JP6918280B2 - Manufacturing method of polysilane - Google Patents

Description

The present invention relates to a method for producing polysilane. In particular, the present invention relates to a method for producing a polysilane containing a long-chain silicon bond by repeating a deprotonation and a nucleophilic addition (substitution) reaction cycle.

Polysilane is a polymer compound whose main chain is a silicon-silicon bond. Polysilane exhibits unique photoreactivity and conductivity depending on the length of the main chain, so it is a nonlinear optical material used in photoresist materials, semiconductor materials, conductor materials, light-light mixers, photomultipliers, etc. Or, it is expected to be applied to ceramic materials.

In order to obtain polysilane having the required properties, there is a need for a technique for efficiently producing polysilane having a specific structure by controlling the number of silicons constituting the main chain. In particular, it is required to selectively synthesize a linear high molecular weight polymer having a monodisperse composition.

The electronegativity of silicon is 1.7, which is lower than the electronegativity of carbon, which is 2.5. For this reason, deprotonation techniques from silane are less well known than carbon deprotonation techniques. Further, conventionally, polysilane has been produced by a reduction dehydrogenation coupling polymerization method using an alkali metal of dihalosilane or a dehydrogenation coupling polymerization from silane using a transition metal catalyst. However, with these methods, it has been difficult to obtain a compound in which a desired number of silicon atoms are linked.

Patent Document 1 describes a method for producing polysilane using a silicon anion species, an oxygen anion species, and a fluorine anion species as a polymerization initiator on biphenyl-masked disylene. In the production method of Patent Document 1, a silicon unit is introduced as Si—Si, but there are problems to be solved that it is difficult to synthesize disylene masked with the raw material biphenyl and it is difficult to control the number of polymerizations. be. Patent Document 2 discloses a technique for producing a halogen element-free polysilane by dehydrogenation-coupling polymerization using a metallocene transition metal catalyst. In the production method disclosed in the patent document, the obtained linear polysilane depends on the activity of the catalyst and the reaction conditions.

Patent Document 3 discloses a method for producing a polysilane containing no halogen element by dehydrogenation coupling polymerization using a metallocene transition metal catalyst. In the production method of Patent Document 3, the molecular structure of the obtained linear polysilane depends on the activity of the catalyst and the reaction conditions. Patent Document 4 introduces a (oligosilyl) (oligoalkyl) syroxy group by nucleophilic addition (substitution) reaction of oligosilyllithium with a siloxane linker having an alkyl group having a leaving group at the ω-position in the side chain. A method for producing a polysilane is disclosed. In the method for producing polysilane in Patent Document 4, the number of silicons in the compound is limited by the length of oligosilyllithium used in the reaction.

Non-Patent Document 1 is a paper in which polysilane is synthesized by a conventional dehalogen reduction condensation method and its physical properties are clarified. It is disclosed that the absorption wavelength is lengthened as expected.

Non-Patent Documents 2 and 3 describe synthetic methods and characteristics of silicon anion species compounds having an alkoxy group, an amino group, an alkylthio group, etc., which are leaving groups in the molecule, by metal-metal substitution or heteroatom-metal substitution. This is a summary of the reactions.

Non-Patent Documents 4 and 5 are papers that disclose a technique for deprotonating a hydride group on silicon and further reacting it with an electrophile and a metal compound. It has been shown that deprotonation was facilitated by having three more silicon functional groups on silicon.

Japanese Unexamined Patent Publication No. 03-91537 Japanese Unexamined Patent Publication No. 07-252363 Japanese Patent No. 3154894 Japanese Patent No. 3452786

Obata, K.K. Kira, M. et al. "Synthesis, Structure, and spectroscopic properties of perhexiglosilinanes" Organometallics, 1999, 18, 2216-2222. Atsushi Kawachi, Kohei Tamao "Synthesis of Silicon Anion Species with Nitrogen, Oxygen and Sulfur Functional Groups, Structural Reactions" Journal of Synthetic Organic Chemistry, 2001, pp. 892-903 Tamao, K.K. Kawachi, A. Asahara, M. et al. Shimitsu, A.M. "Recent developments silicon interlement linkage: the case of siliconized silyllythium, silylenoid and sila-ylide" Pure Appl. Chem. 1999, 71, 393-400. Klinkhammer, K.K. W. "Tris (trimethylanides) of the Heavier Alkali Metals-A Structural Study" Chem. Euro. J. 1997, 3, 1418-1431. Frank, D. Baumgartner, J. Mol. Marchner, C.I. "First successful reaction of a silly anion with hafnium tetrachloride" Chem. Commun. 2002, 1190-1191.

