JPH07103108B2 - Method for producing 1,3-dialkyl-2-imidazolidinone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to N, N′-dialkylethylenediamine represented by the formula (1). (Wherein, R _{-C 2 H 5, -C 3 H} 7, -C a ₄ H _9.) And 1,3-dialkyl-2-imidazo of formula (2) by reaction with urea Ridinone (Wherein R is the same as R in formula (1)).

The 1,3-dialkyl-2-imidazolidinone represented by the above formula (2) is a very useful substance as a polar aprotic solvent. In particular, it is an excellent solvent for high molecular compounds such as polyamides, polyvinyl chloride, polyvinyl alcohol, polystyrene, polyurethane, and phenol resins, and also forms a complex salt with many inorganic salts and dissolves them, and it can be used for many organic reactions. It is a useful substance that is also used as a solvent.

[Conventional technology]

Among the 1,3-dialkyl-2-imidazolidinones, there are various proposals for the production method of 1,3-dimethyl-2-imidazolidinone (DMI), which is generally well known.

For example, a method in which ethylenediamine and urea are reacted to obtain 2-imidazolidinone (ethyleneurea), and a reaction product obtained by adding formalin to this is reduced with trichloroacetic acid, formic acid or the like to be N, N′-dimethylated. In addition, by improving this reduction method and using a noble metal catalyst, hydrogenation is carried out under acidic conditions, and N, N'-dimethylethylenediamine is reacted with phosgene or trichloromethylchloroformate while decomposing it into phosgene. The method etc. are known.

Further, as a method similar to the method of the present invention, N, N'-dimethylethylenediamine and urea are reacted by heating to give 1,1'-dimethyl-1,1'-dimethylenebisurea as an intermediate. Was produced and heated to about 300 ° C. to obtain DMI in a yield of 35%. Journal of the
Chemical Society [JCS (Perkin Trans.) 2.
(1981), 319].

[Problems to be solved by the invention]

Thus, the conventional method for producing 2-imidazolidinone by the reaction of ethylenediamine and urea is industrially possible, but it is not easy to obtain a compound of formula (2) according to the present invention by dialkylating it. Absent. Also, N, N ′
-By reaction of dialkylethylenediamine with urea 1,
In the production of 3-dialkyl-2-imidazolidinone, the yield was extremely low as described in the above-mentioned document and was not industrially satisfactory.

Therefore, if the desired product can be produced directly from N, N'-dialkylethylenediamine and urea in a high yield, the process becomes extremely simple.

[Means for solving problems]

The present inventors have reacted N, N'-dialkylethylenediamine with urea to give the corresponding 1,3-dialkyl-
As a result of diligent studies on a production method for obtaining 2-imidazolidinone, it is shown not only by DMI production but also by the above formula (1) by reacting at 180 ° C or higher in the presence of a polar solvent, preferably a polar aprotic solvent. The inventors have found that the object can be achieved even in the reaction of N, N'-dialkylethylenediamine and urea, and have completed the present invention.

In the present invention, as the N, N'-dialkylethylenediamine represented by the formula (1), N, N'-diethylethylenediamine, N, N'-dipropylethylenediamine, N, N'-diisopropylethylenediamine, N, N ′-
Examples include dibutylethylenediamine. These dialkylethylenediamines can be easily obtained by reacting the corresponding monoamine with ethylene dichloride.

In the method of the present invention using these N, N′-dialkylethylenediamine and urea, it is carried out at 180 ° C. or higher in the presence of a polar solvent, preferably a polar aprotic solvent.
The initial stage of the reaction of the present invention is a reaction for producing an intermediate 1,1′-dialkyl-1,1′-dimethylenebisurea.

Therefore, in the initial stage of the reaction, the reaction of urea itself is controlled to quantitatively generate the intermediate 1,1′-dialkyl-1,1′-dimethylenebisurea, so that the temperature is 180 ° C. or lower, preferably 140 ° C. or lower. It is good to do it at the temperature.

If the reaction is carried out at this temperature, the reaction proceeds quantitatively in the reaction between N, N'-dimethylethylenediamine and urea, which is the initial reaction, and the pressure in the reactor due to the NH ₃ gas released as the reaction proceeds. The temperature gradually rises and becomes a constant pressure, so that the end point of the initial reaction can be confirmed.

Then, the temperature is continuously raised to 180 ° C or higher, preferably 200 to 300.
The corresponding 1,3-dialkyl-2-imidazolidinone can be obtained in high yield by subjecting the obtained intermediate to a thermal decomposition reaction at ℃. Below 180 ° C, the reaction rate is low,
If the temperature is 300 ° C or higher, there is a problem in the heating method.

