JPH11158152A - Preparation of 1,3-dialkyl-2-imidazolidinones - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing the subject compound useful as a solvent or the like for extraction with small amount of by-products in a high yield by a direct one-step process by reacting an alkylene carbonate with a monoalkylamine in the presence of a dialkyl urea. SOLUTION: An alkylene carbonate of formula I (R<1> is H or methyl) is heated with a monoalkylamine (preferably, monomethylamine) of formula II (R<2> is a 1-6C alkyl) in the presence of 1,3-dialkylurea (preferably 1,3- dimethylurea) of formula III (R<3> is a 1-6C alkyl) at >=50C (preferably 100-300 deg.C)to provide the objective 3-dialkyl-2-imidazolidinones of formula IV in the method for preparing the 3-dialkyl-2-imidazolidinones. The reaction is preferably performed in the presence of carbon dioxide. For example, 1,3-dimethyl-2- imidazolidinone is obtained by heating ethylene carbonate and the monomethylamine in the presence of 1,3-dimethylurea at 450 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing 1,3-dialkyl-2-imidazolidinones. 1,3-Dialkyl-2-imidazolidinones are compounds having a wide range of uses as polar aprotic solvents and the like. For example, useful as a solvent for resins such as polyamide, polystyrene, polyester, polyvinyl chloride or phenol resin, a solvent for various organic synthesis reactions, or an extraction solvent for extracting aromatic hydrocarbons from aliphatic hydrocarbons. Compound. Of these, 1,3-
Dimethyl-2-imidazolidinone (hereinafter abbreviated as DMI)
Is particularly resistant to strong alkalis and hardly decomposes when heated with alkali metal hydroxides. Therefore, aromatic organic halides, especially polychlorobiphenyl (PCB)
It is also awarded as a solvent for a dehalogenation reaction such as described above, and is particularly useful.

[0002]

2. Description of the Related Art Heretofore, as a method for producing 1,3-dialkyl-2-imidazolidinones, for example, a method comprising reacting N, N'-dimethylethylenediamine with trichloromethylchloroformate (JP-A-53-73561). ),
A method of reacting N, N'-dimethylethylenediamine with carbon dioxide (JP-A-57-175170);
A method of reacting N'-dimethylethylenediamine and phosgene in the presence of water and a dehydrochlorinating agent (Japanese Patent Application Laid-Open No. 61-1097)
72, JP-A-61-172882), a method of reacting N, N'-dimethylethylenediamine with urea in the presence of a polar solvent (JP-A-61-229866, JP-A-61-229866).
Various methods using N, N'-dimethylethylenediamine as a raw material have been proposed. As a method for producing N, N'-dimethylethylenediamine used as this raw material, a method of obtaining from ethylene dichloride and monomethylamine (Japanese Patent Laid-Open No. 57-120570) is known. A large amount of salt is produced as a by-product, and its treatment poses a problem. Also, a method of reacting ethylene glycol and monomethylamine in the presence of ruthenium and a triphenylphosphine-based homogeneous catalyst (J. Organometallic Che.)
m. 407, 97, 1991), but it is difficult to recover and recycle homogeneous precious metal catalysts in industrial production. Therefore, a method for producing 1,3-dialkyl-2-imidazolidinone using N, N'-dialkylethylenediamine as a raw material is not an ideal method.

Further, a method of reducing 2-imidazolidinone and formaldehyde in the presence of a hydrogenation catalyst (Japanese Patent Laid-Open No.
0-243071), a method of catalytically reducing the dialkyl ether of N, N'-hydroxymethylimidazolidinone (Japanese Patent Publication No. 60-3299), and the like. In these methods, the starting material used is produced from dimethylethylenediamine. Therefore, there is the same problem as described above, and the process is long and not practical. In addition, in the method of reacting ethylene glycol with carbon dioxide and monomethylamine under high temperature and high pressure (JP-A-59-155364), there is no problem of by-products, but the yield is low and it has not reached an industrial level.