In the polysilane production methods known so far, polysilane having a relatively short main chain is mainly produced. Therefore, there is a demand for a method for efficiently synthesizing a longer-chain polysilane. Further, there is a demand for a technique for producing polysilane in which a desired number of silicon atoms are linked, from oligosilane to long-chain polysilane, by controlling the number of silicon bonds. The present invention has been made in view of such circumstances, and has been made as a problem to be solved to provide a manufacturing method for efficiently, safely and easily producing polysilane in which a desired number of silicon atoms are linked.

The method for producing polysilane of the present invention is

_{R 1 R 2 R 3 Si (} R 4 R 5 Si) m M ( Equation 1)

An alkoxysilane having a hydride group is added to the silyl (alkali metal) represented by. Here, _m is 0 to 10, R ₁ is an aryl group, R ₂ , R ₃ , R ₄ and R ₅ each independently represent an alkyl group having 1 to 10 carbon atoms, and M is. It is an alkali metal. Then, by the nucleophilic addition (substitution) reaction and the elimination of the alkali metal alkoxide,

R ₁ R ₂ R ₃ Si (R ₄ R ₅ Si) _{m + 1} H (Equation 2)

It is characterized by producing polysilane represented by.

The method for producing polysilane of the present invention is characterized by deprotonation of silane and subsequent extension by increasing the number of silicon atoms having a silicon-silicon bond by nucleophilic addition. When an alkoxysilane having a hydride group is added to silyl (alkali metal), a nucleophilic addition (substitution) reaction first occurs, followed by elimination of the alkali metal alkoxide. As a result, polysilane in which the number of bound silicon is increased by 1 can be produced.

The method for producing polysilane of the present invention further comprises

R ₁ R ₂ R ₃ Si (R ₄ R ₅ Si) _{m + 1} H (Equation 2)

Cyril (alkali metal) is allowed to act on the polysilane represented by, and the hydride group is deprotonated by a disprotonation reaction based on an acid-base reaction.

R ₁ R ₂ R ₃ Si (R ₄ R ₅ Si) _{m + 1} M (Equation 3)

It further includes a step of producing a silyl (alkali metal) represented by. Then, using the silyl (alkali metal) represented by the formula (3), the nucleophilic addition (substitution) reaction and the elimination of the alkali metal alkoxide are carried out to carry out a linear polysilane in which a desired number of silicon atoms are linked. It is characterized by manufacturing.

In the method for producing polysilane of the present invention, the presence of silyl (alkali metal) causes silyl (alkali metal) to act as a base on polysilane, and polysilane causes a disproportionation reaction based on an acid-base reaction. The hydride group of polysilane is deprotonated to produce the anionic species silyl (alkali metal). Further, when the generated silyl (alkali metal) reacts with alkoxysilane, polysilane in which the number of bound silicon is further increased by 1 is generated, and a hydride group is regenerated at the terminal. The hydride group at the terminal of polysilane is deprotonated again with silyl (alkali metal), and the formation of silyl (alkali metal), which is an anion species with an increased number of silicon-silicon bonds, is repeated. By reacting silyl (alkali metal) with alkoxysilane again, the step of forming a linear polysilane having a hydride group at the end of the extended silicon-silicon bond is repeated.

In the method for producing a polysilane of the present invention, it is preferable that the nucleophilic addition (substitution) reaction and the elimination of the alkali metal alkoxide are carried out at a temperature of -10 degrees Celsius or more and -5 degrees Celsius or less under an argon atmosphere.

