Preparation method of diiodosilane

Abstract

The invention discloses a preparation method of diiodosilane, and belongs to the technical field of material synthesis. The preparation method of diiodosilane comprises the following steps: adding a first iodine source and a second iodine source into a closed reactor in an inert gas atmosphere, and dissolving the first iodine source and the second iodine source in a solvent to form a uniform solution; and reducing the temperature, and adding liquid dichlorosilane. Raising the temperature to 30 to 80 DEG C and reacting; and after the reaction is finished, heating at reduced pressure, rectifying and purifying to obtain the high-purity electronic-grade diiodosilane. The first iodine source is lithium iodide, the second iodine source is at least one of sodium iodide or potassium iodide, and the solvent comprises at least one of acetonitrile, acetone, diethyl ether or ethanol. Lithium iodide and sodium iodide or potassium iodide are compounded, a specific solvent is matched, and a one-step method is used for testing, so that the input cost of raw materials is reduced, the experimental steps are simplified, the reaction rate of a reaction system can be improved, and the purity of a diiodosilane product is improved.

Description

Technical Field

[0001] The present application relates to the technical field of material synthesis, and in particular to a method for preparing diiodosilane. Background Art

[0002] The molecular formula of diiodosilane (DIS) is SiH2I2. It is mainly used as a chemical intermediate and has important application value in materials science, chemical synthesis and semiconductor industry.

[0003] By coating diiodosilane on the surface of different materials, their surface properties can be significantly changed, changing their hydrophobicity. This surface modification is particularly important in optical devices, sensors and medical devices. In organic synthesis, diiodosilane can be used as an effective silicon source to promote various reactions. In the integrated circuit process, diiodosilane can be used as a silicon source for chemical vapor deposition.

[0004] However, the current methods for preparing diiodosilane often have problems such as low preparation efficiency, high cost, great operating difficulty, high risk factor or low purity. Summary of the invention

[0005] Based on the above-mentioned deficiencies, the present application provides a method for preparing diiodosilane to reduce the preparation cost of diiodosilane and improve the preparation efficiency and purity.

[0006] This application is implemented as follows:

[0007] The example of the present application provides a method for preparing diiodosilane, comprising:

[0008] S1. In an inert gas atmosphere, a first iodine source and a second iodine source are added to a closed reactor, and the first iodine source and the second iodine source are dissolved in a solvent to form a uniform solution. The first iodine source is lithium iodide, and the second iodine source is at least one of sodium iodide or potassium iodide. The solvent includes at least one of acetonitrile, acetone, ether or ethanol.

[0009] S2. Lower the temperature and add liquid dichlorosilane.

[0010] S3. Raise the temperature to 30-80°C and react.

[0011] S4. After the reaction is completed, the pressure is reduced, and heating and distillation are performed to purify the product to obtain diiodosilane.

[0012] In the above implementation process, an iodine source prepared by mixing lithium iodide with sodium iodide or potassium iodide is used as a raw material, and the raw material is dissolved in a solvent. The lithium iodide, sodium iodide and potassium iodide in the raw material can react with dichlorosilane to form diiodosilane. The reaction system is a gas-liquid two-phase reaction system with liquid phase reaction as the main body, and has a high reaction driving force and a high reaction rate.

[0013] In addition, the highly reactive lithium iodide in the raw material reacts with dichlorosilane to form lithium chloride in addition to diiodosilane. Lithium chloride can be dissolved in a solvent and can react with unreacted sodium iodide or potassium iodide to form sodium chloride or potassium chloride precipitation to form new lithium iodide. The new lithium iodide can continue to react with dichlorosilane to form diiodosilane. The reaction efficiency of lithium iodide and dichlorosilane is high, but the raw material cost is high. The reaction efficiency of sodium iodide or potassium iodide and dichlorosilane is low, but the raw material cost is low. Sodium iodide or potassium iodide with low cost and low reaction efficiency is used to react with the reaction byproduct of lithium iodide and dichlorosilane to form new lithium iodide, so that lithium iodide replaces sodium iodide or potassium iodide to react with dichlorosilane to form diiodosilane. The reaction rate of the reaction system can be improved without increasing the input amount of high-cost lithium iodide in the raw materials, and the chlorine element in the reaction system can be continuously removed from the reaction system in the form of sodium chloride or potassium chloride precipitation, which can not only further promote the reaction of lithium iodide and dichlorosilane to form diiodosilane and reduce the occurrence of reverse reaction, but also improve the purity of the prepared diiodosilane.

