JPH04193855A - Production of carbamic acid ester - Google Patents

Abstract

PURPOSE:To obtain the objective compound by reacting an NH2-containing compound, an NO2-containing compound, an OH-containing compound and CO, separating the catalyst from the reaction liquid, distilling the liquid, adding an aromatic compound to the bottom product, removing the precipitated material and adding aliphatic hydrocarbon, etc., to the residue. CONSTITUTION:The subject substance is synthesized by reacting an NH2- containing compound (e.g. aniline), an NO2-containing compound (e.g. nitrobenzene), an OH-containing compound (e.g. ethanol) and CO in the presence of a catalyst at 140-230 deg.C under 28-100kg/cm<2> pressure for 2-6hr. The reaction product is separated as a distillation bottom product after separating the catalyst from the reaction liquid. The bottom product is added with an aromatic compound, which is liquid at normal temperature and precipitated diphenylurea is removed from the liquid. The residual liquid is added with an aliphatic and/or an alicyclic hydrocarbon and the crystallized subject substance is separated from the liquid. The catalyst is e.g. a platinum-group transition metal compound, a non-metallic halide and a compound of iron, vanadium, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing carbamate esters, and more specifically, after separating the product as the bottom product of distillation, carbamic acid is produced with high purity and high recovery rate. The present invention relates to a method for producing carbamate esters in which acid esters can be separated by crystallization.

(Prior art) Carbamate esters are
It is important as a precursor of Isocyanates are widely used as raw materials for urethane products such as soft and hard foams, paints, waterproofing agents, adhesives, and elastic fibers.
Demand for methylene diphenyl isocyanate (MDI) is expanding for use in thermoplastic elastomers, paints, adhesives, elastic fibers, automobile bumpers, and the like.

Currently, MDI is manufactured using phosgene, but since phosgene is highly toxic and uses chlorine, which requires a lot of electricity, in order to simplify the process and save energy, we have developed a carbamate ester that does not use phosgene. A method for producing it with high selectivity and high yield is being investigated.

For example, when alcohol and CO are reacted at high temperature and pressure in the presence of a catalyst using nitrobenzene as a raw material, the formula (
A carbamate ester is obtained by the reaction 1).

When a noble metal catalyst such as palladium (Pd) is used in this reaction, Lewis acids and tertiary amines are used, so a large amount of poorly soluble compounds are formed in the reaction solution, resulting in a thick reaction solution. It becomes slurry-like, making it difficult to handle the liquid, collect the precious metal catalyst, and separate and purify the produced carbamate ester, leading to a decrease in product purity (Special Publication No. 52-43).
822, JP-A-51-98240, JP-A-54-145601).

On the other hand, in the above reaction, a catalyst consisting of platinum group metal-hanadium-iron-halogen atom-tertiary amine was used in which the amount of Lewis acid used was low and the amount of halogen atom used relative to all metals was within a specific range. A method has been proposed to facilitate liquid handling. In this case, the carbamate ester can be recovered by filtration after the reaction is completed.
After separating the catalyst, the mother liquor is crystallized to precipitate carbamate ester crystals, which are then filtered.
In this method, the product can be separated well by crystallization and a high recovery rate can be obtained (Japanese Patent Application Laid-open No. 72954/1983). In addition, after the reaction is completed, after separating the catalyst by filtration, part or most of the organic compound containing hydroxyl groups is distilled off, and then the reaction solution is cooled to crystallize and the crystals are filtered. A method for recovering the waste has been proposed (Special Public Interest Publication Act 1986-
56123). However, with these recovery methods, the catalyst may be incorporated into the crystals, making it difficult to recover carbamate esters with high purity.

In addition, in the reaction of formula (1), 3 mol of CO is consumed per 1 mol of ester, and 1/3 of the CO is used to form a carbamate group, but the remaining 2/3 is consumed as useless CO□. Furthermore, a large amount of heat is released during CO2 production, which requires expensive reaction heat removal equipment.

On the other hand, from amine, CO, alcohol and 02 to Pd black and I
A method of directly synthesizing carbamate ester using - as a catalyst has been attempted (formula (2), S, Fukuoka
et al, Chem, Commu, 19
84, 399).