The method for producing polysilane of the present invention is characterized by repeating a step of deprotonating the terminal of the silicon-silicon bond of polysilane and a step of nucleophilic addition (substitution) to alkoxysilane. At the end of each repetition of the process, the terminal hydride group is always regenerated, and a straight line composed of a silicon-silicon bond can be extended. The method for producing polysilane of the present invention can provide a method for extending a silicon chain regardless of the conventional reaction conditions and catalytic activity.

In the polysilane produced by the method for producing polysilane of the present invention, the length of the silicon chain depends on the number of repetitions. Therefore, by repeating the process, it becomes possible to produce a polysilane molecule having a silicon straight chain in which a desired number of silicon atoms are linked.

The method for producing polysilane of the present invention protects the ends of silicon-silicon bonds by introducing a silicon compound having a leaving group such as a halide or triflate (trifluoromethanesulfonato) group before post-treatment. Further, a compound in which the straight chain of silicon is extended can be obtained. In particular, by reacting with oligosilane having leaving groups at both ends, longer-chain polysilane synthesis becomes possible.

In the method for producing polysilane of the present invention, the number of silicon atoms constituting the straight chain of polysilane is determined by the number of repetitions of the deprotonation step at the end of the silicon-silicon bond and the nucleophilic addition (substitution) step to alkoxysilane. It can be easily controlled.

FIG. 1 is a flowchart of the method for producing polysilane of the present invention. FIG. 2 is a diagram schematically showing a reaction for producing polysilane of the present invention. 3, Ph (SiMe ₂₎ prepared by the method of Example of ₃ H, an analysis result by IH NMR. 4, Ph (SiMe ₂₎ which was prepared by the method of example an analysis result by ₄ H of IH NMR. 5, Ph (SiMe ₂₎ which was prepared by the method of example a ₃ H results of EI mass spectrometry. 6, Ph (SiMe ₂₎ which was prepared by the method of example is a ₄ H results of EI mass spectrometry.

(Example 1)
Hereinafter, an example of the production method according to the present invention and an analysis result of polysilane obtained by the production method of this example will be described with reference to the drawings.

FIG. 1 is a flowchart showing an outline of the method for producing polysilane of the present invention. FIG. 2 is a diagram schematically showing a production reaction carried out in the production process of polysilane.

As shown in FIG. 1, the method for producing polysilane of the present invention includes a step of adding an alkoxysilane having a hydride group to silyl (alkali metal) (step 1), a nucleophilic addition (substitution) reaction, and an alkali metal alkoxide. A step of producing polysilane in which the number of silicon engaged is increased by 1 (step 2) and a step of confirming the number of silicon atoms contained in the silicon chain of the produced polysilane (step 3) are provided. ing. When the number of silicon atoms is the specified number, the reaction is terminated.

When the number of silicon atoms constituting the silicon chain of the produced polysilane is less than the specified number, silyl (alkali metal) is allowed to act on this polysilane (step 4). Cyril (alkali metal) is produced by this reaction (step 5). The treatment returns to step 1, and the process of adding the silyl (alkali metal) produced in step 5 to the alkoxysilane is repeated. A nucleophilic addition (substitution) reaction and elimination of the alkali metal alkoxide occur, and polysilane in which the number of silicon bonds is further increased by 1 can be produced.

Hereinafter, as Example 1, dimethylphenylsilyllithium is used as the starting material silyl (alkali metal), and 1-butoxydimethylsilane is used as the alkoxysilane having a hydride group of the starting material, and the number of silicon bonds is 3. An example of producing polysilane (hereinafter, also referred to as oligosilane) of No. 7 will be described.

The structural formulas of the starting materials dimethylphenylsilyllithium and 1-butoxydimethylsilane are shown.

FIG. 2 is a diagram schematically showing an outline of a polysilane formation reaction and production conditions. In the figure, Me indicates a methyl group, Bu indicates a butyl group, and Ph indicates a phenyl group.

