A method for directly synthesizing N,N,N′,N′-tetramethylmethyldiamine from dimethylamine aqueous solution via electrochemical amine methyleneization.

Abstract

This invention belongs to the field of electrochemical synthesis, specifically disclosing a method for directly synthesizing N,N,N′,N′-tetramethylmethyldiamine from an aqueous dimethylamine solution via electrochemical amine methyleneization. This method uses an aqueous dimethylamine solution as a raw material and achieves the synthesis of N,N,N′,N′-tetramethylmethyldiamine through electro-driven oxidation at the anode of a carbon-supported catalyst. This invention differs from existing methods such as the condensation of dimethylamine with formaldehyde and the electrosynthesis of dimethylamine with methanol. It directly uses an industrial-grade aqueous dimethylamine solution as a raw material to synthesize N,N,N′,N′-tetramethylmethyldiamine, simplifying the process flow. It features mild process conditions, high system stability, few byproducts, environmental safety, low cost, and suitability for industrial applications. This method has broad application potential in numerous fields such as electrochemical organic synthesis, energy storage, and pharmaceutical chemicals.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical synthesis, specifically relating to an electrochemical amine methyleneization synthesis method of dimethylamine aqueous solution, and more particularly to a method for synthesizing N,N,N′,N′-tetramethyldiamine on the anode of a carbon-supported catalyst by electro-driven oxidation using industrial dimethylamine aqueous solution as raw material. Background Technology

[0002] N,N,N′,N′-Tetramethylmethyldiamine (TMMDA) is an important amine derivative with wide applications in pharmaceutical synthesis, fine chemicals, and organic synthesis due to its unique structure and chemical properties. As a key intermediate in organic synthesis, it is often used as a building block for drug molecules, a catalyst ligand, and a chemical auxiliary, exhibiting high application value and market demand.

[0003] Currently, the mainstream industrial process for preparing N,N,N′,N′-tetramethylmethyldiamine involves a condensation reaction of dimethylamine and formaldehyde. However, formaldehyde, as a reactant, exhibits high reactivity and readily triggers side reactions, resulting in poor product selectivity. Furthermore, this process requires strict control over reactant ratios and temperature, and the generation of byproducts increases the complexity of post-processing and separation, hindering green and efficient production. Other literature reports methods for synthesizing N,N,N′,N′-tetramethylmethyldiamine using dimethylamine and methanol under electrochemical conditions. These methods typically utilize electrocatalytic oxidation to promote the reaction, avoiding the use of highly reactive raw materials such as formaldehyde. However, methanol undergoes multiple dehydrogenation steps and parallel side reactions in the electrochemical reaction, resulting in a complex reaction pathway and the easy generation of byproducts such as formic acid and dimethyl ether, thereby reducing the selectivity and Faraday efficiency of the target product. Additionally, this method is highly dependent on electrode materials, electrolyte systems, and electrochemical conditions, and has high energy consumption, limiting its feasibility for large-scale industrial application. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for directly synthesizing N,N,N′,N′-tetramethylmethyldiamine from an aqueous dimethylamine solution via electrochemical amine methyleneization. This method eliminates the need for highly reactive raw materials such as formaldehyde, effectively reducing side reactions and thus improving the selectivity and Faraday efficiency of the target product. Furthermore, the process conditions employed in this invention are mild, the system exhibits high stability, and few byproducts, reducing post-processing difficulty and energy consumption. This contributes to achieving a green, efficient, and sustainable synthetic route, demonstrating promising prospects for industrial application.

[0005] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0006] A method for directly synthesizing N,N,N′,N′-tetramethylmethyldiamine from dimethylamine aqueous solution via electrochemical amine methyleneization comprises the following steps: adding dimethylamine aqueous solution to the anode of an electrolyzer, and performing electrochemical amine methyleneization of dimethylamine on the anode of a carbon-supported catalyst using electro-driven oxidation to achieve the synthesis of N,N,N′,N′-tetramethylmethyldiamine.

