JP2746097B2 - Method for producing polysilane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polysilane useful for various reactions such as a photoconductor, a photoresist, a luminescent material, a charge transporting material, and a hydrosilylation reaction.

[0002]

2. Description of the Related Art Conventionally, polysilanes are mainly sodium,
It has been produced by a condensation reaction of organodichlorosilane with an alkali metal such as potassium under a high temperature condition of 100 ° C. or higher (for example, J. Polym. Sci .: Po.
lym. Chem. Ed., VOL22, 159-170 (1984)). However, this method generally has a low yield and is extremely dangerous because the reaction is carried out using an alkali metal, and thus cannot be said to be suitable as a method for producing polysilane.

On the other hand, there has been proposed a method of electrolyzing organodichlorosilane in a polar solvent containing a supporting electrolyte using an aluminum or magnesium electrode (Japanese Patent Application Laid-Open No. 3-108489). However, organodichlorosilane is particularly active in reaction to water, is easily hydrolyzed by moisture in the air, and is not only difficult to handle the raw material, but also acid gas generated at that time,
That is, treatment of hydrogen chloride or anticorrosion measures for the reactor are required. In addition, when the organodichlorosilane is electrolyzed, it is necessary to prevent chloride ions from being produced as by-products, which are oxidized on the electrodes and become harmful chlorine gas. Therefore, it is necessary to use an electrode that reacts with chlorine such as aluminum or magnesium and take measures to remove chlorine as a metal chloride from the reaction system, such as replacing the electrode or recovering a large amount of by-product metal chloride. However, an economically disadvantageous and complicated process is required.

Further, using halosilane as a raw material, Mg, C
A method of producing a disilane having Si—H bonds at both ends by performing an electrolytic reaction using u or the like as an anode is known (Japanese Unexamined Patent Publication No. 3-264683). Since halosilane is used, halogen or halide may be generated as a by-product and may be mixed as an impurity into a product, which may affect various electronic material members.

Further, a method of producing a low molecular weight organohydropolysilane by subjecting organohydrosilanes to a dehydrocondensation reaction using a titanocene-based or zirconocene-based catalyst is known (for example, CTAitk).
en, JF Harrod, E. Samuel, J, Am, Chem. Soc., 108, 4059 (198
6)). However, since the polysilane obtained by this method contains a large amount of reactive SiH groups in the main chain of the polymer, insolubilization may occur due to a crosslinking reaction.
This is not an industrially advantageous method, for example, because the polymerization catalyst is extremely unstable with respect to water and oxygen and is difficult to handle.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have found that the present invention is useful for various uses such as photoconductors, photoresists, luminescent materials, and charge transport materials, and is useful for various reactions such as hydrosilylation reactions. Polysilanes that are not likely to be used in a clean environment without using highly corrosive raw materials such as organodichlorosilane, generating no by-products such as halides, and generating no harmful halogen gas. ,
As a result of intensive research on efficient manufacturing, the present invention was completed.

[0007]

According to the present invention, an organohydrosilane represented by the formula (1) [hereinafter referred to as an organohydrosilane (1)] is converted to a supporting electrolyte (hereinafter referred to as a salt) having no oxygen atom in the molecule. This is a method for producing polysilane (hereinafter, referred to as polysilane (1)) represented by the formula (2), characterized in that electrolysis is carried out in an organic solvent containing a support electrolyte.

[0008]

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[0009]

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The organohydrosilane (1) is as shown by the above formula (1), and R ¹ or R ² is preferably an alkyl group having 1 to 8 carbon atoms or a phenyl group. The number of carbon atoms is from 1 to 6, particularly preferably from 1 to 4. R ¹ or R
² may be the same or different.

Specific examples of preferred alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl.
These alkyl groups may be linear or branched, but are more preferably linear.

Specific examples of suitable organohydrosilanes (1) include dimethylsilane, diethylsilane, dipropylsilane, dibutylsilane, dipentylsilane, dihexylsilane, methylpropylsilane, hexylmethylsilane, methylphenylsilane and diphenylsilane. And the like, and among them, more preferably, dimethylsilane, diethylsilane, di-n-propylsilane, di-n
-Butyl silane, methyl phenyl silane, diphenyl silane, and the like, and in particular, methyl phenyl silane, diphenyl silane, di-n-butyl silane, and the like are optimally used from the viewpoint of easy handling in terms of boiling point and the like.