As a method for producing 1,3-dialkyl-2-imidazolidinones which does not have the above-mentioned problems, a method of reacting ethylene carbonate with a monoalkylamine to directly obtain a desired product by a single-step reaction (WO96) / 0251
6) is disclosed. This production method is a one-step process, and ethylene carbonate, which is a starting material, can be easily produced by the reaction of ethylene oxide and carbon dioxide, and can be an excellent DMI production method because there is no extra by-product at that time. However, according to the knowledge of the present inventors, this production method has a low yield, and N-alkylethanolamine, N, N-bis (2-hydroxyethyl) alkylamine, ethylene glycol and diethylene glycol which are side reaction products There are many disadvantages such as the production of many by-products, and the isolation and purification of the target product is complicated and unsuitable for an industrial production method.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-yield reaction for producing 1,3-dialkyl-2-imidazolidinones from alkylene carbonate and monoalkylamine directly in one step. An object of the present invention is to provide an improved method which has a small amount of by-products and can be easily carried out even in industrial large-scale production.

[0006]

The present inventors have studied in detail the reaction between an alkylene carbonate and a monoalkylamine. As a result, if this reaction is carried out in the presence of a 1,3-dialkylurea, a high yield can be obtained. Thus, 1,3-dialkyl-2-imidazolidinones were obtained, and it was found that the amount of by-products could be reduced, and the present invention was completed. That is, the present invention provides (claim 1) a general formula (1)

[0007]

Embedded image [In the formula, R ¹ represents hydrogen or a methyl group. An alkylene carbonate represented by the general formula (2):

[0008]

Embedded image R ² —NH ₂ (2) wherein R ² represents an alkyl group having 1 to 6 carbon atoms. With a monoalkylamine represented by the general formula (3)

[0009]

Embedded image R ³ NHCONHR ³ (3) wherein R ³ represents an alkyl group having 1 to 6 carbon atoms. 5 in the presence of a 1,3-dialkylurea represented by the formula
General formula (4) characterized by heating to 0 ° C. or more

[0010]

Embedded image [Wherein, R ¹ and R ² are the same as defined above. The method for producing 1,3-dialkyl-2-imidazolidinones represented by the formula:

(Claim 2) The method according to claim 1, wherein R ¹ and R ² are the same alkyl group. (Claim 3) The method according to claim 1 or 2, wherein the monoalkylamine is monomethylamine and the 1,3-dialkylurea is 1,3-dimethylurea. (Claim 4) The method according to any one of claims 1 to 3, wherein the reaction is carried out in the presence of carbon dioxide. (Claim 5) The method according to any one of claims 1 to 4, wherein the reaction temperature is 100 to 300 ° C. (Claim 6) The method according to any one of claims 1 to 5, wherein a 1,3-dialkyl-2-imidazolidinone represented by the general formula (4) or water is used as the solvent. (Claim 7) A method for producing 1,3-dimethyl-2-imidazolidinone, comprising heating ethylene carbonate and monomethylamine to 50 ° C. or more in the presence of 1,3-dimethylurea. It is.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the method of the present invention will be described in detail. General formula (1) which is a raw material used in the method of the present invention
The alkylene carbonate represented by, for example, can be easily obtained by heating carbon dioxide and alkylene oxide in the presence of a quaternary ammonium salt catalyst, but a commercially available product as it is, or an appropriate purification operation was performed Later, it may be used.

The monoalkylamine represented by the general formula (2), which is another raw material used in the present invention, includes monomethylamine, monoethylamine, mono-n-propylamine, mono-i-propylamine and mono-amine. n-butylamine, mono-sec-butylamine, mono-tert
Monobutylamine having 1 to 6 carbon atoms such as -butylamine or monocyclohexylamine;
Of these, monomethylamine and monoethylamine are preferred, and monomethylamine is more preferred.