[0007] Furthermore, the concentration of the dimethylamine aqueous solution is 5-50 wt.%. If it exceeds the specified range, it will lead to a significant decrease in the Faraday efficiency and reaction voltage of the electrochemical amine methyleneization reaction of dimethylamine, resulting in reduced energy efficiency and increased side reactions.

[0008] Furthermore, the electrochemical amine methyleneization reaction is carried out at 10-100 mA cm⁻¹. -2 The test was conducted at a current density below 10 mA cm⁻¹. -2 The yield of dimethylamine in the electrochemical amine methyleneation reaction will be significantly reduced, resulting in low energy efficiency; if the energy level is higher than 100 mA cm⁻¹, the yield will be significantly reduced. -2 The Faraday efficiency of the electrochemical amine methyleneization reaction of dimethylamine will be significantly reduced, resulting in decreased energy efficiency and increased side reactions.

[0009] Furthermore, the electrolyzer is a proton exchange membrane (PEM) bipolar electrolyzer.

[0010] Furthermore, the anode of the electrolyzer can be any conductive electrode supporting the catalyst, including but not limited to conductive supports such as carbon cloth, carbon paper, carbon felt, and titanium mesh; the conductive support can be coated with heteroatom-doped carbon material catalyst to improve conversion efficiency and selectivity, wherein the heteroatom doping includes but is not limited to boron, nitrogen, and other element doping, preferably boron doping; the proportion of doped atoms to the total atoms of the catalyst is 1-20 at.%; if it exceeds this range, the catalyst has a poor catalytic effect on the electrochemical amine methyleneization reaction of dimethylamine, the reaction voltage is high, and the Faraday efficiency and energy efficiency are low.

[0011] Furthermore, the cathode of the electrolyzer can be any conductive electrode loaded with a catalyst, including but not limited to conductive supports such as carbon cloth, carbon paper, carbon felt, and titanium mesh; the conductive support can be coated with a noble metal platinum-based catalyst to reduce the reaction voltage.

[0012] The present invention has the following beneficial effects:

[0013] Using dimethylamine aqueous solution as a raw material, N,N,N′,N′-tetramethylmethyldiamine is synthesized by electro-driven oxidation on the anode of a carbon-supported catalyst through the amine methyleneation reaction of dimethylamine. This synthetic method features simple process, mild conditions, high system stability, few by-products, green and safe operation, easy control, and the ability to achieve large-scale production. Attached Figure Description

[0014] Figure 1 The reaction voltage and the Faradaic efficiency of the product N,N,N′,N′-tetramethyldiamine in Examples 1-3 are given.

[0015] Figure 2 The voltage-current curve is shown for the synthesis of N,N,N′,N′-tetramethylmethyldiamine via electrochemical amine methyleneization of dimethylamine.

[0016] Figure 3 This is a chromatogram of the product analysis after the reaction in Example 1.

[0017] Figure 4 This is a working curve diagram of the long-term stability test in Example 1.

[0018] Figure 5 This is an analysis chart of the anode and cathode products from the long-term stability test in Example 1. In the chart, the yellow bars represent the anode energy efficiency, the yellow curve represents the anode Faraday efficiency, and the green curve represents the cathode Faraday efficiency. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the reagents used in the following embodiments are all commercially available conventional reagents, and the experimental procedures involved are all conventional procedures in the art unless otherwise specified.

[0020] The key sources of the materials are as follows:

