JP2001040210A - Production of silicon-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a silicon-based polymer with a low oxygen content at a low cost by adding a specific electron transfer reactant. SOLUTION: A condensation polymerization reaction of a halogenated silicon compound is carried out by using an alkali metal or an alkaline earth metal as a reducing agent to provide a silicon-based polymer. A compound capable of forming a stable radical anionic species with the alkali metal or alkaline earth metal or its alkali metal salt or alkaline earth metal salt as an electron transfer reactant is added into the system and reacted with the residual silicon- halogen bonds. Thereby, a silicon-based polymer with a low oxygen content is produced.

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 an organosilicon-based polymer having a low oxygen content, which is useful as a conductive material, a photoconductive material, a nonlinear optical material, and the like. The present invention relates to a method for producing an organosilicon-based polymer having high reactivity and low oxygen content.

[0002]

2. Description of the Related Art Conventionally, organic silicon-based polymer materials such as polysilane have been attracting attention for their unique chemical and optical properties, and have been known to be conductive materials and photoconductive materials. Although it is expected as a substance, a nonlinear optical substance, etc., there is a problem in physical strength shortage and compatibility with other substances, and it has not yet been possible to obtain sufficient development. In recent years, examples of polysilanes that have increased resinification by introducing a large number of branched structures, increased physical strength, and improved compatibility with other substances have been reported, and in particular, trichlorosilane and tetrachlorosilane have been reported. In the introduction of the branched structure used, the reaction is less likely to be completed than in the ordinary Wurtz reaction of dichlorosilanes, and the content of oxygen contained in the silicon-based polymer generated by the post-treatment increases, and the organosilicon-based polymer becomes There is a problem that the intrinsic chemical and optical properties are reduced.

In the synthesis of silicon clusters using tetrachlorosilanes as a starting material, Watanabe et al. Treat a reaction terminal with butyllithium after a condensation reaction with magnesium (Japanese Patent Application Laid-Open No. H11-14841) or a vacuum line. After the condensation reaction with magnesium in an atmosphere from which oxygen and moisture have been sufficiently removed using
It has been reported that silicon clusters with extremely low oxygen content can be obtained by performing sufficient reaction with alkyl halides and purifying the generated polymer components by column purification (17th Annual Meeting of the Japanese Society for Inorganic Polymer Research). ing. However, the use of expensive butyllithium, which is chemically very active and expensive, and the use of a vacuum line and column purification are the bottlenecks in industrial mass production considerations. Reduction of the rate is required.

[0004]

Means for Solving the Problems and Embodiments of the Invention The present inventor has conducted intensive studies in order to meet the above-mentioned demand, and as a result, has condensed a silicon halide compound with an alkali metal or an alkaline earth metal as a reducing agent. After the reaction, an electron transfer reactant capable of forming a stable radical anion species, such as sodium naphthalenide, is added at the end of the reaction to efficiently remove highly active Si-Cl remaining in the reaction system. The present invention has been found to be able to efficiently produce an organosilicon-based polymer having a low oxygen content by preventing the formation of Si—O due to hydrolysis or the like during post-treatment. Reached.

That is, according to the present invention, a polycondensation reaction of a silicon halide compound is carried out using an alkali metal or an alkaline earth metal as a reducing agent to obtain a silicon-based polymer. A compound having a low oxygen content, wherein a compound capable of forming an anionic species or an alkali metal or alkaline earth metal salt thereof is added to the system as an electron transfer reactant to react with the remaining silicon-halogen bond. Provided is a method for producing a polymer.

[0006] The method according to the present invention comprises simply adding an electron transfer reactant to a reaction mixture in which a polymerization reaction of polysilane has been performed without using any special equipment, and continuing the reaction.
This is to reduce the oxygen content of the generated polysilanes. The straight-chain type polysilanes can be produced with low oxygen content by carefully purifying them under ordinary reaction conditions, but the method according to the present invention is required for producing polysilanes having a branched structure. Extremely effective. In particular, during the production of polysilane in the condensation polymerization reaction of chlorosilanes including tetrachlorosilane,
When metal sodium or metal lithium is used as a reducing agent, naphthalene or its alkali or alkaline earth metal salt is added to form naphthalenide in the system, or when metal magnesium is used as a reducing agent, sodium naphthalenide is used. By adding and treating, the oxygen content in the resulting polysilane can be reduced to about 1% by weight or less after the usual post-treatment operation. These treatments are effective not only for naphthalenide but also for any electron transfer reactant capable of forming a stable radical anion species.

Hereinafter, the present invention will be described in more detail.
In the method for producing a silicon-based polymer of the present invention, a silicon-based polymer (polysilane) is produced by first conducting a polycondensation reaction using a silicon halide compound with an alkali metal or an alkaline earth metal as a reducing agent.