Preferable examples of the electrode material used for the anode or cathode for electrolysis of the organohydrosilane (1) include platinum, carbon and copper.
These electrode materials are electrochemically inert and can be used repeatedly. In this production method, platinum is particularly preferable because hydrogen gas is generated when polysilane (1) is produced from organohydrosilane (1) because hydrogen gas is generated.

An electrolytic solution for electrolyzing the organohydrosilane (1) contains an electrolytic solution in which the above-mentioned supporting electrolyte is dissolved. The supporting electrolyte is not particularly limited as long as it is a salt having no oxygen atom in the molecule . As the counter cation of the salt, tetraalkylammonium is preferred.

Specific examples of suitable salts include those represented by formula (3)
And preferred R ³ is a linear alkyl group having 2 to 4 carbon atoms.

[0016]

(R ³ ) ₄ NBF ₄ (3) (In the formula, R ³ is an alkyl group having 1 to 4 carbon atoms.)

Specific examples of suitable salts include tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, tetra-i-propylammonium tetrafluoroborate, And tetra-n-butylammonium fluoroborate. Among these, high solubility in organic solvents,
R ³ is a linear alkyl group having 2 to 4 carbon atoms, such as tetraethylammonium tetrafluoroborate, tetra-n-propylammonium tetrafluoroborate, and tetrafluoroborate, from the viewpoint of imparting higher conductivity to the electrolytic solution. Tetra-n-butylammonium is optimal.

[0018] Specific examples of suitable salts include hexafluorophosphate tetraalkylammonium represented by the formula (4), preferred R ⁴ is a linear alkyl group having 2 to 4 carbon atoms .

[0019]

(R ⁴ ) ₄ NPF ₆ (4) (In the formula, R ⁴ is an alkyl group having 1 to ⁴ carbon atoms.)

Specific examples of suitable salts include tetramethylammonium hexafluorophosphate, tetraethylammonium hexafluorophosphate, tetra-n-propylammonium hexafluorophosphate, tetra-i-propylammonium hexafluorophosphate, And tetra-n-butylammonium fluorophosphate. Among these, high solubility in organic solvents,
R ⁴ is a linear alkyl group having 2 to ⁴ carbon atoms such as tetraethylammonium hexafluorophosphate, tetra-n-propylammonium hexafluorophosphate, The acid tetra-n-butylammonium is optimal.

The solvent used for dissolving the supporting electrolyte to form an electrolytic solution is not particularly limited as long as it dissolves the supporting electrolyte, the organohydrosilane (1) and the polysilane (1) to be formed. , 2-dimethoxyethane (DME), dimethylformamide, dimethylsulfoxide, tetrahydrofuran (THF) and the like are preferred, and DME is particularly preferred. These may be used in combination of two or more.

The concentration of the supporting electrolyte in the electrolytic solution is preferably from 0.05 mol / l to 2 mol / l, particularly preferably from 0.1 mol / l to increase the rate of polysilane generation through the electrolytic current. 1
mol / l.

The concentration of the raw material organohydrosilane (1) in the electrolyte is 0.05 mol / l to 1 mol / l.
The concentration is preferably 0 mol / l, more preferably 0.1 mol / l to 5 mol / l, particularly preferably 0.1 mol / l to 2 mol / l. If the concentration is too high, the electric resistance of the electrolyte may increase.

More specifically, the production method of the present invention will be described. An organohydrosilane (1), a supporting electrolyte and a solvent are placed in a sealable electrolytic cell provided with an anode and a cathode, and are preferably stirred mechanically. While passing a predetermined amount of current, the electrolytic reaction is performed. The inside of the electrolytic cell is desirably set to an inert gas atmosphere from which moisture and oxygen have been removed, and specific examples include a dry nitrogen gas atmosphere.

The amount of electricity is preferably 1 F / mol to 10 F / mol, based on the organohydrosilane (1).
It is more preferably from 1 F / mol to 5 F / mol, and particularly preferably from 2 F / mol to 3 F / mol.

