JP2001048987A - Production of network polysilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject polysilane in excellent safety by using an apparatus of general purpose by treating a trihalosilane with a specific reducing agent in an aprotic solvent in the presence of a specific polymerization catalyst. SOLUTION: (A) A trihalosilane of formula I (R is H, an alkyl, an aryl or the like; X is a halogen) (preferably phenyltrichlorosilane) is treated with (D) Mg or a Mg alloy in (B) an aprotic solvent (preferably tetrahydrofuran) in the presence of a Li salt and a metal halide to form a network polysilane of formula II (n is 2-1,000). Preferably the component B and the component C are previously dehydrated with a monohalosilane. For example, phenyltrichlorosilane as a raw material is reacted with the Mg or the Mg alloy by using granular magnesium, lithium chloride, zinc chloride and tetrahydrofuran to give a phenyl network polysilane having l,490 weight-average molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a network polysilane.

[0002]

2. Description of the Related Art Network polysilanes have attracted attention as functional materials for ceramic precursors, heat-resistant material precursors, photoresists, organic photoreceptors, optical waveguides, optical memories, and the like.

Conventionally, as a method for producing a network polysilane, similar to a linear polysilane, halosilanes in a toluene solvent are vigorously stirred at a temperature of 100 ° C. or higher by using an alkali metal such as sodium metal to reduce Is known to be coupled to ｛J.Am.Chem.So
c., 103 (1981) 7352｝. However, in this method, it is necessary to heat the alkali metal ignited in the air and to stir and disperse the alkali metal vigorously, so that there is a great problem in safety when producing on an industrial scale.

In order to overcome these disadvantages, a method has been proposed in which halosilanes are electrode-reduced at a temperature lower than room temperature to produce network polysilane (JP-A-7-309953).
No.).

[0005] Although this method has a great improvement in safety, for example, it can be carried out at room temperature, it requires special reaction equipment such as a power supply and an electrolytic cell. Investment is expected to increase.

A main object of the present invention is to provide a new method which is excellent in safety and can produce a desired network polysilane at low cost using a general-purpose production apparatus.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the state of the prior art as described above, and as a result, have found that, in the presence of a Li salt and a metal halide as a polymerization catalyst,
In the case of reducing trihalosilane by using Mg or a Mg-based alloy as a reducing agent, the reaction can be completed without using a highly dangerous reducing agent such as an alkali metal or the like, and the reaction can be completed only by stirring. Has been found to be substantially eliminated or greatly reduced. Also,
When water contained in the aprotic solvent and the polymerization catalyst is removed by mixing monohalosilane in the reaction solution (a mixture of the aprotic solvent and the polymerization catalyst), the siloxane bond (Si-O bond) It has been found that a high-purity network polysilane having a low (ie, a low oxygen content) is obtained.

That is, the present invention provides the following method for producing a network polysilane: Item 1. A method for producing a network polysilane, comprising:
General formula (1)

[0009]

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(Wherein, R represents a hydrogen atom, an alkyl group, an aryl group or a silyl group. X represents a halogen atom, and the three Xs may be the same or different. ) Is reacted with Mg or a Mg alloy in an aprotic solvent in the coexistence of a Li salt and a metal halide to obtain a compound represented by the general formula (2).

[0011]

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(Wherein R is the same as above corresponding to the starting material; n is 2 to 1000). Item 2. Item 2. The method according to item 1, wherein the aprotic solvent, the Li salt and the metal halide to be used have been previously dehydrated with monohalosilane. Item 3. Item 3. The method according to Item 1 or 2, wherein phenyltrichlorosilane is used as the trihalosilane. Item 4. Item 4. The method according to any one of Items 1 to 3, wherein tetrahydrofuran is used as the aprotic solvent.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in the trihalosilane of the general formula (1) used as a starting material, R
Represents a hydrogen atom, an alkyl group, an aryl group or a silyl group. Examples of the alkyl group include those having about 1 to 10 carbon atoms, and among them, those having 1 to 6 carbon atoms are more preferable. Examples of the aryl group include a phenyl group, a phenyl group having at least one alkyl group having 1 to 10 carbon atoms as a substituent, a biphenyl group, and a naphthyl group. Examples of the silyl group include those having about 1 to 10 silicon atoms, and among them, those having 1 to 6 silicon atoms are more preferable. When R is the above-mentioned alkyl group, aryl group and silyl group, at least one of the hydrogen atoms thereof may be substituted with another alkyl group, aryl group, silyl group or other functional group. Examples of such a functional group include those similar to the above.

