Method for producing monoethanolethylenediamine

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to a method for producing monoethanolethylenediamine used to manufacture a regenerable СО2 absorber for purifying the atmosphere of sealed objects. The method involves mixing, with continuous stirring, ethylenediamine with potassium hydroxide and then with ethylene chlorohydrin in a nitrogen environment, followed by distillation of the azeotropic mixture of ethylenediamine and water at an absolute pressure of 40÷60 mm Hg and a vapour temperature of 80÷110 °C. Next, the reaction mixture is cooled to 20÷25 °C, adding ethanol, separating the precipitated potassium chloride, distilling off the ethanol at a temperature of 80÷85 °C followed by distillation in a weak stream of nitrogen at an absolute pressure of 5÷15 mm Hg and at a temperature in steam of 100÷120 °C monoethanolethylenediamine. The interaction of ethylenediamine with potassium hydroxide and ethylene chlorohydrin is carried out in the temperature range of 45÷55 °C, potassium hydroxide is used in the form of an aqueous solution with a concentration of 15÷30 wt.%, the molar ratio of ethylenediamine / ethylene chlorohydrin is 4.8÷5.2, and the potassium hydroxide / ethylene chlorohydrin molar ratio is 1.0÷1.1.EFFECT: higher content of the main substance in the reaction product and a higher yield of the main substance.1 cl, 3 ex

Description

[0001] The invention relates to a method for producing monoethanolethylenediamine (2-(2-Aminoethyl)-aminoethanol, H2N-CH2-CH2-NH-CH2-CH2-OH) for the further production of a regenerable carbon dioxide absorber for purifying the atmosphere of sealed objects in areas of technology where it is necessary to create a controlled gas environment during long-term operation of the absorber.

[0002] A method is known for producing (N.P. Kozlova, R.V. Dorokhov, Yu.A. Ferapontov, I.V. Glebov. Synthesis of monoethanolethylenediamine and study of its physicochemical properties. Bulletin of Tambov State Technical University. 2025, Vol. 31, No. 2, pp. 301-310) monoethanolethylenediamine (MEEDA) from ethylenediamine (H2NCH2CH2NH2), ethylene chlorohydrin (HOCH2-CH2Cl) and potassium hydroxide (KOH) in a nitrogen environment, followed by extraction of the target product with ethanol (C2H5OH).

[0003] The method for producing MEDA consists of the following main stages:

[0004] 1. Interaction of ethylenediamine (EDA) with ethylene chlorohydrin (ECH) in an alkaline medium.

[0005] 2. Distillation of the azeotropic mixture of ethylenediamine and water and salting out potassium chloride with ethanol.

[0006] 3. Separation of potassium chloride from an alcoholic solution of MEDA by filtration.

[0007] 4. Separation of the salting-out agent (ethanol) and the target product. The process chemistry can be simplified as follows:

[0008] H2NCH2CH2NH2+HOCH2-CH2Cl+KOH→H2N-CH2-CH2-NH-CH2-CH2-OH+KCl+H2O

[0009] The first stage of the synthesis was carried out as follows. 119.7 g (2 mol) of a 99% EDA solution were added through a dropping funnel to a three-necked round-bottomed flask, which was immersed in a container with cold water for cooling. 26 g (0.464 mol) of KOH were added in the same way. A reflux condenser with water connected for cooling was then placed on top. The process was carried out with continuous stirring. A nitrogen blanket was then created in the flask by feeding nitrogen for 1-2 minutes. After stopping the nitrogen supply through the dropping funnel, 31.3 g (0.39 mol) of ECH was added with continuous stirring. An exothermic reaction occurs, and to prevent the temperature of the reaction mixture from rising above 52°C, the flask was cooled with running water. If the temperature rises above the critical value of 52°C, the addition of ECH is stopped until the reaction mixture has cooled. After the addition of ECH is complete, the reaction mixture is kept for 5÷10 minutes with stirring to complete the process.The process is carried out at the following molar ratios of the initial components: EDA / ECH = 5.13; KOH / ECH = 1.19.

[0010] Next, the azeotropic mixture of EDA and water is distilled off, the potassium chloride precipitate is salted out with ethanol, it is separated by filtration, the salting-out agent is distilled off, and then the target product (MEEDA) is distilled off.