The amount of the monoalkylamine to be used is not particularly limited, but usually, the alkylene carbonate 1
It is in the range of 0.1 to 100 mol, preferably 0.5 to 20 mol, more preferably 1 to 10 mol, per mol. The 1,3-dialkyl urea represented by the general formula (3) used in the method of the present invention is 1,3
-Dimethylurea, 1,3-diethylurea, 1,3-di-
n-propyl urea, 1,3-di-i-propyl urea,
An alkyl group represented by R ³ such as 1,3-di-n-butyl urea, 1,3-di-sec-butyl urea, 1,3-di-tert-butyl urea or 1,3-dicyclohexyl urea Examples thereof include 1,3-dialkyl ureas having 1 to 6 carbon atoms, preferably 1,3-dialkyl urea having the same alkyl group as the alkyl group of the monoalkylamine used in the reaction.
Dialkyl urea, and preferably 1,3-dimethyl urea.

The 1,3-dialkyl urea is preferably used as an additive, and the amount of the 1,3-dialkyl urea is not particularly limited, but is usually in the range of 0.1 to 50 mol per mol of alkylene carbonate. , Preferably 0.3
The range is from 10 to 10 mol, and more preferably from 0.5 to 5 mol.

Further, since DMI obtained as a product has a wide range of uses as a solvent, ethylene carbonate is used as an alkylene carbonate, monomethylamine is used as a monoalkylamine, and 1,3-dimethylurea is used as a 1,3-dialkylurea. Most preferably, it is used.

The embodiment of the present invention is not particularly limited, and any method may be used as long as the alkylene carbonate and the monoalkylamine and the 1,3-dialkylurea can be effectively mixed and contacted. ,
Batch type, semi-batch type or continuous flow type may be used. For example, a method in which a raw material and three kinds of 1,3-dialkylureas are charged to a reactor all at once, a method in which one of the two is continuously or intermittently supplied with the other two, and a method in which one of the two is charged with the other one A method of continuously or intermittently supplying one or a method of continuously or intermittently supplying the three can be used.

In the method of the present invention, the reaction is carried out by heating to 50 ° C. or higher. Preferably it is 50 to 400 ° C, more preferably 100 to 300 ° C. The reaction time and pressure vary depending on the amounts of the raw materials used, the reaction temperature and the like, and are not uniform. However, the reaction time is usually within 200 hours, preferably 0.01 to 100 hours, more preferably 0.1 to 100 hours. To 50 hours. The reaction is usually carried out under a pressurized state, preferably 0.1 to 50 MPa, more preferably 0.2 to 20 MPa. The gas used for the replacement or pressurization of the reaction system is not particularly limited, but may be an inert gas such as nitrogen or argon, or preferably carbon dioxide.

In the method of the present invention, the reaction is usually carried out without a solvent, but a solvent may be used in some cases. Any solvent may be used as long as it does not inhibit the reaction. Such solvents include, for example,
Aliphatic or alicyclic hydrocarbons such as water, pentane, hexane, heptane, octane, cyclohexane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; dichloromethane, chloroform, fluorobenzene, chlorobenzene, and dichlorobenzene Aliphatic or aromatic halogen compounds such as diethyl ether,
Methyl-tert-butyl ether, dibutyl ether, diphenyl ether, tetrahydrofuran, dioxane, ethers such as ethylene glycol diethyl ether, acetone, diethyl ketone, methyl isobutyl ketone, ketones such as acetophenone, acetonitrile,
Nitriles such as propionitrile, nitro compounds such as nitromethane, nitrobenzene, and nitrotoluene; esters such as ethyl acetate and ethyl propionate; carbonates such as dimethyl carbonate; Examples include 1,3-dialkyl-2-imidazolidinones. In addition, the reaction can be performed in a multilayer system of two or more layers depending on the solvent used. Of these solvents, the product 1,3-
It is preferred to use dialkyl-2-imidazolidinones or water.

