JPH09143144A - Production of 1,3-dialkylurea - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a 1,3-dialkylurea comprising a step for efficiently removing phenols formed as a by-product from the resultant reactional mixture with a small amount of an organic solvent when reacting a diaryl carbonate with a primary amine and thereby producing the 1,3- dialkylurea. SOLUTION: A >=11C aliphatic hydrocarbon, e.g. n-tridecane is added as an azeoptropic solvent to a reactional mixture after completing the reaction and phenols formed as a by-product are removed together with the hydrocarbon according to azeotropic distillation in the method for reacting a diaryl carbonate with a primary amine and thereby 1,3-dialkylurea is produced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a 1,3-dialkylurea, and more particularly to a method for producing a 1,3-dialkylurea by reacting a diaryl carbonate with a primary amine, The present invention relates to a method for producing a 1,3-dialkylurea that can efficiently remove by-produced phenols from a reaction mixture using a small amount of an organic solvent.

[0002]

As a method for producing a 1,3-dialkylurea, for example, a method using an amine and phosgene as a raw material, a method using an amine and carbon dioxide as a raw material, a method using an amine and urea as a raw material, Several methods are already known, such as a method using an amine and a diaryl carbonate as raw materials.

Among these, Org. Prep. Proced. In
As described in t., 8, 197 (1976), according to the method using amine and diaryl carbonate as raw materials,
After reacting the amine with the diaryl carbonate, the resulting reaction mixture is subjected to steam distillation to remove by-produced phenols, and the desired 1,3-dialkylurea is obtained from the distillation residue. For example, in the case of 1,3-diethylurea, diphenyl carbonate was added little by little to an aqueous solution of ethylamine, heated and reacted to remove phenol from the reaction mixture by steam distillation, thus obtained. The distillation residue is dried, the obtained solid is dissolved in hot ethyl acetate and cooled to precipitate 1,3-diethylurea. In this method, a considerable amount of 1,3-diethylurea remains in the mother liquor.

As described above, according to the conventional method, after the reaction is completed, the obtained reaction mixture is subjected to steam distillation to remove the by-produced phenols, so that the amount of distillate is large. It requires complicated wastewater treatment. In general,
Although various methods for separating a mixture are known, even if an attempt is made to separate 1,3-diethylurea from 1,3-diethylurea containing by-produced phenols, the phenols still remain 1,3-diethylurea. Tend to move along with, and when 1,3-diethylurea containing by-produced phenols is recrystallized to separate 1,3-diethylurea, in the presence of phenols, The solubility of 3-diethylurea is high and recrystallization is difficult. In addition, even if an attempt is made to remove phenols by simple distillation of 1,3-diethylurea containing by-produced phenols, 1,3-diethylurea has a subliming property, so that there is a loss due to distillation.

[0005]

The present invention is based on the reaction of a conventional diaryl carbonate with a primary amine, 1,3
The present invention was made to solve the above-mentioned problems in the production of dialkylurea, and the by-produced phenols can be efficiently removed from the obtained reaction mixture by using a small amount of an organic solvent. 1,3 -To provide a method for producing a dialkyl urea.

[0006]

The present invention is a method for producing a 1,3-dialkylurea by reacting a diaryl carbonate with a primary amine, and in the reaction mixture, after the reaction is completed, the reaction mixture having 11 or more carbon atoms is used. It is characterized in that an aliphatic hydrocarbon is added as an azeotropic solvent and the phenols are removed together with the hydrocarbon by azeotropic distillation.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The production of 1,3-dialkylureas by the reaction of diaryl carbonates with primary amines comprises
As already mentioned, it is already known. Examples of the diaryl carbonate include, in addition to diphenyl carbonate, di (o-toluyl) carbonate, di (m-toluyl) carbonate, di (p-toluyl) carbonate,
Mention may be made of di (alkyl-substituted phenyl) carbonates such as di (ethylphenyl) carbonate. The primary amine is not particularly limited, but usually, for example, methylamine, ethylamine,
Alkylamines such as propylamine and butylamine can be mentioned.

