A process for the preparation of N,N,N,N-tetramethylethylenediamine

Abstract

The application provides a preparation method of N,N,N,N-tetramethylethylenediamine and belongs to the technical field of organic synthesis. The preparation method provided by the application takes N,N-dimethylethanolamine as an initial raw material, first oxidizes the N,N-dimethylethanolamine to obtain N,N dimethylglyoxal, and then carries out a hydrogenation reaction on the N,N dimethylglyoxal and dimethylamine in the presence of hydrogen to obtain N,N,N,N-tetramethylethylenediamine. The preparation method provided by the application is high in selectivity of a target product, high in yield and simple in operation, and the selectivity of the target product N,N,N,N-tetramethylethylenediamine is greater than or equal to 98.3%, so that the product is high in selectivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic matter synthesis, and particularly relates to a preparation method of N,N,N,N-tetramethylethylenediamine. BACKGROUND

[0002] N,N,N,N-tetramethylethylenediamine is a colorless transparent liquid, mainly used as a biochemical reagent, an epoxy resin crosslinking agent, and an intermediate for preparing quaternary ammonium compounds. At present, the preparation methods of N,N,N,N-tetramethylethylenediamine mainly include the following two kinds: one is a dichloromethane method, which uses 1,2-dichloroethane and excess dimethylamine as raw materials, and performs a one-step reaction in a pipeline reactor in the presence of a solvent to obtain N,N,N,N-tetramethylethylenediamine; the other is an ethylenediamine method, which uses formaldehyde aqueous solution or polyformaldehyde as a methylation reagent, and performs hydrogen methylation of ethylenediamine in the presence of a catalyst to obtain tetramethylethylenediamine. For example, Chinese patent CN110317138A discloses a preparation method of tetramethylethylenediamine, polyformaldehyde is dissolved in an organic solvent to obtain a polyformaldehyde solution; the polyformaldehyde solution and ethylenediamine are subjected to methylation hydrogenation reaction in the presence of a catalyst and hydrogen, and the obtained reaction liquid is subjected to rectification to obtain tetramethylethylenediamine, the yield of tetramethylethylenediol is 96.1-98.3%, and the purity is above 99.37%. However, the selectivity of the target product obtained by the above preparation method is only 95.63-98.09%, and the selectivity of the target product is low. SUMMARY

[0003] In view of this, the application aims to provide a preparation method of N,N,N,N-tetramethylethylenediamine, and the selectivity of N,N,N,N-tetramethylethylenediamine prepared by the preparation method is greater than or equal to 98.3%, and the selectivity of the product is high.

[0004] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0005] The application provides a preparation method of N,N,N,N-tetramethylethylenediamine, which comprises the following steps:

[0006] Under an oxygen-containing atmosphere, N,N-dimethylethanolamine, an oxidation catalyst and a soluble N,N-dimethylethanolamine solvent are mixed to perform an oxidation reaction to obtain N,N dimethylglyoxal;

[0007] Under a protective atmosphere, the N,N dimethylglyoxal is mixed with dimethylamine and a hydrogenation catalyst, hydrogen is introduced, and a methylation hydrogenation reaction is performed to obtain N,N,N,N-tetramethylethylenediamine.

[0008] Preferably, the oxidation catalyst comprises a platinum-carbon catalyst.

[0009] Preferably, the mass ratio of the N,N-dimethylethanolamine to the oxidation catalyst is 10-2000:1.

[0010] Preferably, the soluble N,N-dimethylethanolamine solvent comprises dioxane.

[0011] Preferably, the molar ratio of the N,N-dimethylethanolamine to the soluble dimethylethanolamine solvent is 1-4:1.

[0012] Preferably, the temperature of the oxidation reaction is 50-100℃, and the time is 2-6h; the oxygen-containing atmosphere comprises air and / or oxygen; and the pressure of the oxygen-containing atmosphere is 1-4MPa.

[0013] Preferably, the hydrogenation catalyst comprises Raney nickel and / or palladium-carbon catalyst.

[0014] Preferably, the mass ratio of the N,N-dimethylglyoxal to the hydrogenation catalyst is 10-2000:1.

[0015] Preferably, the molar ratio of the N,N-dimethylglyoxal to the dimethylamine is 1:1-1.1.

[0016] Preferably, the temperature of the methylation hydrogenation reaction is 80-130℃, and the time is 0.5-6h; and the pressure of the hydrogen is 1-4MPa.

