Method for producing cyclic silane compound

Abstract

The method for producing a cyclic silane compound includes a first step of subjecting a silane compound to a polymerization reaction in a first solution containing sodium to obtain a reaction solution containing a chain polysilane compound, and a second step of subjecting the chain polysilane compound to a decomposition conversion reaction in a second solution containing the reaction solution to obtain a cyclic silane compound. Then, a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is contained in the first solution or mixed with the reaction solution, and a polyether compound represented by formula (I) or (II) is contained in the first solution or mixed with the reaction solution.

Description

Technical Field

[0001] The present invention relates to a method for producing a cyclic silane compound.

Background Art

[0002] Silicon carbide fiber is a fiber that is excellent in heat resistance and oxidation resistance even in a high-temperature atmosphere of several thousand degrees Celsius. Utilizing this property, the application of silicon carbide fiber in the nuclear power field and aerospace field is expected.

[0003] Silicon carbide fiber is obtained by spinning, infusibilizing, and firing an organosilicon polymer compound such as polycarbosilane which is a precursor. Since silicon carbide fiber containing oxygen decomposes at high temperatures, in order to obtain ultra-high heat-resistant silicon carbide fiber, it is necessary to suppress the introduction of oxygen atoms of the organosilicon polymer compound forming the fiber. Therefore, an organosilicon polymer compound with a low oxygen content is used, and a method of not introducing oxygen during infusibilization is adopted, whereby ultra-high heat-resistant silicon carbide fiber is produced. From cyclic silane compounds such as dodecamethylcyclohexasilane, polycarbosilane with an oxygen content of about 0.1% by weight can be obtained. Therefore, cyclic silane compounds are useful as raw materials for organosilicon polymer compounds that become precursors of silicon carbide fibers.

[0004] As methods for producing cyclic silane compounds, various methods are known. For example, Patent Document 1 discloses a method for producing a cyclic silane compound by dropping a silane monomer into a mixed solution of sodium dispersion, tetrahydrofuran (THF), and a polyether compound and reacting at room temperature.

[0005] Further, Patent Document 2 discloses a method for producing a cyclic silane compound by: 1) dropping a silane monomer into a mixed solution obtained by heating and mixing xylene and metallic sodium and reacting to obtain a chain-like polysilane compound, and then 2) heating and refluxing the purified chain-like polysilane compound, metallic sodium, and a polycyclic aromatic hydrocarbon in THF.

[0006] Further, Patent Document 3 discloses a method for producing a cyclic silane compound, which comprises: 1) adding a silane monomer compound to a mixed solution of a sodium dispersion and a solvent, reacting them, and then 2) adding a polycyclic aromatic hydrocarbon to the reaction solution and heating it under reflux.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] As shown in Patent Documents 2 and 3, in the method of producing a cyclic silane compound via a chain polysilane compound from a silane monomer, compared with the case of directly producing a cyclic silane compound from a silane monomer as shown in Patent Document 1, the use of expensive reactants such as a sodium dispersion can be reduced. However, in the method such as that of Patent Document 2, since it includes a purification operation for removing the solvent from the synthesized polydimethylsilane, there is a problem that the operation is complicated.

[0009] Therefore, it is desired to perform the second step without isolating and purifying the chain polysilane compound produced in the first step to obtain a cyclic silane compound (being able to be produced in one pot). When producing in one pot, since the reaction solution obtained in the first step contains a certain amount or more of components that do not contribute to the decomposition and conversion reaction in the second step, the reaction yield in the second step is likely to decrease. In Patent Document 3, in order to obtain a high reaction yield, it was still necessary to use a large amount of reactants. Therefore, it is desired to obtain a high reaction yield with a small amount of reactants while producing in one pot.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a cyclic silane compound from a silane monomer in one pot with a high reaction yield regardless of the form of the reactant used and even with a small amount of the reactant used.

Means for Solving the Problems

[0011] The present invention relates to a method for producing the following cyclic silane compound.

[0012] [1] A first step of subjecting a silane compound to a polymerization reaction in a first solution containing sodium to obtain a reaction solution containing a chain polysilane compound, and a second step of subjecting the chain polysilane compound to a decomposition conversion reaction in a second solution containing the reaction solution to obtain a cyclic silane compound, including adding a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon to the first solution or mixing it with the reaction solution, and adding a polyether compound represented by the following formula (I) or (II) to the first solution or mixing it with the reaction solution. A method for producing a cyclic silane compound.

Chemical formula

[10] For the method for producing a cyclic silane compound according to any one of [1] to [4], the polycyclic aromatic hydrocarbon or polyphenyl-based hydrocarbon is mixed with the reaction solution.

[11] For the method for producing a cyclic silane compound according to

[10] , biphenyl, anthracene or naphthalene is mixed with the reaction solution as the polycyclic aromatic hydrocarbon.

[12] For the method for producing a cyclic silane compound according to [3] or [4], the hydrocarbon solvent is an aromatic hydrocarbon solvent.

[13] The second solution contains the hydrocarbon solvent and tetrahydrofuran, and the volume ratio of the tetrahydrofuran contained in the second solution is 23% by volume or more and 99% by volume or less with respect to the total volume of the hydrocarbon solvent and the tetrahydrofuran, and it is a method for producing a cyclic silane compound according to [4]. [Effect of the Invention]

[0013] According to the present invention, it is possible to provide a method for producing a cyclic silane compound capable of producing a cyclic silane compound from a silane monomer in one pot with a high reaction yield regardless of the form of the reactant used and even if the amount used is small. [Embodiments for Carrying Out the Invention]

[0014] As described above, when the first step of obtaining a chain polysilane compound from a silane monomer and the second step of subjecting the chain polysilane compound to a decomposition conversion reaction to obtain a cyclic silane compound are carried out in one pot, it is required to increase the reaction yield in the second step.