The reaction temperature may be any temperature from 0 ° C. to the boiling point of the solvent used, more preferably from 10 ° C. to 3 ° C.
0 ° C.

The electrolytic cell used in the present invention may or may not use a diaphragm required in a normal electrolytic reaction.

After the electrolytic reaction is carried out by such a method, if the target product is insoluble, it may be obtained by filtering the target product. If the reaction product is a liquid, n-hexane or n-hexane is added to the reaction solution. After precipitating and removing the supporting electrolyte by adding toluene and the like, purifying by column chromatography or the like packed with silica gel as necessary, eluting with a solvent, distilling off the solvent under reduced pressure, and drying under reduced pressure To obtain the desired product.

R ¹ or R ² of the polysilane (1) obtained by the production method of the present invention is as shown in the above formula (2), and corresponds to R ¹ or R ² of the raw material organohydrosilane (1). Further, both ends of the polysilane (1) are hydrogen atoms.

Preferred specific examples of polysilane (1) include poly [dimethylsilane], poly [diethylsilane], poly [dipropylsilane], poly [dibutylsilane], poly [dipentylsilane], and poly [dihexyl]. Silane], poly [methylpropylsilane], poly [hexylmethylsilane], poly [methylphenylsilane], poly [diphenylsilane] and the like, and among them, poly [dimethylsilane] and poly [diethyl] are more preferable. Silane], poly [di-n-propylsilane], poly [di-n-butylsilane], poly [methylphenylsilane], poly [diphenylsilane], and particularly preferably poly [methylphenylsilane] and poly [diphenylsilane]. [Diphenylsilane] and poly [di-n-butylsilane].

The polymerization degree (n) of the polysilane (1) obtained by the production method of the present invention is a positive number of 2 to 20, and a preferred upper limit is 10, and more preferably 5.

According to the production method of the present invention, the number average molecular weight of the obtained polysilane (1) is preferably from 200 to 200, although it depends on the type of the side chain and the degree of polymerization of the polysilane (1).
2,000, more preferably 300 to 1,000.
It is.

The polysilane (1) obtained by the production method of the present invention is useful for a photoconductor, a photoresist, a luminescent material, a charge transporting material and the like, and the both ends of the polymer are Si—H groups. Therefore, it can be used for polymer terminal modification by a hydrosilylation reaction or the like.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

Example 1 A platinum electrode (2 cm × 2.5 cm ×
0.01 mm) as a supporting electrolyte in a 30-ml cylindrical single-chamber electrolytic cell (hereinafter referred to as an electrolytic cell) provided with two sheets of 0.1-mm-tetraammonium tetrafluoroborate.
66 g (2 mmol) were charged, and the inside was depressurized with a vacuum pump, and then dried argon gas was introduced to make the atmosphere inert.

10 ml of 1,2-dimethoxyethane, which had been previously dehydrated with sodium metal and distilled, was introduced into the sample injection port via a syringe as a solvent for the supporting electrolyte, and stirred with a magnetic stirrer to prepare an electrolytic solution. Next, 0.61 g (5 mmol) of methylphenylsilane was charged to a concentration of 0.5 mol / liter.

A galvanostat was connected to the electrolytic cell, and electrolysis was performed at room temperature with a constant current of 20 mA. The reaction was continued until a current of 2 F / mol based on methylphenylsilane was applied.

After completion of the electrolysis, the reaction solution was concentrated on a rotary evaporator, redissolved in 5 ml of toluene, put into a silica gel column, eluted with 100 ml of toluene, and then the solvent was removed under reduced pressure to remove the product. Was purified and isolated.

The obtained product was analyzed and measured using gel permeation chromatography (in terms of polystyrene), high performance liquid chromatography and a mass spectrometer. As a result, the product had a number average molecular weight of 454 and a dispersity (Mw). / Mn) was 1.05 and the distribution of polymerization degree (n) was 2 to 9 poly [methylphenylsilane]. The yield was 60%.

FIG. 1 shows the results of separation of the products by high performance liquid chromatography. As shown in this figure, the product was separated into six peaks. Of these peaks, the mass spectrum of the two peaks with the shorter retention time was measured by a mass spectrometer.
3 and FIG. 3, and the analysis results are as follows.