In this case, examples of the raw material of the silicon halide compound include halosilanes represented by the following formulas, which may be diorganodihalosilanes or triorganohalosilanes. It is particularly effective when trihalosilane is contained, and a branched (network-like) polysilane having a low oxygen content can be obtained.

[0009]

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Here, R is a monovalent organic group, and specific examples include an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms. Examples of the monovalent hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, an alkyl group such as a decyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a phenyl group, a tolyl group, An aryl group such as a xylyl group or a naphthyl group, an aralkyl group such as a benzyl group, a phenylethyl group, or a phenylpropyl group, and the like.These hydrogen atoms are partially substituted with a functional group such as an alkoxy group or an amino group. May be. Y is a divalent organic group;
Particularly, an alkylene group such as ethylene and an arylene group such as phenylene can be exemplified. That is, the halosilane may include a structure sandwiching an organic group such as silethylene or silphenylene.

X is a halogen atom such as chlorine or bromine. n is 0, 1, 2 or 3, especially 0, 1 or 2, and m is 0, 1 or 2, especially 0 or 1.

On the other hand, an alkali metal used as a reducing agent,
As the alkaline earth metal, metal sodium, metal lithium, metal magnesium and the like can be used, and 1.0 to 4.0 equivalents, particularly 1.5 equivalents to 1 equivalent of the Si-halogen bond in the above silicon halide compound. ~ 2.0 equivalents can be used.

The polycondensation reaction can be carried out by a conventional method, and can be carried out under an inert atmosphere such as nitrogen using an aprotic solvent such as dimethoxyethane, tetrahydrofuran, toluene, xylene and the like. The reaction temperature is preferably from 50 to 140 ° C, and the reaction time is usually from 3 to
24 hours.

After the reaction as described above, an alkyl halide or aralkyl such as butyl bromide, 2-phenylethyl bromide, or benzyl bromide is added to the reaction solution, and the resulting organic silicon-based polymer remains. It is preferable that the polymer is modified with an alkyl group of the alkyl halide or aralkyl by reacting with a Si-halogen bond, thereby reducing the halogen content in the polymer to some extent and dissolving the polymer in an organic solvent. Can be improved (JP-A-2-263831). The amount of the alkyl halide or aralkyl added is usually 10 to 1 based on the amount of the halosilane used.
And the temperature of the reaction is 50-14%.
0 ° C. is preferable, and the reaction time can be 2 to 5 hours.

Next, in the present invention, a compound capable of forming a stable radical anion species with the alkali metal or alkaline earth metal or an alkali metal or alkaline earth metal salt thereof is added to the reaction solution as an electron transfer reactant. And post-reaction.

Here, compounds capable of forming a stable radical anion species forming an electron transfer reactant include aromatic hydrocarbon compounds such as naphthalene, anthracene, biphenyl and tetraphenylethylene, phenyldimethylchlorosilane, diphenylmethyl and the like. Chlorosilane, phenyl group-containing silicon halide compounds such as triphenylchlorosilane can be mentioned, and alkali metal or alkaline earth metal salts thereof, for example, sodium naphthalenide, phenyl group-containing silyllithium and the like may be mentioned. The alkali metal forming the electron transfer reagent can be metallic sodium or metallic lithium. In particular, when sodium metal is used as the reducing agent in the condensation polymerization reaction, naphthalene, anthracene, and the like are preferable,
When metal lithium is used as the reducing agent, biphenyl,
Phenylchlorosilane and the like are preferable, and when metallic magnesium is used as a reducing agent, sodium naphthalenide,
Phenyl group-containing silyl lithium and the like are preferred. Naphthalene, anthracene and the like generate stable alkali metal salts of radical anions such as sodium naphthalenide in the reaction system by reaction with sodium metal and lithium metal.

The amount of the electron transfer reactant is 0.000001 to 0.5 mol, more preferably 0.01 to 0.2 mol, per mol of the silicon-halogen bond contained in the silicon halide compound raw material. Moles, more preferably 0.0
3 to 0.1 mol. If the amount is too small, it takes a long time to reduce oxygen, and it is not practical. If the amount is too large, it is not economical and the treatment of the residue after the deactivation reaction becomes troublesome.

By the addition of the electron transfer reactant, it reacts with the remaining Si-halogen bond in the reaction solution to efficiently consume it, and the generation of Si-O bond based on the hydrolysis of the Si-halogen bond and the like. By being prevented, an organosilicon polymer having a low oxygen content can be obtained. In this case, the reaction is preferably performed at 50 to 140 ° C., and the reaction time is generally 1 to 5 hours. It is.

After the reaction, an organosilicon polymer can be obtained by a usual post-treatment such as filtration, washing with water, concentration, and reprecipitation according to a conventional method.

The polymer obtained according to the present invention has a low oxygen content, that is, a low siloxane content, and consists essentially of Si--Si bonds. In this case, when a halogenated silane as a raw material contains, for example, a compound represented by the above formula R _n SiX _4-n (n = 0 or 1), a polysilane having a branched structure (network structure) containing the following units is obtained.

