Method for producing cyclic silane compound

Abstract

This method for producing a cyclic silane compound comprises: a first step for obtaining a reaction solution containing a chain polysilane compound by subjecting a silane compound to a polymerization reaction in a mixture containing metallic sodium and an aromatic hydrocarbon-based solvent; and a second step for obtaining a cyclic silane compound by subjecting the chain polysilane compound to a decomposition reaction in a solution obtained by mixing the reaction solution with tetrahydrofuran and a polycyclic aromatic hydrocarbon or a polyphenyl hydrocarbon.

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 as methods for manufacturing cyclic silane compounds. For example, Patent Document 1 discloses a method in which: 1) a silane monomer compound is added dropwise to a mixture of tetrahydrofuran (THF) and sodium dispersion under ice-cold conditions, followed by a polymerization reaction to obtain a chain-like polysilane compound; 2) naphthalene is added, and the chain-like polysilane compound is heated under reflux to manufacture a cyclic silane compound.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-156792 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, the aforementioned methods for manufacturing cyclic silane compounds require the use of expensive sodium dispersions in stoichiometric quantities. This results in increased manufacturing costs.

[0010] Furthermore, the sodium dispersion contains a large amount of dispersion oil used to disperse metallic sodium. Dispersion oil is a non-water-soluble organic compound, and cyclic silane compounds have high solubility in dispersion oil, thus posing a challenge for separation and purification.

[0011] Given these circumstances, it is desirable to reduce manufacturing costs and facilitate separation and purification by obtaining cyclic silane compounds in yields exceeding specified limits without using sodium dispersions.

[0012] The present invention was made in view of the above circumstances, and its object is to provide a method for manufacturing cyclic silane compounds that can reduce manufacturing costs and facilitate separation and purification.

[0013] Solution for solving the problem

[0014] This invention relates to a method for manufacturing the following cyclic silane compounds.

[0015] [1] A method for manufacturing a cyclic silane compound, comprising: a first step of polymerizing the silane compound in a mixture containing metallic sodium and an aromatic hydrocarbon solvent to obtain a reaction solution containing a chain polysilane compound; and a second step of decomposing the chain polysilane compound in a solution in which a polycyclic aromatic hydrocarbon or a polyphenylene hydrocarbon and tetrahydrofuran are mixed to the reaction solution to obtain a cyclic silane compound.

[0016] [2] According to the method for manufacturing the cyclic silane compound described in [1], in the second step, the solution contains the tetrahydrofuran and the aromatic hydrocarbon solvent, and the volume ratio of the tetrahydrofuran contained in the solution relative to the total volume of the aromatic hydrocarbon solvent and the tetrahydrofuran is 75% or more and 95% or less.

[0017] [3] The method for manufacturing a cyclic silane compound according to [1] or [2], wherein, in the first step, the mixture is heated to above the melting point of the metallic sodium.

[0018] [4] A method for manufacturing a cyclic silane compound according to any one of [1] to [3], wherein the aromatic hydrocarbon solvent comprises toluene, ethylbenzene or xylene.

[0019] [5] A method for manufacturing a cyclic silane compound according to any one of [1] to [4], wherein the second step is performed by heating the chain polysilane compound in the solution.

[0020] [6] The method for manufacturing the cyclic silane compound according to [5], wherein the heating temperature is set to above 40°C and below the reflux temperature.

[0021] [7] A method for manufacturing a cyclic silane compound according to any one of [1] to [6], wherein, in the second step, biphenyl, anthracene or naphthalene, which are said polycyclic aromatic hydrocarbons, are mixed into the reaction solution.

[0022] Invention Effects

[0023] According to the present invention, a method for manufacturing cyclic silane compounds that reduces manufacturing costs and facilitates separation and purification can be provided. Detailed Implementation

[0024] The aforementioned sodium dispersion (SD) refers to a mixture formed by dispersing solid sodium with an average particle size of 1 µm or more and 100 µm or less in an electrical insulating oil or an aromatic hydrocarbon solvent. Compared to metallic sodium, it exhibits higher reactivity. From the viewpoint of reactivity and safety, the average particle size of the solid sodium in the SD is preferably 2 µm or more and 10 µm or less, more preferably 3 µm or more and 5 µm or less. Examples of electrical insulating oils include liquid paraffin, mineral oil, and other aliphatic hydrocarbons.