[0015] In particular, the sodium dispersion conventionally used is not only expensive but also difficult to separate and recover the cyclic silane compound as described later. Therefore, instead of the sodium dispersion, the use of a mixture obtained by melting massive metallic sodium in a hydrocarbon solvent has been studied. However, since the mixture contains a large amount of a hydrocarbon solvent that does not contribute to the reaction in the second step, the reaction yield is likely to decrease.

[0016] In contrast, as a result of intensive studies, the present inventors have found that by using a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon as a reaction promoting component and further using a specific polyether compound in at least one of the first step and the second step, preferably the first step, the yield of the cyclic silane compound can be significantly increased.

[0017] This mechanism is not clear, but is presumed as follows. In a specific polyether compound, oxygen atoms of a plurality of ether bonds coordinate to sodium ions and are stably captured, thereby easily increasing the reactivity of the silane compound. Thereby, in the first step, not only the polymerization reaction of the silane compound is promoted to increase the yield of the chain polysilane compound, but also in the second step, the decomposition conversion reaction of the chain polysilane compound is promoted.

[0018] Hereinafter, a method for producing a cyclic silane compound according to an embodiment of the present invention will be described in detail.

[0019] 1. Method for producing cyclic silane compound As described above, the method for producing a cyclic silane compound according to an embodiment of the present invention is In a first solution containing metallic sodium, a silane compound is subjected to a polymerization reaction to obtain a reaction solution containing a chain polysilane compound in a first step; In a second solution containing the above reaction solution, the chain polysilane compound is subjected to a decomposition conversion reaction to obtain a cyclic silane compound in a second step; It includes. Then, a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is contained in the first solution or mixed with the reaction solution. Further, a specific polyether compound is contained in the first solution or mixed with the reaction solution.

[0020] As described above, the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon may be contained in the first solution or mixed with the reaction solution. Among them, from the viewpoint of further suppressing the decomposition of the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon due to a side reaction with the silane compound, it is preferable to mix it with the reaction solution. When mixing with the reaction solution, it may be mixed between the first step and the second step, or may be mixed in the second step.

[0021] The specific polyether compound may also be contained in the first solution or mixed with the reaction solution as described above. When mixing with the reaction solution, it may be mixed between the first step and the second step, or may be mixed in the second step. Among them, from the viewpoint of further increasing the yield of the cyclic silane compound, it is preferable to contain it in the first solution.

[0022] That is, in the present embodiment, 1) In a first solution containing metallic sodium and a specific polyether compound, a silane compound is subjected to a polymerization reaction to obtain a reaction solution containing a chain polysilane compound in a first step; 2) In a second solution in which a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is mixed with the above reaction solution, the chain polysilane compound is subjected to a decomposition conversion reaction to obtain a cyclic silane compound in a second step, and it is preferable to perform.

[0023] Hereinafter, each step will be specifically described.

[0024] 1-1. About the First Step In this embodiment, a silane compound is subjected to a polymerization reaction in a first solution containing sodium and a specific polyether compound.

[0025] The sodium in the first solution may be fine particles of metallic sodium or molten metallic sodium. That is, the first solution may contain a sodium dispersion (SD) and a specific polyether compound; or may contain a mixture of (molten) metallic sodium and a hydrocarbon solvent and a polyether compound.

[0026] A sodium dispersion (SD) is a dispersion of fine particles of metallic sodium in an electrical insulating oil and has a higher reactivity than massive metallic sodium. The average particle diameter of the fine particles of sodium in the SD can be 1 μm or more and 100 μm or less. The average particle diameter can be a value measured by a laser diffraction particle size distribution measuring device or the like. Examples of the electrical insulating oil include aliphatic hydrocarbons such as liquid paraffin and mineral oil.

[0027] On the other hand, since the electrical insulating oil is a water-insoluble organic compound and has a high solubility in the dispersion oil of the cyclic silane compound, separation and purification tend to be difficult. Therefore, from the viewpoint of reducing the manufacturing cost and facilitating separation and purification, it is desired to reduce the amount of sodium dispersion used. Therefore, in this embodiment, it is preferable to use a mixture containing metallic sodium and a hydrocarbon solvent.

[0028] In the above mixture, it is preferable that the metallic sodium is molten. The molten state means a state in which metallic sodium is in a liquid state, for example, by heating, and is different from a state in which sodium is uniformly dispersed in fine particle form like a sodium dispersion.

[0029] A first solution containing such a mixed solution can be obtained, for example, by adding metallic sodium to a hydrocarbon solvent, heating the mixture to a temperature equal to or higher than the melting point of metallic sodium (98 °C or higher) to melt it, and then further mixing a polyether compound. Alternatively, it can also be obtained by adding molten metallic sodium to a hydrocarbon solvent heated to a temperature equal to or higher than the melting point of metallic sodium (98 °C or higher), and then further mixing a polyether compound.

[0030] (hydrocarbon solvent) The hydrocarbon solvent may have a boiling point higher than the melting point of metallic sodium (98 °C). That is, the boiling point of the hydrocarbon solvent 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.