Hydrocarbons and halogenated hydrocarbons are not suitable as solvents used in the process of the invention, but polar aprotic solvents are used. Preferred solvents are N, N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea, dimethylsulfoxide, hexamethylphosphoramide, sulfolane, methyl isobutyl ketone, nitrobenzene, tetrahydrofuran, dioxane, and the like polar aprotic solvent. . Further, when the boiling point is low, an excessive pressure-resistant device is required, so a solvent having a boiling point of 180 ° C. or higher is preferable, and in particular, the desired 1,3- Dialkyl-2-
It is preferred to use imidazolidinone as the self-solvent.

In the method of the present invention, by using such a polar aprotic solvent, a mild reaction can be carried out at a relatively low temperature and the desired target product can be obtained in high yield.

The amount ratio of N, N'-dialkylethylenediamine and urea to be charged is usually selected in a molar ratio of 1.0: 0.5 to 1.0: 2.5.
However, when 2 mol or more of urea is used with respect to N, N′-dialkylethylenediamine, that is, when used in a theoretical amount or more, a large amount of cyanuric acid is by-produced during the high temperature heating reaction in the latter stage, and the yield of the target product is increased. The operation for lowering or taking it out becomes complicated. Therefore, preferably
It is preferable to react at a molar ratio of 1.0: 0.6 to 1.0: 1.2, but in that case, unreacted N, N′-dialkylethylenediamine is excessively left in the latter thermal decomposition reaction, and the boiling point of N, N′-dialkylethylenediamine is Since it is lower than the decomposition reaction temperature in the latter stage, the temperature cannot be raised to a desired temperature under normal pressure, and therefore it is necessary to carry out the reaction under pressure.

Therefore, in order to avoid this, in the initial reaction charge, the reaction is carried out using about 2 mol of urea, which is approximately equivalent to N, N'-dialkylethylenediamine, and then the temperature is raised to carry out the late decomposition reaction at 180 ° C or higher. When carrying out, reacting while adding N, N'-dialkylethylenediamine,
It can also be carried out under normal pressure.

To describe the preferred conventional embodiment of the process of the present invention, the homemade N, N'-dialkylethylenediamine, urea and solvent are added to a reactor equipped with a reflux condenser, thermometer, and mechanical stirrer. After the temperature is raised and the initial reaction is performed at 140 ° C. or lower, the temperature is raised to 180 ° C. or higher for the reaction. The target product can be taken out from the reaction-completed liquid by distillation or the like. In particular,
When the same product obtained by the reaction is used as an own solvent,
No separation from the solvent is required during distillation, and the process is extremely simplified.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 116.2 g (1.0 mol) of N, N'-diethylethylenediamine and 60.1 g of urea were placed in a 500 ml stainless steel autoclave.
(1.0 mol) and 1,3-diethyl-2-imidazolidinone
100.0g was charged. The temperature was raised and the reaction was carried out at a reaction temperature of 120 ° C. for 8 hours. After the reaction started, the system pressure gradually increased to 5.5k
Since it became almost constant up to around g / cm ² G, 220 ℃
The temperature was raised to about 30 minutes and the reaction was carried out at that temperature for 3 hours. The maximum system pressure reached 14.0 kg / cm ² G. After completion of the reaction, distill under reduced pressure to obtain a purity of 9 by gas chromatography.
9.5% 1,3-diethyl-2-imidazolidinone fraction 237.
0 g was obtained (yield 95.5%). The residue after the distillation was cyanuric acid partially containing 1,3-diethyl-2-imidazolidinone.

Claims (2)

[Claims] 1. An N, N'-dialkylethylenediamine of the formula (1) (Wherein, R _{-C 2 H 5, -C 3 H} 7, -C a ₄ H _9.) And 1,3-dialkyl-2-imidazo of formula (2) by reaction with urea Ridinone (Wherein R is the same as R in formula (1).) In the presence of a polar aprotic solvent, urea is added to the N, N′-dialkylethylenediamine of formula (1) in an amount of about 2 The reaction was conducted at 140 ° C or lower until the completion of the production of 1,1′-dialkyl-1,1′-dimethylenebisurea in the initial reaction, followed by heating to 180 ° C or higher. A method for producing a 1,3-dialkyl-2-imidazolidinone represented by the formula (2), which is characterized. 2. A charging molar ratio of urea to N, N'-dialkylethylenediamine represented by the formula (1) is 0.6 to 1.2.
The method according to claim 1), which is doubled.