Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/08—Compounds having one or more C—Si linkages
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
  • C07F7/02—Silicon compounds
  • C07F7/21—Cyclic compounds having at least one ring containing silicon, but no carbon in the ring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/60—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule in which all the silicon atoms are connected by linkages other than oxygen atoms

Definitions

• the present invention relates to a method for producing a cyclic silane compound.
• Silicon carbide fiber has excellent heat resistance and oxidation resistance, even in high-temperature air of over one thousand degrees. Taking advantage of these characteristics, silicon carbide fiber is expected to be used in the nuclear and aerospace fields.
• Silicon carbide fiber is obtained by spinning, infusible, and sintering the precursor organosilicon polymer compound such as polycarbosilane. Since oxygen-containing silicon carbide fiber decomposes at high temperatures, in order to obtain ultra-heat-resistant silicon carbide fiber, it is necessary to suppress the introduction of oxygen atoms into the organosilicon polymer compound that forms the fiber. For this reason, ultra-heat-resistant silicon carbide fiber is produced by using an organosilicon polymer compound with a low oxygen content and adopting a method that does not introduce oxygen during infusibility. Polycarbosilane with an oxygen content of about 0.1% by weight can be obtained from cyclic silane compounds such as dodecamethylcyclohexasilane. Therefore, cyclic silane compounds are useful as raw materials for organosilicon polymer compounds that are precursors to silicon carbide fiber.
• Patent Document 1 discloses a method in which a silane monomer compound is dropped into a mixture of THF and sodium dispersion under ice cooling, followed by a polymerization reaction to obtain a chain polysilane compound; naphthalene is then added, and the chain polysilane compound is heated and refluxed to produce a cyclic silane compound.
• Patent Document 2 discloses a method for producing a cyclic silane compound by dripping a silane monomer compound into a mixture of THF, sodium dispersion, and lithium chloride under ice cooling, followed by a polymerization reaction.
• Patent Document 3 discloses a method for producing a cyclic silane compound by reacting a linear polysilane having a degree of polymerization of 10 to 100, an alkali metal, and an aromatic hydrocarbon capable of forming a complex with an alkali metal in an ether solvent.
• naphthalene is used as the aromatic hydrocarbon.
• Patent Document 2 when producing cyclic silanes by polymerizing a silane monomer compound, it is necessary to use a stoichiometric amount of metallic sodium. This results in a certain amount of by-products such as sodium chloride being produced. From the perspective of further improving production efficiency, it is desirable to be able to reduce the amount of by-products such as sodium chloride produced.
• the naphthalene used in Patent Documents 1 and 3 is a water-insoluble solid organic compound, and therefore cannot be removed by washing with water, making purification complicated. For this reason, it is desirable to be able to purify the compound by washing with water alone (to simplify purification).
• the present invention was made in consideration of the above circumstances, and aims to provide a method for producing cyclic silane compounds that can produce cyclic silane compounds in high yields with simple purification while reducing the amount of by-products produced.
• the present invention relates to a method for producing the following cyclic silane compounds.
• a method for producing a cyclic silane compound comprising the step of subjecting a chain polysilane compound having a repeating unit represented by the following formula (1) to a decomposition reaction in a solution containing metallic sodium and a lithium salt to obtain a cyclic silane compound, wherein the chain polysilane compound is not completely dissolved in 1-chloronaphthalene at a temperature of 240° C. or less: (In the formula, R1 and R2 each independently represent a hydrogen atom or a hydrocarbon group.) [2] The method for producing a cyclic silane compound according to [1], wherein the chain polysilane compound is not dissolved in 1-chloronaphthalene at a temperature of 250° C. or less.
• the present invention provides a method for producing cyclic silane compounds that can produce cyclic silane compounds in high yields with simple purification while minimizing the amount of by-products produced.
• FIG. 1A is a photograph showing the results of a dissolution test of silane compound A
• FIG. 1B is a photograph showing the results of a dissolution test of silane compound B.
