CN110317138B - Preparation method of tetramethylethylenediamine - Google Patents
Preparation method of tetramethylethylenediamine Download PDFInfo
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- CN110317138B CN110317138B CN201910689056.5A CN201910689056A CN110317138B CN 110317138 B CN110317138 B CN 110317138B CN 201910689056 A CN201910689056 A CN 201910689056A CN 110317138 B CN110317138 B CN 110317138B
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Abstract
The invention provides a preparation method of tetramethyl ethylenediamine, which comprises the following steps: dissolving paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution; in the presence of a catalyst and hydrogen, performing methylation hydrogenation reaction on paraformaldehyde solution and ethylenediamine, and rectifying the obtained reaction liquid to obtain tetramethyl ethylenediamine. The method takes paraformaldehyde as a raw material, and dissolves the paraformaldehyde by an organic solvent, so that a formaldehyde aqueous solution is avoided, or salt wastewater containing sodium chloride which is difficult to treat and is generated after dichloroethane is used as the raw material is avoided; the process is simple, easy to operate, low in cost and high in yield of tetramethylethylenediamine. The water content in the crude product after reaction is 16.2-19.9%; the residual mass content of the raw material ethylenediamine in the crude product is 0.15-0.23%, and the residual mass content of the paraformaldehyde is 0.11-0.21%; the yield of the tetramethyl glycol is 96.1 to 98.3 percent; the purity is more than 99.37%.
Description
Technical Field
The invention belongs to the technical field of compound synthesis, and particularly relates to a preparation method of tetramethylethylenediamine.
Background
Tetramethyl ethylenediamine is mainly used as biochemical reagents and epoxy resin cross-linking agents, is also an intermediate for preparing quaternary ammonium compounds and the like, and has large market demand.
In the production process of tetramethylethylenediamine on the market, dichloroethane reacts with excessive dimethylamine, the excessive dimethylamine is recovered by processing with excessive liquid alkali, a crude product of the tetramethylethylenediamine is distilled out, and then the product is obtained by drying and dehydration. In the process, a large amount of salt waste water containing sodium chloride is generated and is difficult to treat. Secondly, liquid formaldehyde is adopted to react with ethylenediamine, and due to the fact that the product has a large methylation number, the required amount of formaldehyde water solution is very large, and meanwhile, the amount of formaldehyde-containing wastewater in the post-reaction treatment process is too large, so that the requirement of clean production put forward by the state cannot be met.
Therefore, a new production process which has little environmental pollution and can meet the large-scale production of enterprises is urgently needed to be found.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for preparing tetramethylethylenediamine, which can avoid the generation of a large amount of salt-containing wastewater that is difficult to treat, and has a high yield of tetramethylethylenediamine.
The invention provides a preparation method of tetramethyl ethylenediamine, which comprises the following steps:
dissolving paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution;
in the presence of a catalyst and hydrogen, performing methylation hydrogenation reaction on paraformaldehyde solution and ethylenediamine, and rectifying the obtained reaction liquid to obtain the tetramethyl ethylenediamine.
Preferably, the preparation method of tetramethylethylenediamine comprises the following steps:
dissolving paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution;
in the presence of a catalyst and hydrogen, performing methylation hydrogenation reaction on paraformaldehyde solution and ethylenediamine, and rectifying the obtained reaction liquid to obtain the tetramethyl ethylenediamine.
Preferably, the time for the heat preservation is 1 to 3 hours.
Preferably, the organic solvent is selected from one or more of methanol, ethanol, ethylenediamine and tetramethylethylenediamine.
Preferably, the organic solvent is selected from methanol, ethanol, tetramethylethylenediamine, a mixed solvent of methanol and ethylenediamine in a mass ratio of 1 to 4.
Preferably, the catalyst is selected from palladium on carbon catalysts.
Preferably, the temperature of the methylation hydrogenation reaction is 120-130 ℃; the pressure of the methylation hydrogenation reaction is 2.8-3.2 MPa.
Preferably, the mass ratio of the organic solvent, the paraformaldehyde, the ethylenediamine and the catalyst is 1.
Preferably, the paraformaldehyde solution is reacted with ethylenediamine in a pumped manner; the pumping speed is 40 g/h-100 g/h.
The invention provides a preparation method of tetramethylethylenediamine, which comprises the following steps: dissolving paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution; in the presence of a catalyst and hydrogen, performing methylation hydrogenation reaction on paraformaldehyde solution and ethylenediamine, and rectifying the obtained reaction liquid to obtain the tetramethyl ethylenediamine. The invention takes paraformaldehyde as a raw material, and an organic solvent is used for dissolving the paraformaldehyde, so that a formaldehyde aqueous solution is avoided being used, or sodium chloride-containing salt wastewater which is difficult to treat and is generated after dichloroethane is used as the raw material is avoided; the process is simple, easy to operate and low in cost, and the tetramethylethylenediamine has high yield and high purity. The experimental results show that: the water content in the crude product after reaction is 16.2-19.9%; the residual mass content of the raw material ethylenediamine in the crude product is 0.15-0.23%, and the residual mass content of the paraformaldehyde is 0.11-0.21%; the yield of the tetramethyl glycol is 96.1 to 98.3 percent; the purity is more than 99.37%.
