Synthesis method of diiodosilane

Abstract

The invention belongs to the technical field of organic synthesis, and provides a synthesis method of diiodosilane. The synthesis method is carried out in a first reactor and a second reactor which are connected in series, and comprises the following steps: adding a first metal chloride, a solvent, dichlorosilane (DCS) and iodobenzene into the first reactor, and carrying out a pre-reaction; after the pre-reaction, continuously introducing a solvent, dichlorosilane and iodobenzene into the first reactor; meanwhile, enabling the pre-reaction feed liquid in the first reactor to continuously flow into a second reactor filled with a second metal chloride; the first reactor and the second reactor simultaneously react; and when the volume of the reaction material liquid in the second reactor reaches a target liquid level, continuously extracting and collecting the reaction material liquid in the second reactor to realize continuous preparation of diiodosilane. The synthesis method provided by the invention is high in dichlorosilane conversion rate.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, in particular to a method for synthesizing diiodosilane. Background Art

[0002] Diiodosilane (DIS), as a silicon source for chemical vapor deposition (CVD), efficiently generates highly reactive silicon radicals under plasma-enhanced conditions. Its significant advantages include maintaining high deposition rates while requiring lower reaction chamber temperatures and more controllable pressures. As semiconductor devices (especially chips) continue to miniaturize to overcome the limitations of Moore's Law, the demand for innovative substrate structures is becoming increasingly urgent. DIS, with its excellent adaptability, enables vapor deposition on a variety of substrates.

[0003] Currently, domestic and international companies have two methods for synthesizing DIS: The first method involves reacting phenylsilane with elemental iodine at low temperature and under catalytic conditions, using a batch reactor. The reaction is highly exothermic, with a reactant mixing temperature of -50 to -20°C and a reaction temperature of 0 to 30°C. Ethyl acetate is typically used as the catalyst, and the reaction time is 24 to 40 hours. Finally, the target product, diiodosilane, is obtained by adding copper powder, filtering, and conventional distillation, with a target product content exceeding 90%. The second method involves reacting an iodine metal compound with a chlorosilane, using a batch reactor reaction at a temperature of 0 to 50°C for 12 to 18 hours. Conventional filtration and purification techniques are then used to obtain high-purity diiodosilane with a component content of 80.5%.

[0004] Currently, the main disadvantages of the preparation method of diiodosilane are: the number of side reactions triggered increases accordingly, and the conversion rate of the main reaction decreases accordingly. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for synthesizing diiodosilane. The method provided by the present invention has a high conversion rate of dichlorodihydrosilane and realizes the continuous synthesis of diiodosilane.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for synthesizing diiodosilane, which is carried out in a first reactor and a second reactor connected in series, comprising the following steps: (1) adding a first metal chloride, a solvent, dichlorosilane and iodobenzene into the first reactor to carry out a preliminary reaction; (2) After the pre-reaction, the solvent, dichlorosilane and iodobenzene are continuously introduced into the first reactor; at the same time, the pre-reaction liquid in the first reactor is continuously flowed into the second reactor containing the second metal chloride; the first reactor and the second reactor react simultaneously; (3) When the volume of the reaction liquid in the second reactor reaches the target liquid level, the reaction liquid in the second reactor is continuously withdrawn and collected to achieve continuous preparation of diiodosilane.

[0007] Preferably, the first metal chloride and the second metal chloride independently include one or more of zinc chloride, aluminum chloride and ferric chloride; and the particle sizes of the first metal chloride and the second metal chloride independently range from 1 to 2 mm.

[0008] Preferably, the purity of the dichlorosilane is ≥99.99%, the purity of the iodobenzene is ≥99.0%; the solvent is n-hexane, and the purity of the n-hexane is ≥99.0%.

[0009] Preferably, in step (1), the dichlorosilane is added in the form of dichlorosilane liquid; during the addition of the dichlorosilane, the temperature of the first reactor is controlled to be 0-10° C. and the pressure is controlled to be 0.3-0.5 MPa.

[0010] Preferably, in step (1), the total volume of the solvent, dichlorosilane and iodobenzene is 70-95% of the effective volume of the first reactor.

[0011] Preferably, in step (1), the molar ratio of dichlorosilane to iodobenzene is 0.5-2.5:1, the volume ratio of dichlorosilane to solvent is 1:2-5, and the mass of the first metal chloride is 0.1-10.0% of the mass of dichlorosilane.

