CH642616A5 - METHOD FOR PRODUCING N-AETHYLAETHYLENE DIAMINE. - Google Patents

Description

The invention relates to a process for the preparation of N-ethyl ethylenediamine by reacting an ethyl halide with ethylenediamine.

The known processes for the preparation of N-ethyl-ethylenediamine by reacting ethylenediamine with an ethyl halide provide low yields. The desired product is obtained with low selectivity. Working up the reaction mixture is cumbersome and provides a product of low purity. The known methods therefore have low productivity.

It is an object of the present invention to provide a process for the preparation of N-ethylethylenediamine by reacting ethylenediamine with ethylhalide, which leads to a product of high purity with high yield and high productivity and simple process control.

The invention relates to a process for the preparation of N-ethylethylenediamine of the formula:

HI

C2HSNCH2CH2NH2

(hereinafter referred to as NEED), which is defined in claim 1.

The reaction between the ethyl halide and the EDA is preferably carried out at 25 to 50 ° C. in the presence of 15 to 30% by weight of water and at a molar ratio of EDA to ethyl halide of 2 to 5: 1, and the reaction mixture formed is then carried out with an aqueous sodium hydroxide solution contacted and diluted the organic layer with 0.2 to 20 wt .-% of the aliphatic hydrocarbon solvent before carrying out the distillation.

The method according to the invention can be modified by the following additional steps:

(1) recovery and recycling of the aqueous EDÀ from the azeotropic mixture;

(2) recovery and recycling of the aliphatic hydrocarbon solvent and

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(3) contacting the separated, alkalized aqueous layer with 10 to 100% by weight of the hydrocarbon solvent, based on the weight of the organic layer, separating the extracted aqueous layer and diluting the organic layer with the hydrocarbon extract before carrying out the azeotropic fractional distillation.

The invention further relates to an alternative method for producing NEED with a purity of approximately 99%, which comprises the following steps:

(a) reacting ethyl halide and EDA in a molar ratio of EDA to ethyl halide of 1 to 20: 1 at a temperature of -10 to +120 ° C. under anhydrous conditions and to form an alkylation reaction mixture;

(b) adding 0.2 to 30% by weight of a suitable aliphatic hydrocarbon solvent based on the weight of the alkylation reaction mixture;

(c) fractional distillation of a mixture of EDA and the aliphatic hydrocarbon solvent from the mixture previously obtained to substantially separate the EDA from the mixture obtained;

(d) neutralizing the resulting reaction mixture by contacting it with at least 0.9 mole equivalents of a suitable alkalizing agent per mole of ethyl halide to form a slurry of an alkali halide precipitate;

(e) separating the alkali halide from the slurry and recovering the mother liquor formed;

(f) washing the separated alkali halide with the aliphatic hydrocarbon solvent;

(g) fractional distillation of the aliphatic hydrocarbon wash liquor from step (f) combined with the mother liquor from step (e) to remove substantially all of the water and residual EDA from the mixture formed; and

(h) fractional distillation of the resulting mixture to remove the remaining aliphatic hydrocarbon solvent and to isolate the NEED.

You can do the following:

In a suitable reaction vessel, EDA is mixed either in the form of an anhydrous liquid or in water-containing form with an ethyl halide, preferably with ethyl chloride, with stirring, the temperature of the reaction mixture being in the range from -10 to +120 ° C. (preferably 25 to 50 ° C. ) is maintained, in the course of 5 to 15 h (preferably 7 to 9 h), a molar ratio of EDA to ethyl halide of 1 to 20: 1 (preferably 2 to 5: 1) being selected. The ethyl halide is slowly added to the EDA over the course of the reaction time. A reaction mixture containing 0 to 50% by weight of water (preferably 15 to 30%) is obtained. Suitable ethyl halides are ethyl chloride, ethyl bromide and ethyl iodide. The total residence time in the reaction vessel depends on the temperature used. Shorter dwell times can be selected at higher temperatures.

The reaction mixture is then contacted vigorously with an aqueous solution containing 1 to 2 mole equivalents of an alkalizing agent to form a two-phase liquid mixture. This consists of an organic layer and an alkalized aqueous layer. A suitable alkalizing agent is used so that the pH of the aqueous layer is not below 7 and preferably not below 8. Sodium hydroxide and potassium hydroxide are suitable as alkalizing agents, either alone or in a mixture, and preferably in the form of an aqueous solution. The alkali

tion with an approximately 50% aqueous sodium hydroxide solution.