[0017] The present application provides a preparation method of N,N,N,N-tetramethyl ethylenediamine. The preparation method provided by the present application uses N,N-dimethylethanolamine (DMEA) as the initial raw material, first oxidizes the N,N-dimethylethanolamine to obtain N,N-dimethylglyoxal, and then performs a hydrogenation reaction on the N,N-dimethylglyoxal and dimethylamine in the presence of hydrogen to obtain N,N,N,N-tetramethyl ethylenediamine (TDMEA). The preparation method provided by the present application does not use formaldehyde aqueous solution (which will produce by-product methanol) and ethylenediamine (which will produce by-product N,N-dimethylglycolamine) raw materials, and the selectivity of the target product is high and the yield is high. As shown in the test results of the examples, the selectivity of the N,N,N,N-tetramethyl ethylenediamine prepared by the present application is ≥98.3%, and the selectivity of the product is high. Moreover, compared with the dichloroethane method, the preparation method provided by the present application avoids using dichloroethane as a raw material to produce a large amount of waste salt and waste alkali which are seriously polluting, meets the requirements of green chemical process, has low cost, is simple to operate, and is suitable for industrialized production. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0019] Figure 1 Preparation method flow chart for preparing N,N,N,N-tetramethylethylenediamine according to the present application, wherein catalyst A is an oxidation catalyst and catalyst B is a hydrogenation catalyst.

[0020] Figure 2 Infrared chromatogram of the pure N,N,N,N-tetramethylethylenediamine prepared in Example 1.

[0021] Figure 3 Gas chromatogram of the pure N,N,N,N-tetramethylethylenediamine prepared in Example 1. DETAILED DESCRIPTION

[0022] Figure 1 Preparation method flow chart for preparing N,N,N,N-tetramethylethylenediamine according to the present application, wherein catalyst A is an oxidation catalyst and catalyst B is a hydrogenation catalyst. Figure 1 The preparation method is described in detail.

[0023] The present application provides a preparation method of N,N,N,N-tetramethylethylenediamine, comprising the following steps:

[0024] Under an oxygen-containing atmosphere, N,N-dimethylethanolamine, an oxidation catalyst and a soluble N,N-dimethylethanolamine solvent are mixed to perform an oxidation reaction, so as to obtain N,N-dimethylglyoxal.

[0025] Under a protective atmosphere, the N,N-dimethylglyoxal is mixed with dimethylamine and a hydrogenation catalyst, hydrogen is introduced, and a methylation hydrogenation reaction is performed, so as to obtain N,N,N,N-tetramethylethylenediamine.

[0026] In the present application, all the raw material components are commercially available goods well known to those skilled in the art, unless otherwise specified.

[0027] In the present application, under an oxygen-containing atmosphere, N,N-dimethylethanolamine, an oxidation catalyst and a soluble N,N-dimethylethanolamine solvent are mixed to perform an oxidation reaction, so as to obtain N,N-dimethylglyoxal.

[0028] In the present application, the oxidation catalyst preferably comprises a platinum-carbon catalyst; the loading of platinum in the platinum-carbon catalyst is preferably 3-10 wt%, more preferably 4-8 wt%, and most preferably 5-7 wt%. In the present application, the mass ratio of N,N-dimethylethanolamine to oxidation catalyst is preferably 10-2000:1, more preferably 20-500:1, and most preferably 50-80:1. In the present application, the soluble N,N-dimethylethanolamine solvent preferably comprises dioxane. In the present application, the molar ratio of N,N-dimethylethanolamine to soluble dimethylethanolamine solvent is preferably 1-4:1, more preferably 1.5-3:1, and most preferably 2-2.5:1.

[0029] In the present application, the temperature of the oxidation reaction is preferably 50-100°C, more preferably 60-90°C, and most preferably 70-80°C; the time of the oxidation reaction is preferably 2-6 h, more preferably 3-5 h, and most preferably 4-4.5 h; the oxygen-containing atmosphere preferably comprises air and / or oxygen, and more preferably air; the pressure of the oxygen-containing atmosphere is preferably 1-4 MPa, and more preferably 2-3 MPa.