The amount of these solvents to be used is an amount sufficient to dissolve any of the raw materials used, and is usually 100 parts by weight or less, preferably 50 parts by weight or less, based on the starting material alkylene carbonate. is there. In the method of the present invention, the target product 1,3-dialkyl-2-imidazolidinones can be obtained by treating the reaction product liquid after the completion of the reaction according to a conventional method such as distillation.

[0021]

The present invention will be described in detail with reference to the following examples. Example 1 35.2 g (0.4 mol) of ethylene carbonate and monomethylamine 4 were placed in an autoclave having an internal volume of 400 ml.
9.6 g (1.6 mol), deionized water 14.4 g, 1,
35.2 g (0.4 mol) of 3-dimethylurea were charged. The mixture was heated from the outside of the autoclave and reacted at an internal temperature of 230 ° C. for 5 hours while stirring. The autoclave was cooled, and the reaction product was analyzed by gas chromatography. As a result, the conversion of ethylene carbonate was 97% and the yield of DMI was 62%.
%, The total yield of by-products such as N, N'-dimethylpiperazine, ethylene glycol, N-methylethanolamine was 17%. The reaction product was distilled under reduced pressure to obtain 26.2 g of 1,3-dimethyl-2-imidazolidinone having a purity of 99%.

Example 2 Using the same reactor as in Example 1, 17.6 g of carbon dioxide was injected into the reaction system under the same reaction conditions as in Example 1 to carry out the reaction. The reaction product was analyzed by gas chromatography in the same manner as in Example 1. As a result, the conversion of ethylene carbonate was 98%, the yield of DMI was 68%, and the yield of N, N′-dimethylpiperazine, ethylene glycol, N-methylethanolamine, etc. The total organism yield was 14%.

Comparative Example Using the same reactor as in Example 1, the reaction was carried out under the same reaction conditions as in Example 1 without adding 1,3-dimethylurea to the reaction system. The reaction product was analyzed by gas chromatography in the same manner as in Example 1. As a result, the conversion of ethylene carbonate was 65%, the yield of DMI was 23%, and the yield of N, N′-dimethylpiperazine, ethylene glycol, N-methylethanolamine, etc. The total organism yield was 31%.
Without the addition of 1,3-dimethylurea, by-product formation increased and the DMI yield dropped significantly.

[0024]

According to the method of the present invention, 1,3-dialkyl-2-imidazolidinones can be prepared from alkylene carbonate and monoalkylamine, which are inexpensive starting materials, by coexisting 1,3-dialkylurea in the reaction system. Can be industrially efficiently produced. Further, it is an excellent feature of the method of the present invention that by-products such as salt contaminated with organic compounds are not generated unlike the conventional method.

Claims (7)

[Claims] 1. A compound of the general formula (1) [In the formula, R ¹ represents hydrogen or a methyl group. And an alkylene carbonate represented by the general formula (2): R ² —NH ₂ (2) wherein R ² represents an alkyl group having 1 to 6 carbon atoms. And a monoalkylamine represented by the general formula (3): R ³ NHCONHR ³ (3) wherein R ³ represents an alkyl group having 1 to 6 carbon atoms. 5 in the presence of a 1,3-dialkylurea represented by the formula
General formula (4) characterized by heating to 0 ° C. or higher [Wherein, R ¹ and R ² are the same as defined above. The method for producing 1,3-dialkyl-2-imidazolidinones represented by the formula: 2. The method according to claim 1, wherein R ¹ and R ² are the same alkyl group. 3. The method according to claim 1, wherein the monoalkylamine is monomethylamine and the 1,3-dialkylurea is 1,3-dimethylurea. 4. The method according to claim 1, wherein the reaction is carried out in the presence of carbon dioxide. 5. The method according to claim 1, wherein the reaction temperature is 100 to 300 ° C. 6. The method according to claim 1, wherein a 1,3-dialkyl-2-imidazolidinone represented by the general formula (4) or water is used as the solvent. 7. A process for producing 1,3-dimethyl-2-imidazolidinone, comprising heating ethylene carbonate and monomethylamine to 50 ° C. or higher in the presence of 1,3-dimethylurea.