Method for producing cyclic silane compound

Abstract

This method for producing a cyclic silane compound comprises a step for obtaining a cyclic silane compound by subjecting a chain polysilane compound having a repeating unit represented by formula (1), which is not completely dissolved in 1-chloronaphthalene at a temperature of 240 DEG C or less, to a decomposition reaction in a solution containing sodium metal and a lithium salt. (In the formula, R1 and R2 each independently represent a hydrogen atom or a hydrocarbon group).

Description

Technical Field

[0001] This invention relates to a method for manufacturing cyclic silane compounds. Background Technology

[0002] Silicon carbide fiber exhibits excellent heat resistance and oxidation resistance even in atmospheric temperatures exceeding 1000 degrees Celsius. This property promises potential applications in the atomic energy and aerospace fields.

[0003] Silicon carbide fibers are obtained by spinning, non-melting, and sintering organosilicon polymers such as polycarbosilanes as precursors. Since oxygen-containing silicon carbide fibers decompose at high temperatures, it is necessary to suppress the introduction of oxygen atoms from the organosilicon polymers forming the fibers in order to obtain ultra-heat-resistant silicon carbide fibers. Therefore, ultra-heat-resistant silicon carbide fibers are manufactured by using organosilicon polymers with low oxygen content and avoiding the introduction of oxygen during non-melting. Polycarbosilanes with an oxygen content of approximately 0.1% by weight can be obtained from cyclic silane compounds such as dodecylcyclohexane. Therefore, cyclic silane compounds are useful as raw materials for organosilicon polymers that serve as precursors for silicon carbide fibers.

[0004] Various methods are known for manufacturing cyclic silane compounds. For example, Patent Document 1 discloses a method for manufacturing cyclic silane compounds: under ice-cold conditions, a silane monomer compound is added dropwise to a mixture of tetrahydrofuran (THF) and sodium dispersion to carry out a polymerization reaction to obtain a chain-like polysilane compound; then naphthalene is added, and the chain-like polysilane compound is heated under reflux.

[0005] Patent document 2 discloses a method for manufacturing cyclic silane compounds: under ice conditions, a silane monomer compound is added dropwise to a mixture of tetrahydrofuran (THF), sodium dispersion and lithium chloride, and then a polymerization reaction is carried out.

[0006] Patent document 3 discloses a method for manufacturing cyclic silane compounds: a linear polysilane with a degree of polymerization of 10 to 100, an alkali metal, and an aromatic hydrocarbon capable of forming a complex with the alkali metal are reacted in an ether solvent. In the examples, naphthalene is used as the aromatic hydrocarbon.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2019-156792

[0010] Patent Document 2: International Publication No. 2020 / 045614

[0011] Patent Document 3: Japanese Patent Application Publication No. 54-130541 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] However, as shown in Patent Document 2, when manufacturing cyclic silanes by polymerizing silane monomer compounds, a stoichiometric amount of metallic sodium is required. Therefore, a certain amount of sodium chloride and other byproducts are generated. From the viewpoint of further improving manufacturing efficiency, it is desirable to reduce the amount of byproducts such as sodium chloride generated.

[0014] Furthermore, the naphthalene used in Patent Documents 1 and 3 is a non-water-soluble solid organic compound, which cannot be removed by washing with water, making purification complicated. Therefore, it is desirable to be able to purify it simply by washing with water (so that purification can be performed easily).

[0015] Furthermore, it is hoped that the yield of cyclic silane compounds will be increased to a level previously achieved.

[0016] The present invention was made in view of the above circumstances, and its object is to provide a method for producing cyclic silane compounds, which can reduce the amount of by-products generated and produce cyclic silane compounds in high yield through simple purification.

[0017] Solution for solving the problem

[0018] This invention relates to a method for manufacturing the following cyclic silane compounds.

[0019] [1] A method for manufacturing a cyclic silane compound includes: a step of decomposing a chain polysilane compound having repeating units as shown in the following formula (1) in a solution containing metallic sodium and lithium salt to obtain a cyclic silane compound, wherein the chain polysilane compound is not completely soluble in 1-chloronaphthalene at a temperature below 240°C.

