JPH0555498B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field] The present invention produces an aziridine compound represented by the general formula () by subjecting an alkanolamine represented by the general formula () to a gas phase intramolecular dehydration reaction in the presence of a catalyst. Relating to a method of manufacturing.

(R is hydrogen, methyl group or ethyl group.
X is OH or _NH2 , Y is when X is OH
When NH ₂ and X are NH ₂ , it is OH. ) Aziridine compounds are cyclic compounds having a highly strained three-membered ring, have both ring-opening reactivity and amine reactivity, and are useful as various intermediate raw materials. Among them, ethyleneimine is already widely used in industry as a raw material for agricultural chemicals, medicines, etc., and as a raw material for amine polymers used as fiber treatment agents.

[Prior Art] As a method for producing an aziridine compound from an alkanolamine, a method of producing an aziridine compound by treating a sulfuric acid ester of an alkanolamine with a concentrated alkali in a liquid phase is generally well known. has already been industrialized as a method for producing ethyleneimine. This method uses a large amount of sulfuric acid and alkali as auxiliary raw materials, resulting in low productivity, and also produces a large amount of by-products of inorganic salts with low utilization, and has many disadvantages from an industrial perspective.

On the other hand, in recent years, in order to solve the drawbacks of aziridine production using the liquid phase method, a method has been developed in which an aziridine compound is directly produced by subjecting an alkanolamine to gas phase intramolecular dehydration reaction in the presence of a catalyst without using any auxiliary raw materials. have been reported (Japanese Patent Publication No. 50-10593, U.S. Patent No. 4301036, U.S. Patent No. 4289656, U.S. Patent No. 4337175, U.S. Patent No. 4477591, U.S. Pat.
-149337 Publication, 62-152539 and 62-
Publication No. 152543). In these methods, the raw material alkanolamine is usually diluted with nitrogen, ammonia, etc.
The gas-phase intramolecular dehydration reaction is carried out through the catalyst layer.

[Problems to be Solved by the Invention] However, what is disclosed in the above-mentioned publications regarding the gas phase method mainly relates to catalysts for gas phase intramolecular dehydration reactions, and consideration from the viewpoint of an industrial manufacturing process is insufficient. Not done. Problems when industrially produced using the methods described above include the following.

First, in the production of aziridine compounds from alkanolamines based on these concepts, the raw material alkanolamines are diluted with nitrogen, ammonia, etc. and reacted, so it is necessary to separate the diluent gas from the reaction mixture and recycle it for reuse. be. A part of the gas is disposed of as waste gas to prevent the accumulation of impurities, but the waste gas inevitably contains trace amounts of reaction products, unreacted raw materials, and the like. Therefore, equipment is required to treat a large amount of gas to make the waste gas harmless, such as by burning it, even for trace amounts of harmful substances. In this way, the incidental equipment becomes large-scale, and the cost burden is also large.

Then, when separating the diluent gas from the reaction mixture,
It is expected that reaction products and unreacted raw materials will accompany the gas after separation, reducing the yield of the target product and the recovery rate of the final reaction raw material. This point can be improved by passing the reaction mixture through the process of absorbing and collecting the reaction mixture with a scavenger, but this requires a much larger amount of scavenger compared to the amount of the target aziridine compound, and it is difficult to collect the scavenger. , it has to be recycled and reused, and the equipment including the subsequent purification process becomes complicated and large, and the operational burden is also large.

An object of the present invention is to obtain a target product in a high yield through a simple process without requiring large-scale gas circulation equipment or waste gas treatment equipment, and to recover unreacted raw materials at a high recovery rate.

[Means for solving the problem] Conventionally, according to the above-mentioned publications, alkanolamine was diluted with nitrogen, ammonia, etc. to an appropriate concentration, passed through a catalyst layer, and the reaction was normally carried out at a reaction temperature of 300 to 500°C. Ta. However, the present inventors have discovered that the above object can be achieved by refraining from using diluent gas and subjecting alkanolamine to a gas phase intramolecular dehydration reaction under reduced pressure and in the presence of a catalyst. This is the completed version. That is, in the present invention, the alkanolamine represented by the general formula () is prepared under a reduced pressure of 10 to 500 mmHg so that its partial pressure is 90% of the total pressure.
This is a method for producing an aziridine compound represented by the above general formula (), in which a gas phase intramolecular dehydration reaction is carried out through a catalyst at a concentration of 100%. The present invention will be explained in more detail below.