[0030] In the present application, the oxidation reaction is preferably followed by: sequentially subjecting the obtained oxidation reaction liquid to first heat preservation, first temperature reduction, and pressure release, to obtain N,N-dimethylglyoxal (a reaction liquid containing N,N-dimethylglyoxal), which is directly subjected to subsequent reactions without purification. In the present application, the temperature of the first heat preservation is preferably the same as the temperature of the oxidation reaction; the time of the first heat preservation is preferably 0.1-2 h, more preferably 0.5-1.5 h, and most preferably 1 h. The present application subjects the oxidation reaction liquid to first heat preservation, and air is not introduced during the heat preservation stage so as to make the reaction as complete as possible. In the present application, the end temperature of the first temperature reduction is preferably room temperature. The present application does not have a special limitation on the rate of the first temperature reduction, and the temperature can be reduced to room temperature. In the present application, the first temperature reduction is preferably followed by filtration to recover the oxidation catalyst.

[0031] After obtaining N,N-dimethylglyoxal, the present application mixes the N,N-dimethylglyoxal with dimethylamine and a hydrogenation catalyst under a protective atmosphere, introduces hydrogen, and performs a methylation hydrogenation reaction to obtain N,N,N,N-tetramethyl ethylenediamine.

[0032] In the present application, the protective atmosphere is preferably an inert gas, and more preferably N2.

[0033] In this invention, the hydrogenation catalyst preferably comprises Raney nickel and / or palladium on carbon catalyst, more preferably palladium on carbon catalyst; the palladium loading in the palladium on carbon catalyst is preferably 3-10 wt%, more preferably 4-8 wt%, and most preferably 5-7 wt%. In this invention, the mass ratio of N,N-dimethylglyoxal to the hydrogenation catalyst is preferably 10-2000:1, more preferably 20-500:1, and most preferably 50-80:1.

[0034] In this invention, the dimethylamine is preferably high-purity dimethylamine or a 40wt% aqueous solution of dimethylamine, more preferably high-purity dimethylamine, and the purity of the high-purity dimethylamine is preferably ≥99.5%. In this invention, the molar ratio of N,N-dimethylglyoxal to dimethylamine is preferably 1:1 to 1.1, more preferably 1:1.02 to 1.08, and most preferably 1:1.04 to 1.06.

[0035] In this invention, the temperature of the methylation hydrogenation reaction is preferably 80-130°C, more preferably 90-120°C, and most preferably 100-110°C; the time of the methylation hydrogenation reaction is preferably 0.5-4 h, more preferably 1-3.5 h, and most preferably 1.5-2.5 h; and the pressure of the hydrogen gas is preferably 1-4 MPa, more preferably 2-3 MPa.

[0036] This invention first prepares the intermediate product N,N-dimethylglyoxal, and then mixes it with dimethylamine for a methylation hydrogenation reaction. This avoids the negative impact of using a mixture of hydrogenation and oxidation catalysts, and also avoids the decomposition of dimethylamine during the oxidation reaction stage, which would reduce the product yield.

[0037] Following the methylation hydrogenation reaction, the present invention preferably further includes: subjecting the obtained methylation hydrogenation reaction solution to a second heat preservation, a second cooling, pressure relief, and distillation sequentially to obtain N,N,N,N-tetramethylethylenediamine. In this invention, the temperature of the second heat preservation is preferably the same as the temperature of the methylation hydrogenation reaction; the duration of the second heat preservation is preferably 0.1–2 h, more preferably 0.5–1.5 h, and most preferably 1 h. In this invention, the methylation hydrogenation reaction solution undergoes a second heat preservation, during which no hydrogen gas is introduced, to ensure the reaction is as complete as possible. In this invention, the endpoint temperature of the second cooling is preferably room temperature. The present invention does not have a particular limitation on the rate of the second cooling, as long as the temperature is reduced to room temperature. In this invention, the distillation is preferably carried out in a distillation column. In this invention, the hydrogenation catalyst is preferably recovered after the second cooling.