[0020] [Chemical Formula 1]

[0021] ・・・Form (1)

[0022] (where R) 1 and R 2 Each can be used to independently represent a hydrogen atom or a hydrocarbon group.

[0023] [2] According to the method for manufacturing the cyclic silane compound described in [1], wherein the chain polysilane compound is insoluble in 1-chloronaphthalene at a temperature below 250°C.

[0024] [3] The method for manufacturing the cyclic silane compound according to [1] or [2], wherein the step of obtaining the cyclic silane compound is performed by heating the chain polysilane compound in the solution.

[0025] [4] The method for manufacturing the cyclic silane compound according to [3], wherein the heating is set to 40°C or higher.

[0026] [5] A method for manufacturing a cyclic silane compound according to any one of [1] to [4], wherein the content of the lithium salt in the solution is 2.0 mmol or more relative to 1 g of the chain polysilane compound.

[0027] Invention Effects

[0028] According to the present invention, a method for producing cyclic silane compounds is provided, which produces very few byproducts and produces cyclic silane compounds in high yield through simple purification. Attached Figure Description

[0029] Figure 1 middle, Figure 1 Photograph A shows the results of a dissolution test for silane compound A. Figure 1 B is a photograph showing the results of a dissolution test of silane compound B. Detailed Implementation

[0030] In this specification, the numerical range indicated by “~” refers to the range including the values ​​recorded before and after “~” as the lower and upper limits.

[0031] 1. Method for manufacturing cyclic silane compounds

[0032] One embodiment of the present invention provides a method for manufacturing a cyclic silane compound, comprising a step of decomposing a chain-like polysilane compound in a solution containing metallic sodium and lithium salt to obtain a cyclic silane compound.

[0033] Specifically, cyclic silane compounds can be obtained through the following steps: preparing a solution containing a chain polysilane compound, metallic sodium, and a lithium salt; and decomposing the chain polysilane compound in the solution.

[0034] 1-1. Preparation process

[0035] A solution containing a chain-like polysilane compound, metallic sodium, and lithium salt was prepared.

[0036] (Chain-like polysilane compounds)

[0037] The chain polysilane compound has repeating units as shown in formula (1).

[0038] [Chemical Formula 2]

[0039] ・・・Form (1)

[0040] R in the formula 1 and R 2 Each can be used to represent a hydrogen atom or a hydrocarbon group independently.

[0041] Examples of hydrocarbon groups include alkyl, alkenyl, alkynyl, and aryl.

[0042] R 1 and R 2 It can become a side chain in cyclic silane compounds. Therefore, R is selected based on the cyclic silane compound to be synthesized. 1 and R 2 That's all. R 1 and R 2 For example, hydrogen atoms or hydrocarbon groups are preferred, more preferably hydrocarbon groups, further preferably alkyl groups, and particularly preferably methyl groups.

[0043] Furthermore, in chain-like polysilane compounds, the groups bonded to the silicon atoms at both ends of the molecule can be hydrogen atoms, hydrocarbon groups, alkoxy groups, or hydroxyl groups. Examples of alkoxy groups include methoxy and ethoxy groups. Alkoxy and hydroxyl groups have a large difference in electronegativity from silicon atoms, thus easily causing intramolecular polarization in chain-like polysilane compounds, and may readily function as leaving groups. Therefore, the groups at both ends of chain-like polysilane compound molecules can be alkoxy or hydroxyl groups.

[0044] Specifically, examples of chain polysilane compounds include compounds represented by formula (2) below.

[0045] [Chemical Formula 3]

[0046] ・・・Form (2)

[0047] In equation (2), R 1 and R 2 R in equation (1) 1 and R 2 same.

[0048] X 1 and X 2 These are hydrogen atoms, hydrocarbon groups, alkoxy groups, or hydroxyl groups, respectively, with alkoxy groups or hydroxyl groups as an example.

[0049] n1 is the degree of polymerization of the compound shown in formula (2) that does not completely dissolve at a temperature below 240°C in a dissolution test of 1-chloronaphthalene, which will be described later. For example, it is an integer of 17 or more, preferably 20 or more, and more preferably 30 or more.