In the general formula (1), X represents a halogen atom (Cl, Br, I, F). As the halogen atom, Cl is more preferable. Further, each of the three halogen atoms may be the same or different.

In the present invention, one of the trihalosilanes represented by the general formula (1) may be used alone, or two or more may be used in combination.

In the reaction, trihalosilane is used by dissolving it in a solvent. As the solvent, aprotic solvents can be widely used, and more specifically, tetrahydrofuran,
1,2-dimethoxyethane, propylene carbonate,
Acetonitrile, dimethylformamide, dimethylsulfoxide, bis (2-methoxyethyl) ether, 1,
Polar solvents such as 4-dioxane and methylene chloride; toluene, xylene, benzene, n-pentane, n-hexane, n-
Non-polar solvents such as octane, n-decane and cyclohexane are exemplified. These solvents can be used alone or as a mixture of two or more. The solvent is preferably a single polar solvent, a mixture of two or more polar solvents, or a mixture of a polar solvent and a non-polar solvent. When a mixture of a polar solvent and a non-polar solvent is used, the former: the latter = 1:
It is preferable to be about 0.01 to 20 (weight ratio).
As the polar solvent used alone or as a mixture with another solvent, tetrahydrofuran and 1,2-dimethoxyethane are more preferred.

When the concentration of the trihalosilane in the solvent is too low, the polymerization reaction does not proceed easily, and the degree of polymerization does not increase. On the other hand, when the concentration is too high, the polymerized polysilane is precipitated, so Can no longer respond. Therefore, the concentration of the trihalosilane in the solvent is usually about 0.1 to 10 mol / l, preferably 0.5 to 10 mol / l.
It is about 2.0 mol / l.

The Li salt used in the present invention is LiC
1, LiNO ₃ , Li ₂ CO ₃ , LiClO _{4 and the} like. These Li salts may be used alone or in combination of two or more. Among these Li salts,
LiCl is most preferred.

When the concentration of the Li salt is too low, the start of the reaction becomes unstable and the reaction may be stopped in some cases. On the other hand, when the concentration is too high, the water contained in the Li salt is The amount increases, and the proportion of siloxane bonds (Si-O-Si) in the product increases. Therefore, the concentration of the Li salt in the solvent is usually about 0.01 to 3 mol / l, preferably about 0.05 to 1.0 mol / l.

As the metal halide used in the present invention
Is FeCl_Two, FeCl_Three, FeBr_Two, FeBr_Three, C
uCl_Two, NiCl_Two, AlCl_Three, AlBr_Three, ZnCl
_Two, SnCl_Two, SnCl_Four, CoCl_Two, VCl_Two, Ti
Cl_Four, PdCl_Two, SmCl _Two, SmI_TwoIs exemplified
You. Among these metal halides, FeCl_Three,
ZnCl_Two, NiCl_TwoAnd AlCl_ThreeIs preferable, and F
eCl_ThreeAnd ZnCl _TwoIs more preferred. Metal in solvent
If the halide concentration is too low,
If the reaction rate is too high,
Is faster and linear polysilane, a by-product,
Come. Therefore, the concentration of the metal halide in the solvent is
Usually about 0.005 to 1.0 mol / l, preferably
About 0.02 to 0.5 mol / l, which is more preferable.
Or about 0.05 to 0.2 mol / l.