In the reaction, for example, a diaryl carbonate is dissolved in an aromatic hydrocarbon such as toluene, and this is mixed with a primary alkylamine aqueous solution, and it is preferably heated in an autoclave under an inert gas atmosphere and under heating. Stir for several hours. The primary alkylamine is usually used in an amount of 2 to 3 parts by mole with respect to 1 part by mole of the diaryl carbonate. The pressure during the reaction may be normal pressure or increased pressure.

After completion of the reaction, the reaction mixture was taken out of the autoclave, cooled, and distilled under reduced pressure using a distillation apparatus.
The organic solvent used in the reaction, the unreacted primary amine and water are distilled off at room temperature to about 60 ° C., and the reaction mixture is concentrated.
After this, if necessary, heat under a higher degree of reduced pressure,
The reaction mixture is distilled to remove some of the phenolics from the reaction mixture. If the phenols are excessively removed by distillation, 1,3-dialkylurea tends to be distilled out at the same time, so the distillation of the phenols should be limited to a part.

In this way, after distilling a predetermined amount of phenols from the 1,3-dialkylurea containing by-products, the 1,3-dialkylurea is kept at a temperature at which it does not solidify. Phenols can be removed by adding an azeotropic solvent consisting of an aliphatic hydrocarbon having 11 or more carbon atoms, distilling it under reduced pressure, and distilling phenols together with the azeotropic solvent. The obtained 1,3-dialkylurea can be recrystallized from an aromatic hydrocarbon such as toluene, if necessary, to obtain a purified product.

The azeotropic solvent is an aliphatic hydrocarbon having 11 or more carbon atoms, and examples thereof include undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane and eicosane. Among these, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and the like are preferable, and among them, n-tridecane is preferable. Other than these, for example, hydrocarbons such as butylbenzene and indene, and ethers such as benzyl ethyl ether and di-n-pentyl ether can be used. The amount of the azeotropic solvent used is not particularly limited, but is usually 1 to 10 times by weight of the by-produced phenols to be used for removal.

[0012]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 To a stainless steel autoclave having an internal volume of 100 mL, 10.0 g (0.047 mol) of diphenyl carbonate was charged together with 32 mL of toluene, stirred and dissolved in toluene. Then, after adding 7.5 g of a 70% ethylamine aqueous solution (0.12 mol as ethylamine), the air in the autoclave was replaced with nitrogen (5 kg / cm ² G). The autoclave was immersed in an oil bath at 100 ° C. and stirred for 4 hours. The internal pressure was 1.0 kg / cm ² G.

The autoclave is water cooled and the internal pressure is 0 kg / cm.
After confirming that it became ² G, the obtained reaction mixture was taken out into a 100 mL two-necked flask, and was put under reduced pressure (20 m
mHg) and distilled at 40 ° C. to remove toluene, ethylamine and water. Further, it was heated and distilled under reduced pressure (5 mmHg) to remove part of the by-produced phenol. The distillation residue thus obtained is 1,3-diethylurea
It was a mixture of 5.0 g and 1.0 g of by-produced phenol.

After that, nitrogen was introduced into the flask and cooled under normal pressure. When the internal temperature reached 105 ° C., 5.0 g of n-tridecane which was an azeotropic solvent was added, and the mixture was mixed again under reduced pressure. The boiling distillation was performed. The final bottom temperature was 140 ° C.

As a result, 5.47 g of a distillate and 5.37 g of a bottom (residue) were obtained. The composition of the distillate was 0.13 g of 1,3-diethylurea (2.4% based on the charged amount) and 0.99 g of phenol.
(Charged amount 99%), n-tridecane 4.36 g (charged amount 87%), the composition of the bottom is 1,3-diethylurea 4.75 g (charged amount 95%), phenol 0.0.
The amounts were 2 g (based on the charged amount of 2%) and 0.60 g of n-tridecane (based on the charged amount of 12%), and thus, phenol could be almost separated from 1,3-diethylurea.

28 mL of toluene was added to the obtained bottom, heated to 50 ° C. to dissolve 1,3-diethylurea, and then ice-cooled to crystallize 1,3-diethylurea. It was collected by filtration. The obtained crystals were washed with 23 mL of toluene, and then dried under reduced pressure (10 mmHg) at 50 ° C. for 3 hours to obtain 4.25 g of a purified product of 1,3-diethylurea having a gas chromatography purity of 99% or more as a pale pink powder. Obtained.