[0012] Preferably, in step (1), the temperature of the pre-reaction is 20-50° C., and the pressure is 0.3-0.5 MPa; the pre-reaction is carried out under stirring, and the stirring speed is 100-200 r / min; and the time of the pre-reaction is 5-20 min.

[0013] Preferably, in step (2), the flow rate of continuously introducing dichlorosilane is 0.5-1.5 L / h.

[0014] Preferably, in step (2), the amount of the second metal chloride added is 0.1-10.0% of the mass of dichlorosilane that the second reactor can accommodate.

[0015] Preferably, in step (2), the reaction temperature is 20-50° C. and the pressure is 0.3-0.5 MPa.

[0016] The invention provides a method for synthesizing diiodosilane.

[0017] The synthesis method of the present invention uses dichlorosilane (DCS) as a silicon source, iodobenzene as an iodine source, and a metal chloride as a catalyst. The reaction conditions are mild and easy to control. Two series-connected reactors are used for continuous synthesis of diiodosilane, with fewer side reactions and a conversion rate of dichlorosilane exceeding 76%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides a synthesis flow chart of diiodosilane. DETAILED DESCRIPTION

[0019] Figure 1 The synthesis flow chart of diiodosilane provided by the present invention is shown below in combination with Figure 1 The synthesis method provided by the present invention is described in detail.

[0020] The present invention provides a method for synthesizing diiodosilane, which is carried out in a first reactor and a second reactor connected in series, comprising the following steps: (1) adding a first metal chloride, a solvent, dichlorosilane (DCS) and iodobenzene into the first reactor to carry out a preliminary reaction; (2) After the pre-reaction, the solvent, dichlorosilane and iodobenzene are continuously introduced into the first reactor; at the same time, the pre-reaction liquid in the first reactor is continuously flowed into the second reactor containing the second metal chloride; the first reactor and the second reactor react simultaneously; (3) When the volume of the reaction liquid in the second reactor reaches the target liquid level, the reaction liquid in the second reactor is continuously withdrawn and collected to achieve continuous preparation of diiodosilane.

[0021] Unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0022] In the present invention, the synthesis method is carried out in a first reactor and a second reactor connected in series. In one embodiment of the present invention, the volumes of the first and second reactors are preferably the same. In one embodiment of the present invention, the volumes of the first and second reactors are preferably both 10 L. In the present invention, the material of the first reactor is preferably stainless steel, more preferably 316L stainless steel. In the present invention, the first reactor is preferably equipped with a mechanical stirrer, the blades of which are preferably three-bladed propellers, and the blades of the mechanical stirrer are preferably arranged in multiple layers. In the present invention, the exterior of the first reactor is preferably provided with a temperature-control jacket, the internal medium of which is preferably thermal oil, and the temperature control range of the temperature-control jacket is preferably -20 to 240°C. In the present invention, the top of the first reactor is preferably provided with a nitrogen inlet, a thermometer port, a pressure gauge port, a sight glass port, and a feed port. In the present invention, an outlet pipe is preferably provided at the bottom right side of the first reactor, the bottom of which is preferably surrounded by a filter screen, preferably a 316L stainless steel sintered filter screen, and the filtration accuracy of the filter screen is preferably 0.2 to 0.5 mm. In the present invention, the material and structure of the second reactor are consistent with those of the first reactor and are not further described here. In the present invention, the first and second reactors are preferably connected in series via a pipeline. The pipeline preferably connects the outlet pipe of the first reactor and the feed port of the second reactor respectively, thereby achieving the series connection between the first and second reactors. The pipeline is preferably provided with a valve.

[0023] In the present invention, a first metal chloride, a solvent, dichlorosilane and iodobenzene are added into the first reactor to carry out a preliminary reaction.

[0024] In the present invention, before adding the materials (first metal chloride, solvent, dichlorosilane and iodobenzene) into the first reactor, the process preferably further comprises: purging the first reactor with nitrogen. The present invention does not impose any specific limitation on the time of the nitrogen purge, as long as the dew point is qualified, that is, the dew point is less than -60°C.

[0025] In the present invention, the first metal chloride preferably includes one or more of zinc chloride (ZnCl2), aluminum chloride (AlCl3), and ferric chloride (FeCl3). In the present invention, the particle size of the first metal chloride is preferably 1-2 mm. In the present invention, the purity of the first metal chloride is preferably 99.5%.