[0031] Such a hydrocarbon solvent may be an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent. Examples of aliphatic hydrocarbon solvents include hydrocarbon solvents having 8 to 12 carbon atoms such as octane and decane. Examples of aromatic hydrocarbon solvents include toluene, xylene, ethylbenzene, mesitylene, etc. Among them, from the viewpoint of making it easier to form a complex of a polycyclic aromatic hydrocarbon or polyphenyl-based hydrocarbon and sodium, aromatic hydrocarbon solvents are preferred, toluene, xylene, and ethylbenzene are more preferred, and toluene and xylene are even more preferred.

[0032] The content of the hydrocarbon solvent in the first solution only needs to be such that the resulting chain polysilane is sufficiently stirred and dispersed in the solvent. For example, the content of the hydrocarbon solvent in the first solution relative to 10 parts by mass of the silane compound is preferably 0.7 part by mass or more. When the content of the hydrocarbon solvent is 0.7 part by mass or more, the volume fraction of metallic sodium decreases, making it difficult for the droplets of metallic sodium to coalesce. In that case, the average droplet diameter can be made smaller, increasing the specific surface area of sodium and enhancing the reactivity of the silane compound. When the content of the hydrocarbon solvent is 150.0 parts by weight or less, the concentration of the silane compound in the system increases, facilitating the reaction in the first step. From the same perspective, the content of the hydrocarbon solvent in the first solution relative to 10 parts by mass of the silane compound is more preferably 3.0 parts by mass or more and 100.0 parts by mass or less.

[0033] The content of the hydrocarbon solvent in the first solution relative to 10 parts by mass of metallic sodium is preferably 1.0 part by mass or more and 300.0 parts by mass or less, and more preferably 2.0 parts by mass or more and 250.0 parts by mass or less.

[0034] (Metallic sodium) Metallic sodium can mainly function as a reactant for the polymerization reaction.

[0035] The molar equivalent of metallic sodium in the first solution relative to each functional group of the alkoxy group or halogen atom of the silane compound is preferably 1.00 eq. or more and 1.80 eq. or less. When the molar equivalent of metallic sodium is 1.00 eq. or more, the rate of the polymerization reaction of the silane compound in the first step can be increased. When the molar equivalent of metallic sodium is 1.80 eq. or less, the proportion of metallic sodium remaining unreacted can be reduced. From the same perspective, the molar equivalent of metallic sodium in the first solution is more preferably 1.05 eq. or more and 1.25 eq. or less.

[0036] (Specific polyether compound) A specific polyether compound can stably capture sodium ions in the reaction system by coordinating the oxygen atoms of multiple ether bonds with the sodium ions in the reaction system. Thereby, the polymerization reaction of the silane compound in the first step and the decomposition conversion reaction of the chain polysilane compound in the second step can be accelerated, and a cyclic polysilane compound can be obtained in a high yield.

[0037] The specific polyether compound is a polyether compound represented by formula (I) or (II).

Chemical formula

[0038] In formulas (I) and (II), R a ~R h are each independently a hydrogen atom or an alkyl group. Among them, R a ~R h are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom, an ethyl group or a methyl group, and even more preferably a hydrogen atom or a methyl group.

[0039] m 1 and m 2 are each an integer of 2 or more and 7 or less. Among them, m 1 and m 2 are preferably integers of 2 or more and 6 or less, and from the viewpoint of selectively capturing sodium ions in the reaction system and further accelerating the reaction, 5 is even more preferable.

[0040] The first solution may contain only one of the polyether compound represented by formula (I) and the polyether compound represented by formula (II), or may contain both. Among them, from the viewpoints such as having a high boiling point, high residual property in the reaction system under heating, and being able to further reduce the manufacturing cost, the polyether compound represented by formula (I) is preferable.

[0041] Examples of the polyether compound represented by the formula (I) include diglyme, triglyme, and tetraglyme. Examples of the compound represented by the formula (II) include dioxane, 12-crown-4, 15-crown-5, and 18-crown-6. Among these, tetraglyme and 15-crown-5 are preferable from the viewpoint of high reaction promotion effect.

[0042] The total molar equivalent of the polyether compound represented by the formula (I) or (II) contained in the first solution with respect to the silicon atom of the silane compound is preferably 0.003 eq. or more and 0.180 eq. or less. When the molar equivalent of the polyether compound is 0.003 eq. or more, not only the polymerization reaction of the silane compound is further promoted, but also the decomposition conversion reaction in the second step is further promoted, and the reaction yield can be further increased. When the molar equivalent of the polyether compound is 0.180 eq. or less, the decomposition of the final product, the cyclic silane compound, can be reduced more. From the same viewpoint, the molar equivalent of the polyether compound is more preferably 0.030 eq. or more and 0.120 eq. or less.

[0043] The first solution may further contain other solvents other than the above as necessary. Examples of other solvents include ether solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether, diisopropyl ether, and t-butyl methyl ether (excluding polyethers).

[0044] (Silane compound) Next, a silane compound is added to the first solution. The silane compound is preferably a compound represented by the following formula (1).

Chemical formula

[0045] In formula (1), X 1 and X 2represents an alkoxy group or a halogen atom, respectively. Examples of the alkoxy group include a methoxy group and an ethoxy group. Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom. Since these have a large electronegativity difference from silicon and are likely to cause intramolecular polarization within the silane compound, they are highly reactive and are substituents that function as leaving groups in the reaction. Among them, X 1 and X 2 are preferably halogen atoms and more preferably a chlorine atom from the viewpoint of the reactivity of the silane compound.

