A method and device for preparing tetrakis (dimethylamino) tin

Abstract

The application discloses a method and a matching device for preparing tetra (dimethylamino) tin, and the method comprises the following steps: dimethylamine is vaporized, water is removed through molecular sieve / activated carbon composite adsorption, nitrogen and oxygen are removed through deep cooling, and heavy metals are removed; after being condensed and liquefied, the dimethylamine is accurately sent into a reaction kettle through a liquid metering flowmeter, and then reacts with n-butyllithium to synthesize dimethylaminolithium; then, the dimethylaminolithium reacts with tin tetrachloride, the product is separated through solid-liquid separation and reduced pressure distillation, and the n-hexane solvent is closed-loop recycled (one-way recovery rate is greater than or equal to 95%), so that high-purity tetra (dimethylamino) tin is obtained. Through the synergistic integration of four-stage deep purification, accurate metering of the feed, two-stage temperature control synthesis in a narrow temperature range and solvent closed-loop recovery, the product yield is greater than or equal to 91%, and the metal impurities are less than 100 ppb, so that the method is suitable for large-scale production of high-purity precursors.

Description

Technical Field

[0001] This invention relates to the field of metal-organic compound precursor preparation technology for integrated circuit manufacturing, and particularly to a method and supporting preparation apparatus for preparing high-purity tetra(dimethylamino)tin. Background Technology

[0002] With the continuous development of integrated circuit manufacturing technology and the shrinking feature size of semiconductor devices, atomic layer deposition (ALD) has become a core process for high-performance thin film preparation due to its excellent step coverage and precise film thickness control. Tetra(dimethylamino)tin (TDMASn) is the core ALD precursor for preparing tin oxide thin films. It has the advantages of being liquid at room temperature, having high saturated vapor pressure, and moderate thermal stability, and is widely used in the preparation of thin films in fields such as photovoltaic electronic transport layers, semiconductor sensors, and lithium battery anode modification films.

[0003] The current mainstream synthetic route for tetra(dimethylamino)tin involves synthesizing dimethylaminolithium from dimethylamine and organolithium at low temperature, followed by an aminolysis reaction with tin tetrachloride to generate the target product. However, this route still faces several technical limitations in large-scale production. First, the reaction conditions are harsh. Existing technologies (such as US20220402946A1) use extremely low temperature conditions of -50℃ to synthesize dimethylaminolithium, which has high energy consumption for refrigeration, large equipment investment, high difficulty in safety management, and poor economic efficiency for mass production.

[0004] Second, the solvent is highly toxic. Existing technologies (such as WO2019023797A1) use benzene as a solvent to dissolve tin tetrachloride. Benzene is a Class I carcinogenic solvent, and its environmental treatment costs are high, which seriously limits industrial-scale production expansion.

[0005] Third, the raw material feeding is uncontrollable. Existing technologies (such as WO2019023797A1 and CN117603251A) use a continuous bubbling method for feeding dimethylamine gas, which lacks precise metering methods, resulting in large raw material losses and poor batch-to-batch reaction consistency, leading to significant fluctuations in product purity.

[0006] Fourth, there is a lack of raw material pretreatment. Existing technologies only perform simple drying treatment on dimethylamine, which cannot effectively remove dissolved oxygen, nitrogen, and trace heavy metal impurities from dimethylamine. These impurities will eventually enter the product, reduce the product purity, and increase the difficulty and cost of subsequent distillation and purification.

[0007] Furthermore, prior art document CN117247404A discloses a method for preparing semiconductor-grade tetra(dimethylamino)tin. This method involves adding an organolithium compound and a hydrocarbon solvent to a reactor under inert gas protection, then cooling the mixed solution to -45°C to -25°C, introducing dimethylamine gas to react and produce dimethylaminolithium, and then adding tin tetrachloride (temperature controlled at -50°C to 35°C) to the reactor to react and produce tetra(dimethylamino)tin [Prior Art Document 3]. However, this technical solution still uses a gas bubbling method for feeding, lacks deep purification treatment of the dimethylamine raw material, and does not involve solvent recovery and recycling.

