JPH10298291A - Production of polysilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polysilane under mild conditions in a short time industrially advantageously by reacting an organohalogenosilane with an alkali metal in an inert org. solvent under stirring in the presence of beads. SOLUTION: A polysilane is obtd. by reacting an organohalogenosilane with an alkali metal in an inert org. solvent under stirring in the presence of beads. The amt. of the beads present is about 1-500 wt.% of that of the alkali metal. The beads have an average particle size of about 0.001-5 mm and are pref. spherical. Though any kind of beads may be used without being specifically limited if they are hardly crushable and stable in the atmosphere wherein they are used, beads made of glass, silica, alumina, zirconia, silicon nitride, iron, etc., are pref. The degree of stirring is enough if the surface of the alkali metal is activated; usually the number of revolution in stirring is about 100-700 rpm. The reaction temp. is in the range of from room temp. to 250 deg.C.

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 polysilanes, which can produce polysilanes in a short time under mild conditions with good yield.

[0002]

2. Description of the Related Art As a method for synthesizing a polysilane having a main chain skeleton comprising a silicon-silicon bond and having an organic group in a side chain, a wurtzcup which reacts a dihalogenosilane with metal sodium is known. Although the ring method is known as the most common method, there are problems that this reaction is difficult to control and the yield of high molecular weight polysilane is poor.

[0003] In order to solve this problem, the following methods for producing polysilanes have been proposed, but all have various drawbacks and have not sufficiently solved the above problems. (1) RSiH ₃ is converted to a Cp ₂ MR ₂ type complex (M = Ti, Z
r) to obtain a polysilane by dehydrocondensation (JF Harrod, J. Organom).
et. Chem. , 279, C11 (1985)). The degree of polymerization of the polysilane obtained by this method is about 20, which is insufficient as a method for obtaining a polysilane having a high degree of polymerization. (2) A method of polymerizing polysilane by anionic polymerization using a precursor obtained by crosslinking a disilane unit with biphenyl (Sakurai et al., Nikka 56 Spring Meeting 1IVB0)
3). This method has difficulty in industrial use because the availability of a biphenyl crosslinked disilane unit as a raw material is limited. (3) Synthesis of polysilane by electrochemical polymerization (Dun
ogues, J.M. Organomet. Chem. , 3
82, C17 (1990), Ishikawa et al., JP-A-3-104
No. 893). However, it is difficult to obtain a high polymerization degree polysilane having sufficient mechanical strength by this method.

Further, it has been reported that in a coupling reaction, polymerization is progressed at room temperature by irradiating ultrasonic waves to a reaction system, and a polymer having a narrow molecular weight distribution can be obtained in high yield (J. Am. Chem. Soc., 110 ,
3321 (1988)). However, irradiation with ultrasonic waves breaks the silicon-silicon bond of the polysilane, so that in a long-time reaction, the generated polysilane is decomposed, and there is a problem that the molecular weight is reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing polysilanes that can be industrially and advantageously produced under a short time and under mild conditions.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object, and as a result, reacted organohalogenosilanes with an alkali metal in an inert organic solvent. At this time, it was found that a polysilane having a high degree of polymerization can be easily produced in a short time or at room temperature by adding beads and polymerizing while stirring.

That is, the coupling reaction for reacting an organohalogenosilane with an alkali metal is a heterogeneous reaction, and the polymerization proceeds on the metal surface. However, the polymerization is hindered because the formed polymer covers the metal or the by-produced metal halide covers the metal surface. Therefore, it is possible to increase the stirring efficiency by adding various beads, and to create an active metal surface.
It has been found that polysilanes can be synthesized under reaction conditions at room temperature, and that polysilanes can be synthesized in a very short time when the reaction is carried out at a normal reaction temperature (100 ° C. or higher). This is what led to the invention.

Hereinafter, the present invention will be described in more detail.
The method for producing polysilanes of the present invention comprises reacting an organohalogenosilane with an alkali metal in an inert organic solvent.

In this case, as the organohalogenosilane, a diorganodihalosilane represented by the following general formula (1) RR′SiX ₂ (1) is preferably used.

Here, R and R 'each independently represent a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group.
The unsubstituted monovalent hydrocarbon group is not particularly limited, but preferably has 1 to 12 carbon atoms, particularly preferably 1 to 10 carbon atoms.
Specifically, alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, octyl, and decyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl; phenyl, tolyl, and naphthyl; Aryl groups, benzyl, aralkyl groups such as phenylethyl and the like, and the substituted monovalent hydrocarbon group includes a part or all of the unsubstituted monovalent hydrocarbon group as a fluorine atom, an amino group, an alkylamino group. , Carboxyl group, methoxy, ethoxy and the like. X represents chlorine, bromine or iodine.

As the organohalogenosilanes, the above-mentioned diorganodihalosilanes are preferable, but if necessary, an organohalogenosilane having three or four silicon-halogen bonds in the molecule may be used in combination. . In this case, examples of the organic group include those similar to the above R or R ′.

The alkali metal is preferably sodium metal, which is preferably present as fine particles in the reaction system.

The amounts of halogen and alkali metal used in the organohalogenosilanes are from 1: 1.00 to molar ratio.
The ratio is preferably set to 1: 1.50, particularly 1: 1.05 to 1: 1.25.

The inert solvent may be any solvent which does not hinder the reaction between the organohalogenosilane and the alkali metal.
Known ones can be used, but usually toluene,
Xylene, cumene, decane, dodecane, tetralin, anisole, tetrahydrofuran, diglyme and the like are used.

In the present invention, when the above-mentioned organohalogenosilane is reacted with an alkali metal, beads are added and the reaction is carried out with stirring.