Comparative Example 1 In the same manner as in Example 1, diphenyl carbonate was charged together with toluene in a stainless steel autoclave,
After stirring and dissolving in toluene, a 70% ethylamine aqueous solution was added, the air in the autoclave was replaced with nitrogen, and then the autoclave was immersed in a hot water bath and stirred to carry out the reaction.

After completion of the reaction, the autoclave was cooled with water,
The obtained reaction mixture was taken out in a 100 mL two-necked flask, and distilled under reduced pressure (20 mmHg) at 40 ° C. to remove toluene, ethylamine and water. Further, it was heated and distilled under reduced pressure (5 mmHg) to remove part of the by-produced phenol. In this way, 1,3-diethylurea
A distillation residue consisting of 1.05 g and 1.75 g of phenol was obtained.

To this distillation residue, 17.5 g of n-decane was added and distilled at atmospheric pressure at a final bottom temperature of 200 ° C. As a result, 18.2 g of a distillate and 1.65 g of a bottom (residue) were obtained.
The composition of the distillate was 0.23 g of 1,3-diethylurea (21% charge), 1.48 g of phenol (85% charge).
%, N-decane 16.5 g (based on the charged amount of 94%), and the composition of the bottom is 1,3-diethylurea 0.68 g (based on the charged amount 65%), phenol 0.14 g (based on the charged amount 8).
%), 0.83 g of n-decane (5% of the charged amount),
Separation of phenol from 1,3-diethylurea was inadequate.

Comparative Example 2 16.2 g of mesitylene was added to a distillation residue composed of 1.0 g of 1,3-diethylurea and 1.62 g of phenol, and distilled at atmospheric pressure at a final bottom temperature of 200 ° C. As a result, the fraction 16.4
g and 1.65 g of bottom (residue) were obtained. The composition of the fraction is
1,3-Diethylurea 0.08 g (8% charge), 1.17 g phenol (72% charge), mesitylene 15.
2g (94% of the charged amount), the composition of the bottom is 1,
3-diethylurea 0.84 g (84% charge), phenol 0.43 g (27% charge), mesitylene 0.7
It was 8 g (5% of the charged amount), and the separation of phenol from 1,3-diethylurea was insufficient.

Comparative Example 3 5.59 g of n-decane was added to a distillation residue consisting of 5.59 g of 1,3-diethylurea and 1.12 g of phenol, and distilled under reduced pressure (30 mmHg) at a final bottom temperature of 120 ° C. did. As a result, a fraction of 4.10 g and a bottom (residue) of 6.9 were obtained.
7 g were obtained. The composition of the distillate is 1,3-diethylurea 0.03
5g (0.1% charge), 0.20g phenol (18% charge), 4.91g n-decane (88 charge)
%), And the composition of the bottom is 1,3-diethylurea 5.5
7 g (96% charge), 0.84 g phenol (75% charge), 0.56 g n-decane (10 charge)
%), And the separation of phenol from 1,3-diethylurea was insufficient.

Comparative Example 4 A mixture of 5.0 g of 1,3-diethylurea and 8.1 g of phenol was decompressed (5 mmHg) at a final bottom temperature of 180 ° C.
After distilling up to (water bath temperature 200 ° C.), the distillation rate of phenol remained at 93%, while the distillation rate of 1,3-diethylurea reached 28%.

[0024]

As described above, according to the method of the present invention,
After completion of the reaction between the diaryl carbonate and the primary amine, by using an aliphatic hydrocarbon having 11 or more carbon atoms as an azeotropic solvent, the by-produced phenols are efficiently removed from the reaction mixture by azeotropic distillation. You can

Claims (2)

[Claims] 1. A method for producing a 1,3-dialkylurea by reacting a diaryl carbonate with a primary amine, wherein an azeotropic solvent containing an aliphatic hydrocarbon having 11 or more carbon atoms in the reaction mixture after the reaction is completed. In addition, the above phenols are removed by azeotropic distillation together with this hydrocarbon. 2. The azeotropic solvent is n-tridecane.
The method described in.