[0008] In summary, although the core reaction routes of existing synthetic processes have been disclosed, the entire process lacks a complete, high-purity, and scalable integrated pretreatment-synthesis-posttreatment scheme. The parameters of each step are not synergistically optimized, making it difficult to simultaneously achieve high yield, high purity, and low-cost large-scale production. Therefore, there is an urgent need to develop an integrated preparation process and supporting equipment that integrates multi-stage deep purification of dimethylamine, precise metering, low-temperature controllable synthesis, and solvent closed-loop recovery. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and supporting apparatus for preparing tetra(dimethylamino)tin. Through the synergistic design of four-stage deep purification of dimethylamine, narrow-range mild low-temperature synthesis, precise liquid-phase metering and feeding, and closed-loop solvent recovery, mild reaction conditions, no highly toxic solvents, low raw material loss, and double improvement in product yield and purity are achieved, making it suitable for the large-scale stable production of high-purity precursors.

[0010] To achieve the above objectives, the present invention adopts the following technical solution.

[0011] A set of apparatus for preparing tetra(dimethylamino)tin includes a dimethylamine filtration device (1), a dimethylamine cryogenic trapping device (2), a reaction vessel (3), a solid-liquid separation device (4), and a distillation and desolvation device (5) connected in sequence. The dimethylamine filtration device (1) is arranged in sequence along the material flow direction as a gasification unit and a composite adsorption unit filled with molecular sieve and activated carbon at a mass ratio of 2:1. The composite adsorption unit is used to remove moisture from dimethylamine to a water content of ≤1ppm. The dimethylamine cryogenic collection device (2) is temperature controlled at -70℃ to -60℃ and is used for cryogenic removal of dissolved nitrogen, oxygen and trace heavy metal impurities from dimethylamine. The outlet end of the dimethylamine cryogenic collection device (2) is equipped with a condensation and liquefaction unit with a temperature controlled at -10℃ to 0℃. The outlet of the condensation and liquefaction unit is connected to a liquid metering flow meter, and the flow rate of the liquid metering flow meter is controlled at 0.3L / min to 0.6L / min. The reactor (3) is equipped with a circulating oil bath temperature control system, a mechanical stirring unit, a liquid feeding port, and an inert gas protection pipeline. The feed port of the reactor (3) is sealed and connected to the discharge port of the liquid metering flow meter. The reactor (3) contains a sufficient amount of n-hexane solvent and a 2.5 mol / L n-butyllithium n-hexane solution. The feed inlet of the solid-liquid separation device (4) is connected to the discharge outlet of the reaction vessel (3), the solid outlet of the solid-liquid separation device (4) is connected to the lithium chloride by-product collection tank, and the liquid outlet is connected to the distillation and desolvation device (5). The distillation and desolventizing device (5) is equipped with a vacuum pump unit, a condensation and recovery unit, and a product collection tank. The solvent recovery pipeline of the distillation and desolventizing device (5) is returned to the reaction vessel (3) to realize the recycling and reuse of n-hexane. The single-pass recovery rate of n-hexane is ≥95%.

[0012] The method for preparing tetra(dimethylamino)tin using the above apparatus, with inert gas protection throughout, includes the following stages: S1: Raw Material Preparation Prepare sufficient amounts of n-hexane solvent, dimethylamine, 2.5 mol / L n-butyllithium n-hexane solution, and anhydrous tin tetrachloride; all raw materials should be pre-deoxygenated and sealed for storage.

[0013] S2: Reactor Pretreatment ① Add a 2.5 mol / L n-butyllithium n-hexane solution and n-hexane solvent in a mass ratio of 1:4~5 to the reaction vessel (3), and start the mechanical stirring simultaneously, controlling the stirring speed to 50~150 r / min; ② Cool the system inside the reactor to -12℃~-8℃ using a circulating oil bath, and let it stand at a constant temperature for 30 minutes to complete the low-temperature pretreatment.

[0014] S3: Multi-stage deep purification and precise liquid-phase metering feed of dimethylamine ① Dimethylamine is passed into the dimethylamine filtration device (1). After being completely gasified by the gasification unit, it enters the composite adsorption unit filled with molecular sieve and activated carbon at a mass ratio of 2:1 to remove moisture and water-soluble ammonia impurities from the dimethylamine until the water content is ≤1ppm, thus obtaining purified dimethylamine gas. ② The first-purified dimethylamine gas is introduced into a dimethylamine cryogenic collection device (2) with a temperature control of -70℃ to -60℃ to remove dissolved nitrogen, oxygen and trace heavy metal impurities, and obtain the second-purified dimethylamine gas; ③ The secondary purified dimethylamine gas is introduced into the condensation and liquefaction unit with a temperature control of -10℃~0℃ and completely liquefied. The liquid dimethylamine is fed into the reactor (3) at a flow rate of 0.3L / min~0.6L / min through a liquid metering flow meter. The total amount of injected dimethylamine is 1.05:1 in molar ratio to n-butyllithium. ④ Maintain a constant temperature of -12℃ to -8℃ in the reactor for 1 hour to complete the formation and initial growth of dimethylaminolithium crystal nuclei; then raise the temperature to 20℃ to 30℃ and continue the reaction for 2 hours to promote the full conversion and uniform dispersion of dimethylaminolithium, and complete the synthesis of dimethylaminolithium. The conversion rate of dimethylaminolithium synthesis is not less than 92%.