[0025] In this specification, metallic sodium refers to elemental sodium, and its state is not particularly limited. That is, metallic sodium can be solid sodium or liquid sodium. In the case of solid sodium, the average particle size exceeds 100 µm.

[0026] The aforementioned sodium dispersion (SD) refers to a substance obtained by dispersing microparticles of metallic sodium in electrical insulating oil or aromatic hydrocarbon solvents, and it exhibits higher reactivity compared to bulk metallic sodium. Examples of electrical insulating oils include liquid paraffin, mineral oil, and other aliphatic hydrocarbons.

[0027] As a method for synthesizing cyclic silanes without using sodium dispersions, bulk metallic sodium could be considered instead. However, due to the small specific surface area of ​​bulk metallic sodium, the polymerization reaction of silane compounds is difficult to carry out, and the reaction yield is easily reduced.

[0028] In contrast, by heating metallic sodium or similar substances in an aromatic hydrocarbon solvent, they can be liquefied (to form a mixture).

[0029] Liquid sodium is more easily refined by stirring than solid sodium, thus liquid sodium has a larger specific surface area than solid sodium, which promotes the polymerization reaction of silane compounds. That is, by performing a first step and a second step, cyclic silane compounds can be obtained without using a sodium dispersion. The first step polymerizes the silane compound in a mixture of an aromatic hydrocarbon solvent and liquid metallic sodium to obtain a chain-like polysilane compound, and the second step decomposes the chain-like polysilane compound in the presence of a specified catalyst to obtain a cyclic silane compound.

[0030] From the perspective of improving manufacturing efficiency, it is desirable to proceed with the second step (through a one-pot process) without separating the chain-like polysilane compound generated in the first step. However, the reaction solution obtained in the first step contains a large amount of aromatic hydrocarbon solvent used to liquefy metallic sodium. This aromatic hydrocarbon solvent does not contribute to the decomposition reaction in the second step, thus easily reducing the reaction yield.

[0031] Therefore, in this invention, tetrahydrofuran, which contributes to the decomposition reaction, is mixed into the reaction solution obtained in the first step. That is, in the second step, the reactivity can be improved by carrying out the decomposition reaction of the chain polysilane compound in a solution containing an aromatic hydrocarbon solvent and tetrahydrofuran. Thus, the desired reaction yield can be achieved.

[0032] The following is a detailed description of a method for manufacturing a cyclic silane compound according to one embodiment of the present invention.

[0033] 1. Method for manufacturing cyclic silane compounds

[0034] As described above, a method for manufacturing a cyclic silane compound according to one embodiment of the present invention includes:

[0035] In the first step, a silane compound is polymerized in a mixture containing metallic sodium and an aromatic hydrocarbon solvent to obtain a reaction solution containing chain-like polysilane compounds; and

[0036] In the second step, the chain polysilane compound is decomposed in a solution containing polycyclic aromatic hydrocarbons or polybenzene hydrocarbons and tetrahydrofuran to obtain a cyclic silane compound.

[0037] 1-1. Regarding the first process

[0038] A silane compound is polymerized in a mixture containing metallic sodium and an aromatic hydrocarbon solvent.

[0039] Preferably, the metallic sodium contained in the above mixture is molten. Molten means that the metallic sodium is in a liquid state, for example, through heating, which is different from the state in which solid sodium particles are uniformly dispersed, such as in a sodium dispersion.

[0040] The mixture described above can be obtained, for example, by adding metallic sodium to an aromatic hydrocarbon solvent and heating it to above the melting point of metallic sodium (above 98°C).

[0041] The mixture described above can be obtained, for example, by adding metallic sodium to an aromatic hydrocarbon solvent and then heating it to above the melting point of sodium (above 98°C). Furthermore, if the added metallic sodium is liquid, the sodium melting process can be omitted.