Specific examples of the alkanolamine represented by the general formula () of the present invention include monoethanolamine,
Monoisopropanolamine, 2-amino-1-
Examples include butanol, and corresponding aziridine compounds represented by the general formula () include ethyleneimine, 2-methyl-ethyleneimine, 2-ethyl-ethyleneimine, and the like.

The gas phase intramolecular dehydration reaction is carried out by vaporizing the alkanolamine and passing it through the catalyst bed under reduced pressure as a raw material gas, preferably at a reaction temperature of 300 to 500°C. If necessary, a small amount of nitrogen, ammonia, water vapor, hydrogen, etc. may be added to the raw material gas, but the partial pressure of alkanolamine should be maintained at 90% or more. Lowering the alkanolamine partial pressure below 80% causes the aforementioned problems. As the catalyst, catalysts such as those shown in the above-mentioned publications and the like, particularly phosphorus-based and silicon-based catalysts, can be used as preferred catalysts. The reaction pressure is appropriately selected depending on the type of raw material alkanolamine, the catalyst used, etc., but the reaction is carried out under reduced pressure at 10 to 500 mmHg. If the reaction pressure is too high, the selectivity of the raw material alkanolamine to the target aziridine compound will decrease, and the amount of by-products will increase, which is disadvantageous. On the other hand, if it is too low, it will be disadvantageous in terms of productivity. The reactor may be of fixed bed type, fluidized bed type or moving bed type. The space velocity of the raw material gas varies depending on the reaction pressure, the type and concentration of the raw material alkanolamine, the catalyst used, etc., but can range from 50 to 5000 hr ^-1 .

After the gas phase intramolecular dehydration reaction, for example, the reaction mixture is directly guided to a distillation column without a collection step and purified by distillation, or the reaction mixture is collected by cooling or by absorption using a collection agent, By distilling and purifying the collected liquid, the target aziridine compound can be obtained as a product. Even when using a scavenger, since there is no diluent gas in the system or only a small amount exists, sufficient collection can be achieved even with a small amount of scavenger used, and the collection process and subsequent purification process are relatively simple. This can be done conveniently with a small device. In addition, an amine compound is suitable as a scavenger, and it is especially convenient to use a raw material alkanolamine because it can be easily recovered and reused. This is because the amine compound has an effect of inhibiting the polymerization of the aziridine compound. Furthermore, in the gas phase method, a carbonyl compound corresponding to the raw material alkanolamine is produced as a by-product, and this by-product carbonyl compound forms a high-boiling adduct with the amine compound, making it easier to purify the aziridine compound. Adding an amine compound is also effective when simply collecting by cooling without using a collecting agent. Here, the carbonyl compound corresponding to the raw material alkanolamine is, for example, when the former is monoethanolamine, monoisopropanolamine, or 2-amino-1-butanol, and the latter is acetaldehyde, acetone, or methyl ethyl ketone, respectively.

The following will explain based on FIG. 1, which shows a flow sheet of an aziridine compound production process according to one embodiment of the present invention.

Raw material alkanolamine is introduced into evaporator 2 through line 1 and vaporized under appropriate temperature and pressure. The pressure is regulated by a vacuum source or pressure regulator connected at the end of line 6 or line 8.
When adjusting the pressure of the reactor through line 8 and the pressure of the distillation column through line 6, the pressures of the reaction system and distillation system can be set independently, and when the reaction mixture is condensed and collected in the cooler 4. suitable for The vaporized alkanolamine is introduced into a reactor 3 filled with a catalyst and subjected to an intramolecular dehydration reaction.
The composition of the mixed gas after the reaction is mainly the aziridine compound, unreacted alkanolamine, and water, and also contains small amounts of carbonyl compounds and other by-products. This mixed gas is cooled and collected in a cooler 4, then introduced into the middle stage of a distillation column 5, where it is distilled, an aziridine compound is obtained from a line 6, and unreacted alkanolamine and by-products are extracted from a bottom 7 of the column. If necessary, the aziridine compound fraction is then further purified by distillation to obtain a highly pure product.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Ethyleneimine was produced by the method described below using monoethanolamine as a raw material alkanolamine.