(FIG. 2) (first peak) m / z = 242 Molecular ion peak: H [MePhS
i] ₂ H (degree of polymerization = 2) m / z = 121 Fragment ion peak: HMeP
hSi ⁺ (FIG. 3) (second peak) m / z = 362 Molecular ion peak: H [MePhS
i] ₃ H (degree of polymerization = 3) m / z = 241 Fragment ion peak: H [Me
PhSi] ₂ ⁺ m / z = 121 Fragment ion peak: HMeP
hSi ⁺ (where Me represents a methyl group and Ph represents a phenyl group)

Example 2 In place of tetra-n-butylammonium tetrafluoroborate, 0.77 g of tetra-n-butylammonium hexafluorophosphate (2 m
mol) was used as a supporting electrolyte, and an electrode reaction was carried out in the same manner as in Example 1 to obtain a product.

The obtained product was analyzed and measured using gel permeation chromatography, high performance liquid chromatography and a mass spectrometer in the same manner as in Example 1. As a result, the product had a number average molecular weight of 465 and a dispersity of ( Mw / M
n) was 1.05 and the distribution of the degree of polymerization (n) was 2 to 9 poly [methylphenylsilane]. The yield was 63%.

Example 3 An electrode reaction was carried out in the same manner as in Example 1 except that diphenylsilane was used as a raw material instead of methylphenylsilane, and the amount of electricity was 5 F / mol.
The product was obtained.

The obtained product was analyzed and measured using gel permeation chromatography, high performance liquid chromatography and a mass spectrometer in the same manner as in Example 1. As a result, the product had a number average molecular weight of 356, (Mw
/ Mn) was 1.16, and the distribution of the degree of polymerization (n) was 2 to 10 poly [diphenylsilane]. The yield was 50%.

Example 4 Di-n-butylsilane was used as a raw material instead of methylphenylsilane, and the amount of electricity was 4F.
An electrode reaction was carried out in the same manner as in Example 1 except that the content was changed to / g / mol to obtain a product.

The obtained product was analyzed and measured using gel permeation chromatography, high performance liquid chromatography and a mass spectrometer in the same manner as in Example 1. As a result, the product had a number average molecular weight of 919, (Mw
/ Mn) was 1.10 and the distribution of the degree of polymerization (n) was 2 to 10 poly [di-n-butylsilane].
The yield was 60%.

[0048]

According to the manufacturing method of the present invention, a photoconductor,
Useful for various applications such as photoresists, luminescent materials, charge transport materials, etc., and using polysilane that does not crosslink even when used in various reactions such as hydrosilylation reaction, using inexpensive and non-corrosive raw materials, An economically advantageous production can be achieved in a clean environment without generating by-products such as halides and generating no harmful halogen gas.

[Brief description of the drawings]

FIG. 1 is a high performance liquid chromatography diagram of poly [methylphenylsilane] obtained in Example 1 of the present invention.

FIG. 2 is a mass spectrum diagram of poly [methylphenylsilane] [degree of polymerization (n) = 2] obtained in Example 1 of the present invention.

FIG. 3 is a mass spectrum diagram of poly [methylphenylsilane] [degree of polymerization (n) = 3] obtained in Example 1 of the present invention.

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein the organohydrosilane represented by the formula (1) is electrolyzed in an organic solvent containing a supporting electrolyte comprising a salt having no oxygen atom in the molecule. Method for producing polysilane. Embedded image Embedded image 2. A method for producing polysilane according to claim 1, wherein the Ishio, such an oxygen atom in the molecule is tetrafluoroboric acid tetra-alkylammonium of the formula (3). (R ³ ) ₄ NBF ₄ (3) (In the formula, R ³ is an alkyl group having 1 to 4 carbon atoms.) 3. The process for producing polysilane according to claim 1, wherein the salt having no oxygen atom in the molecule is hexafluorophosphate tetraalkylammonium represented by the formula (4). (R ⁴ ) ₄ NPF ₆ (4) (In the formula, R ⁴ is an alkyl group having 1 to ⁴ carbon atoms.)