[0014] In some possible implementations, the molar ratio of the second iodine source to the first iodine source is 1:(0.1-5).

[0015] In some possible implementations, the molar ratio of the second iodine source to the first iodine source is 1:(1-2).

[0016] In the above implementation process, the molar ratio of the second iodine source to the first iodine source is 1: (0.1-5), which can reduce the cost of raw materials while increasing the reaction rate. If there is too much second iodine source in the reaction raw material, the reaction rate of the reaction system will be greatly reduced. If there is too much first iodine source in the reaction raw material, the cost of preparing the raw material will be greatly increased.

[0017] In some possible embodiments, the second iodine source is selected from sodium iodide.

[0018] In the above implementation process, compared with potassium iodide, using sodium iodide to replace part of lithium iodide can further increase the reaction rate of the reaction system on the basis of reducing the cost of reaction raw materials.

[0019] In some possible implementations, the molar ratio of dichlorosilane to the sum of the molar amounts of the first iodine source and the second iodine source is 1:(1.5-2.5).

[0020] In some possible implementations, in step S2, the temperature is lowered to -40 to 0°C.

[0021] In the above implementation process, the temperature of the reactor is cooled to -40 to 0°C, so that dichlorosilane can be mixed with the iodine source in the solvent in liquid form, so that the reaction raw materials can be more fully contacted, which can promote the reaction and increase the reaction rate.

[0022] In some possible implementations, in step S2, the rate of adding dichlorosilane is 1.5-2 L / h.

[0023] In the above implementation process, adding dichlorosilane into the reaction system at a rate of 1.5-2 L / h can enable the raw materials to be in contact more fully, and can further increase the reaction rate.

[0024] In some possible embodiments, in step S3, the reaction lasts for 3 to 24 hours.

[0025] In the above implementation process, by compounding the first iodine source and the second iodine source in combination with a specific solvent, the reaction rate of the reaction system can be increased while reducing the input of high-cost lithium iodide in the raw materials. After 3 to 24 hours of reaction, a higher yield of diiodosilane can be obtained.

[0026] In some possible implementations, in step S4, the pressure is reduced to below 1 KPa.

[0027] In the above implementation process, the reaction product is distilled and purified after the reaction is completed, which can further improve the purity of diiodosilane.

[0028] In some embodiments, the purity of diiodosilane is not less than 99.9%.

[0029] In the above implementation process, the diiodosilane obtained according to the above preparation has a low impurity content and a high purity, and can meet the impurity content standard of electronic grade diiodosilane. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0031] Figure 1 A process flow chart for preparing diiodosilane provided as an example of this application;

[0032] Figure 2 Schematic diagram of the preparation of diiodosilane provided as an example of this application;

[0033] Figure 3 This is a chromatogram of the diiodosilane product provided in Example 1 of the present application. DETAILED DESCRIPTION

[0034] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0035] The molecular formula of diiodosilane (DIS) is SiH2I2. It is mainly used as a chemical intermediate and has important application value in materials science, chemical synthesis and semiconductor industry.

[0036] Among them, high-purity diiodosilane plays an increasingly important role in high-end semiconductor chips. It can be used as a silicon source for chemical vapor deposition. It can deposit siliconized films on a wide variety of semiconductor substrates through gas phase reaction CVD and single atomic layer deposition ALD methods at lower temperatures and more controllable pressure operations.

