JPH032156A - Production of aromatic urethane - Google Patents

Abstract

PURPOSE:To obtain an aromatic urethane in high yield at a low cost by carbonylating an aromatic mononitro compound and an aromatic primary amine with carbon monoxide and reacting the product with an organic compound having hydroxyl group. CONSTITUTION:An aromatic mononitro compound, an aromatic primary amine and carbon monoxide are made to react with each other in the presence of a catalyst composed mainly of a platinum group metal compound [e.g. Ru3(CO)12] using a compound capable of coordinating to a metal (e.g. N,N,N,' N,'-tetramethylurea) at 30-300 deg.C under 1-500kg/cm<2> pressure and the resultant N,N'-disubstituted urea is made to react with an organic compound containing hydroxyl group (e.g. monohydric alcohol) at 80-300 deg.C without using a catalyst to obtain the objective compound. The aromatic primary amine can be recycled.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a method for producing aromatic urethane.

[Prior art and its problems] Various methods for producing aromatic urethanes have been proposed, but these include a method using an aromatic nitro compound as a starting material and a method using an aromatic primary amine as a starting material. It can be broadly classified.

In the method using an aromatic nitro compound as a starting material, an aromatic nitro compound (e.g., nitrobenzene), a compound containing a hydroxyl group (e.g., an alcohol), and -carbon oxide,
This is a method for producing aromatic urethane through a reductive carbonylation reaction in the presence of a catalyst mainly consisting of a platinum group metal compound such as palladium or rhodium. This method is described, for example, in Japanese Patent Application Laid-open Nos. 51-98240 and 54-223.
No. 39, Japanese Patent Publication No. 43-23939, etc.

In addition, a method using an aromatic primary amine as a starting material involves combining an aromatic primary amine (e.g. aniline) with a concentrated compound (e.g. alcohols) having a hydroxyl group in the presence of an oxidizing agent such as oxygen or an organic nitro compound. This is a method for producing aromatic urethane through an oxidative carbonylation reaction in which carbon oxide is reacted with a catalyst mainly composed of a platinum group metal compound such as palladium or rhodium. This method has been proposed, for example, in Japanese Patent Application Laid-Open No. 55-124050, Japanese Patent Application Publication No. 55-120551, Japanese Patent Application Laid-Open No. 59-172451, etc.

In this case, since the urethane synthesis activity of the platinum group metal compound alone, which is the main catalyst component, is low in either method, a halogen compound such as iron chloride, iron oxychloride, vanadium oxychloride, potassium iodide, etc. is used as a promoter. is dissolved in the reaction system. However, halogen compounds precipitate in reaction vessels, piping, valves, etc., and are highly corrosive to metal materials. Therefore, expensive metal materials with excellent corrosion resistance must be used.

Furthermore, even when the platinum group metal compound, which is the main catalyst, is used dissolved in the reaction solution, and even when used as a solid metal, it is important to avoid part of the platinum group metal eluting into the reaction solution. I can't do it. Therefore, recovering the platinum group metal compound from the reaction solution after the completion of the reaction requires complicated operations and a large amount of cost.

Further, as a reaction solvent, an organic compound having a hydroxyl group, which is a reaction raw material, is used, and aromatic urethane has a very high solubility in this organic compound having a hydroxyl group. Therefore, when aromatic urethane is separated and recovered from the solution after the reaction by crystallization, it is necessary to cool the solution to an extremely low temperature of several tens of degrees below zero, or to precipitate crystals by concentrating the solution and then cooling it. becomes. Moreover, even if this operation is performed, it is difficult to separate and recover the aromatic urethane and the catalyst component dissolved in the solution. Distillation may also be considered as another method for recovering aromatic urethane. However, in this case the aromatic urethane must be distilled off in order to recover the dissolved catalyst as a distillation residue. However, aromatic urethane is a high boiling point compound and has a 1+
Distillation must be carried out in a medium temperature range of 100 to 150° C. under a high vacuum of about 100 mHg.

