JP2917612B2 - 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 high-purity polysilane having a terminal capped with a triorganosilyl group.

[0002]

BACKGROUND OF THE INVENTION Polysilanes are known to be useful as ceramic precursors, photoresists, nonlinear optical materials, optoelectronic materials, organic conductive materials, and the like.

[0003] The polysilanes used in these applications are:
High purity and uniform composition is required, but conventionally,
Polysilane is obtained mainly by the Wurtz coupling reaction, and the polysilane obtained by the Wurtz coupling reaction is not blocked at the end, leaving Si-H groups and the like, which cause contamination of oxygen and the like. Met.

[0004] That is, the production of polysilane by the Wurtz coupling reaction generally involves reacting a dihalosilane with an alkali metal such as sodium under slightly excessive conditions, followed by a purification step such as hydrolysis and reprecipitation.
It was said that the terminal of the obtained polysilane was a Si—H group, but at present, the terminal of the Si—H group was used without any treatment, without any particular treatment.

However, if the terminal of the Si—H group, which is susceptible to an oxidation reaction after polymerization, is used without any treatment, the quality of polysilane may be deteriorated.

On the other hand, a method has been proposed in which the end of polysilane is blocked with an alkyl chloride or the like (Japanese Patent Application Laid-Open No. Hei 2-263831). It is a condensation reaction with alkyls, which has poor reactivity and requires a two-stage production process including isolation of polysilane, which is troublesome.

In addition, the above-mentioned Wurtz coupling reaction has a problem that, due to the nature of the reaction, a considerable concentration of alkali metal ions is mixed in the mixture after the reaction, which causes decomposition of the polysilane during purification of the polysilane. . This decomposition reaction has been reported recently on the decomposition reaction of polysilane compounds by alkali metal ions (Polymer Pre.)
prints, Vol. 31 (2), 276 (199
As shown in 0)), since the reaction is accelerated particularly in a polar solvent, the remaining alkali metal ions can be efficiently removed before proceeding to a hydrolysis step after the reaction or a purification step using an alcohol. There is a need for a way to get rid of it.

[0008]

The present inventors have made intensive studies to solve the above problems, and as a result, after dihalosilane was polymerized in the presence of an alkali metal to synthesize polysilane, the reaction mixture was obtained. It has been found that the terminal of the polysilane can be blocked as a triorganosilyl group by adding a monohalosilane to the mixture in such an amount that the mixture becomes acidic. Monohalosilanes are more reactive than alkyl chlorides and can more efficiently block the terminal Si-H bonds remaining in the polysilane, in which case the polysilane is isolated without isolation and the resulting reaction mixture It has been found that monohalosilane can be reacted as a secondary reaction, so that it can be produced in one pot and is advantageous in terms of the process.

In addition, by using monohalosilane in an excessive amount, terminal blocking can be performed more thoroughly, and at the same time, the reaction system is acidic and the alkali metal ion concentration is made substantially zero or extremely low. Therefore, the decomposition of polysilane during purification is suppressed, and the polysilane represented by the following formula (1) can be converted to high purity, that is, Si—H, depending on the type of dihalosilane and monohalosilane used.
Having no bond and no Si-O bond, and having both ends completely blocked with a triorganosilyl group, having a weight average molecular weight of 5,0.
The present inventors have found that a polysilane having an amount of 00 to 2,000,000 can be obtained, and have accomplished the present invention.

[0010]

Embedded image (However, R ^{1 to} R ⁵ each represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group, and n denotes a weight average molecular weight of the polysilane of 5,000 to
The number is 2,000,000. Hereinafter, the present invention will be described in more detail. The polysilane according to the present invention is represented by the above formula (1), and the polysilane of the present invention has a weight average molecular weight of 5,000 to 2,000,
000 and does not contain a Si—H bond and a Si—O bond.