[0037] However, the existing diiodosilane synthesis method is complicated and dangerous, the preparation cost is high, and the purity of the prepared diiodosilane product is low and needs to be further improved, which seriously limits the industrial application of the product.

[0038] The preparation of diiodosilane requires the selection of a suitable silicon source and an iodine source for chemical combination. The synthesis methods currently used in the market are mainly divided into three categories: silane iodination method, organosilicon source iodination method, and halogen exchange method.

[0039] Among them, the silyl iodination method usually uses hydrogen iodide and silane to generate diiodosilane under the action of a catalyst. This method is usually accompanied by more by-products, such as monoiodosilane, triiodosilane, and tetraiodosilane. And the silane in the raw material is a self-igniting gas, which is extremely flammable and explosive, and very dangerous. In addition, the chemical properties of hydrogen iodide are unstable, the source is not easy to obtain, and a thermal cracking reaction occurs at 80°C. The operation control is difficult, the risk factor is high, and it is difficult to use for large-scale production.

[0040] Among them, the organosilicon source iodination method usually uses phenylsilane to react with iodine to prepare diiodosilane. However, the raw material phenylsilane used explodes when it comes into contact with water, has strong hygroscopicity, is easy to deteriorate, is difficult to store, and is expensive. The carcinogen benzene will be produced as a side reaction during the reaction. Replacing phenylsilane with toluene will also produce toluene as a byproduct. The boiling point of toluene is close to that of diiodosilane, making it difficult to separate.

[0041] Among them, the halogen exchange method usually uses lithium iodide to directly react with dichlorosilane. This reaction raw material is less dangerous, and the temperature is easy to reach during the reaction, and the reaction process is relatively mild. However, lithium iodide is used as a reaction raw material, and the raw material cost is relatively high. In addition, when lithium iodide is used as an iodine source, pentane and hexane systems are usually used as solvents to dissolve dichlorosilane. The lithium iodide in the reaction system is difficult to dissolve, and the reaction system is a gas-liquid-solid three-phase heterogeneous reaction, and the reaction driving force is poor, requiring a long reaction time.

[0042] In order to reduce the cost of raw materials, low-cost sodium iodide is usually used to replace lithium iodide in the prior art. For example, sodium iodide is used as an iodine source to react with dichlorosilane to prepare dichlorosilane. However, when sodium iodide is used as an iodine source, although the raw material price is relatively cheap, the reaction rate of sodium iodide is low and the effect is poor.

[0043] At present, in the process of preparing diiodosilane by halogen exchange method, either sodium iodide is used as a single iodine source to react with dichlorosilane to prepare dichlorosilane to reduce the cost of raw materials; or lithium iodide is used as a single iodine source to react with dichlorosilane to prepare dichlorosilane to increase the reaction rate. Reaction rate and reaction cost are often incompatible.

[0044] Therefore, it is of practical significance to provide a method for preparing diiodosilane which has a mild reaction process, relatively cheap raw materials, can improve the reaction driving force, reduce side reactions and reaction time, and is suitable for industrial production.

[0045] Based on this, the present application provides a method for preparing diiodosilane, which can reduce the cost of the reaction raw materials while increasing the reaction rate. In order to make the purpose, technical solution and advantages of the embodiment of the present application clearer, the technical solution in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application.

[0046] See also Figure 1 The preparation method of diiodosilane provided in the present application example includes:

[0047] S1. In an inert gas atmosphere, a first iodine source and a second iodine source are added to a closed reactor, and the first iodine source and the second iodine source are dissolved in a solvent to form a uniform solution. The first iodine source is lithium iodide, and the second iodine source is at least one of sodium iodide or potassium iodide. The solvent includes at least one of acetonitrile, acetone, ether or ethanol.

[0048] S2. Lower the temperature and add liquid dichlorosilane.

[0049] S3. Raise the temperature to 30-80°C and react.

[0050] S4. After the reaction is completed, the pressure is reduced, and heating and distillation are performed to purify the product to obtain diiodosilane.

