JPH0564142B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing 1,3-dimethyl-2-imidazolidinone. Specifically, 1,3-diamine is reacted with phosgene to obtain 1,3-dimethyl-2-imidazolidinone in the presence of water and a dehydrochlorination agent. The present invention relates to an improved method for producing dimethyl-2-imidazolidinone.

1,3-Dimethyl-2-imidazolidinone (hereinafter abbreviated as DMI) is a substance useful as a polar aprotic solvent. Especially polyamides, polyvinyl chloride, polyvinyl alcohol, polystyrene,
It is an excellent solvent for polymeric compounds such as polyurethane and phenolic resins, and it is a useful substance that forms complex salts with many inorganic salts and dissolves them, and is used as a solvent for many organic reactions.

Prior Art Many methods for manufacturing DMI have been proposed. For example, after reacting ethylenediamine and urea, formalin is added to the reaction product, and the reaction product is reduced with trichloroacetic acid, formic acid, etc., or an improved method of these reduction methods is hydrogenation under acidic conditions using a noble metal catalyst. Proposed.

Furthermore, a method for producing DMI in which N,N'-dimethylethylenediamine and phosgene are reacted is already known. J.Chem.Soc.1947 307), but the yield is only less than 20%. In addition, as a similar technique, a phosgene derivative, trichloromethyl chloroformate, is used instead of phosgene, and the reaction is carried out in an organic solvent such as toluene in the presence of a dehydrochlorination agent and a catalyst, resulting in a yield of 70% or more. A method for manufacturing DMI (Japanese Unexamined Patent Publication No. 73561/1983) has also been proposed.

Problems to be Solved by the Invention Although the method for producing DMI by reacting N,N'-dimethylethylenediamine with phosgene is known, the yield is extremely low and it is not satisfactory as an industrial method. Nakatsuta. As an improved method for this purpose, a method has been proposed in which instead of phosgene, trichloromethyl chloroformate is reacted while being decomposed into phosgene by a catalyst in the reaction system during the reaction. However, the method disclosed in this publication is a cumbersome method in which trichloromethyl chloroformate, which is a phosgene dimer, is produced and used after being decomposed into phosgene again during the production of DMI, and it is directly reacted with phosgene to obtain the product in high yield. If possible, it is obvious that it would be a cheaper industrial manufacturing method.

Means for Solving the Problems The present inventors have conducted intensive studies on an industrial production method that reacts phosgene with N,N'-dimethylethylenediamine to obtain DMI at a lower cost and in a high yield. The present invention was completed by discovering that the object can be achieved by reacting in the presence of water and a dehydrochlorination agent.

Usually, reactions using phosgene are carried out in the absence of water as much as possible, and it is known that phosgene is easily hydrolyzed in an alkaline aqueous solution. It was anticipated that this would be necessary. Surprisingly, however, it has been found that 1.01 to 1.5 times its stoichiometric amount of phosgene is sufficient in the process of the invention. In addition, by allowing water and a dehydrochlorination agent to exist, the yield of DMI was dramatically improved from the conventionally known level of less than 20% to over 70%.

That is, the present invention provides an improved production method in which DMI can be obtained in high yield by reacting N,N'-dimethylethylenediamine and phosgene in the presence of water and a dehydrochlorination agent.

In a typical embodiment of the process of the present invention, water and N,
Add N'-dimethylethylenediamine. While stirring this liquid at an appropriate temperature, phosgene is introduced through the phosgene blowing tube, and at the same time, a dehydrochlorination agent is added dropwise through the dropping funnel.

After the blowing and dropping are completed, the reaction mass is further aged at the same temperature as the dropping or at a slightly higher temperature. After ripening, the solution is adjusted to near neutrality and DMI is extracted using a conventional method such as distillation.

The water used in the present invention may be placed in the reactor in advance, or may be added dropwise together with a dehydrochlorination agent, for example, as an aqueous solution of an alkali metal compound. The amount of water used is not particularly limited, but it is preferably a sufficient amount to maintain a homogeneous reaction, and is preferably 0.5 to 50 times, preferably 5 to 30 times the weight of N,N'-dimethylethylenediamine. Furthermore, it may be used in combination with an organic solvent that is inert to phosgene, raw material amine, and DMI.