[0042] The added metallic sodium can be in elemental form or mixed with a solvent. There are no particular limitations on the solvent, but it is preferably the same as the solvent used in the first step.

[0043] (Aromatic hydrocarbon solvents)

[0044] Aromatic hydrocarbon solvents only need to have a boiling point higher than the melting point of metallic sodium (98°C). That is, the boiling point of aromatic hydrocarbon solvents is more preferably 100°C or higher and 210°C or lower, and even more preferably 110°C or higher and 170°C or lower.

[0045] Examples of such aromatic hydrocarbon solvents include toluene, xylene, ethylbenzene, and mesitylene. Among these, toluene, xylene, and ethylbenzene are preferred from the viewpoint of ease of melting metallic sodium and ease of solvent recovery in manufacturing, with toluene being more preferred.

[0046] The mixture may further include other solvents besides those mentioned above, as needed. Examples of other solvents include aliphatic hydrocarbon solvents such as heptane, octane, and decane.

[0047] The content of the aromatic hydrocarbon solvent in the above mixture is sufficient to allow the generated chain-like polysilane to be adequately dispersed in the solvent through stirring. For example, the content of the aromatic hydrocarbon solvent in the above mixture relative to 10 parts by mass of the silane compound is preferably 1.0 parts by mass or more. When the content of the aromatic hydrocarbon solvent is 1.0 parts by mass or more, the volume fraction of metallic sodium decreases, resulting in a smaller average droplet diameter and an increased specific surface area of ​​sodium, which further enhances the reactivity of the silane compound. When the content of the aromatic hydrocarbon solvent is 25.0 parts by weight or less, the concentration of the silane compound in the system increases, which facilitates the reaction in the second step. From the same point of view, the content of the aromatic hydrocarbon solvent in the above mixture relative to 10 parts by mass of the silane compound is more preferably 3.0 parts by mass or more and 16.0 parts by mass or less.

[0048] The aromatic hydrocarbon solvent in the above mixture is preferably 2.5 parts by mass or more and 60.0 parts by mass or less relative to 10 parts by mass of metallic sodium, more preferably 6.0 parts by mass or more and 40.0 parts by mass or less.

[0049] (Sodium metal)

[0050] Sodium metal primarily functions as a reactant in polymerization reactions.

[0051] In the above mixture, the molar equivalent of sodium metal relative to each functional group of the alkoxy or halogen atom of the silane compound is preferably 1.00 eq. or more and 1.80 eq. or less. If the molar equivalent of sodium metal is 1.00 eq. or more, the polymerization rate of the silane compound in the first step can be further increased. If the molar equivalent of sodium metal is 1.80 eq. or less, the proportion of sodium metal remaining in an unreacted state can be further reduced. From the same viewpoint, the molar equivalent of sodium metal in the above mixture is more preferably 1.05 eq. or more and 1.25 eq. or less.

[0052] (Silane compounds)

[0053] Next, a silane compound is added to the mixture. The silane compound is preferably a compound represented by the following formula (1).

[0054] [Chemical Formula 1]

[0055]

[0056] In equation (1), X 1 and X 2 These represent alkoxy or halogen atoms, respectively. Examples of alkoxy atoms include methoxy and ethoxy. Examples of halogen atoms include chlorine, bromine, and iodine. They have a large electronegativity difference with silicon and readily induce intramolecular polarization in silane compounds, thus exhibiting high reactivity. They function as leaving groups in reactions. From the perspective of the reactivity of silane compounds, X... 1 and X 2 Preferably, it is a halogen atom, and more preferably a chlorine atom.

[0057] R 1 and R 2 It can be a hydrogen atom or a hydrocarbon group. Wherein, R... 1 and R 2 Preferably, it is a hydrocarbon group, more preferably an alkyl group having 1 to 6 carbon atoms, further preferably methyl or ethyl, and particularly preferably methyl.

[0058] n1 is an integer greater than or equal to 1. From the viewpoint of improving the reactivity of silane compounds, n1 is preferably 1 or 2, and more preferably 1.