[0051] In the preparation method provided by the example of the present application, the iodine source is dissolved in a solvent, and dichlorosilane is added to the reactor in liquid form at a relatively low temperature, so that the iodine source and dichlorosilane can be fully contacted. During the reaction, the reaction system can be made into a homogeneous reaction system of gas-liquid two phases, which can improve the mass transfer efficiency, increase the reaction rate, and reduce the reaction time.

[0052] If pentane or hexane is used as a solvent in a reaction vessel, the iodine source is difficult to completely dissolve in the solvent, and the reaction system often presents a gas-liquid-solid three-phase reaction, with low mass transfer efficiency, poor reaction driving force, a long reaction time, and a low reaction rate.

[0053] In the preparation method provided in the example of this application, the iodine source includes a first iodine source of lithium iodide, see Figure 2 , lithium iodide can react with dichlorosilane to form diiodosilane and lithium chloride. The reaction formula is as follows:

[0054] LiI+SiH2Cl2→LiCl+SiH2I2

[0055] The reaction rate of lithium iodide and dichlorosilane is high, and the raw material is less dangerous. However, the cost of lithium iodide raw material is high.

[0056] However, in the iodine source provided by the present application, in addition to the first iodine source of lithium iodide, a certain amount of second iodine source is also provided, and the second iodine source includes sodium iodide or potassium iodide. Replacing part of the lithium iodide with sodium iodide or potassium iodide can reduce the input amount of lithium iodide in the raw material and reduce the cost of raw materials. Sodium iodide or potassium iodide can react with dichlorosilane to generate diiodosilane. The reaction formula of the reaction of sodium iodide and dichlorosilane is as follows:

[0057] NaI+SiH2Cl2→SiH2I2+NaCl↓

[0058] Although the reaction rate of sodium iodide or potassium iodide with dichlorosilane is low, the by-product sodium chloride or potassium chloride generated by sodium iodide or potassium iodide in the example of the present application will precipitate due to the difference in solubility. This phenomenon makes the reaction itself also have a certain activity, so it will not significantly reduce the reaction rate of the entire reaction system.

[0059] The present application utilizes the first iodine source of lithium iodide and the second iodine source of sodium iodide or potassium iodide for compounding. The reaction driving force of dichlorosilane and lithium iodide in the reaction system is higher than the reaction driving force of dichlorosilane and sodium iodide or potassium iodide. The dichlorosilane in the system will preferentially react with lithium iodide to generate diiodosilane and lithium chloride. The reaction byproduct lithium chloride can be dissolved in the solvent and fully contacted with the sodium iodide or potassium iodide in the reaction system. In addition to being able to react with dichlorosilane in the reaction system, sodium iodide or potassium iodide can also react with the byproduct lithium chloride generated in the reaction system. Moreover, compared with the lower driving force of sodium iodide or potassium iodide reacting with dichlorosilane, the activity of sodium iodide or potassium iodide reacting with lithium chloride is relatively high, so that the sodium iodide or potassium iodide in the reaction system can be more inclined to react with lithium chloride. At this time, the sodium iodide or potassium iodide in the reaction system reacts with lithium chloride to generate new lithium iodide. The reaction formula of the reaction of sodium iodide and lithium chloride is as follows:

[0060] LiCl+NaI→LiI+NaCl↓

[0061] Sodium iodide or potassium iodide reacts with lithium chloride in the reaction system to generate new lithium iodide, and the new lithium iodide can react with dichlorosilane to form diiodosilane. The reaction rate is high, thereby increasing the reaction rate of the reaction system.

[0062] In other words, in the preparation method provided by the example of the present application, although a first mass of lithium iodide is added during the feeding process before the reaction, during the reaction process of the entire reaction system, the mass of lithium iodide that actually reacts with dichlorosilane is higher than the first mass, thereby reducing the raw material input cost while increasing the reaction rate of the entire reaction system.