[0021] Material source Boron-doped carbon catalysts Take 0.5g of Ketjen Black and mix it with 0.5-10g (5g specifically in Examples 1-14, yielding a boron doping ratio of approximately 2-5 at.%) of boric acid, then add the mixture to a solution of 150mL deionized water and 20mL ethylene glycol. Heat the solution at 80°C and stir until it reaches a gel state, then calcine it at 800°C for 2 hours under a nitrogen atmosphere. After the sample cools to room temperature, remove it for later use. Nitrogen-doped carbon catalysts Take 0.5 g of Ketjen Black and mix it with 0.5-10 g (5 g specifically in Examples 1-14, yielding a nitrogen doping atomic ratio of approximately 2-5 at.%) of dicyandiamine, then add the mixture to 150 mL of deionized water. Heat and stir the mixture at 80 °C until dry, then calcine it at 800 °C for 2 hours under a nitrogen atmosphere. After the sample cools to room temperature, remove it for later use. KetjenBlack Purchased from Lion Corporation, model number Ketjenblack ECP-600JD. Carbon paper Purchased from Ballard, model GDS3250. Platinum-based catalysts Purchased from Johnson Matthey, model number HiSPEC4000. Nafion solution Purchased from DuPont, model number D-1020. Proton exchange membrane Purchased from DuPont, model number Nafion N115.

[0022] Example 1

[0023] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then assembled with a proton exchange membrane (MEA) via hot pressing to form a membrane electrode assembly (MEA). A platinum-based catalyst-loaded carbon paper served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and placed between bipolar plates. A torque of 7.0 N·m was used to tighten the assembly to ensure close contact between the plates, electrodes, and the MEA, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 40 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0024] Example 2

[0025] 10 mg of Ketjen Black was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. The resulting Ketjen Black-loaded carbon paper, after drying and curing, served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A platinum-based catalyst-loaded carbon paper was used as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, placed between bipolar plates. A torque of 7.0 N·m was used to tighten the structure, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 40 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0026] Example 3

[0027] 10 mg of nitrogen-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the nitrogen-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the structure, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 40 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0028] Example 4

[0029] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of a carbon cloth. After drying and curing, the carbon cloth loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly and placed between bipolar plates. The assembly was tightened with a torque of 7.0 N·m to ensure tight contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 40 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0030] Example 5

[0031] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of a carbon felt. After drying and curing, the carbon felt loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly and placed between bipolar plates. The assembly was tightened with a torque of 7.0 N·m to ensure tight contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 40 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0032] Example 6

[0033] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of a titanium mesh. After drying and curing, the titanium mesh loaded with boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). Carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the structure, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 40 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0034] Example 7

[0035] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the structure, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 5 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0036] Example 8

[0037] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the structure, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 10 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0038] Example 9

[0039] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A platinum-based catalyst-loaded carbon paper served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and placed between bipolar plates. A torque of 7.0 N·m was used to tighten the assembly, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 20 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0040] Example 10

[0041] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the assembly to ensure close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 30 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0042] Example 11

[0043] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A platinum-based catalyst-loaded carbon paper served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and placed between bipolar plates. A torque of 7.0 N·m was used to tighten the assembly, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 50 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 50 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0044] Example 12

[0045] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A platinum-based catalyst-loaded carbon paper served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and placed between bipolar plates. The assembly was tightened with a torque of 7.0 N·m to ensure tight contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 5 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 10 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0046] Example 13

[0047] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the assembly to ensure close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 5 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 20 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0048] Example 14

[0049] 10 mg of boron-doped carbon catalyst was weighed and mixed with 700 μL of ethanol, 200 μL of deionized water, and 100 μL of Nafion solution to prepare a homogeneous slurry. 100 μL of the obtained slurry was uniformly coated onto one side of carbon paper. After drying and curing, the carbon paper loaded with the boron-doped carbon catalyst served as the anode. The catalyst-coated side was then hot-pressed onto a proton exchange membrane to form a membrane electrode assembly (MEA). A carbon paper loaded with a platinum-based catalyst served as the cathode, forming an anode-proton exchange membrane-cathode sandwich structure with the MEA assembly, and was placed between bipolar plates. A torque of 7.0 N·m was used to tighten the structure, ensuring close contact between the plates, electrodes, and membrane electrode, thus assembling a proton exchange membrane (PEM) bipolar electrolyzer for testing. A 5 wt.% dimethylamine aqueous solution was added to the anode chamber, and the mixture was heated to 100 mA cm⁻¹. -2 At a current density and room temperature, the electrochemical methyleneization reaction of amines was carried out at the anode.