The two-phase mixture is allowed to stand, whereupon the separated aqueous layer is separated off. An organic layer is obtained which contains NEED, unreacted EDA and higher alkylation products, e.g. B. N, N'-diethylethylenediamine, N, N-diethylethylenediamine, N, N, N'-triethylethylenediamine, and N, N, N ', N'-tetraethylethylenediamine. The aqueous layer generally contains 1 to 3% EDA and 0.5 to 1% NEED. The organic layer is then mixed with 10 to 100% and preferably 10 to 20% by weight of a suitable aliphatic hydrocarbon solvent based on the weight of the organic layer.

Preferably, the separated aqueous layer is extracted with 10 to 100% by weight, and preferably 10 to 20% by weight, of the appropriate aliphatic hydrocarbon solvent based on the weight of the organic layer, and the two-phase mixture is left to separate into phases . The extracted aqueous layer is then separated and the hydrocarbon solvent extract is used to dilute the above-mentioned organic layer.

A "suitable aliphatic hydrocarbon solvent" is an aliphatic hydrocarbon solvent which is miscible with NEED and immiscible with EDA and which azeotropically merges with water and / or EDA at a temperature below 128 to 131 ° C without carrying any significant amounts of NEED. Suitable aliphatic hydrocarbon solvents are, in particular, n-heptane, isooctane, cyclohexane, n-hexane, methylcyclohexane, n-pentane or the like. The preferred aliphatic hydrocarbon solvent is n-heptane. Aromatic hydrocarbons cannot be used in place of aliphatic hydrocarbons because they are miscible with both EDA and NEED.

The diluted organic layer is then heated to boiling and azeotropically fractionally distilled with a distillation column to remove residual EDA and water. The distillate is left to stand, separating into two layers. The lower EDA-water layer is separated and returned to the alkylation vessel. The top hydrocarbon layer can be returned to the distillation vessel until NEED, which is free of both water and EDA, is obtained. Alternatively, the upper hydrocarbon layer can also be transferred to a vessel for extracting the original two-phase mixture.

The remaining EDA-free reaction mixture containing NEED, the higher alkylated ethylenediamines and the aliphatic hydrocarbon solvent is then fractionally distilled using a fractionation column. This must have a sufficient number of theoretical plates to separate the aliphatic hydrocarbon solvent from the NEED. You can e.g. use a column with 15 theoretical plates.

If n-heptane is used as the solvent in this case, the n-heptane is distilled off as a forerun with a boiling point of 98 to 100.degree. The feed of the hydrocarbon solvent that is obtained can be recycled to the other stages of the process. It can be used in particular to dilute the organic layers or to azeotropically separate EDA and water from the reaction mixture or to extract the aqueous layer.

After removal of the hydrocarbon solvent as the first step, the distillation is continued, with NEED having a boiling point of 130 to 131 ° C. and a

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Purity of more than 99%, in a yield of about 63 to 65%, based on the ethyl halide used.

In an alternative embodiment of the process, ethylenediamine is reacted with an ethyl halide according to the following equation under anhydrous conditions:

C2H5X + H2N-CH2CH2-NH2->

HI

C2HsN-CH2CH2NH2 + HX

where X represents a halogen atom, e.g. a chlorine, bromine, fluorine or iodine atom and preferably a chlorine atom. This method is defined in claim 6.

You can do the following:

The reaction is carried out while stirring the reaction mixture in a suitable reaction vessel at -10 to +120 ° C. and preferably at 25 to 75 ° C. in the course of 1 to 24 hours, preferably 2 to 6 hours. The molar ratio of EDA to ethyl halide is 1 to 20: 1 and preferably 2 to 5: 1. The total residence time in the reaction vessel depends on the reaction temperature, and the residence time is shorter at a higher reaction temperature.