[0015] S4: Crude tetrakis(dimethylamino)tin synthesis ① Cool the reactor (3) system back to -12℃~-8℃, and slowly add anhydrous tin tetrachloride through the liquid feed port. The total amount of tin tetrachloride added is in a molar ratio of 1:4.1 to n-butyllithium. ② After all the tin tetrachloride has been added, the temperature is raised to 40°C and stirred until the reaction is complete. The mixture in the reactor contains tetra(dimethylamino)tin, n-hexane, and lithium chloride solid.

[0016] S5: Product purification and solvent closed-loop recovery ① The mixture in the vessel is fed into the solid-liquid separation device (4) to filter and separate solid lithium chloride. The solid is sent to the by-product collection tank for resource recovery. The filtrate is an organic mixture containing tetra(dimethylamino)tin. ② The organic mixture is fed into the distillation and solvent removal device (5), and the vacuum pump unit is turned on for vacuum distillation. The distilled hexane solvent is condensed by the condensation and recovery unit and then returned to the reactor (3) through the solvent recovery pipeline for recycling and reuse. The single-pass recovery rate of hexane is ≥95%. The liquid at the bottom of the reactor continues to be heated and distilled under reduced pressure to collect high-purity tetra(dimethylamino)tin finished product.

[0017] Preferably, the inert gas is high-purity nitrogen or argon, and the water content of the system is <0.5ppm and the oxygen content is <1ppm throughout the entire process.

[0018] Preferably, the mass ratio of molecular sieve to activated carbon in S3① is 2:1.

[0019] Preferably, the temperature control range of the dimethylamine cryogenic capture device (2) described in S3② is -70℃ to -60℃.

[0020] Preferably, the temperature control range of the condensation and liquefaction unit in S3③ is -10℃ to 0℃.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) A pioneering four-stage tandem deep purification system is proposed, consisting of gasification, composite adsorption for water removal, cryogenic removal of light impurities, and condensation liquefaction. Existing technologies only perform simple drying of dimethylamine, failing to remove dissolved oxygen, nitrogen, and trace heavy metal impurities. In this invention, dimethylamine is completely gasified in a gasification unit, then dehydrated to ≤1ppm using a molecular sieve / activated carbon composite adsorption unit. Dissolved nitrogen, oxygen, and trace heavy metals are then removed via cryogenic capture at -70℃ to -60℃. Finally, the product is condensed and liquefied at -10℃ to 0℃ with precise feeding via a liquid metering flow meter. The synergistic effect of the four-stage purification system eliminates the source of impurities from the raw material end, significantly reducing the load on subsequent distillation purification. The total metal impurities in the product are <100ppb. Comparative data shows that after eliminating the cryogenic capture and liquefaction metering processes, the product yield decreased from 91% to 67%, fully demonstrating the key contribution of multi-stage deep purification and precise metering feeding to product yield and purity.

[0022] (2) Narrow temperature range and mild reaction combined with two-stage temperature control significantly reduce energy consumption and equipment investment. Existing technologies (such as CN117247404A) require the synthesis of dimethylaminolithium to be carried out at extremely low temperatures of -45℃ to -25℃, with a reaction time of 10 to 20 hours, requiring expensive cryogenic equipment and resulting in extremely high energy consumption. This invention optimizes the reaction kinetics conditions to raise the reaction temperature to a narrow temperature range of -12℃ to -8℃, which can be met by only conventional low-temperature refrigeration units. At the same time, the two-stage temperature control mode of "1 hour of constant temperature at -12℃ to -8℃ (crystal nucleation and initial growth) + 2 hour of constant temperature at 20℃ to 30℃ (full conversion and uniform dispersion)" is adopted, and the conversion rate of dimethylaminolithium synthesis is not less than 92%, and the reaction time is shortened from 10 to 20 hours to 3 hours, which significantly reduces the investment in refrigeration equipment and energy consumption costs.