As described above, aromatic urethane is separated and recovered from the solution,
Furthermore, it is difficult to recover and reuse the catalyst, whether by crystallization or distillation.

Furthermore, aromatic amines and N,N'-disubstituted ureas are used when aromatic nitro compounds are used as starting materials, and N,N'-disubstituted ureas are used when aromatic primary amines are used as starting materials.
There is a drawback that di-substituted urea is produced as a by-product and the yield of aromatic urethane is reduced.

In addition, there is a method for producing aromatic urethane through a two-step reaction.
Japanese Patent Application Publication No. 62-111958, Patent Application No. 63-012018
has been proposed. However, JP-A-62-111958
In this case, there is a possibility that the ruthenium complex catalyst will precipitate during the first stage reaction and come out of the system together with the product urea compound crystals. Furthermore, patent application No. 63-01201
In No. 8, catalyst precipitation is suppressed by the added solvent during the first stage reaction, but no increase in the reaction rate due to the addition of the solvent is observed.

[Problems to be Solved by the Invention] This invention has been made in view of the above circumstances, and its purpose is to provide an aromatic urethane that does not use a halogen compound as a promoter and eliminates various problems caused by its use. The purpose is to provide a manufacturing method. In addition, the object of the present invention is to produce aromatic urethanes through a two-step reaction of producing ureas through a carbonylation reaction and reacting the produced ureas with a compound having a hydroxyl group.
The object of the present invention is to provide a method for producing aromatic urethane, which improves the overall yield and selectivity, and also allows easy recovery of the catalyst and the produced aromatic urethane. Furthermore, it is an object of the present invention to further increase the reaction rate by using a compound that has a coordinating ability to the metal as part of the solvent in the urea production step by carbonylation reaction performed in the -stage.
The present invention also aims to provide a method for efficiently recycling a catalyst and, furthermore, for efficiently producing aromatic urethane.

[Means for Solving the Problems] The present invention is a method for producing aromatic urethane, which includes three steps.

In the first step, an aromatic mononitro compound, an aromatic primary amine, and carbon monoxide are reacted using a catalyst mainly composed of a platinum group metal compound to produce an N,N'-disubstituted urea. generate. Here, a compound having a coordinating power to the metal is used as part of the solvent to increase the reaction rate and to stably dissolve the catalyst in the solution. Then, the generated N,
N'-disubstituted urea is separated and recovered from the reaction solution.

In the second step, the N obtained in the first step is
, N'-disubstituted urea and an organic compound having a hydroxyl group are reacted to produce an aromatic primary amine and an aromatic urethane, and then the aromatic primary amine is separated to obtain an aromatic urethane.

In the third step, the separated primary amine is recycled to the first step.

Next, the invention will be specifically explained.

First, the first step is to combine an aromatic primary amine, an aromatic mononitro compound, and carbon monoxide with a catalyst mainly consisting of a platinum group metal compound, and also as part of a solvent to impart a coordination force to the metal. React using a certain compound. This reaction is thought to proceed according to the following reaction formula.

ArNH2+ArNO2+3GO- ArNHCNHAr+2CO2 Examples of aromatic primary amines include anilines, aminonaphthalenes, aminoanthracenes, aminobiphenyls, etc. Specific compounds include aniline, o-,
m- and p-toluidine, o-, m- and p-chloroaniline, α- and β-naphthylamine, 2-methyl-1~
Examples include aminonaphthalene, diaminobenzene isomers, triaminobenzene isomers, aminotoluene isomers, diaminotoluene isomers, aminonaphthalene isomers, and mixtures thereof.