[0063] For example, in step S1, 50 parts of lithium iodide and 50 parts of sodium iodide are added. 50 parts of lithium iodide will preferentially react with 25 parts of dichlorosilane to form 25 parts of diiodosilane and 50 parts of lithium chloride. Among the 50 parts of sodium iodide, 40 parts of sodium iodide react with 40 parts of lithium chloride to generate 40 parts of new lithium iodide. These 40 parts of new lithium iodide can continue to react with 20 parts of dichlorosilane to form 20 parts of diiodosilane and 40 parts of lithium chloride. In this way, although 50 parts of lithium iodide are added to the raw materials of step S1, the number of lithium iodide actually participating in the reaction in the reaction system is 90 parts, which can greatly improve the reaction rate of the entire reaction system. This example is only a brief description of the virtuous cycle within the reaction and does not represent the specific proportion of the actual reaction.

[0064] Compared to reacting 50 parts of lithium iodide with dichlorosilane and reacting 50 parts of sodium iodide with dichlorosilane respectively, the embodiment of the present application directly constructs 50 parts of lithium iodide and 50 parts of sodium iodide into a system to react with dichlorosilane, and selects a solvent that can dissolve sodium iodide, lithium iodide and lithium chloride as the solvent of the reaction system, which can reduce the input amount of lithium iodide in the raw materials and reduce the reaction cost.

[0065] Similarly, compared to reacting 50 parts of lithium iodide with dichlorosilane and reacting 50 parts of sodium iodide with dichlorosilane respectively, the embodiment of the present application directly dissolves 50 parts of lithium iodide and 50 parts of sodium iodide in a solvent to react with dichlorosilane, and selects a solvent that can dissolve sodium iodide, lithium iodide and lithium chloride as the solvent of the reaction system, which can achieve the effect of increasing the reaction rate while simplifying the process steps.

[0066] In addition, in the reaction system, the chlorine element in dichlorosilane can be continuously discharged from the reaction system in the form of sodium chloride precipitation or potassium chloride precipitation, which can not only promote the reaction of sodium iodide or potassium iodide with sodium iodide and increase the reaction rate of the entire reaction system, but also improve the purity of the prepared diiodosilane.

[0067] Furthermore, in some possible embodiments, the molar ratio of the second iodine source to the first iodine source is 1:(0.1-5).

[0068] The molar ratio of the second iodine source to the first iodine source is 1: (0.1-5), which can reduce the cost of raw material input while increasing the reaction rate of the entire reaction system. If the amount of the second iodine source added is too high and the amount of the first iodine source added is too low, the reaction rate of the reaction system will be reduced. If the amount of the second iodine source added is too low and the amount of the first iodine source added is too high, the cost of raw materials will increase.

[0069] As an example, the molar ratio of the second iodine source to the first iodine source can be one of 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.5, 1:2, 1:2.5 or 1:5, or a range between any two of them.

[0070] Furthermore, in some possible embodiments, the molar ratio of the second iodine source to the first iodine source may be 1:0.5-1.

[0071] Alternatively, in some possible embodiments, the molar ratio of the second iodine source to the first iodine source may be 1:1-2.

[0072] Alternatively, in some possible embodiments, the molar ratio of the second iodine source to the first iodine source may be 1:2.5-3.

[0073] In a possible embodiment, the second iodine source is selected from sodium iodide or potassium iodide.

[0074] The solvent includes at least one of acetonitrile, acetone, ether or ethanol.

[0075] As an example, the solvent may be selected from acetonitrile. Alternatively, as an example, the solvent may be selected from acetone. Alternatively, as an example, the solvent may be selected from ether. Alternatively, as an example, the solvent may be selected from ethanol. In order to achieve the desired dissolution effect, it is not entirely limited to the above several solvents.