When the reaction is complete, the reaction mixture is diluted with 0.2 to 30% by weight and preferably 0.5 to 1.0% by weight of a suitable aliphatic hydrocarbon solvent, based on the weight of the reaction mixture. The term "suitable aliphatic hydrocarbon solvent" has the meaning given above. The diluted reaction mixture is then heated to boiling in a distillation column and fractionally distilled azeotropically, with residual EDA passing over. If necessary, the EDA distillate can be recovered and recycled. Suitable aliphatic hydrocarbon solvents are n-heptane, isooctane, cyclohexane, n-hexane, methylcyclohexane, n-pentane and the like. The preferred aliphatic hydrocarbon solvent is n-heptane.

The reaction mixture is then neutralized by contacting with at least 0.9 mole equivalents of a suitable alkalizing agent per mole of alkyl halide. Sodium hydroxide or potassium hydroxide are particularly suitable as “suitable alkalizing agents”, either alone or in a mixture and preferably in the form of a solution. A 50% aqueous sodium hydroxide solution is used as the preferred alkalizing agent.

The alkali halide precipitate formed is separated from the resulting slurry in a conventional manner, e.g. by filtration or centrifugation, and with the aliphatic hydrocarbon solvent described above, preferably with n-heptane. The aliphatic hydrocarbon solvent washes are then separated and combined with the mother liquor, which was obtained when the alkali halide precipitate was separated from the slurry obtained by adding the alkalizing agent to the reaction mixture. The combined liquids are azeotropically fractionally distilled at atmospheric pressure in a packed column, preferably with the heptane distillate returned to the top of the column until the remaining material is substantially free of EDA and water.

The remaining essentially EDA-free reaction mixture contains NEED as well as higher alkylated ethylenediamines and the aliphatic hydrocarbon solvent. This reaction mixture is now fractionally distilled using a fractionation column with a sufficient number of theoretical plates to separate the aliphatic hydrocarbon diluent from the NEED. You can e.g. Legs

Use a column with 15 theoretical plates. In this process, n-heptane passes over with a boiling point of 98 to 100 JC. The feed of the hydrocarbon solvent obtained is recycled to other stages of the process, e.g. B. for dilution of the reaction mixture or for azeotropic separation of the EDA or water from the reaction mixture.

After removing the feed of the hydrocarbon solvent from the reaction mixture, it is preferably clarified to remove insoluble matter. The clarified solution is distilled, giving NEED with a boiling point of 130 to 131 ° C in a purity of more than 99%. This product is obtained in a yield of 62 to 65% of theory, based on the ethyl halide used.

It must be emphasized that the process described can also be carried out continuously, using suitable reaction apparatuses, e.g. continuous flow reactors, separating vessels, distillation columns etc.

Embodiments All parts are parts by weight and all areas are inclusive. The purity of the product is expressed as a percentage of area based on gas chromatographic analysis (VPC).

example 1

This example demonstrates the use of anhydrous

EDA

Ethyl chloride (565 g; 8.76 mol) is added to anhydrous EDA (1420 g; 23.63 mol) at 30 to 40 ° C in the course of 5 h. The reaction mixture is stirred for a further 2 hours after this addition and then 50% NaOH (935 ml; 17.5 mol) is added. The two-phase mixture formed is stirred for 30 min and then left to stand, separating into two phases and the aqueous phase being separated and extracted twice with 150 ml each of n-heptane. The heptane extracts are added to the organic phase and the combined solutions are heated, water and EDA being distilled off azeotropically at 88 to 97 ° C. For this purpose, a fractionation column and a separating device are used, from which the distilled heptane is returned to the distillation vessel. The heavier water / EDA phase is separated off. In this way, the aqueous EDA phase is separated from 394 g of water and 896 g of EDA (14.91 mol). The EDA-free residue is fractionally distilled, giving a heptane feed (bp. 98-102 ° C.) which contains 3 to 4% by weight of NEED. Furthermore, 484 g of NEED (bp. 130-131 ° C.) with a purity of more than 99.8% (VPC) are obtained. The yield is 62.7% of theory, based on ethyl chloride.