Aromatic mononitro compounds include nitrobenzenes,
Nitronaphthalenes, nitroanthracenes, nitrobiphenyls, or at least one hydrogen substituent, such as a halogen atom, a cyano group, an alicyclic group, an aromatic group, an alkyl group, an alkoxy group, a sulfone group, a sulfoxide group, There are nitro compounds substituted with carbonyl groups, ester groups, amide groups, etc., and specific compounds include nitrobenzene, o+, m- and p-nitrotoluene, 0-nitro-p-xylene, 2-methyl-1
-Nitronaphthalene, dinitrobenzene isomers, trinitrobenzene isomers, dinitrotoluene isomers,
Nitronaphthalene isomers, o-, m- and p-chloronitrobenzene, 1-bromo-4-nitrobenzene,
and mixtures thereof. However, it is preferable to use nitro compounds corresponding to aromatic primary amines.

Examples of the coordinating amide compound to be added include amides, specifically N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidinone, etc. Substituted compounds represented by the general formula RI R2NCNR3R4 Urea compounds (RI R2R3R4 is an alkyl group and alkylene containing 3 to 5 carbon atoms connected by a carbon chain), specifically N.

The phosphine-amide compounds represented by N,N',N'-tetramethyl sulfate, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyltetrahydro-2(IH)-pyrimidinone, (R1R2 is an alkyl group having 1 to 5 carbon atoms, n is 1 to 5), R2 is an alkyl group having 1 to 6 carbon atoms, and a phosphine-amide compound (RI R2 is an alkyl group having 1 to 6 carbon atoms, and 3 carbon atoms connected by a carbon chain)
Examples include 5-alkylene), isomers thereof, and mixtures thereof.

Oxygen-containing organic sulfur compounds, such as sulfoxides, are represented by the general formula R1-5o-R2 or RISo2-R2. Here, R1 and R2 are alkyl containing 1 to 8 carbon atoms, substituted with alkoxy, or substituted with phenyl, and Rt and R2 are alkylene containing 4 to 7 carbon atoms connected by a carbon chain. Specific examples include dimethyl sulfoxide, diphenyl sulfoxide, and sulfolane.

In the method of the present invention, it is possible to use only the compound with coordinating power to be added as a solvent, but it is also preferable to carry out the reaction in a mixed solution with another suitable solvent. Examples of such other solvents include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene, halogenated aliphatic hydrocarbons such as chlorohexane and chlorocyclohexane, chlorobenzene, bromobenzene,
Halogenated aromatic hydrocarbons such as dichlorobenzene and trichlorobenzene are used.

- Carbon oxide may be pure or may contain nitrogen, argon, helium, carbon dioxide, halogenated hydrocarbons, and the like.

Compounds containing platinum group metals are compounds such as platinum group elements such as ruthenium, rhodium, palladium, and platinum, and ligands such as carbon oxide and phosphines, or organometallic compounds having an organic group. , those containing no halogen elements are preferred. Specifically, Ru 3 (CO)
12゜H4Ru4 (Co)+2+ [Ru 2 (CO) 4 (HCOO)
2 ko. .

Ru (Co)3 (dppe), Ru (
Co)3(PPh3)2. Ruthenium complex compounds such as Ru (acac)3, Rh 6 (CO) +6,
Rh H(Co) (PPh3) 3,
Rh (acac) (Co) (PPh
3), Rh(acac)(Co)2,
Examples include rhodium complex compounds such as Rh (acac)3. However, pph3 is triphenylphosphine, dppe is diphenylphosphinoethane, acac
indicates acetylacetonate.

In addition to these complex compounds, inorganic platinum group metal compounds that convert into active species in the reaction system can also be used. Specifically, RuO□nH2O, Ru-black, Ru carbon, etc. can be mentioned. It is thought that these compounds convert into carbonyl complexes in the reaction system and provide active species.

Furthermore, cobalt, iron, rhodium, palladium, etc. can be used in combination with these platinum group metals.

The reaction temperature is usually 30-300°C, preferably 120-300°C.
It is carried out in a temperature range of 200°C. Reaction pressure is 1-500
kg/cd, preferably 10-150kg/c
The reaction time varies depending on other conditions, but is usually several minutes to several hours.