The production conditions of polysilane of this example will be described. As a reaction corresponding to step 1 in FIG. 1, 1.1 mL, 1.1 mmol of dimethylphenylsilyllithium (reference numeral 2) at -10 to -5 degrees Celsius under an argon atmosphere, 0.19 mL, Add 1.0 mmol of 1-butoxydimethylsilane (reference numeral 1) and allow to react for 30 minutes. Here, dimethylphenylsilyllithium is prepared from chlorodimethylphenylsilane and lithium.

In addition, 1.1 mL, 1.1 mmol of dimethylphenylsilyllithium was added dropwise very slowly, followed by 0.19 mL, 1.0 mmol of 1-butoxydimethylsilane. This alternating dropping was repeated three more times every 30 minutes, and the reaction was carried out for 3 hours under the same temperature conditions of -10 ° C to -5 ° C. As a result, polysilane was produced.

The method for extracting linear polysilane in which a desired number of silicon atoms are linked from the reaction mixture is as follows. The resulting reaction mixture is washed with saturated brine, extracted with hexane, and separated into an organic layer and an aqueous layer. The aqueous layer is washed with hexane and diethyl ether and combined with the organic layer extracted with hexane. The organic layer is dried over anhydrous sodium sulfate. After distilling off the solvent, oligosilane having an Rf value of around 0.5 was separated by a silica gel column using 1 mL of triethylamine as a developing solvent with respect to 250 mL of hexane. As a result, the impurity silyl ether could be removed from the oligosilane. As a result, the monosilane represented by reference numeral 3 and the disilane represented by reference numeral 4 in FIG. 3 were removed. Further, the extracted mixture of oligosilanes was separated by recycling preparative HPLC using chloroform as a developing solvent and JAIGEL-1H and 2H as packing materials.

The yield and yield of oligosilanes obtained by the production method of Examples are shown below. The oligosilane that could be measured was an oligosilane in which the number of silicon atoms constituting the linear chain was 3 to 7. These structural formulas are shown in FIG. 2 with reference numerals 5 to 9, respectively. Analysis has confirmed that polysilane having 8 or more silicon atoms is also produced, but it was difficult to separate because the yield was low.

_{3 to 6 show the measurement results of oligosilane Ph (SiMe 2} ) _n H (n = 3, 4) produced by the production method of the example. Figure 3 shows the Ph (SiMe _{2) 3} H analysis results by IH NMR of FIG. 4 Ph (SiMe ₂₎ The analytical results of the ₄ H of IH NMR. Figure 5 Ph (SiMe ₂₎ shows the ₃ H results of EI mass spectrometry, showing the results of Ph (SiMe _{2) 4} H EI mass spectrometry of Figure 6.

The results of each analysis will be explained. Ph (SiMe ₂₎ In ₃ H, by NMR, a peak derived from the phenyl group of 7.5 and 7.2 ppm, a peak derived from hydrogen (Si-H) on silicon near 4 ppm, 0.4 A peak derived from a methyl group is observed around −0.0 ppm. The single line at 7.2 ppm is a peak due to residual hydrogen contained in the benzene-d6 measurement solvent. These peaks have reasonable values when compared to other known compounds. Peak hydrogens on the double line and the silicon are observed near 0.5 ppm are coupled, the coupling constant ^{(3 J} _HH) a normal carbon - binding constants carbon bonds ⁽³ J _HH ), Which is a reasonable value for an HC-Si-H vinyl coupling smaller than ~ 7 Hz. Further, since the peak of Si—H is a 7-fold line and the coupling methyl group is a double line, the existence of a partial structure of _{H—Si− (CH 3} ) _{2 is presumed.} Finally, the integrated intensity ratio of the peak derived from the phenyl group, the peak derived from Si—H, and the peak derived from the methyl group is usually measured with a slightly smaller integrated intensity due to the long relaxation time of hydrogen on silicon. , Approximately 5: 1: 12, which is believed to accurately reflect the hydrogen ratio in the chemical formula. In addition, from the results of mass spectrometry in FIG. 5, _{m / e 252 due to C 12} H ₂₄ Si _3, which is considered to be the parent peak, and m / e 253 due to the isotope are observed. Further, m / e 135 is considered to be a peak due to _{C 8} H ₁₁ Si, that is, Ph [Si (CH ₃ ) ₂ ] ^+. This peak has the highest intensity, which is reasonable if the cation is stabilized by a phenyl group. The second largest m / e 116 _{corresponds to one having CH 2} less than m / e 135, and it is presumed that the methyl group is cut off to form a hydride group. Therefore, these measurements are all intended to support the structure Ph (SiMe _{2) 3} H of the produced material.