In this case, the molecular weight of the polysilane is 5,000.
If it is less than 0, the film-forming property is poor, and if it is more than 2,000,000, the solubility in organic solvents is not sufficient, and it is difficult to use polysilane for various uses. In addition, the weight average molecular weight more preferable from the usability of polysilane is 10,000 to 10
It is 0000.

As described above, the polysilane of the present invention does not contain a Si—H bond or a Si—O bond. According to the IR spectrum, a Si-H bond (wavelength 2100
cm ^-1 ) and Si-O bond (wavelength 1000-1100c)
m ^-1 ) is substantially absent.

In the above formula (1), the definitions of R ^{1 to} R ⁵ are as described above. More preferably, R ^{1 to} R ⁵ are the same or different alkyl groups having 1 to 6 carbon atoms. A cycloalkyl group having 5 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 14 carbon atoms.

As a method for obtaining the above-mentioned polysilane, the present invention provides a method for producing a polysilane by polymerizing a dihalosilane in the presence of an alkali metal, and then adding a monohalosilane to the reaction mixture in such an amount that the mixture becomes acidic. A method of performing a reaction of blocking the terminal of the polysilane as a triorganosilyl group is employed.

Here, as the dihalosilane, dichlorosilanes, dibromosilanes and the like which are usually used in the production of polysilane can be used. In particular, the above formula (1)
When the polysilane is obtained, a dihalosilane represented by the following formula (2) is used.

[0016]

Embedded image (However, X represents a halogen atom, and R ⁴ and R ⁵ have the same meanings as described above.) In the present invention, the above dihalosilanes may be used alone or in combination of two or more. You may.

As the alkali metal, sodium is generally used, but lithium and potassium can also be used effectively. In this case, the amount of alkali used is
Slight excess in relation to dihalosilane, specifically 1.05 to 1.2 equivalents, especially 1.05 to 1 mol of dihalosilane
It is preferred to use 1.1 equivalents.

This primary reaction is usually carried out using a solvent. As the solvent, aromatic solvents such as xylene, toluene, and benzene, aliphatic solvents such as dodecane, and a mixed solvent thereof are used. In this case, the reaction is preferably carried out by dispersing an alkali metal in a solvent and then dropwise adding dihalosilane to the reaction. The reaction temperature is usually from 98 ° C. to the reflux temperature of the solvent. The reaction time is usually 1 to 10 hours.

According to the present invention, the polysilane obtained in the first reaction is reacted with the monohalosilane without isolation of the polysilane obtained in the first reaction (secondary reaction), and the polysilane obtained in the first reaction is obtained. Block the end.

As the monohalosilane, a compound represented by the following formula (3) is particularly preferably used.

[0021]

Embedded image

More specifically, in principle, any monohalosilane, such as trimethylchlorosilane, trimethylbromosilane, trimethyliodosilane, dimethylphenylchlorosilane, dimethylbutylbromosilane, which is not decomposed under Wurtz coupling reaction conditions, can be used. Among them, phenylsilanes and bromosilanes having high reactivity among them are particularly preferable.

The amount of the monohalosilane used is such that the reaction mixture can be acidified, and is preferably 1.1 to 20 times the molar amount of the residual alkali metal in the reaction mixture.
More preferably, the alkali metal ion can be effectively removed, and from the viewpoint of economy, the molar ratio is 1.2 to 10 times, more preferably 1.5 to 5 times. If the addition amount of monohalosilane is small and the reaction system remains alkaline, decomposition of polysilane by remaining alkali ions,
The disadvantage of low molecular weight occurs.

The secondary reaction can be carried out, for example, at a temperature of 98 ° C. to the reflux temperature of the solvent. After the primary reaction, the secondary reaction can be carried out by dropping monosilane as it is. The reaction time is usually 1 to 4 hours.

After the completion of the secondary reaction, the reaction mixture is hydrolyzed and concentrated by a conventional method, and then purified with a polar solvent such as alcohol to obtain high-purity polysilane.