[0026] In the present invention, the purity of the dichlorosilane is preferably ≥99.99%. In the present invention, the purity of the iodobenzene is preferably ≥99.0%. In the present invention, the solvent is preferably n-hexane. In the present invention, the purity of the n-hexane is preferably ≥99.0%. In the present invention, the use of higher-purity dichlorosilane, iodobenzene, and solvent can reduce the occurrence of side reactions.

[0027] In the present invention, the total volume of the solvent, dichlorosilane and iodobenzene is preferably 70-95% of the effective volume of the first reactor, specifically preferably 70%, 75%, 80%, 85%, 90%, 91.25%, 92.5% or 95%.

[0028] In the present invention, adding the first metal chloride, solvent, dichlorosilane and iodobenzene into the first reactor is preferably performed by sequentially adding the first metal chloride, solvent, dichlorosilane and iodobenzene into the first reactor.

[0029] In the present invention, the solvent is preferably added at one time.

[0030] In the present invention, the dichlorosilane is preferably added in the form of dichlorosilane liquid. In the present invention, the addition flow rate of the dichlorosilane is preferably 0.5~2L / h, more preferably 1L / h. In the present invention, during the addition of the dichlorosilane, the temperature of the first reactor is preferably controlled to be 0~10°C, specifically preferably 0°C or 5°C; the pressure is preferably 0.3~0.5MPa, specifically preferably 0.3MPa, 0.4MPa or 0.5MPa. In the present invention, during the addition of the dichlorosilane, the temperature of the first reactor is controlled to be 0~10°C and the pressure is controlled to be 0.3~0.5MPa, which can promote the dissolution of dichlorosilane in the solvent, increase the solubility of dichlorosilane in the solvent, and thus increase the conversion rate.

[0031] In the present invention, the flow rate of adding iodobenzene is preferably 0.5~2L / h. In the present invention, during the addition of iodobenzene, the temperature of the first reactor is preferably controlled to be 0~10°C, specifically preferably 0°C or 5°C; the pressure is preferably 0.3~0.5MPa, specifically preferably 0.3MPa, 0.4MPa or 0.5MPa. In the present invention, during the addition of iodobenzene, the temperature of the first reactor is controlled to be 0~10°C and the pressure is controlled to be 0.3~0.5MPa, which is conducive to maintaining the high solubility of dichlorosilane in the solvent, thereby improving the contact and reaction between iodobenzene and dichlorosilane, and ultimately improving the conversion rate.

[0032] In the present invention, the molar ratio of the dichlorosilane to iodobenzene is preferably 0.5 to 2.5: 1, specifically preferably 0.5: 1, 0.9: 1, 0.92: 1, 1: 1, 1.09: 1, 1.1: 1, 1.5: 1, 2: 1 or 2.5: 1. In the present invention, the mass of the first metal chloride is preferably 0.1 to 10.0% of the mass of the dichlorosilane, specifically preferably 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 9.7%, 9.8% or 10%. In the present invention, the volume ratio of the dichlorosilane to the solvent is preferably 1: 2 to 5, specifically preferably 1: 2, 1: 3, 1: 4 or 1: 5.

[0033] In the present invention, the temperature of the pre-reaction is preferably 20-50°C, specifically preferably 20°C, 30°C, 40°C or 50°C; the pressure is preferably 0.3-0.5 MPa, specifically preferably 0.3 MPa, 0.4 MPa or 0.5 MPa; the pre-reaction is preferably carried out under stirring, and the stirring speed is preferably 100-200 r / min; the pre-reaction time is preferably 5-20 min, specifically preferably 5 min, 10 min, 15 min or 20 min. In the present invention, the pre-reaction is preferably carried out under a protective atmosphere, and the protective atmosphere is preferably nitrogen.

[0034] After the preliminary reaction, the present invention preferably proceeds directly to subsequent operations without any post-treatment.

[0035] After the pre-reaction, the present invention continuously introduces solvent, dichlorosilane and iodobenzene into the first reactor; at the same time, the pre-reaction liquid in the first reactor continuously flows into the second reactor filled with the second metal chloride; the first reactor and the second reactor react simultaneously.

[0036] In the present invention, the flow rate of continuously passing dichlorodihydrogen silicon is preferably 0.5~1.5L / h, more preferably 1L / h. In the present invention, the flow rate of continuously passing dichlorodihydrogen silicon and the flow rate of continuously passing iodobenzene are preferably such that the molar ratio of continuously passing dichlorodihydrogen silicon and continuously passing iodobenzene is 1~5:2, and the flow rate of continuously passing dichlorodihydrogen silicon and the flow rate of continuously passing solvent are preferably such that the volume ratio of continuously passing dichlorodihydrogen silicon and continuously passing solvent is 1:2~5.