This method requires only 1 mole of ester to be produced.
It does not require a mol of COL, and unlike the case where the nitro compound of formula (1) is used as a raw material, only water is produced as a by-product, and there is little heat generated by the reaction. However, productivity is low, such as Pd
When Cj2□ was used as a catalyst and Fe0Cffi was used as a co-catalyst, even if the 150°Cl2hT:co pressure was as high as 100 bar, the aniline conversion was 77% and the ester selectivity was 90.
% (Japanese Unexamined Patent Publication No. 120551/1983)
.

In contrast, a method has been proposed in which a carbamate ester is synthesized from a primary amine, CO, and alcohol using an organic nitro compound as an oxidizing agent (Japanese Unexamined Patent Publication No. 55-12
Publication No. 0551). For example, aniline, nitrobenzene,
When synthesizing alkyl N-phenylcarbamates according to formula (3) from CO and yohyalcohols, 2 moles of amine groups per mole of nitro groups are required to obtain the highest yield; If the number of nitro groups in the compound is less than the equivalent amount, the conversion rate of the amine will be low, so the nitro compound is usually added in excess.

Recovery of the carbamate ester is carried out by various methods depending on the solubility of the carbamate ester compound to be synthesized. If the compound is easily soluble in the reaction solution, the catalyst can be separated by filtration and then purified by distillation. If the compound is slightly difficult to dissolve in the solvent, it can be obtained by dissolving the crude carbamic acid ester obtained by crystallization at an elevated temperature, cooling the solvent solution, and recrystallizing it. When recovering a carbamate ester by distillation, if the boiling point of the compound is high, various by-products will be produced, which is not preferable.

JP-A-62-59251 and JP-A-62-59
In Publication No. 252, R based on formulas (4) and (5)
After producing diphenylurea using h or Ru catalyst,
A method has been proposed in which a catalyst liquid is separated and then alcohololyzed at normal pressure in the absence of a catalyst to synthesize a carbamate ester.

In this method, the primary amine also serves as a solvent in the first reaction, and diphenylurea can be easily extracted as crystals. After the reaction of formula (5), ROH and primary amine are separated by distillation, and carbamate ester is recovered as the bottom product. However, since a large amount of expensive Ru is used, recovery of the catalyst is important. Become.

[Problem to be solved by the invention]

The present inventors first reacted a compound having an amino group, a compound having a nitro group, an organic compound having a hydroxyl group, and carbon monoxide using a certain catalyst containing a platinum group to form carbamate esters. We have proposed a method for producing carbamate esters that can be synthesized with high selectivity and high yield (Japanese Patent Application No. 195765/1999).

However, when recovering carbamate esters from the resulting reaction products, polymers such as isocyanates, isocyanate polymers, urea compounds, bulent compounds, allophanate compounds, etc., which have high solubility in hydrous acid group organic compounds like carbamate esters, are used. It has been found that it is very difficult to recover carbamate esters with high purity and high recovery rate by crystallization because it contains complex tar-like substances including such substances. Therefore, in order to industrially produce carbamate esters with even higher purity and higher recovery rate, there is a need for a method that allows the carbamate esters to be easily recovered after the reaction is completed.

The purpose of the present invention is to facilitate handling without slurrying the reaction solution, increase the utilization rate of CO without reducing product purity, and achieve high selectivity and high yield without using an expensive reaction heat removal device. The purpose of the present invention is to propose a method for producing carbamate esters, which can recover carbamate esters with high purity and high recovery rate through simple operations after synthesizing the carbamate esters at a high rate.

[Means to solve the problem]

The present invention involves synthesizing carbamate esters by reacting a compound having an amino group, a compound having a nitro group, an organic compound having a hydroxyl group, and carbon monoxide in the presence of a catalyst, and then separating the catalyst from the reaction solution. Then, the reaction product is taken out as the distillation bottoms, and after removing precipitates by adding an aromatic organic compound that is liquid at room temperature to the bottoms as necessary, aliphatic hydrocarbons and/or fats are removed. The present invention relates to a method for producing carbamate esters, which comprises adding a cyclic hydrocarbon and crystallizing and separating the carbamate esters.