[0076] The present application embodiment makes solid raw material lithium iodide, sodium iodide and potassium iodide dissolve in solvent by making specific selection to solvent, can make the iodine source in reaction raw material fully contact with dichlorosilane, improve the reaction rate of reaction system. And, select specific solvent, make lithium iodide and dichlorosilane react after forming byproduct lithium chloride also dissolve in solvent, make lithium chloride fully contact with sodium iodide or potassium iodide, to form new lithium iodide, and then can improve the reaction rate of reaction system. And, select specific solvent, make different salt composition in the same solvent solubility difference, make the chlorine element in reaction system can be precipitated from solvent in the form of sodium chloride or potassium chloride, reduce the content of chloride ion in liquid phase system, can not only reduce the occurrence probability of reverse reaction of lithium iodide and dichlorosilane reaction to generate diiodosilane and lithium chloride, can also further promote lithium chloride and sodium iodide or potassium iodide reaction to form new lithium iodide, improve reaction rate, can also reduce the content of chlorine element impurity in diiodosilane product, improve the purity of diiodosilane.

[0077] Further, in some possible embodiments, in step S1, the inert gas may be one of nitrogen and argon.

[0078] As an example, the inert gas may be nitrogen.

[0079] Furthermore, in some possible embodiments, in step S1, the first iodine source and the second iodine source may be poured into a solvent and stirred to dissolve.

[0080] Furthermore, before adding the first iodine source and the second iodine source into the reaction kettle, the first iodine source and the second iodine source may be ground and sieved.

[0081] In step S2, the temperature of the reactor is lowered, and dichlorosilane liquid is added into the reactor. The dichlorosilane liquid can be dissolved in the solvent and fully contacted with the first iodine source and the second iodine source, which can further increase the reaction rate.

[0082] In some possible embodiments, in step S2, the temperature of the reactor is lowered to -40 to 0°C.

[0083] As an example, in step S2, the temperature of the reactor can be cooled to one of -40°C, -35°C, -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, -3°C or 0°C, or a range between any two of them.

[0084] In some possible embodiments, in step S2, dichlorosilane is added to the reactor at a rate of 1.5-2 L / h.

[0085] For example, the rate of adding dichlorosilane to the reactor may be in the range of one or any two of 1.5 L / h, 1.6 L / h, 1.7 L / h, 1.8 L / h, 1.9 L / h or 2.0 L / h.

[0086] Furthermore, in step S2, the molar ratio of dichlorosilane to the sum of the molar amounts of the first iodine source and the second iodine source in the reaction system is controlled to be 1:(1.5-2.5).

[0087] As an example, in the reaction system, the molar ratio of dichlorosilane to the sum of the molar amounts of the first iodine source and the second iodine source can be in the range of 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.5 or any two thereof.

[0088] In step S3, the temperature of the reaction system is raised to 30-80° C. and the reaction is carried out for 3-24 hours.

[0089] As an example, the temperature of the reaction system can be raised to one of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 80°C, or a range between any two thereof.

[0090] As an example, the reaction time can be 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h, or a range between any two of them.

[0091] In some embodiments, in step S4, during the reduced pressure heating distillation purification, the pressure is reduced to a pressure below 1 KPa.

[0092] In some possible embodiments, the collection temperature of the distillation may be 55-60°C.

[0093] The above method can improve the preparation efficiency and simplify the synthesis process on the basis of reducing the raw material input cost, and can obtain diiodosilane with high purity. The purity of diiodosilane is 99.9+%, which can meet the standard of high-purity electronic agent diiodosilane.

[0094] The preparation method of diiodosilane of the present application is further described in detail below with reference to the examples.

[0095] Example 1

[0096] Embodiment 1 provides a method for preparing diiodosilane, comprising the following steps:

[0097] (1) Under an inert gas atmosphere, add 669.2 g of lithium iodide and 749.45 g of sodium iodide into a closed reactor, and dissolve the lithium iodide and sodium iodide in acetonitrile to form a uniform solution.

[0098] (2) Lower the temperature of the reactor to -30°C and add liquid dichlorosilane (DCS) to the reactor at a rate of 2 L / h. The mass of DCS is 505 g. After the addition is completed, close the reactor.

[0099] (3) Raise the temperature of the reactor to 60°C and react for 12 hours.