In this final polysilane, monohalosilane is added so as to make the reaction system acidic, and the terminal of the polysilane obtained in the primary reaction is blocked. However, since the reaction system is previously acidic, hydrochloric acid is used. There is no need to use water or a buffer, and the hydrolysis can be carried out directly with deionized water or the like. In addition, even when purified by reprecipitation using an alcohol such as methanol, a ketone such as acetone, or another polar solvent at the time of purification, polysilane is not decomposed, and Si—H
It is a high-purity material containing no bond and no Si—O bond.

[0027]

The production method of the present invention does not contain Si--H bonds and Si--O bonds, has a low ionic content, and has high quality. Therefore, the ceramic precursor, the photoresist, the non-linear optical material, the photoelectron High-purity polysilane that can be used effectively as a material, organic conductive material, etc. can be easily produced in a single pot.The end can be reliably blocked with a triorganosilyl group, and alkali at the time of work-up can be used. It can prevent decomposition of polysilane by metal ions.

[0028]

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 A 500 ml four-necked flask equipped with a motor stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with 150 ml of xylene and 12 g (520 m).
mol) of sodium and heated to 130 ° C. or higher to form a sodium dispersion, and 48.0 g of methylphenyldichlorosilane was added thereto while maintaining vigorous stirring and reflux.
(250 mmol) was slowly added dropwise. 135-1
After reacting at 40 ° C. for 4 hours (primary reaction), 5.0 g (30 mmol) of phenyldimethylchlorosilane was obtained.
Was added dropwise, and reacted for 2 hours under the same conditions (secondary reaction).

The reaction mixture is hydrolyzed and then concentrated,
The product was further purified by reprecipitation with methanol and then acetone, and dried under vacuum to obtain 10.5 g (yield 35%) of polysilane represented by the following formula (4).

This polysilane has a weight average molecular weight of 4
5,000. From the result of the IR spectrum,
It was confirmed that no bond and no Si—O bond were included.

[0033]

Embedded image

Comparative Example In Example 1, the reaction mixture after the primary reaction was purified in the same manner as in Example 1 without performing the secondary reaction with phenyldimethylchlorosilane, and as a result, the reaction mixture having a weight average molecular weight of 45,000 was obtained. Polysilane 10.3
g (yield 34%) was obtained.
The peak of the Si-H bond was clearly recognized from the R spectrum, and the Si-H bond was contained.

[Example 2] In Example 1, the primary reaction was carried out using dihexyldichlorosilane instead of methylphenyldichlorosilane, and the secondary reaction was carried out using trimethylbromosilane instead of phenyldimethylchlorosilane. 8.9 g (yield 18%) of polysilane represented by the following formula (5) was obtained in the same manner as in Example 1 except that the above was carried out.

This polysilane has a weight average molecular weight of 1,
Bimodal distributions of 100,000 and 7.000 were shown. Also, according to the result of IR spectrum, Si-
H bond and Si—O bond were not included.

[0037]

Embedded image

Claims (2)

(57) [Claims] After a dihalosilane is polymerized in the presence of an alkali metal to synthesize a polysilane, a monohalosilane is added to the reaction mixture in such an amount that the mixture becomes acidic, and the terminal Si-H bond in the polysilane is tritiated. A method for producing a polysilane, comprising performing a reaction of blocking as an organosilyl group. 2. The dihalosilane is represented by the following general formula (2): (However, X represents a halogen atom, and R ⁴ and R ⁵ each represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group).
Monohalosilane is represented by the following general formula (3): Wherein X represents a halogen atom, and R ^{1 to} R ³ each represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group.
The polysilane is represented by the following general formula (1): (However, R ^{1 to} R ⁵ are as described above, and n is a weight average molecular weight of the polysilane of 5,000 to 2,000,000.)
It is a number to be. ), Having a weight average molecular weight of 5,0
2. The method for producing a polysilane according to claim 1, wherein the amount is from 00 to 2,000,000.