[0059] Examples of compounds represented by formula (1) include dichlorodimethylsilane, dichlorodiethylsilane, dichlorodipropylsilane, dichlorodibutylsilane, dichlorodipentylsilane, dichlorodihexylsilane, dibromodimethylsilane, dibromodiethylsilane, dibromodipropylsilane, dibromodibutylsilane, dibromodipentylsilane, dibromodihexylsilane, and dichlorotetramethyldisilane. Dichlorodimethylsilane is preferred. The silane compound may be one or more compounds.

[0060] (Polymerization reaction)

[0061] From the viewpoint that the polymerization reaction of silane compounds is carried out in the liquid state of sodium metal, it is preferable to conduct the polymerization reaction under heating. That is, the above-mentioned polymerization reaction is preferably carried out simultaneously with heating to above the melting point of sodium metal.

[0062] The heating temperature is preferably above the melting point of sodium, more preferably above 98°C and below the solvent reflux temperature, and even more preferably above 100°C and below the solvent reflux temperature. The above reaction is preferably carried out under an inert gas atmosphere such as nitrogen or argon. Furthermore, the above reaction is preferably carried out under normal pressure or pressure.

[0063] The addition of silane compounds can be carried out continuously or intermittently. From the point of view of manufacturing efficiency, it is preferable to carry out it continuously in a certain amount.

[0064] The preferred average addition rate of silane compound per unit amount (mol) of metallic sodium is 0.06 hr. -1 Above and 0.50hr -1 Hereinafter, 0.10hr is preferred. -1 Above and 0.30hr -1 the following.

[0065] Average addition rate of silane compounds (mol·hr) -1 The value is obtained by dividing the total amount of silane compound used (mol) by the addition time (hr), and the average addition rate (hr) of silane compound per unit amount (mol) of metallic sodium. -1 ) is the average addition rate of silane compounds (mol·hr) -1 The value is obtained by dividing the amount of sodium metal (mol).

[0066] If the average addition rate of silane compound per unit amount (mol) of metallic sodium is 0.50 hr -1 The following further prevents the temperature of the mixture from dropping below the melting point of sodium, thus further promoting the reaction. If the average addition rate of silane compound per unit amount (mol) of metallic sodium is 0.06 hr... -1 The above can further shorten the total reaction time and further improve manufacturing efficiency.

[0067] From the viewpoint of increasing the amount of chain polysilane compound produced, it is preferable that, after the addition of the silane compound is completed, the mixture is continuously stirred at the above-mentioned reaction temperature for a period of preferably 1 hour or more and 12 hours or less.

[0068] The above reaction yields a reaction solution containing crude polydialkylsilane (chain-like polysilane compound).

[0069] (Chain-like polysilane compounds)

[0070] The chain polysilane compound has repeating units represented by the following formula (2).

[0071] [Chemical Formula 2]

[0072] Equation (2)

[0073] R in equation (2) 1 and R 2 R in equation (1) 1 and R 2 same.

[0074] 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, sodium atoms, or halogen atoms. The alkoxy or halogen atom is bonded to X in formula (1). 1 and X 2 Similarly, sodium atoms are cationized and can coordinate with anionized silicon atoms. The electronegativity difference between alkoxy and halogen atoms and silicon atoms is large, therefore, they are also likely to be easily reduced by sodium and readily generate active sites. Furthermore, the electronegativity difference between sodium and silicon atoms is particularly large, therefore, they are also likely to function as active sites. Therefore, the terminal groups of chain-like polysilane compounds can be alkoxy, halogen, or sodium atoms.

[0075] The number of repeating units is not particularly limited, but can be an integer of 2 or more, preferably an integer of 6 or more and less than 12,000.

[0076] 1-2. Regarding the second process

[0077] Tetrahydrofuran and polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons are mixed into the reaction solution obtained in the first step. That is, the product is not separated from the reaction solution obtained in the first step, but tetrahydrofuran and polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons are mixed into the reaction solution.

[0078] As described above, the aromatic hydrocarbon solvent in the reaction solution obtained in the first step is insufficient to form the sodium complex with polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons required for the decomposition reaction of the chain polysilane compound in the second step, thus hindering the decomposition reaction of the chain polysilane compound. In contrast, by adding tetrahydrofuran to the reaction solution, a sodium complex with polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons can be formed and stabilized, thereby improving the decomposition reactivity of the chain polysilane compound.