[0050] From the viewpoint of increasing the yield of cyclic silane compounds, a high number-average molecular weight is preferred for the chain polysilane compounds. The number-average molecular weight of the chain polysilane compounds is preferably 950 or higher, more preferably 1100 or higher, and even more preferably higher than 1700. When the number-average molecular weight is 1100 or higher, the number of intermediates generated through the decomposition reaction may increase, thus further improving the yield of cyclic silane compounds. There is no particular upper limit to the number-average molecular weight, but from the viewpoint of shortening reaction time, it can be set to, for example, 650,000 or lower.

[0051] The number-average molecular weight of the chain polysilane compound can be evaluated by the temperature at which it dissolves in 1-chloronaphthalene. For example, the higher the number-average molecular weight of the chain polysilane compound, the higher the temperature at which it dissolves in 1-chloronaphthalene. In this embodiment, the chain polysilane compound preferably has a high number-average molecular weight, and therefore preferably dissolves in 1-chloronaphthalene at a high temperature. Specifically, the chain polysilane compound does not completely dissolve in 1-chloronaphthalene at temperatures below 240°C, and preferably does not completely dissolve in 1-chloronaphthalene at temperatures below 250°C.

[0052] The temperature at which 1-chloronaphthalene dissolves can be determined by the following method.

[0053] That is, a 3-5 mm long chain polysilane compound is placed in a glass capillary tube with an inner diameter of 1.0 mm, and then 5-10 mm of 1-chloronaphthalene (about twice the amount of the chain polysilane compound) is filled in. The tube is then replaced with argon gas and sealed.

[0054] Place it in a melting point apparatus (Buchi, B-545) preheated to 240°C and let it stand for 5 minutes. After standing, visually inspect the state of the chain-like polysilane compound filling the glass capillary to determine if it has completely dissolved.

[0055] By repeating this operation at different temperatures, the temperature at which the chain-like polysilane compound completely dissolves can be determined.

[0056] Chain-like polysilane compounds are white solids. Therefore, even if some remains undissolved, the state of the white solid residue can be visually confirmed. Thus, complete dissolution can be judged visually by whether the mixture is transparent and free of any remaining white solid. For example, as described later... Figure 1 At 250℃, part of the white solid remained undissolved, but... Figure 1 At 250°C, B shows the complete dissolution of the white solid. Alternatively, complete dissolution can be confirmed by the transmittance, turbidity, or whiteness of the image processed from the solution.

[0057] Chain-like polysilane compounds can be identified using a Fourier transform infrared spectrophotometer and a micro Raman spectrophotometer.

[0058] In the IR spectrum measured using a Fourier transform infrared spectrophotometer, if at 742 cm⁻¹... -1 831cm -1 1246cm -1 1400cm -1 2892cm -1 2950cm -1 A peak was observed; in the Raman spectrum measured using a micro Raman spectrometer, if it is at 482 cm⁻¹ -1 Observing the peak confirms that the compound in the sample contains repeating units as shown in formula (1) above (a chain-like polysilane compound). Furthermore, through... 29 Si CP / MAS NMR confirmed that it has a chain-like structure with ends.

[0059] Chain-like polysilane compounds can be synthetic or commercially available.

[0060] (Sodium metal)

[0061] Sodium metal can act as a catalyst for decomposition reactions. The form of sodium metal is not particularly limited, but from the viewpoint of increasing surface area to improve reactivity, sodium metal processed into a sodium dispersion is preferred.

[0062] In this specification, sodium dispersion (SD) refers to a substance obtained by dispersing metallic sodium in electrical insulating oil or aromatic hydrocarbons. Examples of electrical insulating oils include aliphatic hydrocarbons such as liquid paraffin and mineral oil, and examples of aromatic hydrocarbons include toluene and xylene.

[0063] From the viewpoint of reactivity and safety, the average particle size of metallic sodium is preferably 1–30 µm, more preferably 2–10 µm, and even more preferably 3–5 µm. The average particle size can be determined using a laser diffraction-based particle size distribution measuring device.