[0038] The present application takes N,N-dimethylethanolamine as the initial raw material, and first oxidizes the N,N-dimethylethanolamine to obtain the intermediate product N,N dimethylglyoxal. The intermediate product is unstable, and needs to be quickly methylated and hydrogenated with dimethylamine. Therefore, the first step reaction liquid is pressed into a secondary kettle by N2, and the hydrogenation reaction is carried out with dimethylamine in the presence of hydrogen to obtain N,N,N,N-tetramethyl ethylenediamine. The raw material is low in price and easy to obtain, the reaction selectivity is good, the product purity is high, the yield is high, the raw material conversion rate is high, and the present application has industrial value. Compared with the ethylenediamine formaldehyde method, the present application avoids the use of formaldehyde aqueous solution (which will produce by-product methanol) and ethylenediamine (which will produce by-product N,N dimethyl ethylenediamine), and the raw material ethylenediamine is relatively high in price, which is not conducive to industrial production and sales; compared with the dichloroethane method, the dimethylamine aqueous solution used in the present application only needs a slight excess, and will not produce a large amount of by-products, and at the same time avoids the production of a large amount of industrial waste salt by the dichloroethane method, causing environmental pollution; compared with the DMEA one-pot method, the present application avoids the use of Cu / Ni catalyst, and thus will not appear the problem that the Cu / Ni catalyst is corroded by amine, resulting in the need to frequently replace the catalyst of the fixed bed, and the yield and conversion rate are higher, and the preparation cost is low.

[0039] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0040] In specific embodiments of the present application, the high-purity dimethylamine is from Nantong Jiuwu Chemical Co., Ltd., with a purity of 99.5% or more; the hydrogen is from Jining Xielv Energy Co., Ltd., with a purity of 99.999%; the air is from Jining Xielv Energy Co., Ltd., with a purity of 99.999%; the oxidation catalyst and the hydrogenation catalyst are from Zhuangxinwanfeng Catalyst Co., Ltd.; the N,N-dimethylethanolamine and the dioxane are from Sinopharm Group Pharmaceutical Co., Ltd.

[0041] Example 1

[0042] Put 100 g of N,N-dimethylethanolamine, 0.5 g of 5 wt% Pt / C catalyst and 100 g of dioxane into a primary reactor, replace the air in the primary reactor with N2, then introduce pure air, maintain the pressure at 2 MPa, start stirring at a speed of 600 rpm, heat to 70°C, react for 5 h, keep the temperature for 1 h, cool to room temperature, release the pressure, recover the oxidation catalyst by filtration, and obtain the reaction liquid in the primary reactor; put 0.5 g of 5 wt% Pd / C catalyst and 130 g of 40 wt% dimethylamine aqueous solution into a secondary reactor, replace the air in the secondary reactor with N2, then press the reaction liquid in the primary reactor into the secondary reactor with N2, start stirring at a speed of 600 rpm, introduce hydrogen, the hydrogen pressure is 2 MPa, heat to 110°C, react for 6 h, keep the temperature for 1 h, cool to room temperature, release the pressure, recover the hydrogenation catalyst by filtration, and obtain the crude N,N,N,N-tetramethylethylenediamine.

[0043] The raw material conversion rate and selectivity were analyzed using an Agilent 7890B gas analyzer, and the gas chromatography analysis conditions were as follows: the chromatographic column was an HP-5 chromatographic column; the vaporization chamber temperature was 240°C; the FID detector temperature was 280°C; the column oven temperature was programmed, the temperature program was 0-1 min, 60°C; 1-15 min, uniformly increased from 60°C to 200°C; 15-19 min, uniformly increased from 200°C to 280°C; 19-21 min, 280°C. The GC test results of the crude N,N,N,N-tetramethylethylenediamine showed that the conversion rate of N,N-dimethylethanolamine was 99.9%, the selectivity of N,N,N,N-tetramethylethylenediamine was 98.5%, and the raw material conversion rate and the target product selectivity were high.

[0044] The crude N,N,N,N-tetramethylethylenediamine was subjected to rectification to obtain pure N,N,N,N-tetramethylethylenediamine with a purity of 99.9%. The obtained pure N,N,N,N-tetramethylethylenediamine was subjected to structure characterization using a Shimadzu IRIaffinity-1S Fourier transform infrared spectrometer and an Agilent 7890B gas analyzer, and the gas chromatography analysis conditions were as follows: the chromatographic column was an HP-5 chromatographic column; the FID detector temperature was 280°C; the SPL1 temperature was 280°C, the column oven temperature was 320°C; the total flow rate was 105 mL / min; the pressure was 150.0 kPa; the split ratio was 50:1; and the carrier gas was nitrogen.

[0045] The structure characterization results of the pure N,N,N,N-tetramethylethylenediamine are shown in Figure 2 and Figure 3 , wherein, Figure 2 is the infrared chromatogram of the pure N,N,N,N-tetramethylethylenediamine; Figure 3 is the gas chromatogram of the pure N,N,N,N-tetramethylethylenediamine. From Figures 2-3It can be confirmed that the product obtained by the preparation method provided by the application is the target product N,N,N,N-tetramethylethylenediamine.