[0011] To do this, place a three-necked flask on a sand bath, immersing it in the sand to the level of the reaction solution. Then connect the vacuum pump and gradually increase the temperature. At an absolute pressure of 40-60 mmHg and a vapor temperature of 80-110°C, the azeotropic mixture of EDA and water is distilled off. This process ends when the vapor temperature above the reflux condenser drops below 80°C. After the azeotropic mixture has been distilled off, the vacuum pump is turned off, the flask contents are cooled to 20-25°C, and 52 ml of ethyl alcohol is added to the flask, acting as a salting-out agent. Potassium chloride (KCl) formed during the synthesis precipitates, and the reaction products are extracted into ethanol. Next, the precipitated potassium chloride is separated by filtration, and the filtrate - an alcohol solution of the reaction products - is loaded back into the flask to distill off the solvent, for which the mixture is heated in a sand bath to 80 ÷ 85°C and the distillation of ethyl alcohol begins.Ethyl alcohol is used without further purification in subsequent syntheses. After distillation of the ethanol, a vacuum pump is connected to the unit, and distillation of the target product, monoethanolethylenediamine, begins at an absolute pressure of 5 to 15 mmHg. Distillation occurs under a weak stream of nitrogen at a vapor temperature of 100 to 120°C. The target product is obtained in a quantity of approximately 32.7 g with a main substance content of ~92%. The yield of the target product is ~80%.

[0012] The disadvantage of this method is the not very high content of the main substance (monoethanolethylenediamine) in the synthesis product, which subsequently leads to an insufficiently high dynamic activity for carbon dioxide of the resulting regenerated absorber and reduces the productivity of the installation for cleaning the atmosphere of sealed objects from CO2.

[0013] The objective of the invention is to increase the content of the main substance (monoethanolethylenediamine) in the synthesis product.

[0014] The problem is solved in that in the method for producing monoethanolethylenediamine, including the interaction with continuous stirring of ethylenediamine (EDA) with potassium hydroxide and ethylene chlorohydrin (ECH) in a nitrogen environment, distillation of the azeotropic mixture of ethylenediamine - water at an absolute pressure of 40 ÷ 60 mm Hg and at a vapor temperature of 80 ÷ 110 ° C, cooling the reaction mixture to 20 ÷ 25 ° C, adding ethanol, separating the precipitated potassium chloride, distilling off ethanol at a vapor temperature of 80 ÷ 85 ° C, followed by distillation in a weak stream of nitrogen at an absolute pressure of 5 ÷ 15 mm Hg. at a temperature in vapors of 100 ÷ 120°C of the target product - monoethanolethylenediamine, the interaction of ethylenediamine (EDA) with potassium hydroxide and ethylene chlorohydrin (ECH) is carried out in the temperature range of 45 ÷ 55°C, potassium hydroxide is used in the form of an aqueous solution with a concentration of 15 ÷ 30% by weight, and the molar ratio of EDA / ECH = 4.8 ÷ 5.2; KOH / ECH = 1.0 ÷ 1.1.

[0015] Using potassium hydroxide in the form of an aqueous solution with a concentration of 15 ÷ 30% by weight reduces the synthesis time (by approximately 2-3 hours) and increases the content of the active substance for the following reasons. The use of highly concentrated EDA and ECH (up to 99%), on the one hand, promotes an increase in the content of the active substance due to the low impurity content, which is well known from the practice of any chemical synthesis. On the other hand, the absence of water in the reaction mixture at the initial stage results in the dissolution of the alkali in EDA to obtain a homogeneous liquid phase proceeding too slowly (can take several hours). Incomplete dissolution of the alkali results in the conversion of ethylene chlorohydrin not exceeding 80%, since nucleophilic substitution and addition reactions (which include the described method) proceed according to the required mechanism in a fairly narrow pH range, which is also well known from the practice of organic synthesis.Fulfillment of these conditions is also facilitated by running the process in a temperature range of 45–55°C. The KOH / ECH molar ratio is 1.0–1.1, since a 10% excess of KOH, compared to the stoichiometry, is sufficient for the nucleophilic substitution reaction to proceed completely. Increasing the excess KOH leads to unnecessary consumption of the starting components and also reduces the content of the main substance in the synthesis product due to the difficulty of separating the large excess of unreacted KOH.

[0016] It's worth noting that at a certain stage of the synthesis, the aqueous EDA solution is distilled off (azeotropic mixture). This means that to create an azeotrope, a sufficient amount of water is required, which is formed during the synthesis and is present in the starting components. Complete distillation of the azeotrope also leads to an increase in the content of the main substance in the synthesis product.

[0017] The method is as follows.