Mg used as a reducing agent in the present invention
Or the shape of the Mg-based alloy is not particularly limited as long as the reaction can be performed, but powder, granules, ribbons, cut pieces, lumps, rods, flat plates, etc. are exemplified. A powder, a granular material, a ribbon-shaped material, a cut piece-shaped material, or the like having a large particle size is preferable. The amount of Mg or Mg-based alloy used is 1.5, which is the theoretical amount of Mg with respect to trihalosilane.
More than twice the molar amount is sufficient, but if it is too much, a large amount of Mg
Remain unreacted, so that the amount of Mg salt to be discarded increases. Therefore, the amount of Mg usually contained is about 1.5 to 10 times the mol of trihalosilane, and preferably 3.
It is about 0 to 7.0 times mol. When an Mg-based alloy is used, the type of metal other than Mg in the alloy is not particularly limited, but Al and Zn are preferable. M in alloy
The content of g is preferably 80% or more.

In the present invention, the aprotic solvent used as the solvent, and the Li salt and metal halide used as the polymerization catalyst are preferably dehydrated by adding and mixing a certain amount of monohalosilane in advance. Monohalosilane acts as a dehydrating agent by reacting with water contained in a solvent or the like as shown in the following formula. Therefore, a high-purity network polysilane having a small number of siloxane bonds in the molecule (that is, a low oxygen content) can be obtained.

[0023]

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In the monohalosilane of the general formula (3) used as a dehydrating agent (drying agent), R and X are the same as those of the trihalosilane of the general formula (1) which is a monomer. As the monohalosilane, trimethylchlorosilane is preferable.

Since the amount of the monohalosilane used depends on the amount of water in the solvent and the polymerization catalyst, the amount of water in the reaction solution containing the solvent and the polymerization catalyst (the total amount of water in the solvent and the polymerization catalyst) is determined in advance by Karl Fischer. Measure and determine by method. The amount of the monohalosilane used is about 1.5 to 3.0 times mol, preferably about 1.8 to 2.5 times mol, based on the total water content.

In practicing the present invention, for example,
A sealable reaction vessel is charged with Mg (or Mg-based alloy), a polymerization catalyst and a solvent, and preferably mechanically or magnetically stirred for about 30 minutes to dissolve the polymerization catalyst. When monohalosilane as a dehydrating agent (drying agent) is used, it is added at this stage, and the mixture is further stirred for about 30 minutes. Next, by slowly dropping trihalosilane,
Allow the reaction to take place. There are no particular restrictions on the shape and structure of the reaction vessel as long as it can be sealed.

The interior of the reaction vessel may be a dry atmosphere, but preferably a dry nitrogen or inert gas atmosphere, and more preferably a deoxygenated and dry nitrogen atmosphere or an inert gas atmosphere. .

In the case of stirring, as in the case of a general reaction, the higher the stirring speed, the more uniform the reaction can be performed. However, the rotation speed of the stirring is preferably about 50 to 700 rpm. More preferably, it is 100 to 400 rpm.

The reaction time depends on the type of trihalosilane, Mg
(And / or Mg alloy) and the amount of polymerization catalyst used, etc., but it is about 30 minutes or more, usually about 0.5 to 5 hours. By adjusting the reaction time, the molecular weight of the network polysilane can be controlled.

The reaction temperature is usually in the temperature range from 0 ° C. to the boiling point of the solvent used, preferably from 20 to 100.
It is in the range of about ° C.

The obtained network polysilane is 3 to
Purification can be performed by stirring and washing with about 10 times the amount of alcohol such as methanol.

The average degree of polymerization of the network polysilane obtained by the present invention is usually 2 to 1000, preferably 5 to 100.

[0033]

According to the present invention, the following remarkable effects are achieved. (A) It is not necessary to use a highly dangerous reducing agent such as an alkali metal, and the network polysilane can be safely produced. (B) It is not necessary to use a special reactor, for example, the reaction can be completed only by stirring the reaction solution, and network polysilane can be produced at low cost. (C) By mixing monohalosilane as a dehydrating agent (drying agent) in a solvent, a high-purity network polysilane having a small number of siloxane bonds (ie, a low oxygen content) can be obtained.