[0046] R 1 and R 2 are a hydrogen atom or a hydrocarbon group. Among them, R 1 and R 2 are preferably hydrocarbon groups, more preferably alkyl groups having 1 to 6 carbon atoms, still more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0047] n 1 is an integer of 1 or more. From the viewpoint of enhancing the reactivity of the silane compound, n 1 is preferably 1 or 2, and more preferably 1.

[0048] Examples of the compound represented by the formula (1) include dichlorodimethylsilane, dichlorodiethylsilane, dichlorodipropylsilane, dichlorodibutylsilane, dichlorodipentylsilane, dichlorodihexylsilane, dibromodimethylsilane, dibromodiethylsilane, dibromodipropylsilane, dibromodibutylsilane, dibromodipentylsilane, dibromodihexylsilane, dichlorotetramethyldisilane, etc. Among these, dichlorodimethylsilane is preferred. The silane compound may be one kind or two or more kinds.

[0049] (Polymerization reaction) The polymerization reaction of the silane compound is preferably carried out at a temperature according to the composition of the first solution.

[0050] For example, when the first solution contains a sodium dispersion, the polymerization reaction is preferably carried out at a temperature of 0 °C or higher and the reflux temperature or lower, and more preferably at room temperature.

[0051] On the other hand, when the first solution contains a mixture containing metallic sodium and a hydrocarbon solvent, from the viewpoint of carrying out the reaction in a state where the metallic sodium is melted, the polymerization reaction is preferably carried out under heating. That is, the polymerization reaction is preferably carried out while heating to a temperature equal to or higher than the melting temperature of metallic sodium.

[0052] The heating temperature is preferably equal to or higher than the melting temperature of metallic sodium, more preferably 98 °C or higher and the solvent reflux temperature or lower, and even more preferably 100 °C or higher and the solvent reflux temperature or lower. The above reaction is preferably carried out in an inert gas atmosphere such as nitrogen or argon. Further, the above reaction is preferably carried out under normal pressure or under pressure.

[0053] The addition of the silane compound may be carried out continuously or intermittently, but from the viewpoint of production efficiency, it is preferably carried out continuously in a certain amount.

[0054] The average addition rate of the silane compound per unit amount (mol) of metallic sodium is 0.06 hr -1 or more and 0.50 hr -1 or less, preferably 0.10 hr -1 or more and 0.30 hr -1 or less.

[0055] The average addition rate (mol·hr -1 ) of the silane compound is the value obtained by dividing the total amount (mol) of the silane compound used by the addition time (hr); the average addition rate (hr -1 ) of the silane compound per unit amount (mol) of metallic sodium is the value obtained by dividing the average addition rate (mol·hr -1 ) of the silane compound by the amount (mol) of metallic sodium.

[0056] When the average addition rate of the silane compound per unit amount (mol) of metallic sodium is 0.50 hr-1 If it is as follows, it is possible to further prevent the temperature of the above-mentioned mixed solution from dropping below the melting temperature of sodium, and it is possible to further promote the reaction. The average addition rate of the silane compound per unit amount (mol) of metallic sodium is 0.06 hr -1 If it is 1 or more, the total reaction time can be further shortened, and the production efficiency can be further increased.

[0057] From the viewpoint of increasing the production amount of the chain polysilane compound, after the addition of the silane compound is completed, it is preferable to continue stirring at the above reaction temperature, preferably for 1 hour or more and 12 hours or less.

[0058] By the above reaction, a reaction solution containing crude polydialkylsilane (chain polysilane compound) is obtained.

[0059] (chain polysilane compound) The chain polysilane compound has a repeating unit represented by the following formula (2).

Chemical formula

[0060] R in formula (2) 1 and R 2 are the same as R in formula (1) 1 and R 2 and are the same.

[0061] In the chain polysilane compound, the groups bonded to the silicon atoms at both ends of the molecule can be a hydrogen atom, a hydrocarbon group, an alkoxy group, a sodium atom or a halogen atom. The alkoxy group or the halogen atom is X in formula (1) 1 and X 2It is the same as. Further, the sodium atom is cationized and can be coordinated to the anionized silicon atom. Since the electronegativity difference between the alkoxy group or halogen atom and the silicon atom is large, it is easily reduced by sodium and may easily generate active sites. Also, since the electronegativity difference between the sodium atom and the silicon atom is particularly large, the silicon atom may easily function as an active site. Therefore, the groups at both ends of the molecular chain of the chain-like polysilane compound may be an alkoxy group, a halogen atom, or a sodium atom.

[0062] The number of repeating units is not particularly limited, but is, for example, an integer of 2 or more, preferably an integer of 6 or more and 12000 or less.

[0063] 1-2. Regarding the second step A polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is mixed with the reaction solution obtained in the first step to obtain a second solution. That is, without isolating the product from the reaction solution obtained in the first step, a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is mixed with the reaction solution.

[0064] The second solution preferably contains tetrahydrofuran in the solution. That is, the second step is preferably carried out in a second solution in which tetrahydrofuran is further mixed with the reaction solution obtained in the first step. Thereby, the decomposition conversion reaction of the chain-like polysilane compound can proceed more highly.

[0065] As described above, in a solvent such as a hydrocarbon solvent contained in the reaction solution obtained in the first step, a complex of sodium and a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon necessary for the decomposition conversion reaction of the chain-like polysilane compound in the second step is difficult to form. In contrast, since the reaction solution contains tetrahydrofuran, a complex of sodium and a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is easily formed and easily exists stably, so that the decomposition reactivity of the chain-like polysilane compound can be further enhanced.