Here, the beads are preferably spherical, and the material thereof is not particularly limited as long as it is hard to be crushed and is stable in the use atmosphere. Among them, glass, silica, alumina, zirconia, nitride Silicon,
Iron and the like are preferred materials. If the surface has an active hydroxyl group or the like, the polymer is decomposed, so that a silylation treatment is required. The average particle diameter of the beads can be 0.001 to 5 mm, and particularly preferably 0.1 to 2 mm.

The added amount of the beads is 1 to 500 parts by weight, more preferably 10 to 500 parts by weight, based on 100 parts by weight of the alkali metal.
The amount is 200 parts by weight, more preferably 20 to 100 parts by weight. If the amount is too small, there is no effect, and if the amount is too large, stirring may not be easy.

When the polymerization is carried out while stirring the beads in the reaction system, the degree of stirring may be such that the alkali metal surface is activated, and the rotation is usually carried out at 100 to 700 rpm.

In the present invention, the reaction temperature is from room temperature to 250
° C, according to the invention, which is the normal reaction temperature of 10
The reaction proceeds sufficiently even at a temperature below 0 ° C.

The reaction proceeds exothermically.
Further, it is preferable to perform stirring for about 1 to 5 hours. After completion of the reaction, excess alkali metal is preferably deactivated using methanol or the like, and then washed with water several times.The obtained organic layer is dried using magnesium sulfate or the like, and then concentrated.
The product can be isolated and polysilanes can be obtained by fractional precipitation of the resulting polymer. In addition, according to the present invention, it differs depending on the reaction conditions and is not particularly limited.
About 100 to 1,000,000 polysilanes can be produced.

[0021]

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.

Example 1 In a four-necked flask, 2.53 g (110 mmol) of metallic sodium, 30 g of xylene, and alumina beads (average particle size 0.01 mm) were placed in a four-necked flask under a nitrogen stream.
2.5 g, and heated and stirred at 140 ° C. to form a very fine sodium dispersion, and then 9.6 g (50 mmol) of phenylmethyldichlorosilane was added to 1
Upon dropping in 0 minutes, the reaction exothermically proceeded, and the solution turned purple. After completion of the dropwise addition, the mixture was refluxed and stirred for 2 hours. After the completion of the reaction, sodium was inactivated by using 10 ml of methanol, and washing was performed several times with water. The obtained organic layer was dried using magnesium sulfate, and then concentrated. The concentrate was dissolved in 25 g of toluene, 60 g of ethanol was slowly added to precipitate a white powder, and methylphenylpolysilane (Mn: 39,
300, Mw: 90,400) as a white solid in a yield of 4
Obtained at 5%.

Example 2 The procedure of Example 1 was repeated, except that 5.3 g of silylated silica beads (average particle size: 0.2 mm) were used instead of the alumina beads of Example 1. As a result, methylphenyl polysilane (Mn:
34,000, Mw: 84,250) as a white solid in a yield of 40%.

Example 3 2.53 g (110 mmol) of metallic sodium, 30 g of xylene, and silica beads (average particle size 0.2 mm) in a four-necked flask under a nitrogen stream.
3 g, and once heated and stirred at 100 ° C. or higher to form a very fine sodium dispersion, then rapidly cooled to room temperature. Next, when 9.6 g (50 mmol) of phenylmethyldichlorosilane was added dropwise in 10 minutes,
The reaction proceeded exothermically and the solution turned purple. After completion of the dropwise addition, the mixture was refluxed and stirred for 4 hours. After completion of the reaction, 2.2 g (20 mmol) of trimethylchlorosilane was added,
The sodium was quenched with 10 ml of methanol. After adding 50 ml of toluene, washing with water was performed several times. The obtained organic layer was dried using magnesium sulfate, and then concentrated. The concentrate is dissolved in 25 g of toluene, and ethanol 60
g was slowly added to precipitate a white powder,
By filtration, methylphenylpolysilane (M
n: 23,100, Mw: 78,900) as a white solid in a yield of 42%.

[Comparative Example 1] The same operation as in Example 1 was carried out except that beads were not used. Under a nitrogen stream, 2.53 g (110 mmol) of metallic sodium was placed in a four-necked flask,
After containing 30 g of xylene and heating / stirring at 140 ° C. to form a sodium dispersion, 9.6 g (50 mmol) of phenylmethyldichlorosilane was added dropwise in 10 minutes. The color was purple. After completion of the dropwise addition, the mixture was refluxed and stirred for 4 hours. After the completion of the reaction, sodium was inactivated by using 10 ml of methanol, and washing was performed several times with water. The obtained organic layer was dried using magnesium sulfate, and then concentrated. The concentrate was dissolved in 25 g of toluene, 60 g of ethanol was slowly added to precipitate a white powder, and methylphenylpolysilane (Mn: 9,350,
Mw: 30,500) as a white solid in a yield of 31%.

Comparative Example 2 The same operation as in Example 3 was performed except that no beads were used. In this case, room temperature stirring 24
Even after the lapse of time, the raw materials did not react, and no polysilanes were obtained.

Table 1 shows the results of the above Examples and Comparative Examples.

[0028]

[Table 1]

[0029]

According to the present invention, beads are added when an organohalogenosilane and an alkali metal are stirred and polymerized in an inert organic solvent, and the alkali metal is finely divided to efficiently convert the polysilane. It can be obtained under mild conditions.

Claims (3)

[Claims] 1. A method for producing a polysilane, comprising adding beads and polymerizing with stirring while reacting an organohalogenosilane with an alkali metal in an inert organic solvent. 2. The method according to claim 1, wherein the added amount of the beads is 1 to 500% by weight based on the alkali metal. 3. An average particle diameter of the beads is 0.001 to 5 mm.
The method according to claim 1, wherein