Compounds having an amine group used in the present invention include:
Examples include aromatic monoamines, aromatic polyamines, aliphatic monoamines, aliphatic polyamines, aromatic amino acids, and aliphatic amino acids, such as aniline, toluidines, xylidine, benzylamines, phenylenediamines, I- Lylene diamines, amine phenols, naphthylamines, oxynaphthyl amines, naphthylene diamines, aminoanthracenes, aminobiphenyls, bis(aminophenyl) alkanes, his(aminophenyl) ethers, bis(aminophenyl) thioethers , bis(aminophenyl)sulfones, aminodiphenoxyalkanes, aminophenothiazines, 2
- Heteroaromatic compounds such as aminopyrimidines, aminoisoquinolines, and aminoindoles.

Specific aromatic amines include aniline, 〇-toluidine, m-toluidine, I)-)luidine, 2.3-xylidine, 2.4-xylidine, 2゜5-xylidine,
2.6-xylidine, 3.4-xylidine, 0-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2゜3-diaminotorylene, 2,4-diaminotorylene, 2.5-diaminotorylene , 2,6-diaminotrilene, 3,4-diamino-1-rylene, hensylamine, xyleneamine, α- or β-naphdylamine, aminebenzoic acid, aminoanthraquinone, O-aminephenol, m-aminophenol, p-amino Phenol, 1,2-naphthylene diamine, 1,3-naphthylene diamine, 1゜4-naphthylene diamine, ■, 5
-naphthylene diamine, 1,6-naphthylene diamine,
1,7-naphthylene diamine, 1,8-naphthylene diamine, 2,3-naphthylene diamine, 2,6-naphthylene diamine, 2,7-naphthylene diamine, ■-andramine, 0-aminobiphenyl, m-aminobiphenyl, p-aminobiphenyl, 1-oxy-2-naphthylamine, 1-oxy-5-naphthylamine, 1-oxy-
7-naphthylamine, 1-oxy-8-naphthylamine, 2-oxy-1-naphthylamine, 3-oxy-1-
naphthylamine, 4-oxy-1-naphthylamine, 5
-oxy-1-naphthylamine, 6-oxy-1-naphthylamine, 7-oxy-1-naphthylamine, 8-oxy-1-naphthylamine, 2゜2゛-diaminobiphenyl, 2.3'-diaminobiphenyl, 2.4 '-diaminobiphenyl, 3゜31-diaminobiphenyl, 3,
4-diaminobiphenyl, 4,4'-diaminobiphenyl, 2゜2"-diaminodiphenylmethane, 2.4'-
Diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,41-diaminodiphenylmethane, 4
, 4'-diaminodiphenylmethane, bis(4-aminophenyl) ether, 4,4I-diaminosulfone, bis(4-aminophenoxy)ethane, 0-chloroaniline, m-chloroaniline, p-chloroaniline, 4-chloro -1゜3-phenylenediamine, p-bromoaniline, 4-fluoro-1,3-phenylenediamine, 〇-
Aminophenylene urethane, m-aminophenylene urethane p-aminophenylene urethane, 0-anilidine, m-anilidine, p-anilidine, 2,4-diaminophenethol, 0-aminohenzaldehyde, m-aminohenzaldehyde, p- aminohenzaldehyde, p
-Amine hendiyl chloride and the like.

In addition, aliphatic amines include primary amines such as methylamine, ethylamine, and amylamine, secondary amines such as dimethylamine and diethylamine, cyclopentylamine,
Examples include B'tJJ amines such as cyclohexylamine, diamines such as ethylenediamine, trimethylenediamine, 4,4-diaminodicyclohexylmethane and hexamethylenediamine, and triamines such as 1°2.3-)riaminopropane.

These compounds can be used alone or in combination of two or more.

Compounds having a nitro group used in the present invention include:
Examples include aromatic mononitro compounds, aromatic polynitro compounds, aliphatic mononitro compounds, and aliphatic polynitro compounds.