• a numerical range expressed using “ ⁇ ” means a range that includes the numerical values written before and after " ⁇ " as the lower and upper limits.
• a method for producing a cyclic silane compound according to one embodiment of the present invention includes a step of subjecting a chain polysilane compound to a decomposition reaction in a solution containing metallic sodium and a lithium salt to obtain a cyclic silane compound.
• a cyclic silane compound can be obtained through a process of preparing a solution containing a chain polysilane compound, metallic sodium, and a lithium salt, and a process of decomposing the chain polysilane compound in the solution.
• Chain polysilane compound has a repeating unit represented by the following formula (1).
• R 1 and R 2 each independently represent a hydrogen atom or a hydrocarbon group.
• hydrocarbon groups examples include alkyl groups, alkenyl groups, alkynyl groups, and aryl groups.
• R1 and R2 can be side chains in the cyclic silane compound. Therefore, they may be selected according to the cyclic silane compound to be synthesized.
• R1 and R2 are preferably, for example, a hydrogen atom or a hydrocarbon group, more preferably a hydrocarbon group, even more preferably an alkyl group, and even more preferably a methyl group.
• the groups bonded to the silicon atoms at both ends of the molecule can be hydrogen atoms, hydrocarbon groups, alkoxy groups, or hydroxy groups.
• alkoxy groups include methoxy groups and ethoxy groups. Since alkoxy groups and hydroxy groups have a large difference in electronegativity with silicon atoms, they are likely to cause intramolecular polarization within the chain polysilane compound and may also be likely to function as leaving groups. Therefore, the groups at both ends of the molecule of a chain polysilane compound may be alkoxy groups or hydroxy groups.
• chain polysilane compound examples include the compound represented by the following formula (2).
• R 1 and R 2 are the same as R 1 and R 2 in formula (1).
• X1 and X2 each represent a hydrogen atom, a hydrocarbon group, an alkoxy group, or a hydroxy group, and an example thereof is an alkoxy group or a hydroxy group.
• n1 is a degree of polymerization such that the compound represented by formula (2) is not completely dissolved at a temperature of 240° C. or less in a solubility test in 1-chloronaphthalene described later, and is, for example, an integer of 17 or more, preferably 20 or more, and more preferably 30 or more.
• the number average molecular weight of the chain polysilane compound is preferably high from the viewpoint of increasing the yield of the cyclic silane compound.
• the number average molecular weight of the chain polysilane compound is preferably, for example, 950 or more, more preferably 1100 or more, and even more preferably higher than 1700. If the number average molecular weight is 1100 or more, the amount of intermediates produced by the decomposition reaction can be increased, so that the yield of the cyclic silane compound can be further increased.
• the number average molecular weight of a chain polysilane compound can be evaluated using the temperature at which it dissolves in 1-chloronaphthalene as an index. For example, the higher the number average molecular weight of a chain polysilane compound, the higher the temperature at which it dissolves in 1-chloronaphthalene. Since the chain polysilane compound used in this embodiment preferably has a high number average molecular weight, it is also preferable that the temperature at which it dissolves in 1-chloronaphthalene is high. Specifically, it is preferable that the chain polysilane compound does not completely dissolve in 1-chloronaphthalene at temperatures of 240°C or lower, and does not completely dissolve in 1-chloronaphthalene even at temperatures of 250°C or lower.
• the temperature at which a substance dissolves in 1-chloronaphthalene can be confirmed by the following method. That is, a glass capillary having an inner diameter of 1.0 mm is filled with about 3 to 5 mm of a chain polysilane compound and 5 to 10 mm of 1-chloronaphthalene (about twice the amount of the chain polysilane compound), and then the inside is replaced with argon gas and sealed. This is placed in a melting point measuring device (B-545, manufactured by Buchi) whose internal temperature has been raised to 240° C. in advance, and left to stand for 5 minutes. After standing, the state of the chain polysilane compound filled in the glass capillary is visually confirmed to determine whether it is completely dissolved. By repeating this procedure at different temperatures, the temperature at which the chain polysilane compound completely dissolves can be identified.
• a melting point measuring device B-545, manufactured by Buchi