[0046] Example 2

[0047] 100 g of N,N-dimethylethanolamine, 1.5 g of 5 wt% Pt / C catalyst and 100 g of dioxane were put into a primary kettle, the primary kettle was replaced with N2 after air replacement, pure air was introduced, the pressure was maintained at 1.5 MPa, stirring was started, the rotating speed was 600 rpm, the temperature was raised to 90°C, reaction was carried out for 5 h, the temperature was maintained for 1 h, the temperature was cooled to room temperature, pressure relief was carried out, the oxidation catalyst was recovered by filtration, and the reaction liquid of the primary kettle was obtained; 1 g of Raney nickel catalyst and 52 g of high-purity dimethylamine were put into a secondary kettle, the secondary kettle was replaced with N2 after air replacement, the reaction liquid of the primary kettle was pressurized into the secondary kettle using N2, stirring was started, the rotating speed was 600 rpm, the temperature was raised to 110°C, hydrogen was introduced, the hydrogen pressure was 2 MPa, reaction was carried out for 6 h, the temperature was maintained for 1 h, the temperature was cooled to room temperature, pressure relief was carried out, the hydrogenation catalyst was recovered by filtration, and N,N,N,N-tetramethylethylenediamine crude product was obtained.

[0048] The raw material conversion rate and selectivity were analyzed using an Agilent 7890B gas analyzer, and the gas chromatography analysis conditions were the same as in Example 1. The GC test results of the N,N,N,N-tetramethylethylenediamine crude product showed that the conversion rate of N,N-dimethylethanolamine was 99.8%, and the selectivity of N,N,N,N-tetramethylethylenediamine was 98.3%. The N,N,N,N-tetramethylethylenediamine crude product was subjected to rectification, and N,N,N,N-tetramethylethylenediamine pure product was obtained, with a purity of 99.9%.

[0049] Example 3

[0050] 100 g of N,N-dimethylethanolamine, 1.5 g of 5 wt% Pt / C catalyst and 100 g of dioxane were put into a primary kettle, the primary kettle was replaced with N2 after air replacement, pure air was introduced, the pressure was maintained at 1.5 MPa, stirring was started, the rotating speed was 600 rpm, the temperature was raised to 90°C, reaction was carried out for 5 h, the temperature was maintained for 1 h, the temperature was cooled to room temperature, pressure relief was carried out, the oxidation catalyst was recovered by filtration, and the reaction liquid of the primary kettle was obtained; 1 g of Raney nickel catalyst and 52 g of high-purity dimethylamine were put into a secondary kettle, the secondary kettle was replaced with N2 after air replacement, the reaction liquid of the primary kettle was pressurized into the secondary kettle using N2, stirring was started, the rotating speed was 600 rpm, the temperature was raised to 110°C, hydrogen was introduced, the hydrogen pressure was 2 MPa, reaction was carried out for 6 h, the temperature was maintained for 1 h, the temperature was cooled to room temperature, pressure relief was carried out, the hydrogenation catalyst was recovered by filtration, and N,N,N,N-tetramethylethylenediamine crude product was obtained.

[0051] The raw material conversion rate and selectivity were analyzed using Agilent 7890B gas analyzer, and the gas chromatography analysis conditions were the same as in Example 1. The GC test results of the crude N,N,N,N-tetramethylethylenediamine showed that the conversion rate of N,N-dimethylethanolamine was 99.9%, and the selectivity of N,N,N,N-tetramethylethylenediamine was 98.7%. The crude N,N,N,N-tetramethylethylenediamine was subjected to rectification to obtain pure N,N,N,N-tetramethylethylenediamine with a purity of 99.9%.

[0052] Example 4

[0053] Performance verification of catalyst reuse

[0054] In similar reactions or other processes of the product, it is difficult for the hydrogenation catalyst to be reused for many times due to corrosion by amines and consumption in reactions, and frequent replacement of the catalyst greatly affects production efficiency and production cost. Therefore, it is very important that the catalyst can be reused for many times and the performance of the catalyst is stable. In this embodiment, based on the preparation method provided in Example 1, 10 cycles of reuse tests of the oxidation catalyst and the hydrogenation catalyst were carried out, and the test results are shown in Table 1.