[0079] (Tetrahydrofuran)

[0080] As described above, the solution in the second step contains an aromatic hydrocarbon solvent and tetrahydrofuran. Preferably, the amount of tetrahydrofuran added is such that the volume ratio of tetrahydrofuran in the solution after addition is 60% to 98% by volume relative to the total volume of the aromatic hydrocarbon solvent and tetrahydrofuran. If the volume ratio of tetrahydrofuran is 60% to 60%, the decomposition reaction of the chain polysilane compound can be further promoted, and the yield of the cyclic silane compound can be further improved. If the volume ratio of tetrahydrofuran is 98% to 98%, the volume ratio of the aromatic hydrocarbon solvent to sodium metal can be increased, thus enabling efficient synthesis of the chain polysilane in the first reaction, thereby further improving the yield of the cyclic silane.

[0081] From the same point of view, in terms of the amount of tetrahydrofuran added, the volume ratio of tetrahydrofuran in the solution after addition is more preferably 75% by volume or more and 98% by volume or less relative to the total volume of the aromatic hydrocarbon solvent and tetrahydrofuran, and particularly preferably 75% by volume or more and 95% by volume or less.

[0082] The total volume of the aromatic hydrocarbon solvent and tetrahydrofuran in the above solution is preferably 50.0 mL or more relative to 10 parts by mass of sodium metal. If the total volume of the aromatic hydrocarbon solvent and tetrahydrofuran in the above solution is 50.0 mL or more relative to 10 parts by mass of sodium metal, the decomposition of the generated cyclic silane compound can be further suppressed. Furthermore, if the total volume of the aromatic hydrocarbon solvent and tetrahydrofuran in the above solution is 700.0 mL or less relative to 10 parts by mass of sodium metal, the concentration of the silane compound in the system increases, thus easily promoting the reaction in the second step.

[0083] From the same point of view, the total volume of the aromatic hydrocarbon solvent and tetrahydrofuran contained in the above solution is more preferably 80.0 mL or more and 580 mL or less relative to 10 parts by mass of sodium metal, and particularly preferably 100 mL or more and 560 mL or less relative to 10 parts by mass of sodium metal.

[0084] (Polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons)

[0085] Polycyclic aromatic hydrocarbons (PAHs) or polyphenylene hydrocarbons primarily function as catalysts in the decomposition reactions of chain-like polysilane compounds. In the aforementioned reaction solution, either PAHs or polyphenylene hydrocarbons can be mixed, or both can be mixed.

[0086] Polycyclic aromatic hydrocarbons (PAHs) or polyphenylene hydrocarbons are preferably compounds that form complexes with sodium. PAHs are hydrocarbon compounds containing two or more condensed aromatic rings. Polyphenylene hydrocarbons are hydrocarbon compounds containing two or more aromatic rings bonded by single bonds. In the case of these compounds, due to the π-electron conjugation of multiple aromatic rings, these complexes can act as reducing agents. Therefore, it is believed that the breaking of silicon-silicon bonds in chain polysilane compounds or the bonds between silicon and functional groups at the ends of chain polysilanes promotes decomposition reactions. The complexes of PAHs or polyphenylene hydrocarbons with sodium are preferably formed in the presence of tetrahydrofuran.

[0087] Examples of such polycyclic aromatic hydrocarbons include naphthalene, anthracene, and phenanthrene. Examples of polyphenyl aromatic hydrocarbons include biphenyl and terphenyl. Among these, biphenyl, naphthalene, and anthracene are preferred from the viewpoint of further promoting decomposition reactions, and naphthalene and biphenyl are more preferred.