[0050] All of the above examples successfully synthesized N,N,N′,N′-tetramethylmethyldiamine. Based on Examples 1-3, the synthesis method of N,N,N′,N′-tetramethylmethyldiamine by electrochemical amine methyleneization of dimethylamine is evaluated as follows.

[0051] Figure 1 The figures show the reaction voltage and the Faradaic efficiency of the product N,N,N′,N′-tetramethylmethyldiamine in Examples 1-3. It can be seen that the reaction voltage and Faradaic efficiency in the process of synthesizing N,N,N′,N′-tetramethylmethyldiamine by electrochemical amine methyleneization of dimethylamine depend on the type of anode support material. Boron-doped carbon has a lower reaction voltage and a higher Faradaic efficiency, indicating that the boron-doped catalyst has higher activity, higher selectivity and produces fewer byproducts for this reaction.

[0052] Figure 2 The voltage-current curve for the synthesis of N,N,N′,N′-tetramethylmethyldiamine via electrochemical amine methyleneization of dimethylamine was obtained by varying the current conditions based on Example 1. Figure 2 It can be seen that the current density of the electrochemical amine methyleneization process gradually increases with the increase of the reaction voltage, indicating that it can operate stably in a wide electrochemical window and the reaction has good controllability.

[0053] Figure 3 The analysis of the product after the reaction in Example 1, by comparing with the gas chromatography of the standard N,N,N′,N′-tetramethylmethylenediamine solution, proved that N,N,N′,N′-tetramethylmethylenediamine can be effectively synthesized by electrochemical amine methyleneization.

[0054] Figure 4The working curves for the long-term stability test in Example 1 show that the process of synthesizing N,N,N′,N′-tetramethyldiamine by electrochemical amine methyleneization of dimethylamine has good stability, and no significant performance degradation was observed after continuous operation for more than 200 hours.

[0055] Figure 5 Analysis of the anode and cathode products from the long-term stability test in Example 1 shows that the process of synthesizing N,N,N′,N′-tetramethylmethyldiamine via electrochemical amine methyleneization of dimethylamine can ensure continuous and efficient production of N,N,N′,N′-tetramethylmethyldiamine at the anode, with a Faraday efficiency >90% and an energy efficiency of approximately 2.71 mmol kJ. −1 Meanwhile, the cathode can stably produce hydrogen with a Faraday efficiency of over 90%, indicating that this method has low energy consumption and good stability.

[0056] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims of the present invention, will be protected by patent law.

Claims

1. A method for directly synthesizing N,N,N′,N′-tetramethylmethyldiamine from an aqueous dimethylamine solution via electrochemical amine methyleneization, characterized in that, The steps are as follows: The dimethylamine aqueous solution is added to the anode of the electrolyzer, and the electrochemical amine methyleneization reaction of dimethylamine is carried out on the anode of the carbon-supported catalyst by electro-driven oxidation to achieve the synthesis of N,N,N′,N′-tetramethylmethyldiamine. The concentration of the dimethylamine aqueous solution is 5-50 wt.%; the anode includes a conductive support and a heteroatom-doped carbon material catalyst coated on the conductive support, wherein the heteroatom doping includes boron and nitrogen doping, and the heteroatom accounts for 1-20 at.% of the total atomic ratio of the catalyst.

2. The method according to claim 1, characterized in that, The electrochemical amine methyleneation reaction is carried out at 10-100 mAcm. -2 The experiment was conducted at a current density of [specific value].

3. The method according to claim 1, characterized in that, The electrolyzer is a proton exchange membrane bipolar electrolyzer.

4. The method according to claim 1, characterized in that, The conductive carrier of the anode is selected from carbon cloth, carbon paper, carbon felt or titanium mesh.

5. The method according to any one of claims 1-4, characterized in that, The cathode of the electrolyzer includes a conductive support and a noble metal platinum-based catalyst coated on the conductive support.

6. The method according to claim 5, characterized in that, The conductive carrier of the cathode is selected from carbon cloth, carbon paper, carbon felt or titanium mesh.

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