[0064] From the viewpoint of yield of cyclic silane compounds, the amount of metallic sodium contained in the above solution is preferably 0.1 to 120 mmol relative to 1 g of the chain polysilane compound. When the content of metallic sodium is 0.1 mmol or more, the decomposition reaction of the chain polysilane compound is easier to proceed. When the content of metallic sodium is 120 mmol or less, the reaction can proceed fully and unreacted metallic sodium is reduced. Furthermore, when the chain polysilane compound is dichlorodimethylpolysilane or the like, the amount of byproducts such as sodium alkoxide generated is also reduced. From the viewpoint of ensuring the reaction proceeds fully and further reducing unreacted metallic sodium, the amount of metallic sodium relative to 1 g of the chain polysilane compound is more preferably 0.5 to 80 mmol, more preferably 0.5 to 20 mmol, and particularly preferably 1.0 to 10.0 mmol.

[0065] (Lithium salts)

[0066] Lithium salts primarily contribute to the stabilization of intermediates generated during decomposition reactions. Lithium salts can be either inorganic or organic.

[0067] As inorganic salts, examples include salts of halides and salts of inorganic acids. Examples of halides include lithium chloride, lithium bromide, lithium iodide, and lithium fluoride. Examples of salts of inorganic acids include lithium carbonate, lithium bicarbonate, lithium nitrate, lithium nitrite, lithium sulfate, and lithium sulfite.

[0068] Examples of organic salts include carboxylates, sulfonates, and phenolic salts. Examples of carboxylates include lithium acetate, lithium formate, and lithium citrate. Examples of sulfonates include lithium methanesulfonate, lithium benzenesulfonate, and lithium p-toluenesulfonate. Examples of phenolic salts include lithium phenolate, lithium salicylate, and lithium cresol.

[0069] The preferred form is an inorganic salt, more preferably a halide. Among the halides, lithium chloride and lithium bromide are preferred, more preferably lithium chloride. A single lithium salt or a mixture of multiple lithium salts can be used.

[0070] The molar ratio of lithium salt to sodium metal in the above solution (lithium salt / sodium metal) also depends on the content of sodium metal, and is preferably 0.01 or more, more preferably 0.06 or more, further preferably more than 1.0, and most preferably 1.3 or more. When the above molar ratio is 0.06 or more, it is easy to moderately stabilize the intermediates generated in the decomposition reaction of the chain polysilane compound, and it is easy to further improve the yield of the cyclic silane compound. In addition, even if the content of sodium metal is low, it is easy to maintain the yield of the cyclic silane compound. On the other hand, the above molar ratio of lithium is preferably 10.0 or less, more preferably 6.0 or less, further preferably 3.0 or less, and most preferably 2.0 or less. When the above molar ratio is 3.0 or less, the decomposition of the generated cyclic silane compound can be further suppressed.

[0071] Thus, by setting the molar ratio of lithium salt in the solution within the above range, the yield of cyclic silane compounds can be further improved.

[0072] The amount of lithium salt contained in the above solution is acceptable as long as it reaches the above molar ratio. It is preferably 1.0 mmol or more, more preferably 1.5 mmol or more, and even more preferably 2.0 mmol or more, relative to 1 g of the chain polysilane compound. The upper limit of the amount of lithium salt is preferably 9.0 mmol or less, more preferably 5.0 mmol or less.

[0073] It should be noted that the amount of metallic sodium, lithium salt, and their molar ratio are as described above. From the viewpoint of further improving reactivity and yield, it is preferable to satisfy these quantitative relationships simultaneously.

[0074] For example, the amount of sodium metal contained in the above solution relative to 1g of the chain polysilane compound is preferably 0.1 to 120 mmol, more preferably 0.5 to 20 mmol; the amount of lithium salt is preferably 1.0 to 9.0 mmol, more preferably 2.0 to 5.0 mmol; and the above molar ratio (lithium salt / sodium metal) is preferably 0.01 or more, more preferably more than 1.0.

[0075] (solvent)

[0076] The solution preferably further comprises a solvent. Any solvent capable of dispersing metallic sodium or dissolving lithium salts is acceptable.

[0077] Examples of solvents include, for example, aprotic polar solvents. Examples of aprotic polar solvents include tetrahydrofuran (THF), 1,2-dimethoxyethane, 4-methyltetrahydropyran, bis(2-methoxyethyl) ether, 1,4-dioxane, and cyclopentylmethyl ether. These solvents can be used alone or in mixtures of two or more. Tetrahydrofuran, 4-methyltetrahydropyran, and cyclopentylmethyl ether are preferred, with tetrahydrofuran being more preferred.