The N,N'-disubstituted urea obtained by the method of this invention has low solubility in solvents and raw materials such as aromatic amines and aromatic nitro compounds. Therefore, simply by cooling the solution after the reaction to about room temperature, the produced N,N'-disubstituted urea will precipitate out as crystals. Therefore, by filtering this solution, N,N'-disubstituted urea can be efficiently obtained as a solid. On the other hand, the catalyst is stabilized by the added coordinating solvent and exists in the filtrate without being precipitated, so it can be reused as is. After the reaction, when cooling to room temperature and crystallizing, components other than di-substituted urea in the reaction mixture can be easily separated by washing with a solvent such as toluene or benzene, making it possible to take out only the di-substituted urea alone. can.

Next, in the second step, the obtained N,N'-disubstituted urea and an organic compound having a hydroxyl group are reacted as shown in the following formula to produce an aromatic primary amine and an aromatic urethane.

A r-NHCNH-A r +ROH→A r
-NHCOOR+A r-NH2 (2) Organic compounds with hydroxyl groups include -hydric alcohols, -valent phenols, etc. Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and monohydric alcohols such as t-butyl, and alkylphenols having alkyl groups such as phenol, chlorophenol, methyl, ethyl, n-propyl, and isopropyl.

The reaction temperature is usually 80-300°C, preferably 120-300°C.
It is preferable to carry out at a temperature range of 200°C. The pressure is set at the autogenous pressure at the reaction temperature of the organic compound containing a hydroxyl group or the solvent that is commonly used.

And this reaction can be carried out without using a catalyst.

After completion of this reaction, a distillation operation is performed to recover the aromatic urethane as a distillation residue, while the aromatic primary amine is recovered by distillation. This aromatic primary amine has - stage N,
It is reused in the reaction for producing N'-disubstituted urea.

As mentioned above, if the first step (reaction formula (1)) and the second step (reaction formula (2)) are carried out consecutively, the aromatic primary amine will not change formally. , only the aromatic nitro compound participates in the reaction, and overall the aromatic nitro compound is reductively converted to the aromatic urethane, which is more economical than using aromatic primary amines as starting materials.

[Operations and Effects of the Invention] According to the present invention, N generated in the -th stage reaction,
Since N'-disubstituted urea has low solubility in solvents and raw materials such as aromatic amines and aromatic nitro compounds, it can be easily crystallized by cooling it to room temperature.
Filtration increases efficiency (N.

N'-disubstituted urea can be recovered. Moreover, since the catalyst is stabilized by the added coordinating solvent and exists in the solution, it can be reused as it is in the second-stage reaction, which is economical.

Further, in this invention, since there is no need to use a halogen compound, corrosion of equipment materials is extremely low, and there is no need to use expensive materials for the reactor.

Furthermore, this second stage reaction has fewer side reactions and can provide N,N'-disubstituted urea in high yield.

Further, in the second stage reaction, since it is not necessary to use a catalyst, the aromatic urethane can be recovered as a distillation residue without being distilled off. Furthermore, since the aromatic primary amine that is the substance to be distilled and the remaining organic compound having a hydroxyl group have relatively low boiling points, the distillation operation can be carried out under mild conditions, making the operation easy. Moreover, the recovered aromatic primary amine can be reused in the -stage N,N'-disubstituted urea production reaction. Furthermore, the second stage reaction proceeds almost quantitatively without any catalyst, and there are few side reactions. Therefore, although it is a two-step reaction, aromatic urethane can be produced in high yield.

[Example] Next, an example of the present invention will be described. In addition, in each example, the term "alkyl carbamate" is used instead of the term "urethane", which is a common name, and the names of the individual substances are clearly indicated.

