JPH0987252A - Method for producing 2-methylimidazoline - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce 2-methylimidazoline having a high melting point and sublimability by adding propanediamine to ethylenediamine and acetonitrile when reacting both. SOLUTION: Propanediamine (preferably 1,2-propanediamine) is added to ethylenediamine and acetonitrile when reacting both. The propanediamine is preferably used in an amount so as to provide 0.5-5 molar ratio of the ethylenediamine/propanediamine. The reaction is preferably carried out in the presence of a catalyst comprising a metallic salt or a metallic oxide at 150-250 deg.C and usually in the liquid phase. A copper salt, an iron salt, a chromate, etc., have high activities and are preferably used as the metallic salt. Copper oxide, manganese oxide, zinc oxide and niobium oxide have high activities and are preferably used as the metallic oxide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing 2-methylimidazoline.

[0002]

2. Description of the Prior Art There are many methods for producing 2-methylimidazoline from ethylenediamine and acetonitrile.

Japanese Patent Publication No. 39-24965 discloses a method of reacting in the presence of sulfur. Tokoku 5
No. 39943 discloses a copper salt catalyst such as copper acetate and copper chloride,
JP-A-62-195369 describes a method in which a zinc salt such as zinc acetate or zinc chloride is used as a catalyst.

By the way, since 2-methylimidazoline has a high melting point and has a sublimation property, it is not easy to handle.
In industrial production, troubles such as solidification of 2-methylimidazoline and blockage of piping occur in the reactor. Japanese Examined Patent Publication No. 5-39943 and Japanese Unexamined Patent Publication No. 62-
In 195369, it is described that a solvent which is inactive under the reaction conditions, such as an aliphatic hydrocarbon or an aromatic hydrocarbon, is used as a solvent, but since 2-methylimidazoline is not dissolved in these, solidification occurs. It is not a means to solve such troubles.

[0005]

The conventional method is not sufficient to efficiently produce sublimable 2-methylimidazoline having a high melting point without problems such as caking. Therefore, it has been desired to develop a method for producing 2-methylimidazoline without solidifying it.

[0006]

Means for Solving the Problems As a result of diligent studies on a method for producing 2-methylimidazoline, the present inventors have found that 2-methylimidazoline can be obtained by adding propanediamine in addition to ethylenediamine and acetonitrile as raw materials. The present invention has been completed by discovering a new fact that it can be manufactured without solidification.

That is, the present invention is a method for producing 2-methylimidazoline, characterized in that propanediamine is added when 2-methylimidazoline is produced by reacting ethylenediamine and acetonitrile.

Hereinafter, the present invention will be described in more detail.

In the method of the present invention, ethylenediamine, acetonitrile and propanediamine are reacted in the presence of a catalyst. A metal salt or a metal oxide can be used as the catalyst.

The metal salt is not particularly limited, but copper salts, zinc salts, iron salts, cobalt salts, manganese salts, aluminum salts, tin salts, mercury salts, chromium salts, and cadmium salts are preferred because of their high activity. Used. As these salts, any of inorganic salts such as chloride salts and organic acid salts such as acetate salts may be used.

In the present invention, the metal oxide is, for example,
Aluminum oxide, silicon oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, silver oxide, cadmium oxide. , Indium oxide, tin oxide, tantalum oxide, tungsten oxide, rhenium oxide,
It refers to lead oxide, lanthanum oxide, cerium oxide, etc., among which copper oxide, chromium oxide, manganese oxide, zinc oxide,
Niobium oxide is preferably used because it has a particularly high activity.
The metal oxide can also be used by mixing with a carboxylic acid such as acetic acid.

In the method of the present invention, the propanediamine used may be 1,3-propanediamine or 1,2-propanediamine.
Although -propanediamine may be used, 1,2-propanediamine is preferable. Propanediamine reacts with acetonitrile, but when 1,2-propanediamine is used, dimethylimidazoline is produced. Since dimethylimidazoline is a useful substance, it is preferable to use 1,2-propanediamine, but there is no problem with using a 3-membered ring compound using 1,3-propanediamine.

In the method of the present invention, the ratio of ethylenediamine and propanediamine used is not particularly limited, but ethylenediamine / propanediamine is preferably 0.1 to 10 and more preferably 0.5 to 5 in terms of molar ratio. When it is less than 0.1, the production amount of 2-methylimidazoline decreases unrealistically, and when it exceeds 10, the effect of adding propanediamine is small and 2-methylimidazoline may be solidified.

The diamine compound and the nitrile compound can be reacted in stoichiometric amounts or in excess of one.

In the method of the present invention, the reaction temperature is usually 1.
It can be carried out in the range of 00 to 300 ° C., but 150 to
It is preferable to carry out at 250 ° C. If the temperature is lower than 100 ° C, the reaction is impractically slow, and if the temperature is higher than 300 ° C, the amines are decomposed and the yield of the imidazolines is lowered.

The method of the present invention is usually carried out in the liquid phase.

In the method of the present invention, the reaction may be carried out under normal pressure or under pressure as long as the raw materials are kept in a liquid state. In this reaction, the reaction pressure rises because ammonia is produced during the reaction, but this ammonia can be removed during the reaction or can be removed after the reaction is completed. When the reaction temperature exceeds the boiling point of the raw material, it is necessary to carry out the reaction under pressure or to liquefy the raw material by providing a condenser.