Drawings
FIG. 1 shows the NMR spectrum of tetramethylethylenediamine prepared in example 1 of the present invention.
Detailed Description
The invention provides a preparation method of tetramethylethylenediamine, which comprises the following steps:
dissolving paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution;
in the presence of a catalyst and hydrogen, performing methylation hydrogenation reaction on paraformaldehyde solution and ethylenediamine, and rectifying the obtained reaction liquid to obtain the tetramethyl ethylenediamine.
The method takes paraformaldehyde as a raw material, and dissolves the paraformaldehyde by an organic solvent, so that a formaldehyde aqueous solution is avoided, or salt wastewater containing sodium chloride which is difficult to treat and is generated after dichloroethane is used as the raw material is avoided; the process is simple, easy to operate, low in cost and high in yield of tetramethylethylenediamine.
The invention dissolves paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution. In the present invention, the molecular formula of the paraformaldehyde is (HCHO) n Wherein the value of n is 8-100.
In the present invention, the organic solvent is preferably selected from one or more of methanol, ethanol, ethylenediamine, and tetramethylethylenediamine; more preferably one or more selected from the group consisting of methanol, ethanol, tetramethylethylenediamine, a mixed solvent of methanol and ethylenediamine in a mass ratio of 1 to 4, and a mixed solvent of tetramethylethylenediamine and ethylenediamine in a mass ratio of 1. In a specific embodiment, the organic solvent is selected from methanol, ethanol, tetramethylethylenediamine, a mixed solvent of tetramethylethylenediamine and ethylenediamine in a mass ratio of 3. If the organic solvent is selected from ethylenediamine and/or tetramethylethylenediamine, the ethylenediamine is a reactant and a solvent, the tetramethylethylenediamine is a reaction solvent and a reaction product, the reaction system has few substances, the reaction solvent is easy to recycle, and the method is environment-friendly and clean.
The dissolving of the paraformaldehyde in the organic solvent to obtain the paraformaldehyde solution specifically comprises:
heating the organic solvent to 30-80 ℃, adding paraformaldehyde, keeping the temperature, stirring for dissolving, and cooling to 20-25 ℃ to obtain a paraformaldehyde solution.
In the present invention, the temperature of the organic solvent is preferably raised to 40 to 60 ℃ and more preferably raised to 45 to 55 ℃. The time for heat preservation is preferably 1 to 3 hours.
After obtaining the paraformaldehyde solution, the invention carries out methylation hydrogenation reaction on the paraformaldehyde solution and ethylenediamine in the presence of a catalyst and hydrogen, and the obtained reaction liquid is rectified to obtain the tetramethyl ethylenediamine. In the present invention, the catalyst is preferably selected from palladium on carbon catalysts, more preferably from 5% palladium on carbon catalysts.
The invention preferably carries out methylation hydrogenation reaction in an autoclave; the temperature of the methylation hydrogenation reaction is preferably 120-130 ℃; the pressure of the methylation hydrogenation reaction is preferably 2.8 to 3.2MPa.
In the invention, the main reaction in the methylation hydrogenation reaction process is as follows:
NH 2 CH 2 CH 2 NH 2 +(HCHO) n +H 2 →(CH 3 ) 2 NCH 2 CH 2 N(CH 3 ) 2 +H 2 O；
the side reaction is as follows:
NH 2 CH 2 CH 2 NH 2 +(HCHO) n +H 2 →CH 3 NHCH 2 CH 2 NH 2 +H 2 O；
NH 2 CH 2 CH 2 NH 2 +(HCHO) n +H 2 →CH 3 NHCH 2 CH 2 NHCH 3 +H 2 O；
NH 2 CH 2 CH 2 NH 2 +(HCHO) n +H 2 →(CH 3 ) 2 NCH 2 CH 2 NHCH 3 +H 2 O；
(HCHO) n +H 2 →CH 3 OH。
in the present invention, the mass ratio of the organic solvent, paraformaldehyde, ethylenediamine, and catalyst is preferably 1:1 to 9: 0.01.
the paraformaldehyde solution reacts with ethylenediamine in a pumping mode; the pumping speed is preferably 40 g/h-100 g/h, more preferably 60 g/h-80 g/h; in one embodiment, the pumping rate is 70g/h. The pumping time is preferably 7 to 8 hours.