• the chain polysilane compound is a white solid. Therefore, if even a portion of it remains undissolved, it can be visually confirmed that the white solid remains. Therefore, whether or not it has completely dissolved can be determined by visually checking whether or not the white solid remains and whether it is transparent. For example, at 250°C in Figure 1A described below, part of the white solid remains undissolved, but at 250°C in Figure 1B, the white solid is shown to have completely dissolved. Whether or not it has completely dissolved can also be confirmed by the transmittance or turbidity of the solution, or the whiteness obtained by image processing of the solution image.
• the chain polysilane compound can be identified using a Fourier transform infrared spectrophotometer and a micro Raman spectrometer. If peaks are observed at 742 cm -1 , 831 cm -1 , 1246 cm -1 , 1400 cm -1 , 2892 cm -1 and 2950 cm -1 in the IR spectrum measured by a Fourier transform infrared spectrophotometer, and if a peak is observed at 482 cm -1 in the Raman spectrum measured by a microscopic Raman spectrometer, it can be determined that the compound contained in the sample has the repeating unit represented by the above formula (1) (is a chain polysilane compound). In addition, it can be confirmed by 29 Si CP/MAS NMR that the compound has a chain structure having terminals.
• the chain polysilane compound may be a synthetic product or a commercially available product.
• Metallic sodium can function as a catalyst for the decomposition reaction.
• the form of metallic sodium is not particularly limited, but from the viewpoint of increasing the surface area and enhancing the reactivity, it is preferable that the metallic sodium is processed into a sodium dispersion.
• the average particle size of metallic sodium is preferably 1 to 30 ⁇ m, more preferably 2 to 10 ⁇ m, and even more preferably 3 to 5 ⁇ m.
• the average particle size can be measured using a laser diffraction particle size distribution measuring device.
• the amount of metallic sodium contained in the above solution is preferably 0.1 to 120 mmol per 1 g of the chain polysilane compound from the viewpoint of the yield of the cyclic silane compound. If the content of metallic sodium is 0.1 mmol or more, the decomposition reaction of the chain polysilane compound is more likely to proceed. If the content of metallic sodium is 120 mmol or less, the reaction can be sufficiently proceeded while the amount of unreacted metallic sodium can be reduced. In addition, when the chain polysilane compound is dichlorodimethylpolysilane or the like, the amount of by-products such as sodium alkoxide produced can also be reduced.
• the amount of metallic sodium is more preferably 0.5 to 80 mmol per 1 g of the chain polysilane compound, even more preferably 0.5 to 20 mmol, and particularly preferably 1.0 to 10.0 mmol.
• the lithium salt mainly contributes to stabilizing an intermediate produced in the decomposition reaction.
• the lithium salt may be an inorganic salt or an organic salt.
• Inorganic salts include halides and salts of inorganic acids.
• halides include lithium chloride, lithium bromide, lithium iodide, and lithium fluoride.
• salts of inorganic acids include lithium carbonate, lithium bicarbonate, lithium nitrate, lithium nitrite, lithium sulfate, and lithium sulfite.
• Organic salts include carboxylates, sulfonates, and salts of phenols.
• carboxylates include lithium acetate, lithium formate, and lithium citrate.
• sulfonates include lithium methanesulfonate, lithium benzenesulfonate, and lithium p-toluenesulfonate.
• phenol salts include lithium phenoxide, lithium salicylate, and lithium cresol salt.
• inorganic salts are preferred, and halides are more preferred.
• halides are more preferred.
• lithium chloride and lithium bromide are preferred, and lithium chloride is more preferred. Only one type of lithium salt may be used alone, or multiple types may be used in combination.
• the molar ratio of the lithium salt to the metallic sodium contained in the solution depends on the content of metallic sodium, but is preferably 0.01 or more, more preferably 0.06 or more, even more preferably more than 1.0, and most preferably 1.3 or more.
• the molar ratio is 0.06 or more, it is easy to moderately stabilize the intermediate generated by the decomposition reaction of the chain polysilane compound, and it is easy to further increase the yield of the cyclic silane compound.
• even if the content of metallic sodium is small, it is easy to maintain the yield of the cyclic silane compound.
• the molar ratio of lithium is preferably 10.0 or less, more preferably 6.0 or less, even more preferably 3.0 or less, and most preferably 2.0 or less.
• the molar ratio is 3.0 or less, the decomposition of the generated cyclic silane compound can be further suppressed.
• the yield of the cyclic silane compound can be further increased.
• the amount of lithium salt contained in the solution may be within the range that results in the above molar ratio, and is preferably 1.0 mmol or more, more preferably 1.5 mmol or more, and even more preferably 2.0 mmol or more per 1 g of chain polysilane compound.