For example, aromatic nitro compounds include 21-lohenzenes, dinitrohairzenes, dinitrotoluenes, nitronaphthalenes, nitroanthracenes, nitrobiphenyls, bis-trophenyl) alkanes, bis-trophenyl) ethers. , bis(nitrophenyl)thioethers, bis(nitrophenyl)sulfones, nitrodiphenoxyalkanes, nitrophenothiazines, and heteroaromatic compounds such as 5-nitropyrimidine.Specifically, nitrohenzene, 0 - ditrotoluene,
m-nitrotoluene, p-nitrotoluene, 0-nitro-p-xylene, 1-21-naphthalene, m-dinitrohenzene, p-dinitrohenzene, 2,4-dinitrotoluene, 2゜6-di Nitrotoluene, dinitrotoluene, 4゜41-dinitrobiphenyl, 4,4'-dinitroethandyl, bis(4-nitrophenyl)ether,
Bis(2,4-dinitrophenyl)ether, bis(4
-nitrophenyl)thioether, bis(4-nitrophenyl)sulfone, bis(4-nitrophenoxy)ethane, α,α“-dinitro-p-xylene, α,α1-dinitro-m-xylene, 2,4,61 Nitrotoluene, 0-chloronitrobenzene, m-chloronitrobenzene, p-chloronitrobenzene, ■-chloro 2.4
- Cinitrohenzene, 1-bromo-4-nitrohenzene, 1-fluoro-2,4-dinitrohenzene, 0-nitrophenylcarbamic acid, m-nitrophenylcarbamic acid, p-nitrophenylcarbamic acid, 0-nitroanisole, m -Nitroanisole, p-nitroanisole, 2,4-dinitrophenylur, m-nitrobenzaldehyde, p-nitrohencyclolide, ethyl-p
-Nitrohenshade, m-nitrohenzenesulfonyl chloride, p-nitrophthalic anhydride, 3゜3'-dimethyl-4,4'-dinitrobiphenyl, 4,4'-dinitrobiphenyl, 1,5-dinitronaphthalene Examples include.

In addition, aliphatic nitro compounds include nitromethane, nitrobutane, 2.2″-dimethylnitrobutane, nitrocyclopencune, 3-methylnitrobutane, nitrooctane,
3-nitropropene-1, phenylnitromethane, p-
Examples thereof include bromophenylnitromethane, p-methoxyphenylnitromethane, dinitroethane, dinitrohexane, dinitrocyclohexane, di(trohexyl)methane, and the like.

These compounds can be used alone or in combination of two or more.

It is preferable that the compound having an amino group and the compound having a nitro group have the same skeleton structure, but they may be different.

Examples of the organic compound having a hydroxyl group used in the present invention include m alcohols or polyhydric alcohols containing primary, secondary, or tertiary hydroxyl groups. Specific compounds include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, L-butyl alcohol, n-amyl alcohol, isoamyl alcohol,
Aliphatic alcohols such as hexyl alcohol, lauryl alcohol and cetyl alcohol; alicyclic alcohols such as cyclopentanol and cyclohexyl alcohol; aromatic alcohols such as benzyl alcohol, chlorobenzyl alcohol and methoxyhensyl alcohol;
Dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol, and trihydric alcohols such as glycerol and hexanetriol can be used alone or in combination of two or more.

In the present invention, as a catalyst, a transition metal belonging to the platinum group and/or a compound thereof, a nonmetal halide and/or an aqueous solution thereof, iron and/or a compound thereof,
It is also preferable to use vanadium and/or its compounds.

Examples of transition metals belonging to the platinum group include metals such as palladium, rhodium, and ruthenium, and at least one of their compounds such as halides, oxides, cyanides, thiocyanides, sulfates, nitrates, and acetates is used. .

As the iron compound, ferrous chloride, ferric chloride, ferrous oxide, ferric oxide, ferrous sulfate, ferric sulfate, iron hydroxide or acid chloride, etc. are used.

Vanadium compounds include vanadium oxytrichloride,
Vanadium oxytrichloride, pyrovanadic acid, metavanadate, vanadium sulfate, vanadium oxalate, vanadyl sulfate, vanadyl oxalate, vanadium trioxide, vanadium pentoxide, hanadium sesquioxide, and the like are used.

Hydrogen chloride, hydrogen bromide, hydrogen iodide, etc. are used as the nonmetal halide.

The above-mentioned metals and/or their compounds can be supported on the same carrier or on separate carriers. By doing so, it becomes easy to separate and recover the product from the reaction solution. For example, a platinum group component and an iron component can be supported on high silica mordenite, and a vanadium component can be supported on chikunia.