[0018] The required amount of EDA with a purity of ~99% is added through a dropping funnel into a three-necked round-bottomed flask. The required amount of KOH solution with a concentration of 15 ÷ 30% is added in the same way. Mixing is carried out with continuous stirring. After this, nitrogen is introduced into the flask for 1 ÷ 2 minutes to create an inert atmosphere. Then, the required amount of ECH with a purity of ~99% is added through a dropping funnel with continuous stirring. The molar ratio of EDA / ECH = 4.8 ÷ 5.2; KOH / ECH = 1.0 ÷ 1.1. The process is carried out at a reaction mixture temperature of 45 ÷ 55°C, for which the three-necked round-bottomed flask is cooled with running water, if necessary. Excessive cooling of the reaction mixture is unacceptable to avoid the process proceeding according to a different mechanism with the formation of other reaction products. After adding all the ECH, the reaction mixture is kept for 5 ÷ 10 min with stirring to complete the synthesis process.Next, the azeotropic mixture of EDA and water is distilled stepwise, along with the solvent and target product (MEEDA). For this, the three-necked flask is placed on a sand bath, a vacuum pump is connected, and the temperature is gradually increased. At a vapor temperature of 80 ÷ 110°C and an absolute pressure of 40 ÷ 60 mmHg, the azeotropic mixture of EDA and water is distilled. Distillation of the azeotropic mixture of EDA and water is complete when the vapor temperature drops below 80°C. After this, the flask contents are cooled to 20 ÷ 25°C, the vacuum pump is turned off, and the required amount of ethyl alcohol is added through a dropping funnel. Potassium chloride (KCl) formed during the synthesis precipitates, and the reaction products are extracted into ethanol. The precipitate is separated by filtration, then at a temperature in steam of 80 ÷ 85°C, ethanol is distilled off, which is then used in subsequent syntheses without additional purification.After distillation of the ethanol, a vacuum pump is connected to the unit, and distillation of the target product, monoethanolethylenediamine, begins at an absolute pressure of 5 to 15 mmHg. Distillation occurs under a weak stream of nitrogen at a vapor temperature of 100 to 120°C. The resulting product has a purity of approximately 98%. The yield of the target product is approximately 90%.

[0019] The invention is illustrated by the examples below.

[0020] Example 1.

[0021] 288 g (4.8 mol) of EDA with a purity of ~99% are added through a dropping funnel into a three-necked round-bottomed flask. 373 g of an aqueous solution of KOH with a concentration of 15.0% by weight are added in the same way. Mixing is carried out with continuous stirring. After this, nitrogen is introduced into the flask for 1-2 min to create an inert atmosphere. Then 80.5 g (1 mol) of ECH with a purity of ~99% are added through a dropping funnel with continuous stirring. The EDA / ECH molar ratio is 4.8, the KOH / ECH molar ratio is 1. The process is carried out at a reaction mixture temperature of 45°C, for which the flask is cooled with running water if necessary. After adding the specified amount of ECH, the reaction mixture is kept for 5-10 min with stirring to complete the synthesis process. Next, place the three-necked flask on a sand bath, immersing it in the sand to the level of the reaction solution. Connect the vacuum pump, and begin gradually increasing the temperature in the flask. At an absolute pressure of 40–60 mmHg,and a vapor temperature of 80 ÷ 110°C, an aqueous azeotropic solution of EDA is distilled off. Distillation of the EDA-water azeotropic mixture is completed when the vapor temperature drops below 80°C. After this, the vacuum pump is switched off, the contents of the flask are cooled to 20 ÷ 25°C, and 315 ml of ethyl alcohol are added to the flask. The precipitated KCl (74.1 g) is separated by filtration, then at a vapor temperature of 80 ÷ 85°C, ethanol is distilled off, which is then used in subsequent syntheses. After distilling off the ethanol, the vacuum pump is turned on and at an absolute pressure of 5 ÷ 15 mmHg, the target product, monoethanolethylenediamine, is distilled off. Distillation takes place in a weak stream of nitrogen at a vapor temperature of 100 ÷ 120°C. The obtained product yield is 94 g with a main substance content of ~95%. The yield of the target product is ~89%.

[0022] Example 2.