• the upper limit of the amount of lithium salt is, for example, preferably 9.0 mmol or less, and more preferably 5.0 mmol or less.
• the amounts of metallic sodium, the lithium salt, and the molar ratios thereof are as described above, but from the viewpoint of increasing the reactivity and the yield, it is preferable that these quantitative relationships are satisfied simultaneously.
• the amount of metallic sodium contained in the solution is preferably 0.1 to 120 mmol, more preferably 0.5 to 20 mmol, relative to 1 g of the chain polysilane compound;
• the amount of lithium salt is preferably 1.0 to 9.0 mmol, more preferably 2.0 to 5.0 mmol;
• the molar ratio (lithium salt/metallic sodium) is preferably 0.01 or more, more preferably more than 1.0.
• the solution preferably further contains a solvent, which may be any solvent capable of dispersing metallic sodium and dispersing or dissolving lithium salt.
• Examples of the solvent include aprotic polar solvents.
• Examples of the aprotic polar solvent include tetrahydrofuran (THF), 1,2-dimethoxyethane, 4-methyltetrahydropyran, bis(2-methoxyethyl)ether, 1,4-dioxane, and cyclopentyl methyl ether. These solvents may be used alone or as a mixture of two or more. Among them, tetrahydrofuran, 4-methyltetrahydropyran, and cyclopentyl methyl ether are preferred, and tetrahydrofuran is more preferred.
• the solution can be prepared by mixing the components.
• the mixing method and procedure are not particularly limited, but for example, the solution can be obtained by adding metallic sodium, a lithium salt, and a chain polysilane compound to a solvent while stirring, followed by stirring and mixing.
• metallic sodium is preferably added as a dispersion (SD) dispersed in the above-mentioned electrical insulating oil or aromatic hydrocarbon.
• SD dispersion
• the content of metallic sodium in the sodium dispersion to be added is not particularly limited, but from the viewpoint of safety, it is preferably 20 to 45 mass%.
• the chain polysilane compound is decomposed in the solution prepared above.
• the decomposition reaction may be carried out at room temperature or under heating.
• the temperature of the solution during the decomposition reaction can be from 20°C to the reflux temperature.
• the reflux temperature corresponds to the temperature of the solution when it reaches a reflux state at normal pressure. From the viewpoint of obtaining a cyclic silane compound in a higher yield, it is preferable to carry out the decomposition reaction under heating, that is, by heating the chain polysilane compound in the solution.
• the temperature of the solution is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher.
• the upper limit of the solution temperature is preferably 200°C or lower from the viewpoint of suppressing the decomposition of the reaction product, etc.
• the heating method is not particularly limited, but may be, for example, a method in which the solution is placed in an atmosphere at a predetermined temperature, or a method in which the solution is heated by a heater, a water bath, an oil bath, electromagnetic waves, or the like.
• the reaction time refers to the time elapsed from when the entire amount of the raw material chain polysilane compound is added and the target reaction temperature is reached.
• the reaction time depends on the temperature of the solution, but when the reaction is carried out under heating, it is preferably, for example, from 1 hour to 35 hours, and more preferably from 3 hours to 10 hours.
• a chain polysilane compound is decomposed in the presence of a specific catalyst to produce a cyclic silane compound.
• This makes it possible to obtain a cyclic silane compound in a higher yield than in the conventional method of polymerizing a silane monomer.
• the content of functional groups that react with metallic sodium in the chain polysilane compound is extremely low, and the amount of metallic sodium used as a catalyst can be reduced, so that the amount of by-products such as sodium alkoxides produced can be significantly reduced.
• the group (e.g., alkoxy group) at the molecular end of the chain polysilane compound is eliminated by the action of metallic sodium, or the silicon-silicon bond is cleaved by the action of metallic sodium, whereby the electronic state changes and active points are generated.
• the molecular chain is then cut at predetermined intervals by these active points to form cyclization, thereby generating a cyclic silane compound.
• the generated active points are stabilized by lithium salts or the like, so they are not easily deactivated, and an appropriate level of reactivity is maintained, so that the reactivity is improved by adding lithium salts or the like.