In order to further illustrate the present invention, the following examples are provided to describe the preparation method of tetramethylethylenediamine according to the present invention in detail, but they should not be construed as limiting the scope of the present invention.
Example 1
Weighing 200g of methanol, raising the temperature to 45 ℃, adding 130g of paraformaldehyde, raising the temperature of an organic solvent to 45 ℃, preserving the heat for 1 hour, stirring for dissolving, and then cooling to 20-25 ℃ to obtain a mixed solution which is used as a reaction raw material for the synthesis reaction of tetramethylethylenediamine. 60g of ethylenediamine and 0.3g of 5% palladium-carbon catalyst are added into an autoclave, nitrogen and hydrogen are replaced, the temperature is increased to 120 ℃, then hydrogen is introduced, the pressure is 2.8-3.2 Mpa, mixed liquor is pumped into the autoclave at the pumping speed of 70g/h, methylation hydrogenation reaction is carried out, after the reaction is finished, the reaction liquid is rectified, and 114g of tetramethyl ethylenediamine is obtained by separation, wherein the product content is 99.64%. The water content and the conversion rate of the raw materials in the system are measured. The test data are shown in Table 1.
The invention performs a nuclear magnetic resonance hydrogen spectrum test on the tetramethylethylenediamine prepared in example 1, and the result is shown in fig. 1, and fig. 1 is a nuclear magnetic resonance hydrogen spectrum of the tetramethylethylenediamine prepared in example 1 of the invention. As can be seen from fig. 1: the product obtained by rectification and separation in example 1 is tetramethylethylenediamine.
Example 2
Weighing 260g of tetramethylethylenediamine, heating to 55 ℃, adding 130g of paraformaldehyde, heating an organic solvent to 60 ℃, keeping the temperature for 1 hour, stirring for dissolving, and then cooling to 20-25 ℃ to obtain a mixed solution, wherein the mixed solution is used as a reaction raw material for the synthesis reaction of tetramethylethylenediamine. 60g of ethylenediamine and 0.3g of 5% palladium-carbon catalyst are added into an autoclave, nitrogen and hydrogen are replaced, the temperature is increased to 120 ℃, then hydrogen is introduced, the pressure is increased to 2.8-3.2 MPa, the mixed liquid is pumped into the autoclave at the pumping speed of 70g/h, the methylation hydrogenation reaction is carried out, after the reaction is finished, the reaction liquid is rectified, and the tetramethyl ethylenediamine 371.8g and the product content is 99.43 are obtained through separation. The water content and the conversion rate of the raw materials in the system are measured. The test data are shown in Table 1.
Example 3
Weighing 150g of tetramethylethylenediamine and 50g of ethylenediamine, mixing, heating to 45 ℃, adding 130g of paraformaldehyde, heating an organic solvent to 45 ℃, keeping the temperature for 1 hour, stirring for dissolving, and then cooling to 20-25 ℃ to obtain a mixed solution, wherein the mixed solution is used as a reaction raw material for the synthesis reaction of tetramethylethylenediamine. Adding 10g of ethylenediamine and 0.3g of 5% palladium-carbon catalyst into an autoclave, replacing nitrogen with hydrogen, heating to 120 ℃, introducing hydrogen, introducing the hydrogen with the pressure of 2.8-3.2 Mpa, pumping mixed solution into the autoclave at the pumping speed of 70g/h, carrying out methylation hydrogenation reaction, rectifying reaction liquid after the reaction is finished, and separating to obtain 260g of tetramethyl ethylenediamine with the product content of 99.51%. The water content and the conversion rate of the raw materials in the system are measured. The test data are shown in Table 1.
Example 4
Weighing 150g of methanol and 50g of ethylenediamine, raising the temperature to 45 ℃, adding 130g of paraformaldehyde, raising the temperature of an organic solvent to 45 ℃, preserving the heat for 1 hour, stirring for dissolving, and then cooling to 20-25 ℃ to obtain a mixed solution, wherein the mixed solution is used as a reaction raw material for the synthesis reaction of tetramethylethylenediamine. Adding 60g of ethylenediamine and 0.3g of 5% palladium-carbon catalyst into an autoclave, replacing nitrogen with hydrogen, heating to 120 ℃, introducing hydrogen, pumping mixed liquor into the autoclave at a pressure of 2.8-3.2 Mpa, wherein the pumping rate is 70g/h, carrying out methylation hydrogenation reaction, rectifying reaction liquid after the reaction is finished, and separating to obtain 112g of tetramethyl ethylenediamine with the product content of 99.58%. The water content and the conversion rate of the raw materials in the system are measured. The test data are shown in Table 1.