[0066] (tetrahydrofuran) When the second solution contains a hydrocarbon solvent and tetrahydrofuran, the addition amount of tetrahydrofuran to the reaction solution is preferably such that the volume ratio of tetrahydrofuran to the total volume of the hydrocarbon solvent and tetrahydrofuran in the second solution is 23% by volume or more and 99% by volume or less. When the above volume ratio of tetrahydrofuran is 23% by volume or more, the decomposition conversion reaction of the chain polysilane compound can be further promoted, and the yield of the cyclic silane compound can be further increased. When the above volume ratio of tetrahydrofuran is 99% by volume or less, the volume ratio of the hydrocarbon solvent to sodium metal can be increased, so that the synthesis of the chain polysilane in the first reaction can be efficiently carried out, and the yield of the cyclic silane can be further increased. From the same perspective, the addition amount of tetrahydrofuran to the above reaction solution is more preferably such that the above volume ratio of tetrahydrofuran in the second solution is 25% by volume or more and 95% by volume or less, and even more preferably 35% by volume or more and 95% by volume or less.

[0067] When the second solution contains a hydrocarbon solvent and tetrahydrofuran, the total volume of the hydrocarbon solvent and tetrahydrofuran contained in the second solution is preferably 50.0 mL or more with respect to 10 parts by mass of sodium metal. When the total volume of the hydrocarbon solvent and tetrahydrofuran contained in the second solution is 50.0 mL or more with respect to 10 parts by mass of sodium metal, the decomposition of the produced cyclic silane compound can be further suppressed. Further, when the total volume of the hydrocarbon solvent and tetrahydrofuran contained in the second solution is 700.0 mL or less with respect to 10 parts by mass of sodium metal, the concentration of the silane compound in the system becomes large, so that the reaction in the second step is likely to be promoted. From the same perspective, the total volume of the hydrocarbon solvent and tetrahydrofuran contained in the second solution is more preferably 50 mL or more and 600 mL or less with respect to 10 parts by mass of sodium metal, and particularly preferably 50 mL or more and 550 mL or less with respect to 10 parts by mass of sodium metal.

[0068] (Polycyclic aromatic hydrocarbon or polyphenyl-based hydrocarbon) Polycyclic aromatic hydrocarbons or polyphenyl-based hydrocarbons can mainly function as catalysts for the decomposition and conversion reaction of chain polysilane compounds. In the above reaction solution, only one of polycyclic aromatic hydrocarbons and polyphenyl-based hydrocarbons may be mixed, or both may be mixed.

[0069] The polycyclic aromatic hydrocarbon or polyphenyl-based hydrocarbon preferably forms a complex with sodium. The polycyclic aromatic hydrocarbon is a hydrocarbon compound containing two or more condensed aromatic rings. The polyphenyl-based hydrocarbon is a hydrocarbon compound containing two or more aromatic rings bonded by single bonds. Since the π electrons of the plurality of aromatic rings in these compounds are conjugated, they easily form a complex with sodium, and these complexes can act as reducing agents. Thereby, it is considered that the silicon-silicon bond of the chain polysilane compound or the bond between silicon at the end of the chain polysilane and the functional group is cleaved, promoting the decomposition and conversion reaction. The complex of the polycyclic aromatic hydrocarbon or polyphenyl-based hydrocarbon and sodium is more preferably formed in the presence of tetrahydrofuran.

[0070] Examples of such polycyclic aromatic hydrocarbons include naphthalene, anthracene, phenanthrene, etc. Examples of polyphenyl-based aromatic hydrocarbons include biphenyl, terphenyl, etc. Among them, from the viewpoint of being able to further promote the decomposition and conversion reaction, biphenyl, naphthalene, and anthracene are preferred, and naphthalene and biphenyl are more preferred.

[0071] In the second solution, the total molar equivalent of the polycyclic aromatic hydrocarbon and the polyphenyl-based hydrocarbon with respect to the silicon atom of the charged silane compound is preferably 0.01 eq. or more and 0.50 eq. or less. When the total molar equivalent of the polycyclic aromatic hydrocarbon and the polyphenyl-based hydrocarbon is 0.01 eq. or more, the decomposition reaction of the chain polysilane compound is more likely to be promoted, and the yield of the cyclic silane compound is more likely to be increased. When the total molar equivalent of the polycyclic aromatic hydrocarbon and the polyphenyl-based hydrocarbon is 0.50 eq. or less, the decomposition of the produced cyclic silane compound can be further suppressed. From the same viewpoint, the total molar equivalent of the polycyclic aromatic hydrocarbon and the polyphenyl-based hydrocarbon is more preferably 0.04 eq. or more and 0.32 eq. or less, and particularly preferably 0.04 eq. or more and 0.24 eq. or less.

[0072] (Addition and mixing) The order of mixing the reaction solution, the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon, and tetrahydrofuran is not particularly limited. The polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon and tetrahydrofuran may be added to the reaction solution simultaneously, or tetrahydrofuran may be added to the reaction solution and stirred, and then the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon may be added. Further, after mixing the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon and tetrahydrofuran, the reaction solution may be added, or after mixing the reaction solution with tetrahydrofuran, the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon may be added. In the present embodiment, as an example, it is preferable to add the polycyclic aromatic hydrocarbon or the polyphenyl-based hydrocarbon and tetrahydrofuran to the reaction solution obtained in the first step simultaneously.

[0073] (Decomposition conversion reaction) Then, in the obtained solution, the chain polysilane compound is subjected to a decomposition conversion reaction to obtain a cyclic silane compound. The decomposition conversion reaction may be carried out at room temperature or under heating. From the viewpoint of obtaining the cyclic silane compound in a higher yield, the decomposition conversion reaction is preferably carried out under heating, that is, by heating the chain polysilane compound in the solution.