[0088] In the above solution, the total molar equivalent of polycyclic aromatic hydrocarbons and polyphenylene hydrocarbons relative to the silicon atoms of the incorporated silane compound (monomer) is preferably 0.01 eq. or more and 0.50 eq. or less. If the total molar equivalent of the polycyclic aromatic hydrocarbons and polyphenylene hydrocarbons is 0.01 eq. or more, the decomposition reaction of the chain polysilane compound is more easily promoted, and the yield of the cyclic silane compound is more easily increased. If the total molar equivalent of the polycyclic aromatic hydrocarbons and polyphenylene hydrocarbons is 0.50 eq. or less, the decomposition of the generated cyclic silane compound can be further suppressed. From the same viewpoint, the total molar equivalent of the polycyclic aromatic hydrocarbons and polyphenylene hydrocarbons is more preferably 0.04 eq. or more and 0.32 eq. or less, more preferably 0.06 eq. or more and 0.20 eq. or less, and particularly preferably 0.08 eq. or more and 0.16 eq. or less.

[0089] (Adding and mixing)

[0090] The order in which the above-mentioned reaction solution, polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons, and tetrahydrofuran are mixed is not particularly limited. Polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons and tetrahydrofuran can be added to the above-mentioned reaction solution simultaneously, or tetrahydrofuran can be added to the above-mentioned reaction solution and stirred before adding the polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons. Furthermore, the polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons can be mixed with tetrahydrofuran before adding the above-mentioned reaction solution, or the above-mentioned reaction solution can be mixed with tetrahydrofuran before adding the polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons. In this embodiment, as an example, it is preferable to add polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons to the reaction solution obtained in the first step to prepare a reaction solution containing an aromatic hydrocarbon solvent and polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons, and then further add tetrahydrofuran.

[0091] (Decomposition reaction)

[0092] The chain-like polysilane compound is then decomposed in the resulting solution to obtain a cyclic silane compound. The decomposition reaction can be carried out at room temperature or under heating. From the viewpoint of obtaining the cyclic silane compound in a higher yield, the decomposition reaction is preferably carried out under heating, i.e., preferably by heating the chain-like polysilane compound in solution.

[0093] The heating temperature can be below the reflux temperature, for example, 40°C or higher, 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 heating temperature is preferably 200°C or lower.

[0094] There are no particular limitations 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.

[0095] The reaction time refers to the elapsed time from reaching the target reaction temperature. The reaction time also depends on the temperature of the solution, and 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.

[0096] The mechanism of the decomposition reaction is speculated as follows.

[0097] Through the action of complexes formed between polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons and metallic sodium, the bonds between the terminal groups (e.g., halogen atoms) of chain-like polysilane compounds and silicon, or silicon-silicon bonds, break, resulting in a change in electronic state and the creation of active sites. Subsequently, through these active sites, the molecular chain breaks at predetermined intervals and cyclizes, thereby generating cyclic silane compounds.

[0098] 1-3. Functions

[0099] According to the above embodiment, in the first step, the silane compound is polymerized in a mixture containing metallic sodium and an aromatic hydrocarbon solvent. In this mixture, the metallic sodium exists in a liquid state, thus having a moderately large specific surface area. Therefore, the polymerization reaction of the silane compound can proceed smoothly in the first step.

[0100] Furthermore, in the second step, since the decomposition reaction of the chain polysilane compound is carried out in a solution containing aromatic hydrocarbon solvents and tetrahydrofuran, the catalytic activity brought by sodium and its complexes with polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons is readily obtained, which can improve the decomposition reactivity.

[0101] Therefore, cyclic silane compounds can be obtained in good yields without the use of sodium dispersions. This reduces manufacturing costs and simplifies separation and purification.

[0102] 2. Cyclic silane compounds

[0103] 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 (3).

[0104] [Chemical Formula 3]

[0105] Equation (3)

[0106] R in equation (3) 1 and R 2 R in equation (1) 1 and R 2 same.

[0107] n2 is an integer of 3 or more. n2 is preferably 3 or more and 10 or less, more preferably 5 or more and 7 or less, and even more preferably 6.

[0108] Cyclic silanes via R 1 and R 2 It can have any structure; for example, decamethylcyclopentylsilane, dodecylcyclohexylsilane, tetradecylcycloheptane, etc.