Example 2

This example demonstrates the use of recovered aqueous EDA ethyl chloride (545 g; 8.45 mol) at 30 to 40 ° C over 5n to a mixture of anhydrous EDA (555 g; 9.23 mol) and of that in the example 1 recovered aqueous EDA (1245 g, containing 14.39 moles of EDA). The reaction mixture is stirred for 2 hours after the addition has ended and then 902 ml of a 50% strength sodium hydroxide solution (16.9 moles) are added. The two-phase mixture obtained is worked up according to Example I, the n-heptane recovered according to Example 1 being used to extract the separated aqueous phase. In the fractional distillation of the s

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of EDA-free mixture, heptane is obtained as a forerun with a content of 3 to 4% by weight NEED and a fraction of 483 g NEED (bp. 130-131 C) with a purity of more than 99.8% (VPC). The yield is 65% of theory based on ethyl chloride.

Method 1

This method explains the separation of EDA and NEED by azeotropic distillation

A mixture of EDA (500 g) and NEED (500 g) is diluted with 200 ml of n-heptane and heated and azeotropically fractionally distilled, EDA (bp. 87-90 ° C.) passing over. A distillation column and a device for returning the separated heptane to the distillation device are used. The denser EDA phase is separated off. The EDA recovered in this way contains less than 1% NEED (VPC). The remaining EDA-free material is then fractionally distilled to give pure NEED (bp. 130-131 ° C). In the same way, cyclohexane, n-hexane or isooctane can be used instead of n-heptane, with similar results.

Method 2

This method demonstrates the separation of water and NEED by azeotropic distillation

50 ml of n-heptane are added to a mixture of 56 g of NEED and 10 g of water. The mixture is heated to boiling and the water is fractionally azeotropically distilled (bp 88 to 98 ° C). A distillation column and a separating device are used from which the separated heptane is returned to the distillation apparatus. The denser aqueous phase is separated off. After the separation of the water has ended, the remaining material is subjected to fractional distillation, firstly obtaining a heptane pre-run and then NEED (bp. 130-131 ° C.) with a content of less than 0.2% water (VPC). Similarly, cyclohexane, n-hexane or isooctane can be used in place of n-heptane, with similar results.

Example 3

Ethyl chloride (62.4 g; 0.967 mol) is added with stirring to ethylenediamine (146.3 g; 2.43 mol) over the course of 1 h, the temperature being allowed to rise to 95 ° C. After the addition of the ethyl chloride has ended, 34.2 g of n-heptane are added and the mixture obtained is distilled azeotropically with the aid of a fractionation column and a Dean-Stark device. A two-phase liquid distillate is collected, which consists of a lower layer of ethylenediamine (85.09 g) and an upper layer of heptane. The latter is returned to the fractionation column until all of the ethylenediamine has been removed. The remaining reaction mixture is cooled to 80 ° C and neutralized with 50% aqueous sodium hydroxide solution (77.36 g; 0.967 mol). The precipitate of sodium chloride formed is filtered off, giving a filter cake and a two-phase liquid filtrate. The filter cake is washed with heptane (50 ml) and the washing liquid is combined with the two-phase filtrate. The two-phase liquid obtained is then azeotropically distilled using a fractionation column and a Dean-Stark device. A two-phase distillate is obtained, which consists of n-heptane and water. After all of the water has been removed, the remaining material is fractionally distilled to remove any heptane. Then the N-ethyl ethylenediamine (54.5 g; bp. 130-131 ° C; 64% of theory) is isolated in a purity of 99%.

Example 4

The procedure of Example 3 is repeated in detail, to the point of the last distillation. After all of the water has been removed by azeotropic distillation, the remaining material is filtered to remove a white precipitate (4.32 g). The filter cake is then washed with heptane (16 g) and the washing liquid is combined with the filtrate. The combined mixture of filtrate and washing liquid is then fractionally distilled to remove heptane and to isolate N-ethylethylenediamine (53.7 g; bp. 130-131 ° C; 63% of theory). The product is 99% pure.

Example 5

A glass-lined reactor is charged with 848 parts of ethylenediamine (98%), followed by 331 parts of liquid ethyl chloride, which is introduced through a dip tube at a rate such that the reaction temperature of the mixture is kept at 45 to 55 ° C. The mixture is stirred for 2 hours and 91 parts of heptane are then added. The excess ethylenediamine is azeotropically distilled through a packed column, with the separated heptane distillate being returned to the top of the column. A total of 492 parts of ethylenediamine is thus recovered from the distillate and recycled. The reaction mixture is neutralized with 402 parts of 50% aqueous sodium hydroxide solution and cooled to room temperature and then centrifuged to remove sodium chloride. The salt cake is washed with 70 parts of heptane and the washing liquid is combined with the mother liquor in a glass-lined vessel. Then water is distilled off azeotropically from the combined liquids over a packed column and the passing heptane is returned to the top of the column. After all of the water is removed, the heptane is fractionally distilled off through the packed column to give a residue with 273 parts of N-ethylethylenediamine. The residue is stored for the subsequent combination with the residues of Examples 6 to 8.