[0074] The heating temperature may be equal to or lower than the reflux temperature. For example, it is more preferably 40°C or higher, preferably 50°C or higher, and even more preferably 60°C or higher. However, from the perspective of suppressing the decomposition of the reaction product, the upper limit of the heating temperature is preferably 200°C or lower.

[0075] When the second solution contains a hydrocarbon solvent and tetrahydrofuran, the reflux temperature is greater than 68°C depending on the volume ratio of tetrahydrofuran and becomes the temperature corresponding to the volume ratio less than the boiling point of the hydrocarbon solvent.

[0076] The heating method is not particularly limited. For example, it may be a method of placing the second solution in a predetermined temperature atmosphere, or a method of heating by a heater, a water bath, an oil bath, electromagnetic waves, etc.

[0077] The reaction time indicates the elapsed time after reaching the target reaction temperature. The reaction time depends on the temperature of the solution, but when reacting under heating, it is preferably, for example, 1 hour or more and 35 hours or less, and more preferably 3 hours or more and 10 hours or less.

[0078] The mechanism of the decomposition conversion reaction is presumed as follows. The bond between the group (e.g., halogen atom) at the molecular end of the chain polysilane compound and silicon or the silicon-silicon bond is cleaved by the action of a complex formed by a polycyclic aromatic hydrocarbon or the like and sodium, resulting in a change in the electronic state and the generation of active sites. Thereafter, due to this active site, the molecular chain is cut at predetermined intervals and cyclized to generate a cyclic silane compound.

[0079] 2. Cyclic silane compound The cyclic silane compound obtained by the method for producing a cyclic silane compound according to this embodiment has, for example, a structure represented by the following formula (3).

Chemical formula

[0080] R in formula (3) 1 and R 2 are the same as R in formula (1) 1 and R 2 respectively.

[0081] n 2 is an integer of 3 or more. n 2 is preferably from 3 to 10, more preferably from 5 to 7, and even more preferably 6.

[0082] The cyclic silane has an arbitrary structure depending on R 1 and R 2 Examples include decamethylcyclopentasilane, dodecamethylcyclohexasilane, tetradecamethylcycloheptasilane, and the like.

[0083] The resulting cyclic silane compound may contain a plurality of types of cyclic silane compounds with different n 2 values. The molar yield of the cyclic silane compound with n 2 equal to 6 (6-membered ring) is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. The yield of the cyclic silane compound can be determined by analyzing the reaction product by gas chromatography. The measurement conditions can be the same as those in the examples described later.

[0084] 3. Modification In the above embodiment, an example was shown in which a polyether compound was contained in the first solution and a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon was mixed in the reaction solution. However, the present invention is not limited to this. For example, both a specific polyether compound and a polycyclic aromatic hydrocarbon or the like may be mixed in the reaction solution. In that case as well, the molar equivalent of the polyether compound to the silane compound can be the same as described above.

[0085] Also, in the above embodiment, an example was shown in which a mixed solution obtained by melting metallic sodium in a hydrocarbon solvent was used, but a sodium dispersion may also be used. In that case, the molar equivalent of the fine particles of metallic sodium to the alkoxy group or halogen atom of the silane compound, per functional group, can be the same as described above.

[0086] Also, in the above-described embodiment, an example was shown in which the second step is carried out in a second solution in which tetrahydrofuran is mixed with the reaction solution obtained in the first step, but the present invention is not limited thereto.

[0087] In the present embodiment, the reaction solution contains a specific polyether compound. Therefore, in the second step, a complex of sodium and a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon can be formed without mixing tetrahydrofuran into the reaction solution. That is, even when the amount of THF used is reduced or a reaction solvent other than THF is used, the decomposition conversion reaction of the chain polysilane compound can proceed favorably. Accordingly, the second step may be carried out without mixing tetrahydrofuran into the reaction solution obtained in the first step.

Example

[0088] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[0089] 〔Test 1〕 (1) First step Into a 200 mL four-necked flask purged with argon, 34 mL of toluene (an aromatic hydrocarbon-based solvent, solvent A), metallic sodium with a molar equivalent X of 2.4 eq. to dichlorodimethylsilane, and tetraglyme with a molar equivalent Y of 0.04 eq. to dichlorodimethylsilane (a polyether compound represented by formula (I) or (II), additive 1) were placed, and while heating at the reflux temperature (110°C), the mixture was stirred to melt the metallic sodium. Next, 10.0 g of dichlorodimethylsilane (silane compound) was dropped into the obtained mixed solution (first solution) over 150 minutes (average addition rate of the silane compound per unit amount (mol) of metallic sodium: 0.17 hr -1Thereafter, the mixture was stirred and reacted at a reflux temperature in the range of 105°C or higher and 115°C or lower for 1.5 hours, thereby obtaining a reaction solution containing a chain polysilane compound. The obtained reaction solution was cooled to room temperature. Incidentally, the content of toluene in the mixed solution (the first solution) was 29.5 parts by mass with respect to 10 parts by mass of the silane compound and 68.6 parts by mass with respect to 10 parts by mass of sodium metal.