The platinum group component is reaction solution 1! 0.01-30mg-at
It is preferable to contain om, more preferably 0, 1
~10 mg-atom. The amount of the platinum group component supported on the carrier is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight.

The iron component is 0.1 to 30 mg-atom in the reaction solution 11.
is preferably contained, more preferably 0.2 to 1
0 mg-atom. The ratio of the iron component to the platinum group component is preferably 0.05 to 1 Og-atom times, more preferably 0.5 to 3 g-atom times in metal ratio.

The iron component helps to improve the reaction rate and reaction yield, but if it is present too much, the reaction solution may turn black and undesirable by-products may be produced.

The vanadium component is added to the reaction solution 11 in an amount of 0.1 to 30 mg-a.
tom is preferable, more preferably 0.2 to 10 mg
-atom. The ratio of the iron component to the vanadium component is preferably 0.1 to 20 g-atom times, more preferably 1 to 8 g-atom times the metal ratio.

When the vanadium component exceeds a certain amount relative to the iron component, the conversion rate of the nitro compound increases, but the conversion rate of aniline decreases, and as a result, the yield of carbamate ester may decrease. On the other hand, if the hanadium component is less than a certain level relative to the iron component, the reaction solution may turn black and undesirable by-products may be produced.

Furthermore, if the iron and vanadium components are too large, the reaction solution may become slurry.

The nonmetal halide is preferably contained in the reaction solution 1j2 in an amount of 10 to 300 mmol, more preferably 20 mmol.
~120 mmol. If the nonmetal halide is too small, the conversion of nitrobenzene will be low, and if it is too large, the conversion of aniline will be low and the amount of undesirable by-products may increase. When using a nonmetal halide as an aqueous solution, the reaction rate may be low if the amount of water is too large, so the
A range of is preferred.

The reaction of the present invention will be explained in detail by taking as an example a case where aniline, nitrobenzene, alcohol, and CO are reacted (Formula (6)).

It is preferable that the amounts of aniline and nitrobenzene used are equal moles, but if one is in excess compared to the other, the reaction performance will deteriorate, so nitrobenzene is usually used in an amount of 0.5 to 1.5 times the mole per mole of aniline. range, preferably 0.8-1
．． The range is 3 times the mole. The amount of alcohol used is usually at least 2 moles per mole of aniline, preferably 3 moles or more.
~14 mole times.

The above reaction can also be carried out without the presence of a solvent, but
A solvent may also be used. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; nitriles such as acetonitrile, propionitrile, and hendinitrile; organic phosphorus compounds such as hmpa; sulfolane solvents such as sulfolane and dimethylsulforane; Examples include halogenated aromatic hydrocarbons such as benzene and dichlorohenzene, heptane, methylcyclohexane, ketones, esters, THF, 1,4-dioxane, propylene carbonate, N-methylpyrrolidone, 1°2-dimethoxyethane, etc. These may be used alone or in combination of two or more.

The reaction can be carried out batchwise or continuously. For example, in a batch method, a compound having an amine group, a compound having a 2l/4 group, an organic compound having a hydroxyl group, an organic solvent and a catalyst to be used as necessary are charged into the reaction system, and CO is introduced to raise the temperature. This can be carried out by stirring the mixture. Reaction temperature is 140~230°C1 pressure is normal pressure~200kg
/c, preferably 28 to 100 kg/cffl, and reaction time is 0.5 to 10 hours, preferably 2 to 6 hours.

In the present invention, carbamate ester is recovered with high purity and high recovery rate from the reaction product obtained by the above reaction in the following manner. The reaction solution contains the above-mentioned tar-like substance and therefore takes on a slightly red color.

First, after separating and removing the catalyst from the reaction solution, low-boiling compounds are removed by distillation. At this time, it is preferable to set the temperature of the pot to a temperature at which the carbamate ester does not decompose, and from the viewpoint of suppressing the production of diphenylurea,
The temperature is preferably 0°C or lower, more preferably 110°C or lower. When carbamate esters are taken out as the bottoms of distillation, tar-like substances with high boiling points are mixed in the bottoms.