Example 1 In a magnetic stirring autoclave with an internal volume of 200 ml, 5.6 g of nitrobenzene, 7.8 g of aniline, 27 ml of ) toluene, and N, N, N', N'-tetramethylurea (hereinafter abbreviated as TMU) 8. 3 gs Ru 3
(Co)+:+20+ng was added, and after replacing the inside of the system with carbon monoxide, -carbon oxide was press-injected at a rate of 50 kg/cd. The reaction was carried out at 160'C for 2.0 hours without stirring. After the reaction was completed, the reaction solution was cooled to room temperature, evacuated, and filtered to obtain 3.5 g of N,N'-diphenylurea crystals.
I got it. When the filtrate was analyzed by gas chromatography and high performance liquid chromatography, it was found to be N.

N'-diphenylurea 0.1g, nitrobenzene 2°9
g was included. From this, T OF (Turn 0
verFrequency) was 100 h-1, and the selectivity based on nitrobenzene was 94%.

Next, isolated N,N'-diphenylurea crystal 3
．． 0 g, methanol 50 g, another internal volume 200 ml
Place in a magnetic stirring autoclave and stir while stirring.
The reaction was carried out at 60°C for 3 hours. After the reaction was completed, the reaction solution was analyzed by gas chromatography, and the yield of methyl N-phenylcarbamate was 96% and the yield of aniline was 95%.

Example 2 Next, using the same apparatus and the same operation as shown in Example 1, the amount of TMU was 18.4 g, and the amount of toluene was 15 m
Table 1 shows the results of an experiment to produce N,N'-diphenylurea instead of Example 1.

Furthermore, when 3.0 g of N,N'-diphenylurea isolated here and 50 g of methanol were reacted in the same apparatus and operation as in Example 1, methyl N-phenylcarbamate and aniline were produced. Yield 9 each
5% and 94% were obtained.

Comparative Example 1 Using the same equipment as in Example 1 and using the same operation, TMU was not added and the amount of toluene was changed to 32 ml.
Table 1 shows the results of an experiment for producing N,N'-diphenylurea.

Comparative Example 2 In the same apparatus and the same operation as shown in Example 1, pyridine was added instead of TMU, and N, N'-
Table 1 shows the results of the diphenyl urea production experiment.

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

Examples 3 to 8 Table 2 shows the results of N,N'-diphenylurea production experiments conducted using the same apparatus and the same operation as shown in Example 1, but with different coordinating solvents added. .

Furthermore, 3.0 g of N,N'-diphenylurea isolated here and 50 g of methanol were each reacted in the same apparatus and operation as in Example 1 to produce methyl N-phenylcarbamate and aniline. The results of the experiment are shown in Table 3.

Example 9 In the same apparatus and in the same operation as shown in Example 1, the catalyst used was [Ru2(Co)4(HCOO)2
]. Table 4 shows the results of an experiment to produce N,N'-diphenylurea instead of .

Furthermore, when 3.0 g of N,N'-diphenylurea isolated here and 50 g of methanol were reacted in the same apparatus and operation as in Example 1, methyl N-phenylcarbamate and aniline were produced. Yield 9 each
5% and 95% were obtained.

table MPC: N-phenylcarbami Methyl acid

Claims (3)

[Claims] (1) When reacting an aromatic primary amine, an aromatic nitro compound, and carbon monoxide, a catalyst mainly consisting of a compound containing a platinum group metal is used, and an amide with coordination power to those metals is used. Urea in which N,N'-disubstituted urea is produced using a compound or an oxygen-containing sulfur compound as part of the solvent or a ligand, and then the produced N,N'-disubstituted urea is separated and recovered from the reaction solution. producing an aromatic primary amine and an aromatic urethane by reacting the N,N'-disubstituted urea obtained in the urea producing step with an organic compound containing a hydroxyl group; A method for producing an aromatic urethane, comprising: a step of separating a primary amine to obtain an aromatic urethane; and a step of circulating the separated aromatic primary amine to the urea production step. (2) The method for producing aromatic urethane according to claim 1, wherein the first urea production step is carried out without using a halogen compound. (3) Reaction A method for producing an aromatic urethane according to claim 1, in which the reaction between the N,N'-disubstituted urea and the organic compound containing a hydroxyl group is carried out without using a catalyst.