[0021]

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The weight average molecular weight of the obtained polymer is usually 500 to 20,000, especially 2,000 to 1
It is 0000. The oxygen content is usually 0 to 3% by weight, particularly 0 to 1% by weight.

[0023]

According to the present invention, a silicon-based polymer having a low oxygen content can be efficiently and inexpensively produced.

[0024]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The oxygen content was determined by an inert gas melting oxygen analysis method (Inert-Gas Fus) shown below.
ion with Platinum-Carbon
Converter; JP-A-8-304381)
According to That is, a sample is put together with a solution (flux) component into a carbon crucible in a high-temperature state in advance, and the generated oxygen-containing gas is converted into CO by high-temperature carbon or by contact with high-temperature platinum carbon, and then quantified by gas analysis. did.

Example 1 21.9 g (0.9 mol) of magnesium and 50 ml of DME (dimethoxyethane) were placed in a 500 ml flask, the surface was activated with iodine, and 42.5 g of tetrachlorosilane (0. 25m
ol) in 300 ml of DME was slowly added. After the exothermic reaction had subsided to some extent, then 34.3 g (0.25 mol) of butyl bromide in 230 ml of DME
1 solution was slowly added, and the surface of the silicon cluster previously formed was modified with butyl groups. Then, D of sodium naphthalenide (0.025 mol) separately prepared
The remaining Si-Cl was consumed by adding the ME solution and further reacting for 1 hour. The oxygen content of the silicon cluster of the product obtained by the usual post-treatments of filtration, washing, concentration and reprecipitation was 0.5% by weight. In addition,
Mw of the obtained silicon cluster was 6,810, and Mn was Mn.
Was 3,380.

Example 2 After performing magnesium condensation of tetrachlorosilane in the same manner as in Example 1, the surface of the cluster was modified using 1-bromo-2-phenylethane in place of butyl bromide, and then separately. By adding the prepared DME solution of sodium naphthalenide and performing post-treatment, a silicon cluster having an oxygen content of 1.1% by weight was obtained. The Mw of the obtained silicon cluster was 8,
970 and Mn were 3,950.

Example 3 The same reaction as in Example 1 was performed using triphenylsilyllithium as a treating agent to obtain a silicon cluster having an oxygen content of 1.0% by weight. The Mw of the obtained silicon cluster was 9,230,
Mn was 3,730.

Example 4 The same reaction as in Example 1 was performed using phenyldimethylsilyllithium as a treating agent to obtain a silicon cluster having an oxygen content of 0.8% by weight. The Mw of the obtained silicon cluster was 17,
420 and Mn were 6,550.

Example 5 Using sodium metal as a reducing agent, the same reaction as in Example 1 was carried out, and after a condensation reaction and butyl group modification, naphthalene was added for further reaction. After ordinary post-treatment, the oxygen content of the obtained silicon cluster was measured and was found to be 0.7% by weight. The Mw of the obtained silicon cluster was 5,
000 and Mn were 2,840.

[Comparative Example 1] A silicon cluster which had been subjected to coupling of tetrachlorosilane with magnesium and then surface modification with butyl bromide according to Example 1 was filtered, washed with water, concentrated without performing sodium naphthalenide treatment. The usual post-treatment of reprecipitation was performed. The oxygen content of the obtained silicon cluster was 9% by weight according to an inert gas molten oxygen analysis method. In addition, Mw of the obtained silicon cluster was 7,290, and Mn was 2,2.
It was 10.

Claims (7)

[Claims] 1. A polycondensation reaction of a silicon halide compound using an alkali metal or an alkaline earth metal as a reducing agent to obtain a silicon-based polymer, and then forming a stable radical anion species with the alkali metal or the alkaline earth metal. Producing a silicon-based polymer having a low oxygen content, characterized by adding a compound which can be reacted or an alkali metal or alkaline earth metal salt thereof to the system as an electron transfer reactant and reacting with a remaining silicon-halogen bond. Method. 2. The method according to claim 1, wherein the amount of the electron transfer reactant is 0.000001 to 0.5 mol per 1 mol of silicon-halogen bond contained in the silicon halide compound raw material. . 3. The method according to claim 1, wherein the alkali metal forming the electron transfer reactant is sodium metal or lithium metal. 4. The method according to claim 1, wherein the compound capable of forming a stable radical anion species forming the electron transfer reactant is an aromatic hydrocarbon compound. Method. 5. The compound according to claim 1, wherein the compound capable of forming a stable radical anion species forming the electron transfer reactant is a phenyl group-containing silicon halide compound. Manufacturing method. 6. The method according to claim 1, wherein the reaction is carried out in an aprotic solvent. 7. The method according to claim 1, wherein the raw material of the silicon halide compound contains trihalosilane and / or tetrahalosilane.