[0037] In the present invention, the flow rate of the pre-reaction liquid continuously flowing into the second reactor is preferably such that the liquid level of the first reactor is at a high level, and the high level is preferably 65-70% of the total liquid level; the total liquid level refers to the liquid level corresponding to the effective volume of the first reactor.

[0038] In the present invention, the amount of the second metal chloride added is preferably 0.1 to 10.0% of the mass of the dichlorosilane that the second reactor can accommodate, specifically preferably 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 9.7%, 9.8% or 10%. In the present invention, the amount of dichlorosilane that the second reactor can accommodate refers to: the solvent, dichlorosilane and iodobenzene are introduced into the second reactor according to a molar ratio of dichlorosilane to iodobenzene of 1 to 5:2 and a volume ratio of solvent to dichlorosilane of 2 to 5:1; when the total volume of the solvent, dichlorosilane and iodobenzene is the effective volume of the second reactor, the corresponding amount of the dichlorosilane. In a specific embodiment of the present invention, in the second reactor, the amount of the second metal chloride added is preferably the same as the amount of the first metal chloride added in the first reactor.

[0039] In the present invention, the reaction temperature is preferably 20-50°C, specifically preferably 20°C, 30°C, 40°C or 50°C; the pressure is preferably 0.3-0.5 MPa, specifically preferably 0.3 MPa, 0.4 MPa or 0.5 MPa; the pre-reaction is preferably carried out under stirring, and the stirring speed is preferably 100-200 r / min. In the present invention, the reaction is preferably carried out under a protective atmosphere, and the protective atmosphere is preferably nitrogen.

[0040] When the volume of the reaction liquid in the second reactor reaches the target liquid level, the present invention continuously extracts and collects the reaction liquid in the second reactor to achieve continuous preparation of diiodosilane.

[0041] In the present invention, the target liquid level is preferably 65-70% of the total liquid level, and the total liquid level refers to the liquid level corresponding to the effective volume of the second reactor.

[0042] In the present invention, the flow rate for continuously withdrawing and collecting the reaction liquid in the second reactor is preferably such that the liquid level of the second reactor is at a high level, and the high level is preferably 65-70% of the total liquid level, and the total liquid level refers to the liquid level corresponding to the effective volume of the second reactor.

[0043] In the present invention, the collected reaction liquid is preferably placed in a reaction product tank.

[0044] In the present invention, the collected reaction liquid is preferably subjected to post-treatment, and the post-treatment preferably includes but is not limited to atmospheric distillation, vacuum distillation, adsorption removal, sub-boiling distillation, and membrane filtration. The present invention does not specifically limit the parameters of the atmospheric distillation, vacuum distillation, adsorption removal, sub-boiling distillation, and membrane filtration.

[0045] In the present invention, the process of the pre-reaction and the reaction is as follows: SiH2Cl2+2C6H5I→SiH2I2+2C6H5Cl.

[0046] It can be seen that no solid is generated before and after the reaction of the present invention.

[0047] The synthesis method of diiodosilane provided by the present invention is described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0048] Example 1 according to Figure 1 The synthetic flow chart shown is used to prepare diiodosilane. The steps are: First, the first and second reactors (both 10L in volume and 8L in effective volume) were thoroughly purged with nitrogen to a dew point of -60°C. Then, under nitrogen protection and sealed conditions, 120g of 2mm-sized, 99.5% pure ZnCl2 powder was added through the feed port, followed by 5L of 99% pure n-hexane. The temperature of the first reactor's temperature-controlled jacket was set at 5°C and the pressure at 0.3MPa. 1L of high-purity DCS liquid (99.99%) and 1.3L of iodobenzene (99.0%) were introduced at a rate of 1L / h, respectively (wherein the volume ratio of n-hexane to dichlorosilane was 5:1, and the molar ratio of dichlorosilane to iodobenzene was 1:1). Mechanical stirring was started (200r / min), and the temperature of the first reactor's temperature-controlled jacket was controlled at 30-40°C and the pressure at 0.4MPa. A pre-reaction was conducted for 10 minutes. After the pre-reaction, high-purity DCS liquid, iodobenzene and n-hexane are continuously introduced into the first reactor according to the ratio (the volume ratio of n-hexane and dichlorodihydrogen silicon is 5:1, and the molar ratio of dichlorodihydrogen silicon and iodobenzene is 1:1), wherein the introduction rate of the high-purity DCS liquid is 1 L / h; at the same time, the outlet pipe valve of the first reactor is opened to allow the pre-reaction liquid in the first reactor to flow into the second reactor. When the pre-reaction liquid in the second reactor submerges the mechanical stirrer, the mechanical stirrer is turned on, the temperature of the temperature control jacket is set to 30-40° C., and the pressure is 0.3 MPa. The outflow rate of the pre-reaction liquid in the first reactor is controlled to maintain the liquid level of the first reactor at 70% of the total liquid level; the first reactor and the second reactor react simultaneously.