[0055] Table 1: Test results of 10 cycles of reuse tests of the oxidation catalyst and the hydrogenation catalyst

[0056] Number of applications DMEA conversion TMEDA selectivity 1 99.9 98.7 2 99.9 98.5 3 99.8 98.4 4 99.8 98.5 5 99.8 98.6 6 99.7 98.7 7 99.7 98.6 8 99.7 98.7 9 99.7 98.4 10 99.7 98.5

[0057] As shown in Table 1, after 10 cycles of reuse tests of the oxidation catalyst and the hydrogenation catalyst adopted in the present application, the conversion rate of DMEA is ≥99.7%, and the selectivity of TMEDA is higher than 98.4%. It is indicated that after multiple cycles of reuse of the oxidation catalyst and the hydrogenation catalyst adopted in the present application, the catalytic activity almost does not decrease obviously, the stability is good, the catalytic performance is good, and the raw material conversion rate and the selectivity of the target product are high.

[0058] Comparative Example 1

[0059] 15.3 g of ethylenediamine and 0.1 g of 5% Pt / C catalyst were put into a reaction kettle, N2 was used to replace air, then hydrogen was introduced, the pressure was maintained at 2.5 MPa, stirring was started, the rotation speed was 600 rpm, and the temperature was increased to 110°C. 37% formaldehyde aqueous solution was added into the reaction kettle through a laminar flow pump at a flow rate of 0.01 ml / min, the dropping reaction was carried out for 6 h, the temperature was maintained for 1 h, then the temperature was cooled to room temperature, the pressure was released, the 5 wt% Pt / C catalyst was recovered by filtration, and crude N,N,N,N-tetramethylethylenediamine was obtained. The crude product was subjected to rectification to obtain pure N,N,N,N-tetramethylethylenediamine.

[0060] The raw material conversion rate and selectivity were analyzed using Agilent 7890B gas analyzer, and the gas chromatography analysis conditions were the same as those in Example 1. GC results of crude N,N,N,N-tetramethylethylenediamine: EDA conversion rate 86.9%, TMEDA selectivity 78.7%.

[0061] As can be seen by comparing Example 1 and Comparative Example 1, the preparation method provided by the present application has higher raw material conversion rate and target product selectivity, and has excellent industrial value.

[0062] Although the above examples have described the present application in detail, they are only part of the examples of the present application, but not all the examples, and other examples can be obtained according to the examples without creativity, which all belong to the protection scope of the present application.

Claims

1. A process for the preparation of N,N,N,N-tetramethylethylenediamine, characterized in that, The method comprises the following steps: Mixing N,N-dimethylethanolamine, an oxidation catalyst and a soluble N,N-dimethylethanolamine solvent in an oxygen-containing atmosphere to perform an oxidation reaction to obtain N,N-dimethylaminoacetaldehyde; the oxidation catalyst comprises a platinum-carbon catalyst, and the loading of platinum in the platinum-carbon catalyst is 4-8 wt%; Mixing the N,N-dimethylaminoacetaldehyde with dimethylamine and a hydrogenation catalyst in a protective atmosphere, introducing hydrogen, and performing a reductive amination reaction to obtain N,N,N,N-tetramethylethylenediamine; the hydrogenation catalyst is Raney nickel or a palladium-carbon catalyst; the temperature of the reductive amination reaction is 100-110 DEG C; and the pressure of the hydrogen is 2-3 MPa.

2. The production method according to claim 1, characterized by, The mass ratio of the N,N-dimethylethanolamine to the oxidation catalyst is 10-2000:

1.

3. The preparation method according to claim 1, characterized in that, The soluble N,N-dimethylethanolamine solvent comprises dioxane.

4. The production method according to claim 1 or 3, characterized by, The molar ratio of the N,N-dimethylethanolamine to the soluble dimethylethanolamine solvent is 1-4:

1.

5. The production method according to claim 1 or 3, characterized by, The temperature of the oxidation reaction is 50-100 DEG C, and the time is 2-6 h; the oxygen-containing atmosphere comprises air and / or oxygen; and the pressure of the oxygen-containing atmosphere is 1-4 MPa.

6. The method of claim 1, wherein, The mass ratio of the N,N-dimethylaminoacetaldehyde to the hydrogenation catalyst is 10-2000:

1.

7. The preparation method according to claim 1, characterized in that, The molar ratio of the N,N-dimethylaminoacetaldehyde to the dimethylamine is 1:1-1.

1.

8. The method of claim 1, wherein, The time of the reductive amination reaction is 0.5-6 h.

Images