1. Catalyst Preparation 900 g of aluminum nitrate (nase hydrate) was dissolved in 2.4 g of water, and a solution of 357.6 g of triammonium phosphate in 2.4 g of water was added with stirring. After filtering and washing the obtained precipitate with water, 73.6 g of barium oxide and water were added.
Using 100 ml, it was thoroughly kneaded. The resulting clay-like material was formed into a cylindrical pellet with an outer diameter of about 5 mm and a length of about 5 mm, dried, and then calcined at 1000°C for ₂ hours to form a pellet with an atomic ratio of Al ₁ P ₁ Ba _0.2 excluding oxygen. A catalyst was obtained.

2 Dehydration Reaction Step Catalyst 1 prepared in 1 was filled into a stainless steel reaction tube with an inner diameter of 25 mm installed in reactor 3, and heated to 420° C. with a heating medium. Monoethanolamine was supplied to the evaporator 2, and the vaporized monoethanolamine was passed into the reaction tube at a reaction tube outlet pressure of 400 mmHg and a space velocity of 1000 hr ^-1 to carry out a continuous reaction. The composition of the mixed gas produced by the reaction is monoethanolamine.
67.6% by volume, ethyleneimine 12.7% by volume, water 15.6%
% by volume, acetaldehyde 1.35% by volume; others were ammonia, dimerized products, etc.

3 Distillation process The mixed gas discharged from the dehydration reaction process is heated to 100℃.
It was cooled to about 1/3 from the top of distillation column 5, which was made of a stainless steel tube with an inner diameter of 50 mm and a height of 2000 mm. Inside the column, 6.35 mm packing (McMahon packing) is installed, 400 mm in the concentration section and 400 mm in the recovery section.
It is filled with a bed height of 1200mm. The reflux ratio was 4.

291 g of crude ethyleneimine having an ethyleneimine concentration of 98.1% by weight was obtained from the top 6 of the column per hour, and 99.0% of the ethyleneimine produced in the reaction was recovered. Most of the impurities were water, and acetaldehyde reacted with unreacted monoethanolamine to form adducts that were recovered from the bottom.

Example 2 2-Methyl-ethyleneimine was produced by the method described below using monoisopropanolamine as the raw material alkanolamine.

1 Dehydration Reaction Step The same catalyst 1 as in Example 1 was filled into a stainless steel reaction tube with an inner diameter of 25 mm installed in the reactor 3, and heated to 420° C. with a heating medium. Monoisopropanolamine is supplied to evaporator 2, and the vaporized monoisopropanolamine is fed into the reaction tube at a reaction tube outlet pressure of 60 mm.
Continuous reaction was carried out by passing Hg at a space velocity of 200 hr ^-1 .
The composition of the mixed gas produced in the reaction was 9.9% by volume of monoisopropanolamine, 36.0% by volume of 2-methylethyleneimine, 40.1% by volume of water, 5.0% by volume of acetone, and the others were ammonia, dimerized products, etc.

2 Distillation process The mixed gas discharged from the dehydration reaction process was led to a cooler. 447 g of monoisopropanolamine was added per hour from a sprayer installed in the cooler, and the mixed gas was cooled to 90° C. and introduced into the same distillation column as in Example 1. The operating conditions were the same as in Example 1 except that the pressure was 60 mmHg and the reflux ratio was 8.

2-methyl-ethyleneimine concentration from column top 6
335 g of 97.8% by weight crude 2-methyl-ethyleneimine was obtained per hour, and 98.1% of the 2-methyl-ethyleneimine produced in the reaction was recovered. Most of the impurities were water, and acetone reacted with monoisopropanolamine to form an adduct, most of which was recovered from the bottom.

Example 3 Ethyleneimine was produced by the method described below using monoethanolamine as a raw material alkanolamine.