Example 5
Weighing 200g of ethanol, heating the temperature to 45 ℃, adding 130g of paraformaldehyde, heating the organic solvent to 45 ℃, keeping the temperature for 1 hour, stirring for dissolving, and then cooling to 20-25 ℃ to obtain a mixed solution which is used as a reaction raw material for the synthesis reaction of tetramethylethylenediamine. 60g of ethylenediamine and 0.3g of 5% palladium-carbon catalyst are added into an autoclave, nitrogen and hydrogen are replaced, the temperature is increased to 120 ℃, then hydrogen is introduced, the pressure is increased to 2.8-3.2 Mpa, the autoclave is pumped with mixed liquid, methylation hydrogenation reaction is carried out, after the reaction is finished, the reaction liquid is rectified and separated to obtain 111.5g of tetramethylethylenediamine with the product content of 99.37%. The water content and the conversion rate of the raw materials in the system are measured. The test data are shown in Table 1.
Comparative example 1
Weighing 262.5g of 60% dimethylamine aqueous solution, adding the dimethylamine aqueous solution into a high-pressure kettle, stirring and heating to 80 ℃, keeping the pressure at 1MPa, pumping 99g of dichloroethane, controlling the temperature to react at 80 ℃, carrying out heat preservation reaction for 2 hours after pumping, discharging, adding 220g of 40% liquid alkali, adjusting the pH value, and obtaining strong alkalinity. The product and unreacted dimethylamine were distilled off at atmospheric pressure to give 220g of a 20% aqueous mixture, and the remainder was diluted with 100g of tap water to give 461g of a salt-containing wastewater. The distilled mixture is dried again by caustic soda flakes and rectified to obtain 105g of tetramethylethylenediamine with the product content of 99.44 percent. The water content and the conversion rate of the raw materials in the system are measured. The test data are shown in Table 1.
Table 1 water content and conversion of raw material in the systems of examples 1 to 5 of the present invention and comparative example 1
As can be seen from the results in Table 1, the process of the present invention in examples 1-5 has a product yield of over 96%, while the process of the present invention in comparative example 1 has a product yield of 90.4% and is a conventional process, so the process of the present invention has significant yield advantages, and the process of the present invention has a low crude product water content and a low waste water content.
From the above embodiments, the present invention provides a preparation method of tetramethylethylenediamine, including the following steps: dissolving paraformaldehyde in an organic solvent to obtain a paraformaldehyde solution; in the presence of a catalyst and hydrogen, performing methylation hydrogenation reaction on paraformaldehyde solution and ethylenediamine, and rectifying the obtained reaction liquid to obtain the tetramethyl ethylenediamine. The invention takes paraformaldehyde as a raw material, and an organic solvent is used for dissolving the paraformaldehyde, so that a formaldehyde aqueous solution is avoided being used, or sodium chloride-containing salt wastewater which is difficult to treat and is generated after dichloroethane is used as the raw material is avoided; the process is simple, easy to operate, low in cost and high in tetramethyl ethylenediamine yield. The experimental results show that: the water content in the crude product after reaction is 16.2-19.9%; the residual mass content of the raw material ethylenediamine in the crude product is 0.15-0.23%, and the residual mass content of the paraformaldehyde is 0.11-0.21%; the yield of the tetramethyl ethylenediamine is 96.1 to 98.3 percent; the purity is more than 99.37%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and amendments can be made without departing from the principle of the present invention, and these modifications and amendments should also be considered as the protection scope of the present invention.
Claims (1)
1. The preparation method of tetramethylethylenediamine is characterized by comprising the following steps:
heating an organic solvent to 30-80 ℃, adding paraformaldehyde, keeping the temperature, stirring and dissolving, and cooling to 20-25 ℃ to obtain a paraformaldehyde solution; the heat preservation time is 1 to 3 hours;
carrying out methylation hydrogenation reaction on the paraformaldehyde solution and ethylenediamine in the presence of a 5% palladium-carbon catalyst and hydrogen, and rectifying the obtained reaction liquid to obtain tetramethyl ethylenediamine; reacting the paraformaldehyde solution with ethylenediamine in a pumping mode; the pumping speed is 60 g/h-80 g/h;
the temperature of the methylation hydrogenation reaction is 120-130 ℃; the pressure of the methylation hydrogenation reaction is 2.8-3.2 MPa;
the mass ratio of the organic solvent to the paraformaldehyde to the ethylenediamine to the catalyst is 1-9;
the organic solvent is selected from methanol, ethanol, tetramethylethylenediamine, a mixed solvent of methanol and ethylenediamine in a mass ratio of 1-4, or a mixed solvent of tetramethylethylenediamine and ethylenediamine in a mass ratio of 1.
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| Xin Ge等.RANEY® nickel-catalyzed reductive N-methylation of amines with paraformaldehyde: theoretical and experimental study.《RSC Adv.》.2014,第4卷(第81期), * |
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