Example 6

A glass-lined reactor is charged with 492 parts of recovered ethylenediamine from Example 5 and 375 parts of fresh ethylenediamine (98%). 331 parts of ethyl chloride are added to this reaction mixture at such a rate that the temperature of the reaction mixture is kept at 55 to 65.degree. The mixture is stirred for 2 hours and 45 parts of the recovered heptane from Example 5 are added. The excess ethylenediamine is distilled off azeotropically through a packed column and the passing heptane distillate is returned to the top of the column. A total of 501 parts of ethylenediamine is recovered from the distillate and also recycled. The reaction mixture is neutralized with 407 parts of 50% sodium hydroxide solution and cooled to room temperature and then centrifuged to remove the sodium chloride. The salt cake is washed with 78 parts of heptane and the washing liquid is combined with the mother liquor in the glass-lined vessel. The water is distilled off azeotropically from the combined liquids via a packed column. The passing heptane is returned to the top of the column. After all the water has been removed, the heptane is fractionated

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distilled off over the packed column, a residue liquid containing 288 parts of N-ethylethylenediamine being obtained. This residue is kept for subsequent combination with the residues of Examples 5, 7 and 8.

Example 7

A glass-lined reactor is charged with 501 parts of the recovered ethylenediamine according to Example 6 and 396 parts of fresh ethylenediamine (98%). 331 parts of ethyl chloride are added to this mixture at such a rate that the temperature of the reaction mixture is kept at 65 to 75.degree. The reaction mixture is stirred for 2 hours and 28 parts of the heptane recovered according to Example 6 are added. The excess ethylenediamine is distilled off azeotropically through a packed column and the heptane in the distillate is returned to the top of the column. A total of 504 parts of ethylenediamine is obtained in this way, which is obtained from the distillate and can be recycled. The reaction mixture is neutralized with 409 parts of a 50% aqueous sodium hydroxide solution and cooled to room temperature and then centrifuged, the sodium chloride being separated off. The salt cake is washed with 82 parts of heptane and the washing liquid is combined with the mother liquor in a glass-lined vessel. The water distills azeotropically from the combined liquids through the packed column and the passing heptane is returned to the top of the column. After all the water has been removed, fractional distillation of the heptane is carried out over the packed column. A residue liquid containing 310 parts of N-ethylethylenediamine is obtained. This residue liquid is kept for subsequent combination with the residue mixtures of Examples 5, 6 and 8.

Example 8

s A glass-lined reactor is charged with 504 parts of recovered ethylenediamine from Example 7 and 388 parts of fresh ethylenediamine (98%). 331 parts of ethyl chloride are added to this mixture at such a rate that the temperature of the reaction mixture is kept at 55 to 65.degree. The mixture is stirred for 2 hours and 30 parts of recovered heptane from Example 7 are added. The excess ethylenediamine is distilled off azeotropically through a packed column, the separated hexane from the distillate 15 being returned to the top of the column. A total of 523 parts of ethylenediamine is recovered from the distillate and recycled. The reaction mixture is neutralized with 409 parts of a 50% aqueous sodium hydroxide solution, cooled to room temperature and centrifuged to remove the sodium chloride. The salt cake is washed with 91 parts of heptane and the washing liquid is combined with the mother liquor in a glass-lined vessel. The water is distilled off azeotropically from the combined liquids via a packed column 25 and the passing heptane is returned to the top of the column. After all the water has been removed, the heptane is fractionally distilled off through the packed column, giving a residue containing 317 parts of N-ethylethylenediamine. This residue liquid is combined with that of Examples 5, 6 and 7. The mixture obtained is fractionally distilled through a packed column at atmospheric pressure. 1120 parts of N-ethylethylenediamine with a bp of 129-131 ° C. are obtained. The yield is 61.9% of 35 theory, based on ethyl chloride.