1 Dehydration Reaction Step The same catalyst 1 as in Example 1 was filled into a stainless steel reaction tube with an inner diameter of 25 mm installed in the reactor 3, and heated to 410° C. with a heating medium. Monoethanolamine was supplied to the evaporator 2, and the vaporized monoethanolamine was passed into the reaction tube at a reaction tube outlet pressure of 80 mmHg and a space velocity of 300 hr ^-1 to carry out a continuous reaction. The composition of the mixed gas produced by the reaction is monoethanolamine.
37.9% by volume, ethyleneimine 24.8% by volume, water 28.6%
% by volume, acetaldehyde 2.48% by volume.Others were ammonia, dimerized products, etc.

2 Distillation process The mixed gas discharged from the dehydration reaction process is heated to -5°C.
The mixture was cooled to a temperature of 100%, condensed, and introduced into the same distillation column as in Example 1. The operating conditions were the same as in Example 1 except that the pressure was 250 mmHg.

214 g of crude ethyleneimine with an ethyleneimine concentration of 94.8% by weight was obtained per hour from the top 6 of the column, and 97.2% of the ethyleneimine produced in the reaction was recovered. Most of the impurities were water, and acetaldehyde reacted with unreacted monoethanolamine to form adducts that were recovered from the bottom.

Example 4 Ethyleneimine was produced by the method described below using monoethanolamine as a raw material alkanolamine.

1 Dehydration Reaction Step The same catalyst 1 as in Example 1 was filled into a stainless steel reaction tube with an inner diameter of 25 mm installed in the reactor 3, and heated to 405° C. with a heating medium. Monoethanolamine was supplied to the evaporator 2, ammonia was added to the vaporized monoethanolamine, and the monoethanolamine in the gas was supplied into the reaction tube so that the concentration was 90% by volume. Speed 330hr ^-1
A continuous reaction was carried out. The composition of the mixed gas produced in the reaction was 40.3% by volume of monoethanolamine,
Ethyleneimine was 22.3% by volume, water was 25.0% by volume, acetaldehyde was 1.88% by volume, and the others were dimerized products.

2 Distillation process The mixed gas discharged from the dehydration reaction process is heated to -10℃.
The mixture was cooled to a temperature of 50%, condensed, and introduced into the same distillation column as in Example 1. The operating conditions were the same as in Example 1 except that the pressure was 250 mmHg.

193 g of crude ethyleneimine with an ethyleneimine concentration of 95.1% by weight was obtained per hour from the top 6 of the column, and 96.8% of the ethyleneimine produced in the reaction was recovered. Most of the impurities were water, and acetaldehyde reacted with unreacted monoethanolamine to form adducts that were recovered from the bottom.

[Effects of the Invention] According to the present invention, no diluent gas is used or only a small amount is used, so large-scale gas circulation equipment and waste gas treatment equipment are not required. The reaction mixture can be collected by cooling, and even if a collection agent is used for absorption and collection, only a small amount of the collection agent is required, so the collection and purification processes are relatively simple and compact equipment. Therefore, the target product can be obtained with a high yield, and unreacted raw materials can be recovered with a high recovery rate. The present inventors further added 10 to 500 alkanolamines.
The method of the present invention, in which gas-phase intramolecular dehydration is carried out through a catalyst at a partial pressure of 90 to 100% of the total pressure under a reduced pressure of mmHg, has a higher selectivity from alkanolamine to aziridine compound than conventional methods. We also found that there was an improvement.

The present invention has the above-mentioned effects and is an industrially excellent method.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing the process for producing an aziridine compound according to the present invention. 1... Alkanolamine supply line, 2...
Evaporator, 3... Reactor, 4... Cooler, 5... Distillation column, 6... Aziridine compound extraction line, 7...
... Tower bottom liquid extraction line, 8... Exhaust gas line.

Claims (1)

[Claims] 1. General formula (R is hydrogen, methyl group or ethyl group.
X is OH or _NH2 , Y is when X is OH
When NH ₂ and X are NH ₂ , it is OH. ) is passed through a catalyst at a reduced pressure of 10 to 500 mmHg at a partial pressure of 90 to 100% of the total pressure to cause an intramolecular dehydration reaction in the gas phase. (R is the same as the formula ()) A method for producing an aziridine compound represented by the following.