[0090] (2) Second step To the reaction solution containing the chain polysilane compound, 38 mL of tetrahydrofuran (THF) and naphthalene (a polycyclic aromatic hydrocarbon, additive 2) with a molar equivalent Z of 0.08 eq. with respect to dichlorodimethylsilane were simultaneously added, followed by stirring and mixing to prepare a solution (the second solution). Then, the obtained solution was stirred and reacted at a reflux temperature (73°C) for 6 hours while heating with an oil bath, thereby obtaining a solution containing a cyclic silane compound. Incidentally, the total volume of toluene and tetrahydrofuran in the second solution with respect to 10 parts by mass of the sodium metal used in the first step was 167 mL, and the volume ratio of tetrahydrofuran to the total volume of toluene and tetrahydrofuran was 52.8% by volume.

[0091] The reaction scheme of Test 1 is shown below.

Chemical formula

[0092] [Tests 2 to 4] A solution containing a cyclic silane compound was obtained in the same manner as in Test 1, except that the type and amount of additive 1 contained in the first step were changed as shown in Table 1.

[0093] [Test 5] A solution containing a cyclic silane compound was obtained in the same manner as in Test 1, except that naphthalene was not mixed in the second step.

[0094] [Test 6] Except for changing the type of sodium to be contained in the first step to sodium dispersion (SD) as shown in Table 1, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0095] 〔Test 7〕 Except for changing the reaction temperature in the first step and the type of sodium to be contained as shown in Table 1, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0096] 〔Test 8〕 Except for changing the type of sodium to be contained in the first step and not containing tetraglyme, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0097] 〔Tests 9 - 13〕 Except for changing the volume ratio of solvent A to be contained in the first step and THF to be mixed in the second step (the volume ratio of THF to the total volume of solvent A and THF in the second solution) as shown in Table 1, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0098] 〔Tests 14 - 17〕 Except for changing the total amount of the solvents of solvent A to be contained in the first step and THF to be mixed in the second step as shown in Table 1, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0099] 〔Tests 18 - 21〕 Except for changing the content of tetraglyme (additive 1) in the first step as shown in Table 2, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0100] 〔Tests 22 - 23〕 Except for changing the content of metallic sodium in the first step as shown in Table 2, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1.

[0101] 〔Tests 24 - 27〕 A solution containing a cyclic silane compound was obtained in the same manner as in Test 1, except that the content of metallic sodium in the first step and the molar equivalent of Additive 2 mixed in the second step were changed as shown in Table 2.

[0102] [Test 28] A solution containing a cyclic silane compound was obtained in the same manner as in Test 1, except that the type of Solvent A contained in the first step was changed as shown in Table 2.

[0103] [Test 29] A solution containing a cyclic silane compound was obtained in the same manner as in Test 1, except that the type of Additive 2 mixed in the second step was changed as shown in Table 2.

[0104] [Test 30] A solution containing a cyclic silane compound was obtained in the same manner as in Test 1, except that while maintaining the volume ratio of THF constant, the amount of THF shown in Table 2 was contained together with diglyme in the first step.

[0105] [Test 31] (1) First step Into a 200 mL four-necked flask subjected to argon substitution, 38 mL of xylene and metallic sodium with a molar equivalent of 2.15 eq. to dichlorodimethylsilane were contained, and while heating at 120 °C, it was stirred to melt the metallic sodium. Next, 4.9 g of dichlorodimethylsilane (silane compound) was dropped into the obtained mixed solution over 60 minutes, and then it was stirred at 120 °C for 7 hours to cause a reaction. Thereby, a reaction solution containing a chain polysilane compound was obtained. The obtained reaction solution was cooled to room temperature. The content of xylene in the mixed solution (first solution) was 66.2 parts by mass with respect to 10 parts by mass of the silane compound and 164.2 parts by mass with respect to 10 parts by mass of metallic sodium.

[0106] (2) Second step To the reaction solution containing the above chain polysilane compound, 50 mL of tetrahydrofuran (THF )And naphthalene (polycyclic aromatic hydrocarbon) with a molar equivalent Z of 0.23 eq. to dichlorodimethylsilane was added, followed by stirring and mixing to prepare a solution. Then, the obtained solution was stirred at room temperature for 2 hours for reaction, and then further reacted at the reflux temperature (74 °C) for 3 hours while heating with an oil bath. Thereby, a solution containing a cyclic silane compound was obtained. The total volume of toluene and tetrahydrofuran in the reaction solution with respect to 10 parts by mass of sodium metal used in the first step was 442.2 mL, and the volume ratio of tetrahydrofuran to the total volume of toluene and tetrahydrofuran was 57% by volume.

[0107] 〔Test 32〕 In the first step, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1 except that both tetraglyme and naphthalene were contained, and in the second step, they were not mixed at all.

[0108] 〔Test 33〕 In the second step, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1 except that both tetraglyme and naphthalene were mixed, and in the first step, they were not contained at all.

[0109] 〔Test 34〕 In the second step, a solution containing a cyclic silane compound was obtained in the same manner as in Test 1 except that THF was not mixed into the reaction solution.

[0110] 〔Test 35〕 In the first step, a solution containing a cyclic silane compound was obtained in the same manner as in Test 34 except that the content of tetraglyme was changed as shown in Table 2.

[0111] 〔Test 36〕 In the first step, a solution containing a cyclic silane compound was obtained in the same manner as in Test 35 except that triglyme was used instead of tetraglyme.

[0112] 〔Test 37〕 In the first step, a solution containing a cyclic silane compound was obtained in the same manner as in Test 35, except that octane was used instead of toluene.

[0113] 〔Test 38〕 A solution containing a cyclic silane compound was obtained in the same manner as in Test 35, except that the content of metallic sodium in the first step was changed as shown in Table 2.

[0114] For the reaction products obtained in Tests 1 to 38, the reaction solution was analyzed using gas chromatography. The measurement conditions were as follows.