Next, an aromatic organic compound that is liquid at room temperature is added to the bottom liquor to precipitate and remove diphenylurea, and then an aliphatic hydrocarbon and/or alicyclic hydrocarbon is added to the carbamine. The acid ester is separated by crystallization.

The amount of the aliphatic or alicyclic hydrocarbon added to the crystallization separation is not particularly limited, but is 0.5 to 5 per mole of carbamate! is preferred. When diphenylurea is not present in the bottoms, the treatment with the aromatic compound can be omitted.

Examples of aromatic organic compounds include benzene, toluene, 0-
Examples include aromatic hydrocarbons such as xylene, m-xylene, and p-xylene, and halogenated aromatic hydrocarbons such as monochlorohenzene and dichlorohenzene. Examples of aliphatic hydrocarbons include n-pentane, 1-pentane, n-hexane, i-hexane, n-hebutane, i-hebutane,
Examples include n-octane and i-octane. Examples of alicyclic hydrocarbons include cyclopenkune and cyclohexane. These can be used alone or in combination.

According to the above recovery method, tar-like substances containing various by-products can be separated very easily from carbamate esters.

The reaction mother liquor from which the solvent and raw materials (aniline, nitrohenzene, aniline salts such as aniline hydrochloride) used in crystallization separation are separated by distillation can be recycled and reused as is in the reaction system. Furthermore, the nonmetal halide may be neutralized with an alkali, if necessary. When aniline is used, neutralization may not be necessary because the nonmetal halide forms a salt. The nonmetal halide may be neutralized with an alkali before distillation, or after crystallization. Furthermore, it is also possible to precipitate and recover catalyst components that are partially eluted in the reaction solution after the catalyst has been separated.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Preparation of supported catalyst A nitric acid aqueous solution of P d (NO3) 2 was mixed with high silica mordenite (S iOz /ARz 03 ) powder, heated at 110°C for 2 hours and pulverized, and then FeC1
2 and vocx□ with an aqueous hydrochloric acid solution, and further heated this mixture at 110°C for 2 hours, and then calcined at 500°C for 2 hours to obtain 3.4% by weight of palladium and 7.2% by weight of Fe. , 1.8% by weight of a supported catalyst was prepared. It was confirmed from X-ray diffraction that palladium was converted into PdO by firing.

(2) Synthesis of carbamate ester In a Teflon-coated autoclave with an internal volume of 300 m1, 220 mg of the carrier catalyst prepared above (0.06 mmol of palladium, 0.33 mmol of iron, 0.12 mmol of vanadium) and 5.57 g of aniline ( 0,06
mol), nitrohenzene 7.42 g (0.06 mol)
, ethanol 19.3g (0.42 mol), hydrochloric acid 0.3
19 g (3.06 mmol) and toluene 13.
9g (0.15 mol) of CO
CO gas was introduced at room temperature up to 50 kg/afl, and the reaction was carried out at a reaction temperature of 190°C for 3 hours. After the reaction, the reaction mixture was cooled to room temperature and the pressure inside the system was returned to atmospheric pressure. When the obtained reaction product was analyzed by gas chromatography and liquid chromatography, it was found that 16.8 g (0,102
mole) was generated.

Example 2 NPU was synthesized in the same manner as in Example 1, except that the air in the reaction system was not replaced with CO. As a result, NPU16. Og was obtained.

Example 3 Collect 500ml of the reaction solution obtained in (2) of Example 1,
Ethanol, H2C, and toluene were distilled off, and the distillation temperature was raised to 150°C, and then the bottom liquid was taken out. When this bottoms liquid was cooled to room temperature, it became a hard solid. 60 m2 of toluene was added to the product, heated and dissolved, and filtered to recover 3 g of diphenylurea. Next, when n-penkune was added to the toluene solution and the product was dissolved under the boiling point and cooled, NPU was found as white needle crystals at 129
g was obtained. The purity of NPU was 99.7% (the remainder was diphenylurea), and the recovery rate was 92%.

In addition, trace amounts of red substances were completely separated.

Example 4 500 m of the reaction solution obtained in Example 1 (2)! gather,
After distilling off ethanol and H2C at a distillation temperature of 110'C, part of toluene was distilled off, distillation was stopped, bottoms were taken out, and NPU was recovered from n-pentane in the same manner as in Example 3. did. Diphenylurea was hardly detected, NPU purity was 100%, and recovery rate was 98%.