[0078] (mix)

[0079] The above solution can be prepared by mixing the components. There are no particular restrictions on the mixing method or order. For example, sodium metal, lithium salt, and chain polysilane compounds can be added while stirring the solvent, and then stirred and mixed to obtain the solution.

[0080] At this point, metallic sodium is preferably added in the form of a dispersion (SD) obtained by dispersing the aforementioned electrical insulating oil or aromatic hydrocarbon. There is no particular limitation on the content of metallic sodium in the added sodium dispersion, but from a safety point of view, it is preferably 20–45% by mass.

[0081] 1-2. Processes in which decomposition reactions occur

[0082] In the solution prepared above, the chain-like polysilane compound undergoes a decomposition reaction. The decomposition reaction can be carried out at room temperature or under heating.

[0083] That is, the solution temperature during the decomposition reaction can be from 20°C to the reflux temperature. The reflux temperature is equivalent to the temperature of the solution under reflux at atmospheric pressure. From the viewpoint of obtaining cyclic silane compounds in higher yields, the decomposition reaction is preferably carried out under heating, i.e., by heating the chain polysilane compound in solution. In this case, the solution temperature is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. From the viewpoint of suppressing the decomposition of reaction products, the upper limit of the solution temperature is preferably 200°C or lower.

[0084] There are no particular restrictions on the heating method. For example, it can be a method of placing the above solution in an atmosphere at a specified temperature, or it can be a method of heating by a heater, water bath, oil bath, or electromagnetic waves.

[0085] The reaction time refers to the time elapsed after all the raw material chain polysilane compound has been added and the target reaction temperature has been reached. The reaction time also depends on the temperature of the solution. When the reaction is carried out under heating, it is preferably 1 hour or more and 35 hours or less, more preferably 3 hours or more and 10 hours or less.

[0086] 1-3. Functions

[0087] According to the above embodiments, cyclic silane compounds are produced by decomposing chain-like polysilane compounds in the presence of a prescribed catalyst. Therefore, compared to conventional methods that polymerize silane monomers, cyclic silane compounds can be obtained in high yield. Furthermore, the chain-like polysilane compounds contain very few functional groups that react with metallic sodium, reducing the amount of metallic sodium used as a catalyst, and thus significantly reducing the amount of byproducts such as sodium alkoxides generated.

[0088] The specific reaction mechanism is not yet clear, but the following is a hypothesis.

[0089] In conventional methods of producing cyclic silane compounds by polymerizing silane monomers, substituents (e.g., halogen atoms) in the silane monomers are desorbed by the action of metallic sodium, and the silane monomers undergo chain polymerization to form cyclic silane compounds. Therefore, the amount of metallic sodium required increases, and the amount of byproducts also tends to increase. Furthermore, it is difficult to further improve the yield of cyclic silane compounds.

[0090] In contrast, as in this embodiment, in the method for causing the chain polysilane compound to undergo a decomposition reaction, the terminal groups (e.g., alkoxy groups) of the chain polysilane compound molecule are removed by the action of metallic sodium, or the silicon-silicon bonds are broken by the action of metallic sodium, thereby changing the electronic state and generating active sites. Subsequently, through these active sites, the molecular chain breaks at predetermined intervals and cyclizes, thereby generating cyclic silane compounds. Here, the generated active sites are stabilized by lithium salts or the like, thus preventing deactivation and maintaining appropriate reactivity; therefore, reactivity is improved by adding lithium salts or the like. In this way, fewer groups are removed from each molecule of the chain polysilane compound, and less metallic sodium is required for the decomposition reaction, thus reducing the amount of byproducts. Furthermore, the stabilization of active sites by lithium salts or the like also increases the yield of cyclic silane compounds.

[0091] Furthermore, since it does not require the use of non-water-soluble solid organic compounds such as naphthalene, purification can be carried out simply by washing with water, making purification easy.

[0092] 2. Cyclic silane compounds

[0093] The cyclic silane compound obtained by the method for manufacturing cyclic silane compounds according to this embodiment has, for example, the structure shown in the following formula.