[0100] (4) After the reaction is completed, the product is purified by distillation under reduced pressure and heating to obtain high-purity electronic grade diiodosilane. The output of diiodosilane (DIS for short) is 1099.3 g, and the yield is 77.44%. Some parameters are shown in Table 1. The product diiodosilane is subjected to chromatographic analysis, and the chromatogram is shown in Figure 3 .

[0101] Example 2

[0102] Example 2 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0103] In step (1), the mass of lithium iodide is 267.68 g, and the mass of sodium iodide is 1199.12 g.

[0104] In step (4), the yield of diiodosilane is 977.2182 g, and the yield is 68.84%. Some parameters are shown in Table 1.

[0105] Example 3

[0106] Example 3 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0107] In step (1), the mass of lithium iodide is 1070.72 g, and the mass of sodium iodide is 299.78 g.

[0108] In step (4), the yield of diiodosilane is 1204.346 g, and the yield is 84.84%. Some parameters are shown in Table 1.

[0109] Comparative Example 1

[0110] Comparative Example 1 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0111] In step (1), the mass of lithium iodide is 1338.4 g, and no sodium iodide is added.

[0112] In step (4), the yield of diiodosilane is 1247.008 g, and the yield is 87.85%. Some parameters are shown in Table 1.

[0113] Comparative Example 2

[0114] Comparative Example 2 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0115] In step (1), the mass of lithium iodide is 1338.4 g, and no sodium iodide is added. The solvent is hexane.

[0116] In step (3), the reaction time is 24 h.

[0117] In step (4), the yield of diiodosilane is 616.8699 g, and the yield is 43.46%. Some parameters are shown in Table 1.

[0118] Comparative Example 3

[0119] Comparative Example 3 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0120] In step (1), the mass of sodium iodide is 1498.9 g, and no lithium iodide is added.

[0121] In step (4), the yield of diiodosilane is 162.2546 g, and the conversion rate is 11.43%. Some parameters are shown in Table 1.

[0122] Comparative Example 4

[0123] Comparative Example 4 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0124] In step (1), the mass of sodium iodide is 1498.9 g, and no lithium iodide is added. The solvent is hexane.

[0125] In step (3), the reaction time is 24 h.

[0126] In step (4), the yield of diiodosilane is 192.1503 g, and the conversion rate is 13.54%. Some parameters are shown in Table 1.

[0127] Comparative Example 5

[0128] Comparative Example 5 provides a method for preparing diiodosilane, which differs from Example 1 in that:

[0129] In step (1), the mass of lithium iodide is 669.2 g, the mass of sodium iodide is 749.45 g, and the solvent is hexane.

[0130] In step (3), the reaction time is 24 h.

[0131] In step (4), the yield of diiodosilane was 261.1972 g, and the conversion rate was 18.4%. Some parameters are shown in Table 1.

[0132] Table 1

[0133]

[0134]

[0135] Result analysis:

[0136] In Table 1, Examples 1 to 3 can all obtain diiodosilane with a high yield of not less than 68.84% within a short reaction time of 12 hours. Figure 3 It can be seen that the content of diiodosilane in the product obtained by the preparation method provided in the embodiment of the present application is relatively high, indicating that the diiodosilane prepared in the embodiment of the present application has a relatively high purity.

[0137] In Table 1, it can be seen from the comparison of Example 3 and Comparative Example 1 that the iodine source in Comparative Example 1 is all lithium iodide, and the yield of diiodosilane is 87.86%, and the iodine source in Example 3 includes lithium iodide and sodium iodide, and the yield of diiodosilane is 84.84%. The yields of diiodosilane in Example 3 and Comparative Example 1 are not much different, but the raw material cost of Example 3 is lower than that of Comparative Example 1. It is explained that the embodiment of the present application utilizes the first iodine source and the second iodine source to cooperate, which can reduce the raw material input cost while improving the preparation efficiency. In other words, the proportion of lithium iodide in the iodine source is reduced in Example 3, which greatly reduces the cost of raw materials, but the yield has only a small decrease.