[0023] 300 g (5.0 mol) of EDA with a purity of ~99% are added through a dropping funnel into a three-necked round-bottomed flask. 250 g of an aqueous solution of KOH with a concentration of 23.5% by weight are added in the same way. Mixing is carried out with continuous stirring. After this, nitrogen is introduced into the flask for 1-2 min to create an inert atmosphere. Then 80.5 g (1 mol) of ECH with a purity of ~99% are added through a dropping funnel with continuous stirring. The EDA / ECH molar ratio is 5.0, the KOH / ECH molar ratio is 1.05. The process is carried out at a reaction mixture temperature of 50°C, for which the flask is cooled with running water, if necessary. After adding the specified amount of ECH, the reaction mixture is kept for 5-10 min with stirring to complete the synthesis process. Next, place the three-necked flask on a sand bath, immersing it in the sand to the level of the reaction solution. Connect the vacuum pump, and begin gradually increasing the temperature in the flask. At an absolute pressure of 40–60 mmHg,and a vapor temperature of 80 ÷ 110°C, an aqueous azeotropic solution of EDA is distilled off. Distillation of the EDA-water azeotropic mixture is completed when the vapor temperature drops below 80°C. After this, the vacuum pump is switched off, the contents of the flask are cooled to 20 ÷ 25°C, and 325 ml of ethyl alcohol are added to the flask. The precipitated KCl (73.4 g) is separated by filtration, then at a vapor temperature of 80 ÷ 85°C, ethanol is distilled off, which is then used in subsequent syntheses. After distilling off the ethanol, the vacuum pump is turned on and at an absolute pressure of 5 ÷ 15 mmHg, the target product, monoethanolethylenediamine, is distilled off. Distillation takes place in a weak stream of nitrogen at a vapor temperature of 100 ÷ 120°C. The obtained product yields 95 g of the target product with a content of the main substance of ~97%. The yield of the target product is ~91%.

[0024] Example 3.

[0025] 312 g (5.2 mol) of EDA with a purity of ~99% are added through a dropping funnel into a three-necked round-bottomed flask. 205 g of an aqueous solution of KOH with a concentration of 30.0% by weight are added in the same way. Mixing is carried out with continuous stirring. After this, nitrogen is introduced into the flask for 1-2 min to create an inert atmosphere. Then 80.5 g (1 mol) of ECH with a purity of ~99% are added through a dropping funnel with continuous stirring. The EDA / ECH molar ratio is 5.2, the KOH / ECH molar ratio is 1.1. The process is carried out at a reaction mixture temperature of 55°C, for which the flask is cooled with running water if necessary. After adding the specified amount of ECH, the reaction mixture is kept for 5-10 min with stirring to complete the synthesis process. Next, place the three-necked flask on a sand bath, immersing it in the sand to the level of the reaction solution. Connect the vacuum pump, and begin gradually increasing the temperature in the flask. At an absolute pressure of 40–60 mmHg,An aqueous azeotropic solution of EDA is distilled off at a vapor temperature of 80 ÷ 110°C. Distillation of the EDA-water azeotropic mixture is completed when the vapor temperature drops below 80°C. After this, the vacuum pump is switched off, the contents of the flask are cooled to 20 ÷ 25°C, and 338 ml of ethyl alcohol are added to the flask. 73.8 g of KCl precipitate are separated by filtration, and then ethanol is distilled off at a vapor temperature of 80 ÷ 85°C, which is then used in subsequent syntheses. After distilling off the ethanol, the vacuum pump is switched on, and the target product, monoethanolethylenediamine, is distilled off at an absolute pressure of 5 ÷ 15 mmHg. Distillation takes place in a weak stream of nitrogen at a vapor temperature of 100 ÷ 120°C. The obtained product yields 94 g of the target product with a content of the main substance of ~98%. The yield of the target product is ~90%.

[0026] As can be seen from the data provided in the examples, the proposed method for producing monoethanolethylenediamine provides a higher content of the active substance in the reaction product and a higher reaction yield of the target component than the analog discussed above. Furthermore, the proposed method reduces the time required for the synthesis of monoethanolethylenediamine.

Claims

A method for producing monoethanolethylenediamine, including mixing ethylenediamine with potassium hydroxide and then with ethylene chlorohydrin in a nitrogen atmosphere with continuous stirring, distilling off the ethylenediamine-water azeotropic mixture at an absolute pressure of 40-60 mm Hg and a vapor temperature of 80-110°C, cooling the reaction mixture to 20-25°C, adding ethanol, separating the precipitated potassium chloride, distilling off the ethanol at a vapor temperature of 80-85°C, followed by distillation in a weak stream of nitrogen at an absolute pressure of 5-15 mm Hg. and at a temperature in vapors of 100÷120°C of monoethanolethylenediamine, characterized in that the interaction of ethylenediamine with potassium hydroxide and ethylene chlorohydrin is carried out in a temperature range of 45÷55°C, potassium hydroxide is used in the form of an aqueous solution with a concentration of 15÷30 wt.%, the molar ratio of ethylenediamine / ethylene chlorohydrin is 4.8÷5.2, and the molar ratio of potassium hydroxide / ethylene chlorohydrin is 1.0÷1.1.