Example 5 33.08 g (0.2 mol) of NPU with 100% purity was weighed into a volumetric flask, m-dichlorobenzene was added as a solvent to make 200rr+42, and the NPU in this solution was
When the amount of diphenylurea (DPU) was measured by liquid chromatography, DPU/NPU=0.17%
Met. Transfer the above solution to a distillation pot and add 1.05 g of hydrochloric acid (
10.15 mmol) was added and heated at 110°C for 1 hour. After heating, the solution was cooled to room temperature and the amounts of NPU and DPU in the solution were measured in the same manner as above.
PU=O.

The value was 175%, which was almost unchanged compared to the value before heating the NPU, and it was found that diphenylurea was not produced at a heating temperature of 110°C.

Exile 6.7 In Example 5, the heating temperature was 80°C and 53°C.
When the same operation as in Example 5 was performed except that D
There was almost no change in the P U/N P U value, indicating that diphenylurea was not produced even at these temperatures.

Comparative Examples 1 to 3 In Example 5, the heating temperature was 115°C11
Example 5 except that the temperature was increased to 15°C and 150°C.
Perform the same operation as above to check the DPU/NPU before and after heating.
The values were compared. Increases as the heating temperature rises, 12
At temperatures above 0°C, diphenylurea crystals began to precipitate in the liquid, and at 150°C, the amount further increased. These results are shown in Table 1.

Below is the margin Table 1 Example 8 In Example 5, the same operation as in Example 5 was performed except that the heating time was 3 hours. No significant change was observed in the value of , and no diphenylurea crystals were observed.

Example 9 In Example 5, 165 g (0.2 mol) of NPU was weighed into a volumetric flask, 6 g (20 mmol) of 1-heptatool was added as a hydrous acid group organic compound, and m-dichlorobenzene was further added as a solvent. 20'O
mj2, and the amount of hydrochloric acid added is 1',05g (10,15
The same operation as in Example 5 was performed except that the heating temperature was 150°C. D P U/N before and after heating
It was found that there was almost no change in the PU value and no diphenylurea was produced.

From the results of Examples 5 to 9 and Comparative Examples 1 to 3 above, the production of diphenylurea is influenced by the heating temperature when diluting the reaction solution, and when no hydrous acid group organic compound is present in the reaction solution, the production of diphenylurea is 110°C. It was found that the formation of diphenylurea can be prevented by heating at a temperature below 150'C, and when a hydrous acid group organic compound is present in the reaction solution, the formation of diphenylurea can be prevented by heating at a temperature below 150'C.

〔Effect of the invention〕

According to the production method of the present invention, a compound having an amine group,
By reacting a compound with a nitro group, an organic compound with a hydroxyl group, and C○ in the presence of a certain catalyst, the reaction solution does not become a slurry, is easy to handle, and has a high purity without reducing product purity. Carbamate esters can be synthesized selectively and in high yields, and the bottoms obtained by distilling the reaction solution from which the catalyst has been separated are treated with an aromatic organic compound that is liquid at room temperature if necessary. By crystallizing and separating aliphatic hydrocarbons and/or alicyclic hydrocarbons, carbamic acid esters can be easily recovered with high purity and high yield.

Applicant: Hubcock Hitachi Co., Ltd. Agent: Patent Attorney Kawakita Takecho

Claims (2)

[Claims] (1) After synthesizing carbamate esters by reacting a compound having an amino group, a compound having a nitro group, an organic compound having a hydroxyl group, and carbon monoxide in the presence of a catalyst, the catalyst is separated from the reaction solution. , the reaction product is taken out as the distillation bottoms, and an aromatic organic compound that is liquid at room temperature is added to the bottoms as necessary to remove precipitates, and then
A method for producing carbamate esters, which comprises adding an aliphatic hydrocarbon and/or an alicyclic hydrocarbon to crystallize and separate the carbamate esters. (2) As the catalyst, a transition metal belonging to the platinum group and/or its compound, a nonmetal halide and/or its aqueous solution, iron and/or its compound, and vanadium and/or its compound are used. The method for producing carbamate esters according to claim (1).