carbon and the like. It is considered that these compounds are converted into carbonyl complexes in the reaction system to give active species.

Further, cobalt, iron, rhodium, palladium and the like can be used in combination with these platinum group metals.

The reaction temperature is usually 30 to 300 ° C, preferably 120 to 200 ° C. The reaction pressure is in the range of 1 to 500 kg / cm ² , preferably 10 to 150 kg / cm ² , and the reaction time is usually several minutes to several hours, although it varies depending on other conditions.

[Operations and Effects of the Invention] The ureas obtained by the method of the present invention have a low solubility in the solvent and the raw material aromatic amine or aromatic nitro compound. Therefore, simply by cooling the solution after the reaction to room temperature, the generated ureas are precipitated as crystals. Therefore, by filtering this solution, ureas can be efficiently obtained as a solid. On the other hand, the catalyst is stabilized by the added coordinating solvent and is present in the filtrate without being precipitated. Therefore, the catalyst can be reused as it is, which is economical. When the reaction mixture is cooled to room temperature and crystallized after the reaction, components other than ureas in the reaction mixture can be easily separated by washing with a solvent such as toluene or benzene, and ureas alone can be taken out.

In this reaction, a compound that does not participate in the reaction, such as toluene or cyclohexane, can be used as a part of the solvent. In addition, since the reaction rate increases as the concentration of the aromatic primary amine increases, the reaction can be performed at a high reaction rate by adding the aromatic primary amine in a large excess and using it as a part of the solvent. .

Further, in the method of the present invention, by adding a coordinating solvent,
An increase in reaction rate occurs and can be performed at a higher reaction rate.

Further, in the present invention, since it is not necessary to use a halogen compound, corrosion of equipment materials is extremely small, and it is not necessary to use an expensive material for the reactor.

Further, this reaction has few side reactions, and ureas can be obtained in high yield.

Example 1 Example 1 In an autoclave with an internal volume of 200 ml and an electrode stirring type autoclave, 5.6 g of nitrobenzene, 7.8 g of aniline, 27 ml of toluene, N, N, N ',
6.3 g of N'-tetramethylurea (hereinafter abbreviated as TMU), Ru ₃ (C
O) ₁₂ 20 mg, and after replacing the system with carbon monoxide,
Carbon monoxide was injected under pressure to give a pressure of 50 kg / cm ² . The mixture was reacted at 160 ° C for 2.0 hours with stirring. After completion of the reaction, the mixture was cooled to room temperature, and after evacuation, the reaction solution was filtered to obtain 3.5 g of N, N'-diphenylurea crystals. When the filtrate was analyzed by gas chromatography and high performance liquid chromatography, N, N'-
It contained 0.1 g of diphenylurea and 2.9 g of nitrobenzene. From this, the TOF (Turn Over Frequency) based on the catalytic metal atom of N, N'-diphenylurea formation was 100 h ^-1 , and the selectivity based on the nitrobenzene was 94%.

Example 2 Next, in the same apparatus and operation as shown in Example 1, the amount of TMU was changed to 16.4 g and toluene was changed to 15 ml, and N,
Table 1 shows the results of the N'-diphenylurea production experiment.

Comparative Example 1 In the same apparatus and operation as shown in Example 1, TMU was not added and the amount of toluene was changed to 32 ml.
Table 1 shows the results of the experiment for producing diphenylurea.

Comparative Example 2 Table 1 shows the results of an experiment for producing N, N′-diphenylurea by adding pyridine instead of TMU in the same apparatus and operation as those shown in Example 1.

Comparative Example 3 In the same apparatus and operation as shown in Example 1, benzonitrile was added instead of TMU, and N, N′-
Table 1 shows the results of the diphenylurea production experiment.

Examples 3 to 8 Table 2 shows the results of an N, N'-diphenylurea production experiment conducted by changing the coordinating solvent to be added in the same apparatus and operation as those shown in Example 1. .

Example 9 In the same apparatus and operation as shown in Example 1, the catalyst used was changed to [Ru ₂ (CO) ₄ (HCOO) ₂ ] n, and N, N ′.
Table 3 shows the results of an experiment for producing -diphenylurea.

Example 10 Inner volume 200 ml, electrode stirring type, stainless steel autoclave, 5.6 g of nitrobenzene, 7.8 g of aniline, 30 toluene
ml, 1,3-dimethyltetrahydro-2 (1H) -pyrimidinone (the following structural formula) 3.1 g, and Ru ₃ (CO) ₁₂ 20 mg were charged.

After replacing the inside of the reaction system with carbon monoxide, 50 kg of carbon monoxide
The mixture was press-fitted at a pressure of / cm ² and reacted at 160 ° C for 2 hours with stirring. After the reaction was completed, it was cooled to room temperature. After the exhaust
The reaction solution was filtered to obtain 3.4 g of N, N′-diphenylurea crystals.

When the separated filtrate was analyzed by gas chromatography and high performance liquid chromatography, it contained 0.1 g of N, N'-diphenylurea and 3.4 g of nitrobenzene.
From this result, the TOF (Turn Over Frequency) based on the catalytic metal atom in the production of N, N′-diphenylurea was 88.
The selectivity based on h ⁻¹ and nitrobenzene was 92%.

Example 11 In the same apparatus and method as used in Example 10, 5.6 g of nitrobenzene, 7.9 g of aniline and 30 parts of toluene were charged.
ml, N, N-dimethylacetamide (the following structural formula) 3.0 g, Ru
_The reaction was carried out with ₃ (CO) ₁₂ 20 mg.

As a result, 3.3 g of N, N'-diphenylurea was produced and 2.1 g of nitrobenzene was consumed. From this result, N, N′-
The catalytic TOF in diphenylurea production was 83 h ^-1 , and the selectivity based on nitrobenzene was 91%.

Example 12 Using the same apparatus and method as those used in Example 10, 5.6 g of nitrobenzene, 7.9 g of aniline and 30 parts of toluene were charged.
ml, N, N-dimethylformamide (the following structural formula) 3.0 g, Ru
_The reaction was carried out by changing to ₃ (CO) ₁₂ 20 mg.

As a result, 3.2 g of N, N'-diphenylurea was produced and 2.0 g of nitrobenzene was consumed. From this result, N, N′−
The catalytic TOF in diphenylurea production was 80 h ^-1 , and the selectivity based on nitrobenzene was 93%.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatsugu Mizuguchi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor Tetsuo Hachiya 1-2-1-2, Marunouchi, Chiyoda-ku, Tokyo Inside the Steel Pipe Co., Ltd. (72) Inventor Tomochi Nakamura 1-2 1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Steel Pipe Co., Ltd.

Claims (2)

[Claims] 1. When a urea-based compound is produced by reacting an aromatic primary amine with an aromatic nitro compound and carbon monoxide, a catalyst mainly containing a compound containing a platinum group metal is used, and A process for producing ureas, which comprises using an amide having a metal-coordinating force or a substituted urea compound represented by the following general formula as a part of a solvent or a ligand. (General formula) However, R ¹ , R ² , R ³ and R ⁴ are alkylene containing 3 to 5 carbon atoms linked by an alkyl group and a carbon chain. 2. The method for producing ureas according to claim 1, wherein a halogen compound is not used.