[0138] In Table 1, it can be seen from the comparison between Example 3 and Comparative Example 2 that the yield of diiodosilane in Comparative Example 2, which is all lithium iodide, the solvent is hexane, and the reaction time is 24 hours, is 43.46%, while the yield of diiodosilane in Example 3, which includes lithium iodide and sodium iodide, the solvent is acetonitrile, and the reaction time is 12 hours, is 84.84%. Although the input amount of raw materials in Example 3 is lower than that in Comparative Example 2, the reaction time of Example 3 is shorter than that of Comparative Example 2, and the yield of diiodosilane in Example 3 is much higher than that in Comparative Example 2.

[0139] Moreover, it can be seen from the comparison between Example 2, Comparative Example 3 and Comparative Example 4 that a small amount of lithium iodide is added to cooperate with sodium iodide in Example 2, and acetonitrile is used as a solvent to dissolve lithium iodide and sodium iodide. Example 2 can obtain diiodosilane with a yield of 68.84% within a reaction time of 12 hours, compared with a yield of 11.43% of diiodosilane in Comparative Example 3 and a yield of 13.54% of diiodosilane in Comparative Example 4 after a reaction of 24 hours, Example 2 can greatly improve the conversion efficiency and the yield of diiodosilane.

[0140] By comparing Example 1 and Comparative Example 5, it can be seen that although both Example 1 and Comparative Example 5 use the first iodine source and the second iodine source, Example 1 uses acetonitrile to dissolve the first iodine source and the second iodine source, and can obtain diiodosilane with a yield of 77.44% after a reaction of 12 hours; while Comparative Example 5 uses hexane as a solvent, and the yield of diiodosilane obtained after a reaction of 24 hours is only 18.4%. The reaction time of Comparative Example 5 is much longer than that of Example 1, but the yield of Comparative Example 5 is much lower than that of Example 1.

[0141] It is explained that the embodiment of the present application utilizes a first iodine source and a second iodine source to cooperate, and utilizes a solvent to dissolve the first iodine source and the second iodine source. The reaction system is a gas-liquid two-phase reaction system with a liquid phase reaction as the main body. The reaction driving force is high and the reaction rate is high. While being able to significantly reduce the input cost of raw materials, the decrease in reaction rate and yield is small, and a higher yield of diiodosilane can be obtained in a shorter time.

[0142] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing diiodosilane, characterized in that: include: S1. Under an inert gas atmosphere, a first iodine source and a second iodine source are added to a closed reactor, and the first iodine source and the second iodine source are dissolved in a solvent to form a uniform solution; the first iodine source is lithium iodide, and the second iodine source is at least one of sodium iodide and potassium iodide; the solvent includes at least one of acetonitrile, acetone, ether or ethanol; S2, lower the temperature and add liquid dichlorosilane; S3, heating to 30-80°C, reacting; S4. After the reaction is completed, the pressure is reduced, and heating and distillation are performed to purify the product to obtain diiodosilane.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the second iodine source to the first iodine source is 1:(0.1-5).

3. The preparation method according to claim 2, characterized in that: The molar ratio of the second iodine source to the first iodine source is 1:(1-2).

4. The preparation method according to claim 1, characterized in that: The second iodine source is selected from sodium iodide.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the dichlorosilane to the sum of the molar amounts of the first iodine source and the second iodine source is 1:(1.5-2.5).

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step S2, the temperature is lowered to -40 to 0°C.

7. The preparation method according to any one of claims 1 to 5, characterized in that: In step S2, the rate of adding the dichlorosilane is 1.5 to 2 L / h.

8. The preparation method according to any one of claims 1 to 5, characterized in that: In step S3, the reaction is carried out for 3 to 24 hours.

9. The preparation method according to any one of claims 1 to 5, characterized in that: In step S4, the pressure is reduced to below 1 KPa.

10. The preparation method according to claim 1, characterized in that: The purity of the diiodosilane is not less than 99.9%.

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