Similarly IH NMR spectrum of Figure 4, Ph represents (SiMe ₂₎ consistently the structure ₄ H. From the result of mass spectrometry in FIG. 6, the parent peak m / e 310 was observed. This is the molecular weight corresponding to _{C 14} H ₃₀ Si _4. Similarly, a peak due to _{C 8} H ₁₁ Si of m / e 135, that is, Ph [Si (CH ₃ ) ₂ ] ^{+ is observed.} Furthermore, as a noteworthy point, a large peak of m / e 251 is observed. Since this is a value with a mass number one less than the parent peak of the composition formula C ₁₂ H ₂₄ Si _{3 of Ph (SiMe 2} ) _{3 H, it is considered to be C 12} H ₂₃ Si ₃ ^+, that is, Ph (SiMe ₂ ) ₃ ^+. It is the peak to be. This is a peak of m / e 251 is, Ph (SiMe _{2) 4} H terminal dimethylsilyl group SiH _{(CH 3)} from the considered _second involves cutting generated cations, have continuous silicon four straight chain It is clear that the structure has a dimethylsilyl group at the end. As described above, from the analysis results, _{it was confirmed that Ph (SiMe 2} ) _n H (n = 3, 4) was produced by the production method of this example.

By the method for producing polysilane of the present invention, long-chain polysilane can be efficiently synthesized, and the number of silicon bonds is controlled so that a desired number of silicon atoms are linked from oligosilane to long-chain polysilane. It was confirmed that polysilane can be produced.

Polysilane produced by the production method of the present invention can impart specific photoreactive properties and conductivity by controlling the number of silicon atoms in the main chain. Therefore, it is expected to be applied to photoresist materials, semiconductor materials, conductor materials, nonlinear optical materials used for light-light mixers and photomultipliers, ceramic materials, and the like.

Claims (3)

A method for producing polysilane, wherein the formula (1):
_{R 1 R 2 R 3 Si (} R 4 R 5 Si) m M (1),
(Here, _m is 0 to 10, R ₁ is an aryl group, and R ₂ , R ₃ , R ₄ , and R ₅ each independently represent an alkyl group having 1 to 10 carbon atoms, and M. Is an alkali metal), an alkoxysilane having a hydride group is added to the silyl alkali metal represented by), and the nucleophilic addition reaction and the elimination of the alkali metal alkoxide are carried out.
Equation (2):
R ₁ R ₂ R ₃ Si (R ₄ R ₅ Si) _{m + 1} H (2)
It is characterized by producing polysilane represented by, and the alkali metal alkoxide has 1 to 4 carbon atoms.
Method for producing polysilane. The formula (2):
R ₁ R ₂ R ₃ Si (R ₄ R ₅ Si) _{m + 1} H (2)
A silyl alkali metal is allowed to act on the polysilane represented by, and the hydride group is deprotonated by a disprotonation reaction based on an acid-base reaction.
Equation (3):
R ₁ R ₂ R ₃ Si (R ₄ R ₅ Si) _{m + 1} M (3)
It is further equipped with a process for producing the silyl alkali metal represented by.
Using the silyl alkali metal represented by the formula (3), the nucleophilic addition reaction and the elimination of the alkali metal alkoxide are carried out to produce a linear polysilane in which a desired number of silicon atoms are linked. The method for producing polysilane according to claim 1. The method for producing a polysilane according to claim 1 or 2, wherein the nucleophilic addition reaction and desorption of the alkali metal alkoxide are carried out at a temperature of −10 ° C. or higher and −5 ° C. or lower in an argon atmosphere.

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