[0023] (3) Precise liquid-phase metering feed eliminates raw material loss and batch fluctuations. Existing technologies use continuous bubbling of dimethylamine gas for feeding, which lacks precise metering, resulting in significant raw material loss and poor batch-to-batch reaction consistency. In this invention, deeply purified dimethylamine is condensed and liquefied, and then fed into the reactor at a uniform flow rate of 0.3 L / min to 0.6 L / min using a liquid metering flow meter. This achieves precise quantitative feeding of dimethylamine, ensuring consistency in the ratio of each batch of reaction and product stability.

[0024] (4) Solvent closed-loop recovery, green and environmentally friendly, low cost. This invention uses only n-hexane as a single solvent throughout the entire process, eliminating carcinogenic solvents such as benzene. The distillation and solvent removal device is equipped with a solvent recovery pipeline, which condenses the distilled n-hexane and returns it to the reactor for recycling and reuse. The single-pass recovery rate of n-hexane is ≥95%, which greatly reduces the cost of raw materials and hazardous waste disposal, and is suitable for large-scale continuous production.

[0025] (5) The integrated process yields significant comprehensive technical advantages. This invention fully integrates four-stage deep purification of dimethylamine, precise liquid-phase metering, two-stage temperature-controlled synthesis in a narrow temperature range, and closed-loop solvent recovery. Each process is mutually compatible—high-purity, low-impurity dimethylamine reduces aminolysis byproducts, precise liquid-phase metering stabilizes batch ratios, mild low-temperature reaction reduces system impurity generation, and solvent recovery reduces the introduction of foreign impurities. The entire process synergistically achieves comprehensive technical advantages of high product yield (≥91%), high purity (metal impurities <100ppb), and low production cost. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the supporting apparatus for preparing tetra(dimethylamino)tin according to the present invention.

[0027] In the diagram: 1-Dimethylamine filtration device, 2-Dimethylamine cryogenic collection device, 3-Reaction vessel, 4-Solid-liquid separation device, 5-Distillation and desolvation device. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments and comparative examples, but the implementation of the present invention is not limited thereto. Example

[0029] A method for preparing tetra(dimethylamino)tin includes the following stages: S1: Raw Material Preparation Prepare 10L of 2.5mol / L n-butyllithium hexane solution, 40L of n-hexane, dimethylamine, and anhydrous tin tetrachloride; all raw materials are pre-deoxygenated and sealed for storage, and protected by high-purity nitrogen throughout the process.

[0030] S2: Reactor Pretreatment ① Add 10L of 2.5mol / L n-butyllithium hexane solution and 40L of n-hexane solvent (mass ratio of approximately 1:4) to reactor 3, and simultaneously start mechanical stirring at a speed of 100r / min. ② Cool the system inside the reactor to -10℃ using a circulating oil bath, and let it stand at a constant temperature for 30 minutes to complete the low-temperature pretreatment.

[0031] S3: Multi-stage deep purification and precise liquid-phase metering feed of dimethylamine ① Dimethylamine is passed into dimethylamine filtration device 1. After being completely gasified by the gasification unit, it enters the composite adsorption unit filled with molecular sieve and activated carbon at a mass ratio of 2:1 to remove moisture and water-soluble ammonia impurities from the dimethylamine until the water content is ≤1ppm, thus obtaining primary purified dimethylamine gas. ② The first-purified dimethylamine gas is introduced into the dimethylamine cryogenic collection device 2 with a temperature control of -65℃, and the dissolved nitrogen, oxygen and trace heavy metal impurities are removed by cryogenic removal to obtain the second-purified dimethylamine gas. ③ The secondary purified dimethylamine gas is introduced into the condensation and liquefaction unit with a temperature control of -5℃ and completely liquefied. The liquid dimethylamine is fed into the reaction vessel 3 at a constant flow rate of 0.4L / min through a liquid metering flow meter. The total amount of dimethylamine injected is 1.05:1 in molar ratio to n-butyllithium. ④ Maintain a constant temperature of -10℃ in the reactor for 1 hour, then raise the temperature to 25℃ and continue the reaction for 2 hours to complete the synthesis of dimethylaminolithium.