[0094] [Chemical Formula 4]

[0095] ...Form (3)

[0096] R in equation (3) 1 and R 2 R in equation (1)1 and R 2 same.

[0097] n2 is an integer of 3 or more. n2 is preferably 3 to 10, more preferably 5 to 7, and even more preferably 6.

[0098] Cyclic silanes via R 1 and R 2 It can have any structure; for example, decamethylcyclopentylsilane, dodecylcyclohexylsilane, tetradecylcycloheptane, etc.

[0099] The obtained cyclic silane compounds may also contain various cyclic silane compounds with different n2 values. The yield of cyclic silane compounds with n2 of 6 (six-membered rings) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The yield of the cyclic silane compounds can be determined by analyzing the reaction products using gas chromatography. The determination conditions can be set to be the same as in the examples described later.

[0100] Example

[0101] The present invention will be specifically described below through embodiments, but the present invention is not limited thereto.

[0102] 1. Materials

[0103] (1) Silane compounds

[0104] Silane compound A: Chain-like polydimethylsilane (solid at room temperature, number average molecular weight exceeding 1700, R of formula (1) 1 R 2 =Methyl).

[0105] Silane compound B: Chain-like polydimethylsilane (solid at room temperature, number average molecular weight 1100-1700, R in formula (1) 1 R 2 =Methyl).

[0106] Silane compound C: Dichlorodimethylsilane (monosilanes, liquid at room temperature, molecular weight 129).

[0107] The dissolution temperatures of these compounds in 1-chloronaphthalene were determined.

[0108] (Determination of dissolution temperature)

[0109] A silane compound of approximately 3–5 mm was placed in a 1.0 mm inner diameter glass capillary tube, followed by approximately 5–10 mm of 1-chloronaphthalene (about twice the amount of the silane compound). The tube was then purged with argon gas and sealed. It was placed in a melting point apparatus (Buchi, B-545) preheated to 240°C or 250°C and allowed to stand for 5 minutes. After standing, the state of the silane compound in the glass capillary tube was visually confirmed. The results of the dissolution test for silane compound A are shown below. Figure 1 A, The results of the dissolution test of silane compound B are shown in Figure 1 B.

[0110] As a result, silane compound A did not completely dissolve at either 240°C or 250°C (see reference). Figure 1 A). On the other hand, silane compound B did not completely dissolve at 240°C, but dissolved completely at 250°C (see reference). Figure 1 B). These results correspond to the situation where the number-average molecular weight of silane compound A is higher than that of silane compound B.

[0111] (2) Sodium metal

[0112] Sodium dispersion (25% sodium dispersion, average particle size 3.40µm).

[0113] (3) Lithium salts

[0114] Lithium chloride (LiCl)

[0115] Lithium bromide (LiBr)

[0116] (4) Solvent

[0117] Tetrahydrofuran (THF)

[0118] 2. Preparation of cyclic silane compounds

[0119] [Example 1]

[0120] In a 200 mL four-necked flask purged with argon, 0.98 g of silane compound A (chain polysilane), 20.4 mL of tetrahydrofuran (THF) / 1 g of the above silane compound, 1.6 mmol of sodium dispersion (25.72% by mass) as metallic sodium / 1 g of the above silane compound, and 2.23 mmol of lithium chloride as lithium salt / 1 g of the above silane compound were added, and the mixture was stirred and mixed to prepare a solution.

[0121] The resulting solution was heated in an oil bath while being stirred at a reflux temperature of 68°C for 5 hours to allow the reaction to proceed.

[0122] [Examples 2-10, Comparative Examples 3 and 4]

[0123] The type of silane compound, the amount of tetrahydrofuran (THF) added, the ratio of sodium metal to lithium salt, the type and amount of lithium salt, and the reaction conditions were changed as shown in Table 1. Otherwise, the solution was prepared in the same manner as in Example 1 and the reaction was carried out.

[0124] [Comparative Example 1]

[0125] In a 500 mL four-necked flask purged with argon, 180 mL of THF and 29.90 g of sodium dispersion (25% by weight) were added, and a mixture was prepared by stirring. A silane compound solution was prepared by dissolving 19.33 g of silane compound C (dichlorodimethylsilane) in 150 mL of THF.