[0049] When the volume of the reaction liquid in the second reactor reaches the target liquid level (70% of the total liquid level), open the outlet pipe of the second reactor, and continuously extract and collect the reaction liquid in the second reactor and collect it in the reaction product tank. Control the extraction and collection rate to maintain the liquid level of the second reactor at 70% of the total liquid level.

[0050] The materials collected in the reaction product tank were tested by gas chromatography-mass spectrometry (GC), and the DIS content reached 42.2% and the DCS conversion rate reached 76.8%.

[0051] Example 2 according to Figure 1 The synthetic flow chart shown is used to prepare diiodosilane. The steps are: First, the first and second reactors (both 10L in volume, 8L in effective volume) were thoroughly purged with nitrogen to a dew point of -60°C. Then, under nitrogen protection and sealed conditions, 120g of 99.5% pure FeCl3 powder with a particle size of 1mm was added through the feed port, followed by 5L of 99% pure n-hexane. The temperature of the first reactor's temperature-controlled jacket was set at 0°C and the pressure at 0.3MPa. 1L of high-purity DCS liquid (99.99%) and 1.4L of iodobenzene (99.0%) were introduced at a rate of 1L / h, respectively (wherein the volume ratio of n-hexane to dichlorosilane was 5:1, and the molar ratio of dichlorosilane to iodobenzene was 0.92:1). Mechanical stirring was initiated (150r / min), and the temperature of the first reactor's temperature-controlled jacket was controlled at 30-40°C and the pressure at 0.4MPa. The pre-reaction was allowed to proceed for 10min. After the pre-reaction, high-purity DCS liquid, iodobenzene and n-hexane are continuously introduced into the first reactor according to the ratio (the volume ratio of n-hexane and dichlorodihydrogen silicon is 5:1, and the molar ratio of dichlorodihydrogen silicon to iodobenzene is 0.92:1), wherein the introduction rate of the high-purity DCS liquid is 1 L / h; at the same time, the outlet pipe valve of the first reactor is opened to allow the pre-reaction liquid in the first reactor to flow into the second reactor. When the pre-reaction liquid in the second reactor submerges the mechanical stirrer, the mechanical stirrer is turned on, the temperature of the temperature control jacket is set to 30-40° C., and the pressure is 0.3 MPa. The outflow rate of the pre-reaction liquid in the first reactor is controlled to maintain the liquid level of the first reactor at 70% of the total liquid level; the first reactor and the second reactor react simultaneously.

[0052] When the volume of the reaction liquid in the second reactor reaches the target liquid level (70% of the total liquid level), open the outlet pipe of the second reactor, and continuously extract and collect the reaction liquid in the second reactor and collect it in the reaction product tank. Control the extraction and collection rate to maintain the liquid level of the second reactor at 70% of the total liquid level.

[0053] The materials collected in the reaction product tank were tested by gas chromatography-mass spectrometry (GC), and the DIS content reached 43.5% and the DCS conversion rate reached 77.1%.