Claims (11)

642 616 1. A process for the preparation of N-ethyl-ethylenediamine NEED, characterized in that ethylenediamine EDA and an ethyl halide at a molar ratio of EDA to ethyl halide of 1 to 20: 1 and at a temperature of -10 to +120 'C in the presence from 0 to 50% by weight of water to produce an alkylation reaction mixture, which neutralizes the reaction mixture by contacting with an aqueous solution containing 1 to 2 molar equivalents of an inorganic alkalizing agent, based on the ethyl halide, which separating the aqueous layer from the neutralized organic layer and adding 0.2 to 100% by weight, based on the weight of the organic layer, of a suitable aliphatic hydrocarbon solvent to the organic layer, azeotropically distilling off all the water and EDA from the resulting mixture and the remaining reaction mixture is fractionally distilled to add the remaining hydrocarbon solvent remove and win NEED with a purity of more than 99%. 2. The method according to claim 1, characterized in that the EDA and the ethyl halide at a molar ratio of EDA to ethyl halide of 2 to 5: 1 and at a temperature of 25 to 50 ° C in the presence of 15 to 30 wt .-% Reacts water to obtain the alkylation reaction mixture, neutralizes the reaction mixture by contacting with an aqueous sodium hydroxide solution and the organic layer with 0.2 to 20 wt .-%. of the aliphatic hydrocarbon solvent. 2nd PATENT CLAIMS 3. The method according to claim 1 or 2, characterized in that n-heptane is used as the aliphatic hydrocarbon. 4. The method according to any one of claims 1 to 3, characterized in that additionally (a) aqueous EDA is obtained from the azeotropic mixture and recycled into the reaction with the ethyl halide and (b) the hydrocarbon solvent is obtained from the preliminary distillation of the NEED and leads back into the distillation mixture. 5. The method according to any one of claims 1 to 4, characterized in that the aqueous layer with 10 to 100 wt .-% of the hydrocarbon solvent, based on the weight of the organic layer, is contacted, the extracted aqueous layer is separated and the hydrocarbon extract before implementation the azeotropic fractional distillation to the organic layer. 6. Process for the preparation of N-ethyl ethylenediamine NEED with 99% purity, characterized in that (a) an ethyl halide and ethylenediamine EDA at a molar ratio of EDA to ethyl halide of 1 to 20: 1 and at a temperature of -10 to + 120 C under anhydrous conditions to produce an alkylation reaction mixture, (b) 0.2 to 30% by weight of a suitable aliphatic hydrocarbon solvent, based on the weight of the reaction mixture, is added to the reaction mixture, (c) the EDA and the aliphatic hydrocarbon solvent is fractionally distilled to substantially remove EDA; (d) neutralizing the resulting mixture by contacting with at least 0.9 mole equivalents of a suitable alkalizing agent per mole of the ethyl halide to form a slurry of an alkali halide precipitate, (e) separating the alkali halide precipitate from the slurry and the resulting mother liquor (f) washes the separated alkali halide with the aliphatic hydrocarbon solvent, (g) fractionally distilled the aliphatic hydrocarbon washing liquid from step (f) combined with the mother liquor from step (e) to remove substantially all of the water and residual EDA from the to remove the mixture formed, and (h) the resulting mixture is fractionally distilled to remove residual aliphatic hydrocarbon solvent and to obtain the NEED. 7. The method according to claim 6, characterized in that one uses n-heptane as the aliphatic hydrocarbon solvent. 8. The method according to claim 6 or 7, characterized in that one carries out stage (a) at a temperature of 25 to 75 ° C. 9. The method according to any one of claims 6 to 8, characterized in that in step (a) a molar ratio of EDA to ethyl halide of 2 to 5: 1 is used. 10. The method according to any one of claims 6 to 9, characterized in that the aliphatic hydrocarbon solvent, preferably n-hexane, in step (b) in an amount of 0.5 to 1.0 wt .-%, based on the reaction mixture , used. 11. The method according to any one of claims 6 to 10, characterized in that an approximately 50% aqueous sodium hydroxide solution is used in step (d) as the alkalizing agent.