A solvent may or may not be used in the method of the present invention. The solvent is not particularly limited as long as it is inert to the reaction conditions, and it is not preferable to use a solvent such as water that decomposes imidazolines.

The method of the present invention may be carried out as a continuous reaction, a batch reaction or a semi-batch reaction. Also,
The reaction can be carried out on a fixed bed or a suspension bed. As for the form of the catalyst, an optimum one may be selected depending on the reaction mode, and it may be used in the form of powder or may be used by molding.

In the method of the present invention, the imidazolines as a reaction product may be purified or may be dehydrogenated to be an imidazole without being purified. Various methods such as distillation and recrystallization are known as methods for purifying imidazolines, but any method can be used.

When the 2-methylimidazoline produced by the method of the present invention is dehydrogenated to give 2-methylimidazole, it is preferable to carry out the reaction without removing the dimethylimidazoline derived from propanediamine. When dimethyl imidazoline derived from propane diamine is present in the system, the solidification and sublimation of 2-methyl imidazoline can be prevented.

[0022]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 Ethylenediamine: 34.0 g, acetonitrile: 4 in a 200 ml electromagnetic stirring type stainless steel autoclave.
5.2 g, 1,2-propanediamine: 20.0 g, activated zinc white: 1.5 g and acetic acid: 1.5 g were added, and the atmosphere was replaced with nitrogen, followed by heating to 180 ° C. Reaction pressure is 2.0 MPa
When the above was reached, the pressure was released through a pipe having an inner diameter of 1 mm, the pressure was reduced, and the reaction was carried out for 3 hours. There was no blockage of the piping. After completion of the reaction, the reaction solution was cooled and analyzed by gas chromatography to find that the conversion of ethylenediamine was 100.0.
%, 1,2-propanediamine conversion rate was 99.7%, and selectivity for 2-methylimidazoline was 98%. The reaction liquid did not solidify even at 60 ° C. and could be stirred.

Subsequently, dehydrogenation of 2-methylimidazoline was performed to carry out a reaction to give 2-methylimidazole. Stabilized nickel: 3.4 g was added to the above reaction solution, and heated to 180 ° C. The pressure was atmospheric pressure, and the reaction was performed for 3 hours while extracting the generated hydrogen through a pipe having an inner diameter of 1 mm. There was no blockage of the piping. 99.7% of the 2-methylimidazoline was converted to 2-methylimidazole.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that 1,2-propanediamine was not charged in the same autoclave as in Example 1 but 50.2 g of ethylenediamine was charged. After starting the reaction
The pipe was blocked after 2 hours and 15 minutes. After the reaction was completed, the reaction solution was cooled and analyzed by gas chromatography.
The conversion of ethylenediamine was 100.0%, the conversion of 1,2-propanediamine was 97.7%, and the selectivity of 2-methylimidazoline was 98%. This reaction is 6
It solidified at 0 ° C, and it became impossible to stir the reaction solution.

Subsequently, the dehydrogenation of 2-methylimidazoline was carried out in the same manner as in Example 1 to carry out the reaction to give 2-methylimidazole. During the reaction time of 3 hours, the pipe was clogged three times. In this reaction, 2-methylimidazoline 9
3.2% was converted to 2-methylimidazole.

Example 2 Ethylenediamine: 30.0 g, acetonitrile: 4 in a 200 ml electromagnetic stirring type stainless steel autoclave.
5.2 g, 1,2-propanediamine (37.0 g) and copper acetate (3 g) were added, the atmosphere was replaced with nitrogen, and the mixture was heated to 180 ° C. When the reaction pressure exceeds 2.0 MPa, the inner diameter is 1
The pressure was released through a mm pipe and the pressure was lowered to react for 3 hours. There was no blockage of the piping. After completion of the reaction, the reaction solution was cooled and analyzed by gas chromatography to find that the ethylenediamine conversion rate was 96.6% and the 1,2-propanediamine conversion rate was 93.7%. Was 99%. The reaction liquid did not solidify even at 60 ° C. and could be stirred.

[0028]

INDUSTRIAL APPLICABILITY The present invention has a high melting point and is sublimable.
-It provides a method for efficiently producing methyl imidazoline without problems such as caking, and is extremely significant.

Claims (7)

[Claims] 1. A method for producing 2-methylimidazoline, which comprises adding propanediamine when producing 2-methylimidazoline by reacting ethylenediamine and acetonitrile. 2. The method of claim 1, wherein the propanediamine is 1,2-propanediamine. 3. The method according to claim 1 or 2, wherein the reaction is carried out in the presence of a metal salt. 4. The metal salt is a copper salt, a zinc salt, an iron salt, a cobalt salt, a manganese salt, an aluminum salt, a tin salt, a mercury salt,
The method according to claim 3, which is a chromium salt or a cadmium salt. 5. The method according to claim 1, wherein the reaction is carried out in the presence of a metal oxide. 6. The metal oxide is aluminum oxide, silicon oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, yttrium oxide, zirconium oxide, oxidation. The method according to claim 5, which is niobium, molybdenum oxide, silver oxide, cadmium oxide, indium oxide, tin oxide, tantalum oxide, tungsten oxide, rhenium oxide, lead oxide, lanthanum oxide or cerium oxide. 7. The method according to claim 1, wherein the reaction is carried out in a liquid phase.
The method according to any of the above.