[0034]

EXAMPLES Examples are shown below to further clarify the features of the present invention.

Example 1 22.8 g of granular magnesium, 12.5 g of lithium chloride, and 8.0 g of zinc chloride were charged into a reactor having an inner volume of 1 L equipped with a three-way cock, and dried at room temperature (25 ° C.) with argon gas. Was introduced into the reactor. Tetrahydrofuran 400
of the starting material phenyltrichlorosilane (87.8 g (0.416 mol).
l) was slowly added dropwise, and the rate of addition was adjusted while cooling so that the temperature was maintained at 20 to 30 ° C. After the addition was completed, the mixture was stirred at room temperature for about 1 hour.

After the completion of the reaction, 380 ml of isopropyl ether was added to the reaction solution, and the mixture was stirred. Further, 20 ml of water was added to stop the reaction. This reaction solution was subjected to suction filtration to remove metal salts.

The ether layer was washed and extracted in the order of 200 ml of pure water, 50 ml of 1N hydrochloric acid and 200 ml of pure water (twice). After drying the ether layer with anhydrous magnesium sulfate,
The ether was distilled off to obtain 43.7 g of crude polysilane (yield: 10
0%).

As a result of measuring the molecular weight by GPC, it was found that the phenyl network polysilane had a weight average molecular weight of 1490 (average degree of polymerization: about 14).

Example 2 6.0 g (55.3 mmol) of trimethylchlorosilane
Was carried out in the same manner as in Example 1 except that was added after 400 ml of tetrahydrofuran was charged.

As a result, a phenyl network polysilane having a weight average molecular weight of 1560 (average degree of polymerization of about 14) was obtained at a yield of 100%.

In the IR absorption spectrum, 31
1100c for absorption by CH stretching of 00cm ^-1
The absorption intensity ratio of the Si—O bending angle of m ⁻¹ is described for the samples of Example 1 and Example 2.

[0042] From this, it can be said that the sample of Example 2 has a lower Si-O absorption intensity and a smaller amount of Si-O.

Example 3 A reaction was carried out in the same manner as in Example 1 except that the temperature at which the raw material phenyltrichlorosilane was dropped was maintained at the reflux temperature (67 ° C.).

As a result, a phenyl network polysilane having a weight average molecular weight of 1560 (average degree of polymerization of about 14) was obtained at a yield of 100%.

Example 4 62.2 g (0.4%) of methyltrichlorosilane was used as a raw material.
The reaction was carried out in the same manner as in Example 1 except that 16 mol) was used.

As a result, a methyl network polysilane having a weight average molecular weight of 950 (average degree of polymerization of about 22) was obtained at a yield of 100%.

Example 5 As a raw material, 31.1 g (0.2%) of methyltrichlorosilane was used.
08 mol) and 43.9 g of phenyltrichlorosilane
The reaction was carried out in the same manner as in Example 1 except that (0.208 mol) was used.

As a result, a methyl network-phenyl network copolymerized polysilane having a weight average molecular weight of 1410 (average degree of polymerization of about 19) was obtained at a yield of 93%.

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Claims (4)

[Claims] 1. A method for producing a network polysilane, comprising the following general formula (1): (In the formula, R represents a hydrogen atom, an alkyl group, an aryl group, or a silyl group. X represents a halogen atom, and three Xs may be the same or different.) The trihalosilane is reacted with Mg or a Mg alloy in an aprotic solvent in the presence of a Li salt and a metal halide to obtain a compound of the general formula (2). Wherein R is the same as above corresponding to the starting material.
n is 2 to 1000. A) forming a network polysilane represented by the following formula: 2. The process according to claim 1, wherein the aprotic solvent, the Li salt and the metal halide used have been previously dehydrated with a monohalosilane. 3. The method according to claim 1, wherein phenyltrichlorosilane is used as the trihalosilane.
The method described in. 4. The process according to claim 1, wherein tetrahydrofuran is used as the aprotic solvent.