[0109] The obtained cyclic silane compounds may also contain various cyclic silane compounds with different n2 values. The molar yield of cyclic silane compounds with n2 of 6 (six-membered rings) is preferably 50% or more, more preferably 60% or more, and even more preferably 70% 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 those in the examples described later.

[0110] Furthermore, in the generated cyclic silanes, the six-membered rings exhibit good stability; therefore, the obtained cyclic silanes preferably contain more six-membered rings. The selectivity of the six-membered rings is preferably 80% or more, and more preferably 85% or more. It should be noted that the selectivity of the six-membered rings is the percentage obtained by dividing the molar yield (%) of the six-membered rings by the total yield (%) of the cyclic silanes.

[0111] Example

[0112] The present invention will be specifically described below through embodiments, but the present invention is not limited thereto.

[0113] [Example 1]

[0114] (1) First process

[0115] In a 200 mL four-necked flask purged with argon, 12 mL of toluene (an aromatic hydrocarbon solvent, solvent [A]) and sodium metal with a molar equivalent X of 2.4 eq. relative to dimethyldichlorosilane were added. The mixture was heated and stirred at reflux temperature (110 °C) until the sodium metal melted.

[0116] Next, 10 g of dimethyldichlorosilane (silane compound) was added dropwise to the resulting mixture over 150 minutes (average addition rate of silane compound per unit amount (mol) relative to metallic sodium: 0.17 hr). -1 The mixture was then stirred for 6 hours at a reflux temperature above 100°C and below 110°C. This yielded a reaction solution containing chain-like polysilane compounds. The resulting reaction solution was cooled to room temperature. It should be noted that the toluene content in the mixed solution was 10.3 parts by mass relative to 10 parts by mass of the silane compound and 24.0 parts by mass relative to 10 parts by mass of metallic sodium.

[0117] (2) Second process

[0118] To the reaction solution containing the chain polysilane compound described above, 60 mL of tetrahydrofuran (THF, solvent [B]) and naphthalene (polycyclic aromatic hydrocarbon) with a molar equivalent Y of 0.08 eq. relative to dimethyldichlorosilane were added, and the mixture was stirred and mixed to prepare a solution.

[0119] The resulting solution was then heated in an oil bath while being stirred at reflux temperature (71°C) for 6 hours to carry out the reaction. This yielded a solution containing cyclic silane compounds. It should be noted that the total volume of toluene and tetrahydrofuran in the reaction solution was 167 mL relative to 10 parts by mass of metallic sodium used in the first step, and the volume ratio of tetrahydrofuran to the total volume of toluene and tetrahydrofuran was 83% by volume.

[0120] The reaction diagram of Example 1 is shown below.

[0121] [Chemical Formula 4]

[0122]

[0123] [Examples 2-5]

[0124] By changing the amount of toluene added in the first step and the amount of tetrahydrofuran (THF) added in the second step, the volume ratio of tetrahydrofuran to the total volume of toluene and tetrahydrofuran in the solution obtained in the second step is as shown in Table 1. Otherwise, a solution containing cyclic silane compounds is obtained in the same manner as in Example 1.

[0125] [Comparative Example 1]

[0126] In the reaction solution obtained in the first step, toluene was added instead of tetrahydrofuran (THF), otherwise a solution containing cyclic silane compounds was obtained in the same manner as in Example 1.

[0127] [Comparative Example 2]

[0128] In the first step, tetrahydrofuran (THF) was used instead of toluene, and otherwise, a solution containing a cyclic silane compound was obtained in the same manner as in Example 1.

[0129] [Comparative Example 3]

[0130] In the second step, no naphthalene is added; otherwise, a solution containing a cyclic silane compound is obtained in the same manner as in Example 1.

[0131] [Examples 6-10]

[0132] In the first step, the amount of toluene added was varied (relative to 10 parts by mass of the silane compound) as shown in Table 1. Otherwise, a solution containing the cyclic silane compound was obtained in the same manner as in Example 1.

[0133] [Examples 11-14]

[0134] In the second step, the amount of naphthalene added (relative to the molar equivalent of the silane compound) was changed as shown in Table 1. Otherwise, a solution containing a cyclic silane compound was obtained in the same manner as in Example 2.