[0054] Example 3 according to Figure 1 The synthetic flow chart shown is used to prepare diiodosilane. The steps are: First, the first and second reactors (both 10L in volume and 8L in effective volume) were thoroughly purged with nitrogen to a dew point of -60°C. Then, under nitrogen protection and sealed conditions, 120g of 2mm-sized, 99.5% pure AlCl3 powder was added through the feed port, followed by 5L of 99% pure n-hexane. The temperature of the first reactor's temperature-controlled jacket was set at 5°C and the pressure at 0.3MPa. 1L of high-purity DCS liquid (99.99%) and 1.2L of iodobenzene (99.0%) were introduced at a rate of 1L / h, respectively (wherein the volume ratio of n-hexane to dichlorosilane was 5:1, and the molar ratio of dichlorosilane to iodobenzene was 1.09:1). Mechanical stirring was started (150r / min), and the temperature of the first reactor's temperature-controlled jacket was controlled at 30-40°C and the pressure at 0.5MPa. A pre-reaction was carried out for 5min. After the pre-reaction, DCS, iodobenzene and n-hexane are continuously introduced into the first reactor according to the ratio (the volume ratio of n-hexane and dichlorodihydrogen silicon is 5:1, and the molar ratio of dichlorodihydrogen silicon is 1.09:1), and the introduction rate of high-purity DCS liquid is 1 L / h; at the same time, the outlet pipe valve of the first reactor is opened to allow the pre-reaction liquid in the first reactor to flow into the second reactor. When the pre-reaction liquid in the second reactor submerges the mechanical stirrer, the mechanical stirrer is turned on, the temperature of the temperature control jacket is set to 40-50° C., and the pressure is set to 0.4 MPa, the outflow rate of the pre-reaction liquid in the first reactor is controlled, and the liquid level height of the first reactor is maintained at 70% of the total liquid level; the first reactor and the second reactor react simultaneously.

[0055] When the volume of the reaction liquid in the second reactor reaches the target liquid level (70% of the total liquid level), open the outlet pipe of the second reactor, and continuously extract and collect the reaction liquid in the second reactor and collect it in the reaction product tank. Control the extraction and collection rate to maintain the liquid level of the second reactor at 70% of the total liquid level.

[0056] GC analysis of the material collected in the reaction product tank showed that the DIS content reached 45.8% and the DCS conversion rate reached 78.3%.

[0057] Table 1 shows the GC test results of the reaction solutions obtained in Examples 1 to 3.

[0058] Table 1 Main component information of DIS

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for synthesizing diiodosilane, characterized in that: The synthesis method is carried out in a first reactor and a second reactor connected in series, comprising the following steps: (1) adding a first metal chloride, a solvent, dichlorosilane and iodobenzene into the first reactor to carry out a preliminary reaction; (2) After the pre-reaction, the solvent, dichlorosilane and iodobenzene are continuously introduced into the first reactor; at the same time, the pre-reaction liquid in the first reactor is continuously flowed into the second reactor containing the second metal chloride; the first reactor and the second reactor react simultaneously; (3) When the volume of the reaction liquid in the second reactor reaches the target liquid level, the reaction liquid in the second reactor is continuously withdrawn and collected to achieve continuous preparation of diiodosilane.

2. The synthesis method according to claim 1, wherein The first metal chloride and the second metal chloride independently include one or more of zinc chloride, aluminum chloride and ferric chloride; and the particle sizes of the first metal chloride and the second metal chloride independently range from 1 to 2 mm.

3. The synthesis method according to claim 1, wherein The purity of the dichlorosilane is ≥99.99%, and the purity of the iodobenzene is ≥99.0%. The solvent is n-hexane, and the purity of the n-hexane is ≥99.0%.

4. The synthesis method according to claim 1, characterized in that In step (1), the dichlorosilane is added in the form of dichlorosilane liquid; during the addition of the dichlorosilane, the temperature of the first reactor is controlled to be 0-10° C. and the pressure is controlled to be 0.3-0.5 MPa.

5. The synthesis method according to claim 1, characterized in that In step (1), the total volume of the solvent, dichlorosilane and iodobenzene is 70-95% of the effective volume of the first reactor.

6. The synthesis method according to claim 1, characterized in that In step (1), the molar ratio of dichlorosilane to iodobenzene is 0.5-2.5:1, the volume ratio of dichlorosilane to solvent is 1:2-5, and the mass of the first metal chloride is 0.1-10.0% of the mass of dichlorosilane.

7. The synthesis method according to claim 1 or 6, characterized in that In step (1), the temperature of the pre-reaction is 20-50° C., and the pressure is 0.3-0.5 MPa; the pre-reaction is carried out under stirring, and the stirring speed is 100-200 r / min; and the time of the pre-reaction is 5-20 min.

8. The synthesis method according to claim 1, characterized in that In step (2), the flow rate of continuously introducing dichlorosilane is 0.5~1.5L / h.

9. The synthesis method according to claim 1, characterized in that In step (2), the amount of the second metal chloride added is 0.1-10.0% of the mass of dichlorosilane that the second reactor can accommodate.

10. The synthesis method according to claim 1, characterized in that In step (2), the reaction temperature is 20-50° C. and the pressure is 0.3-0.5 MPa.

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