[0032] S4: Crude tetrakis(dimethylamino)tin synthesis ① Cool the reaction vessel 3 system back to -10℃, and slowly add anhydrous tin tetrachloride dropwise through the liquid feed port. The total amount of tin tetrachloride added is in a molar ratio of 1:4.1 to n-butyllithium. ② After all the tin tetrachloride has been added, the temperature is raised to 40°C and stirred for 8 hours until the reaction is complete. The mixture in the reactor contains tetra(dimethylamino)tin, n-hexane, and lithium chloride solid.

[0033] S5: Product purification and solvent closed-loop recovery ① The mixture in the reactor is fed into the solid-liquid separation device 4, where solid lithium chloride is separated by filtration. The solid is sent to the by-product collection tank for resource recovery. The filtrate is an organic mixture containing tetra(dimethylamino)tin. ② The organic mixture is fed into the distillation and desolventizing device 5, and the vacuum pump unit is turned on for reduced pressure distillation. The distilled hexane solvent is condensed by the condensation and recovery unit and then returned to the reaction vessel 3 through the solvent recovery pipeline for recycling. The liquid at the bottom of the vessel is heated and distilled under reduced pressure to obtain high-purity tetra(dimethylamino)tin finished product.

[0034] According to the test results, in this embodiment, the total yield of tetra(dimethylamino)tin was 91%, the total amount of metal impurities in the product was <100ppb, and the water and oxygen content was <1ppm.

[0035] Comparative Example 1 (without cryogenic capture and liquefaction metering) The difference between this comparative example and Example 1 is that the dimethylamine cryogenic capture device 2, the condensation and liquefaction unit and the liquid metering flow meter are omitted. The dimethylamine is only dried by molecular sieve / activated carbon adsorption and then continuously bubbled into the reaction vessel in a gaseous state. The other raw material ratios, temperatures and reaction times are completely consistent with those of Example 1.

[0036] Testing revealed that the final product yield was only 67%, and the metal impurity content was >1000 ppb, requiring additional secondary distillation purification.

[0037] Comparative Example 2 (Refer to the ultra-low temperature scheme in Comparative Document 3) Referring to the method disclosed in prior art document 3 (CN117247404A), the reaction system was cooled to -45℃ to -25℃, and dimethylamine gas was introduced and reacted for 10 to 20 hours to obtain dimethylaminolithium. Then, it was reacted with tin tetrachloride (temperature controlled at -50℃ to 35℃) to obtain tetra(dimethylamino)tin. The remaining operations were the same as in Example 1.

[0038] Testing revealed a product yield of approximately 85% and a metal impurity content of approximately 500 ppb. However, the investment in refrigeration equipment and energy consumption costs were significantly higher than those in Example 1.

Claims

1. An apparatus for preparing tetra(dimethylamino)tin, characterized in that, It includes a dimethylamine filtration device (1), a dimethylamine cryogenic collection device (2), a reaction vessel (3), a solid-liquid separation device (4), and a distillation and desolvation device (5) connected in sequence. The dimethylamine filtration device (1) is arranged in sequence along the material flow direction as a gasification unit and a composite adsorption unit filled with molecular sieve and activated carbon at a mass ratio of 2:

1. The composite adsorption unit is used to remove moisture from dimethylamine to a water content of ≤1ppm. The dimethylamine cryogenic collection device (2) is temperature controlled at -70℃ to -60℃ and is used for cryogenic removal of dissolved nitrogen, oxygen and trace heavy metal impurities from dimethylamine. The outlet end of the dimethylamine cryogenic collection device (2) is equipped with a condensation and liquefaction unit with a temperature controlled at -10℃ to 0℃. The outlet of the condensation and liquefaction unit is connected to a liquid metering flow meter, and the flow rate of the liquid metering flow meter is controlled at 0.3L / min to 0.6L / min. The reactor (3) is equipped with a circulating oil bath temperature control system, a mechanical stirring unit, a liquid feeding port, and an inert gas protection pipeline. The feed port of the reactor (3) is sealed and connected to the discharge port of the liquid metering flow meter. The reactor (3) contains a sufficient amount of n-hexane solvent and a 2.5 mol / L n-butyllithium n-hexane solution. The feed inlet of the solid-liquid separation device (4) is connected to the discharge outlet of the reaction vessel (3), the solid outlet of the solid-liquid separation device (4) is connected to the lithium chloride by-product collection tank, and the liquid outlet is connected to the distillation and desolvation device (5). The distillation and solvent removal device (5) is equipped with a vacuum pump unit, a condensation and recovery unit, and a product collection tank. The solvent recovery pipeline of the distillation and solvent removal device (5) is returned to the reaction vessel (3). The above-described apparatus for preparing tetra(dimethylamino)tin, using inert gas protection throughout the process, is employed to prepare tetra(dimethylamino)tin. Includes the following stages: S1: Raw Material Preparation Prepare sufficient quantities of n-hexane solvent, dimethylamine, 2.5 mol / L n-butyllithium n-hexane solution, and anhydrous tin tetrachloride; all raw materials should be pre-deoxygenated and stored in sealed containers. S2: Reactor Pretreatment ① Add a 2.5 mol / L n-butyllithium n-hexane solution and n-hexane solvent in a mass ratio of 1:4~5 to the reaction vessel (3), and start the mechanical stirring simultaneously, controlling the stirring speed to 50~150 r / min; ② Cool the system inside the reactor to -12℃~-8℃ using a circulating oil bath, and let it stand at a constant temperature for 30 minutes to complete the low-temperature pretreatment; S3: Multi-stage deep purification and precise liquid-phase metering feed of dimethylamine ① Dimethylamine is passed into the dimethylamine filtration device (1). After being completely gasified by the gasification unit, it enters the composite adsorption unit filled with molecular sieve and activated carbon at a mass ratio of 2:1 to remove moisture and water-soluble ammonia impurities from the dimethylamine until the water content is ≤1ppm, thus obtaining purified dimethylamine gas. ② The first-purified dimethylamine gas is introduced into a dimethylamine cryogenic collection device (2) with a temperature control of -70℃ to -60℃ to remove dissolved nitrogen, oxygen and trace heavy metal impurities, and obtain the second-purified dimethylamine gas; ③ The secondary purified dimethylamine gas is introduced into the condensation and liquefaction unit with a temperature control of -10℃~0℃ and completely liquefied. The liquid dimethylamine is fed into the reactor (3) at a flow rate of 0.3L / min~0.6L / min through a liquid metering flow meter. The total amount of injected dimethylamine is 1.05:1 in molar ratio to n-butyllithium. ④ Maintain a constant temperature of -12℃ to -8℃ in the reactor for 1 hour to complete the formation and initial growth of dimethylaminolithium crystal nuclei; then raise the temperature to 20℃ to 30℃ and continue the reaction for 2 hours to promote the full conversion and uniform dispersion of dimethylaminolithium, thus completing the synthesis of dimethylaminolithium. The conversion rate of dimethylaminolithium synthesis is not less than 92%. S4: Crude tetrakis(dimethylamino)tin synthesis ① Cool the reactor (3) system back to -12℃~-8℃, and slowly add anhydrous tin tetrachloride through the liquid feed port. The total amount of tin tetrachloride added is in a molar ratio of 1:4.1 to n-butyllithium. ② After all the tin tetrachloride has been added, the temperature is raised to 40°C and stirred until the reaction is complete. The mixture in the reactor contains tetra(dimethylamino)tin, n-hexane, and lithium chloride solid. S5: Product purification and solvent closed-loop recovery ① The mixture in the vessel is fed into the solid-liquid separation device (4) to filter and separate solid lithium chloride. The solid is sent to the by-product collection tank for resource recovery. The filtrate is an organic mixture containing tetra(dimethylamino)tin. ② The organic mixture is fed into the distillation and solvent removal device (5), and the vacuum pump unit is turned on for vacuum distillation. The distilled hexane solvent is condensed by the condensation and recovery unit and then returned to the reactor (3) through the solvent recovery pipeline for recycling and reuse. The single-pass recovery rate of hexane is ≥95%. The liquid at the bottom of the reactor continues to be heated and distilled under reduced pressure to collect high-purity tetra(dimethylamino)tin finished product.

2. A method for preparing tetra(dimethylamino)tin using the apparatus of claim 1, characterized in that, The inert gas is high-purity nitrogen or argon, and the water content of the system is <0.5ppm and the oxygen content is <1ppm throughout the entire process.

3. A method for preparing tetra(dimethylamino)tin using the apparatus of claim 1, characterized in that, The mass ratio of molecular sieve to activated carbon described in S3① is 2:

1.

4. A method for preparing tetrakis(dimethylamino)tin using the apparatus of claim 1, characterized in that, The temperature control range of the dimethylamine cryogenic capture device (2) described in S3② is -70℃ to -60℃.

5. A method for preparing tetra(dimethylamino)tin using the apparatus of claim 1, characterized in that, The temperature control range of the condensation and liquefaction unit described in S3③ is -10℃ to 0℃.

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