[0115] (Gas chromatography measurement) Apparatus: GC-2025 (manufactured by Shimadzu Corporation) Column: DB1301 (Agilent Technologies), length (30m), Diam. (0.320m), Film (0.25m) Carrier gas: He Detector: FID

[0116] Then, the formation of cyclic silanes (dodecamethylcyclohexasilane (6-membered ring), decamethylcyclopentasilane (5-membered ring), tetradecamethylcycloheptasilane (7-membered ring)) was confirmed, and the yields of these were determined respectively.

[0117] The preparation conditions and evaluation results of Tests 1 to 17 are shown in Table 1, and the preparation conditions and measurement results of Tests 18 to 38 are shown in Table 2.

[0118]

Table 1

[0119]

Table 2

[0120] As shown in Tables 1 and 2, Tests 1, 2, 6, 7, 9 to 30, and 32 to 38 using a specific polyether compound and a polycyclic aromatic hydrocarbon, etc. respectively, show higher yields regardless of the form of metallic sodium compared to Tests 3 to 5, 8, and 31 where at least one of them was not used.

[0121] In particular, it can be seen that tetraglyme (the polyether compound represented by formula (I)) has a higher yield when added in the first step than when added in the second step (comparison between Test 1 and Test 33).

[0122] Also, it can be seen that naphthalene (a polycyclic aromatic hydrocarbon) has a higher yield when added in the second step than when added in the first step (comparison between Test 1 and Test 32).

[0123] Moreover, it can be seen that by setting the content of tetraglyme in the first step to a predetermined amount or more, the yield is further increased (comparison between Tests 18 to 21 and Test 1). Also, it can be seen that even tetraglyme (chain-like) shows a yield equivalent to that of 15-crown-5 (cyclic) (comparison between Test 1 and Test 2).

[0124] Furthermore, it can be seen that even if the molar equivalent of naphthalene mixed in the second step is small, a high yield can be maintained (comparison between Tests 24 to 27).

[0125] In addition, it can be seen that even if other solvents are contained in the first step, a high yield can be maintained (comparison between Test 1 and Test 30).

[0126] Also, it can be seen that even if THF is not mixed into the reaction solution in the second step, a good yield can be obtained (comparison between Tests 34 to 38 and Tests 3 to 5, 8, and 31). This is presumably because since the reaction solution contains the polyether compound added in the first step, in the second step, even without mixing THF into the reaction solution, a complex of sodium and a polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is formed, and the decomposition conversion reaction of the chain-like polysilane compound proceeds well.

[0127] This application claims priority based on Japanese Patent Application No. 2023-140015 filed on August 30, 2023. All of the contents described in the specification of the said application are incorporated herein by reference.

Industrial Applicability

[0128] According to the present invention, it is possible to provide a method for producing a cyclic silane compound that can produce a cyclic silane compound from a silane monomer in one pot with a high reaction yield regardless of the form of the reactant used and even if the amount used is small.

Claims

1. A method for producing a reaction liquid containing a chain polysilane compound by polymerizing a silane compound in a first solution containing a mixed liquid containing metallic sodium and a hydrocarbon-based solvent; a second step of subjecting the chain polysilane compound to a decomposition and conversion reaction in a second solution containing the reaction liquid to obtain a cyclic silane compound; Including, A polycyclic aromatic hydrocarbon or a polyphenyl-based hydrocarbon is contained in the first solution or mixed with the reaction liquid, A polyether compound represented by formula (I) or (II) is contained in the first solution or mixed into the reaction liquid, In the first step, the first solution is heated to a melting temperature of the metallic sodium or higher. A method for producing a cyclic silane compound. 【Chemistry 1】 In the formulas (I) and (II), R ａ ~R ｈ each independently represents a hydrogen atom or an alkyl group, m １ and m ２ are integers between 2 and 7,

2. The second step is carried out in a second solution obtained by mixing the reaction solution with tetrahydrofuran. A method for producing the cyclic silane compound according to claim 1.

3. The second step is carried out by heating the chain polysilane compound in the second solution. A method for producing the cyclic silane compound according to claim 1.

4. The heating temperature is 40° C. or higher and reflux temperature or lower. A method for producing the cyclic silane compound according to claim 3.

5. The polyether compound represented by formula (I) or (II) is contained in the first solution. A method for producing the cyclic silane compound according to claim 1.

6. The polyether compound represented by formula (I) is contained in the first solution. A method for producing the cyclic silane compound according to claim 5.

7. The total molar equivalent of the polyether compound represented by formula (I) or (II) relative to the silicon atoms of the silane compound is 0.003 eq. or more and 0.180 eq. or less. A method for producing the cyclic silane compound according to claim 5.

8. The polycyclic aromatic hydrocarbon or polyphenyl hydrocarbon is mixed into the reaction liquid. A method for producing the cyclic silane compound according to claim 1.

9. biphenyl, anthracene or naphthalene is mixed into the reaction solution as the polycyclic aromatic hydrocarbon or polyphenyl hydrocarbon; A method for producing the cyclic silane compound according to claim 8.

10. The hydrocarbon solvent is an aromatic hydrocarbon solvent. A method for producing the cyclic silane compound according to claim 1.

11. the second solution contains the hydrocarbon solvent and tetrahydrofuran; A volume ratio of the tetrahydrofuran contained in the second solution is 23 vol% or more and 99 vol% or less with respect to the total volume of the hydrocarbon solvent and the tetrahydrofuran. A method for producing the cyclic silane compound according to claim 1.

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