[0135] [Examples 15-16]

[0136] In the first step, the aromatic hydrocarbon solvent shown in Table 1 was changed instead of toluene. Otherwise, a solution containing cyclic silane compounds was obtained in the same manner as in Example 1.

[0137] [Example 17]

[0138] In the first step, biphenyl was used instead of naphthalene, but otherwise, a solution containing a cyclic silane compound was obtained in the same manner as in Example 1.

[0139] The reaction products obtained in Examples 1-17 and Comparative Examples 1-3 were analyzed by gas chromatography. The determination conditions are as follows.

[0140] (Gas chromatography determination)

[0141] Device: GC-2025 (manufactured by Shimadzu Corporation).

[0142] Column: DB1301 (Agilent Technologies), length (30m), diameter (0.320m), film thickness (0.25m).

[0143] Carrier gas: He.

[0144] Detector: FID.

[0145] 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 1.

[0146]

[0147]

[0148]

[0149] As shown in Table 1, it can be seen that in Comparative Example 1, where the solution in the second process does not contain THF, the total yield was extremely low. Similarly, it can be seen that in Comparative Example 2, where the solution in the second process does not contain toluene, the total yield was also low. Furthermore, it can be seen that in Comparative Example 3, where the solution in the second process does not contain naphthalene, the total yield was also low.

[0150] In contrast, it can be seen that the solution in the second process contains aromatic hydrocarbon solvents and THF, and in Examples 1 to 17 containing naphthalene, the total yield is increased to over 38%.

[0151] In particular, it can be seen that when the volume ratio of THF to the total volume of aromatic hydrocarbon solvent and THF in the second process is 67% or more, the total yield becomes higher (comparison of Examples 1 to 5).

[0152] Therefore, it can be seen that by using an aromatic hydrocarbon solvent and THF in the solution of the second step, specifically by melting metallic sodium with toluene in the first step, and mixing THF and polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons in the second step, the complex of sodium with polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons promotes the decomposition reaction of chain polysilane compounds, thereby enabling the production of cyclic silane compounds without the use of sodium dispersion.

[0153] This application claims priority based on Japanese Patent Application No. 2023-127054, filed on August 3, 2023. The entire contents of that application are incorporated herein by reference.

[0154] Industrial availability

[0155] According to the present invention, a method for manufacturing cyclic silane compounds that reduces manufacturing costs and facilitates separation and purification can be provided.

Claims

1. A method for manufacturing a cyclic silane compound, wherein, include: In the first step, a silane compound is polymerized in a mixture containing metallic sodium and an aromatic hydrocarbon solvent to obtain a reaction solution containing chain-like polysilane compounds. as well as In the second step, the chain-like polysilane compound is decomposed in a solution containing polycyclic aromatic hydrocarbons or polyphenylene hydrocarbons and tetrahydrofuran to obtain a cyclic silane compound.

2. The method for manufacturing the cyclic silane compound according to claim 1, wherein, In the second step, the solution comprises the tetrahydrofuran and the aromatic hydrocarbon solvent. The volume ratio of the tetrahydrofuran contained in the solution is 75% to 95% of the total volume of the aromatic hydrocarbon solvent and the tetrahydrofuran.

3. The method for manufacturing the cyclic silane compound according to claim 1 or 2, wherein, In the first step, the mixture is heated to above the melting point of the metallic sodium.

4. The method for producing the cyclic silane compound according to any one of claims 1 to 3, wherein, The aromatic hydrocarbon solvent includes toluene, ethylbenzene, or xylene.

5. The method for producing the cyclic silane compound according to any one of claims 1 to 4, wherein, The second step is performed by heating the chain-like polysilane compound in the solution.

6. The method for manufacturing the cyclic silane compound according to claim 5, wherein, The heating temperature is set above 40°C and below the reflux temperature.

7. The method for producing the cyclic silane compound according to any one of claims 1 to 6, wherein, In the second step, biphenyl, anthracene, or naphthalene, which are polycyclic aromatic hydrocarbons, are mixed into the reaction solution.

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