The dehydrochlorination agent used in the present invention includes tertiary amines such as aliphatic tertiary amines such as trimethylamine and triethylamine, heterocyclic tertiary amines such as pyridine and pyrazine, sodium hydroxide, Alkali metal compounds such as sodium carbonate are preferred.

Further, the reaction temperature in the present invention is not particularly limited, but is preferably carried out at 0 to 70°C.

The amounts of phosgene and dehydrochlorination agent used in the present invention are not particularly limited, but 1.01 to 1.5 times the stoichiometric amount relative to the raw material diamine is sufficient. Further, the amount of dehydrochlorination agent relative to phosgene may be approximately stoichiometric.

In the method of the present invention, DMI can be obtained in a higher yield of 70% or more compared to the conventional reaction using phosgene.
The reason for this is not well understood, but by using the dehydrochloride agent and water together, the dehydrochloride agent can effectively catch the by-product hydrochloric acid generated from the production of carbamoyl chloride and the by-product acidity generated from the ring-closing reaction of carbamoyl chloride to DMI. This seems to be because it works well.

If a dehydrochlorination agent is not used, the raw material itself becomes a by-product acidic catch agent, making it difficult to proceed with the reaction any further.

Furthermore, the advantage of the present invention is that since cheap water is used as a solvent, the raw material diamine is soluble in water, and the dehydrochlorination agent or its generated salt is also soluble in water, and the reaction is usually carried out under a homogeneous liquid. is carried out, the reaction speed is fast,
Yield is improved.

Furthermore, another advantage of the present invention is that even when the reaction is carried out in an aqueous solution in the presence of a base, there is almost no loss of phosgene, and the reaction proceeds in approximately equimolar amounts.

Examples and comparative examples will be given below to explain in more detail.

Example 1 100 ml of water and 8.8 g (0.1 mol) of N,N'-dimethylethylenediamine were placed in a 300 ml four-necked flask equipped with a reflux condenser, a thermometer, a dropping funnel, a phosgene blowing tube, and a stirrer. 20.2 g (0.2 mol) of triethylamine was prepared in the dropping funnel. The flask was maintained at 20° C. and phosgene was bubbled through the phosgene blow tube at 10 g/hr for 1 hour while stirring. At the same time, triethylamine was added dropwise from the dropping funnel over a period of 1 hour. After blowing and dropping, the mixture was aged at 20°C for 1 hour. This reaction mass was sampled and DMI was quantified by gas chromatography. Theoretical yield is 75.1
It was %.

Comparative Example 100 ml of toluene and 8.8 g (0.1 mol) of N,N'-dimethylethylenediamine were placed in a 300 ml four-necked flask equipped with a reflux condenser, thermometer, phosgene blowing tube, and stirrer. The flask was maintained at 20° C. and phosgene was bubbled through the phosgene blow tube at 10 g/hr for 1 hour while stirring. After the blowing was completed, the mixture was aged for 1 hour at the same temperature. Gas chromatography analysis of this reaction mass was performed to quantify DMI, and the theoretical yield was 19.2.
% and was only generated by DMI.

Example 2 The reaction was carried out in exactly the same manner as in Example 1, except that 212 g (0.2 mol) of a 10% aqueous sodium carbonate solution was used instead of toluethylamine.

The theoretical yield by gas chromatography analysis is
It was 70.8%.

Example 3 Except that 80 g (0.20 mol) of a 10% aqueous sodium hydroxide solution was used instead of triethylamine.
The reaction was carried out in exactly the same manner as in Example 1.

The theoretical yield by gas chromatography analysis is
It was 81.3%.

Claims (1)

[Claims] 1 When reacting N,N'-dimethylethylenediamine and phosgene to obtain 1,3-dimethyl-2-imidazolidinone, water and trimethylamine, triethylamine, pyridine, pyrazine,
In the presence of at least one dehydrochlorination agent selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, phosgene is added in a stoichiometric amount of 1.01 to N,N'-dimethylethylenediamine.
1. A method for producing 1,3-dimethyl-2-imidazolidinone, characterized in that the reaction is carried out in a homogeneous solution using 1.5 times the amount.