[0126] After cooling the mixture to 0°C, 0.71 g of lithium chloride was added. The silane compound solution was then added dropwise over approximately 5 hours with stirring while remaining chilled. Following the addition, stirring was continued for another 3 hours, followed by a reaction at room temperature for 21 hours.

[0127] [Comparative Example 2 and Comparative Example 5]

[0128] Using silane compound C (dichlorodimethylsilane), the loading amounts of each component were varied as shown in Table 1, and the solution was prepared in the same manner as in Example 1.

[0129] The resulting solution was then stirred and reacted under the reaction conditions shown in Table 1, otherwise reacted in the same manner as in Example 1.

[0130] The reaction products obtained in Examples 1-10 and Comparative Examples 1-5 were analyzed by gas chromatography. The determination conditions are as follows.

[0131] (Gas chromatography determination)

[0132] Device: GC-2025 (manufactured by Shimadzu Corporation).

[0133] Column: DB1301 (Agilent Technologies), length (30m), diameter (0.320m), film thickness (0.25m), carrier gas: He.

[0134] Detector: FID.

[0135] Then, the formation of cyclic silanes (dodecylcyclohexylsilane (six-membered ring), decamethylcyclopentylsilane (five-membered ring), and tetradecylcycloheptane (seven-membered ring)) was confirmed, and their yields were calculated. The results are shown in Table 2.

[0136]

[0137]

[0138]

[0139]

[0140] As shown in Table 2, in Comparative Examples 1, 2, and 5, which used silane compound C (monomer) as a raw material, the total yield of cyclic silanes was less than 46.6%. Furthermore, it was found that even when using silane compound A (polymer) as a raw material, in Comparative Examples 3 and 4, which did not use lithium salt, the total yield was less than 22%.

[0141] In contrast, it can be seen that in Examples 1-9, which used silane compounds A or B (polymers) as raw materials and lithium salts, the total yield was all above 67.5%. Furthermore, it can be seen that the total yield of Example 10 was higher than that of Comparative Examples 4 and 5.

[0142] Therefore, it can be seen that by decomposing the chain polysilane compound in a solution containing metallic sodium and lithium salt, and allowing the reaction to proceed fully, cyclic silanes can be obtained in high yield.

[0143] In particular, it can be seen that by setting the reaction temperature to above 40°C, the total yield is further improved (comparison of Examples 5 and 8, and comparison of Examples 1, 3 and 9).

[0144] Furthermore, it is known that by setting the amount of lithium salt to 2.0 mmol or more relative to 1 g of the chain polysilane compound, or by setting the molar ratio (lithium salt / sodium metal) to be higher than 1.0, the total yield is further improved (comparison between Examples 1 and 10).

[0145] This application claims priority based on Japanese Patent Application No. 2023-113668, filed on July 11, 2023. The entire contents of that application are incorporated herein by reference.

[0146] Industrial availability

[0147] According to the present invention, a method for manufacturing cyclic silane compounds can be provided, which can produce high-purity cyclic silane compounds in high yield even when the amount of metallic sodium used is small.

Claims

1. A method for manufacturing a cyclic silane compound, comprising: The process of decomposing a chain-like polysilane compound having repeating units as shown in formula (1) in a solution containing metallic sodium and lithium salt to obtain a cyclic silane compound. The chain-like polysilane compound is not completely soluble in 1-chloronaphthalene at temperatures below 240°C. [Chemical Formula 1] ・・・Form (1) In the formula, R 1 and R 2 Each can be used to represent a hydrogen atom or a hydrocarbon group independently.

2. The method for manufacturing the cyclic silane compound according to claim 1, wherein, The chain-like polysilane compound is insoluble in 1-chloronaphthalene at temperatures below 250°C.

3. The method for manufacturing the cyclic silane compound according to claim 1 or 2, wherein, The process of obtaining the cyclic silane compound is carried out by heating the chain polysilane compound in the solution.

4. The method for manufacturing the cyclic silane compound according to claim 3, wherein, The heating temperature is set to above 40°C.

5. The method for producing the cyclic silane compound according to any one of claims 1 to 4, wherein, The content of the lithium salt in the solution is more than 2.0 mmol per 1g of the chain polysilane compound.

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