• the chain polysilane compound has few groups that are eliminated per molecule, and the amount of metallic sodium required for the decomposition reaction is also small, so the amount of by-products can be reduced.
• the stabilization of the active points by lithium salts or the like can increase the yield of the cyclic silane compound.
• 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.
• R 1 and R 2 in formula (3) are the same as R 1 and R 2 in formula (1), respectively.
• n2 is an integer of 3 or more. n2 is preferably an integer of 3 to 10, more preferably an integer of 5 to 7, and even more preferably 6.
• the cyclic silane may have any structure depending on R 1 and R 2 , and examples include decamethylcyclopentasilane, dodecamethylcyclohexasilane, and tetradecamethylcycloheptasilane.
• the obtained cyclic silane compound may contain a plurality of kinds of cyclic silane compounds with different n2 .
• the yield of the cyclic silane compound (6-membered ring) with n2 being 6 is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.
• the yield of the cyclic silane compound can be obtained by analyzing the reaction product by gas chromatography. The measurement conditions can be the same as those in the examples described below.
• Silane compound C Dichlorodimethylsilane (monosilane, liquid at room temperature, molecular weight 129)
• a glass capillary with an inner diameter of 1.0 mm was filled with a silane compound to a depth of about 3 to 5 mm, and filled with 1-chloronaphthalene to a depth of about 5 to 10 mm (about twice the amount of the silane compound), purged with argon gas, and sealed. This was placed in a melting point measuring device (B-545, manufactured by Buchi) whose internal temperature had been previously raised to 240°C or 250°C, and left to stand for 5 minutes. After standing, the state of the silane compound filled in the glass capillary was visually confirmed.
• the results of the dissolution test of silane compound A are shown in Figure 1A
• the results of the dissolution test of silane compound B are shown in Figure 1B.
• silane compound A did not completely dissolve at either 240°C or 250°C (see Figure 1A).
• silane compound B did not completely dissolve at 240°C, but did completely dissolve at 250°C (see Figure 1B).
• cyclic silane compound [Example 1] A 200 mL four-neck flask that had been purged with argon was charged with 0.98 g of silane compound A (chain polysilane), 20.4 mL of tetrahydrofuran (THF)/1 g of the above-mentioned silane compound, sodium dispersion (25.72 mass % sodium dispersion) as metallic sodium in an amount of 1.6 mmol in terms of Na/1 g of the above-mentioned silane compound, and lithium chloride as a lithium salt in an amount of 2.23 mmol/1 g of the above-mentioned silane compound, followed by stirring and mixing to prepare a solution.
• silane compound A chain polysilane
• THF tetrahydrofuran
• sodium dispersion 25.72 mass % sodium dispersion
• lithium chloride as a lithium salt in an amount of 2.23 mmol/1 g of the above-mentioned silane compound
• the resulting solution was heated in an oil bath at a reflux temperature of 68°C and stirred for 5 hours to allow the reaction to occur.
• Examples 2 to 10 Comparative Examples 3 and 4
• Solutions were prepared and reacted in the same manner as in Example 1, except that one or more of the type of silane compound, the amount of tetrahydrofuran (THF) charged, the ratio of metallic sodium to lithium salt, the type and amount of lithium salt, and reaction conditions were changed as shown in Table 1.
• THF tetrahydrofuran
• Comparative Example 1 A 500 mL four-neck flask in which the air had been replaced with argon was charged with 180 mL of THF and 29.90 g of a sodium dispersion (25 wt % sodium dispersion), and the resulting mixture was stirred to prepare a mixed solution. 19.33 g of silane compound C (dichlorodimethylsilane) was dissolved in 150 mL of THF to prepare a silane compound solution.
• silane compound C dichlorodimethylsilane
• Example 10 had a higher total yield than Comparative Examples 4 and 5.
• the total yield is increased by setting the amount of lithium salt to 2.0 mmol or more per 1 g of chain polysilane compound, or by setting the molar ratio (lithium salt/metallic sodium) to more than 1.0 (Compare Examples 1 and 10).
• the present invention provides a method for producing cyclic silane compounds that can produce high-purity cyclic silane compounds in high yields even with a small amount of metallic sodium used.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Silicon Polymers (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=94215537

Family Applications (1)

Country Status (3)

Citations (6)

• 2024
  • 2024-07-08 JP JP2025532769A patent/JPWO2025013836A1/ja active Pending
  • 2024-07-08 CN CN202480040865.2A patent/CN121399142A/zh active Pending
  • 2024-07-08 WO PCT/JP2024/024645 patent/WO2025013836A1/ja active Pending

Patent Citations (6)

Also Published As

Similar Documents

Legal Events