JPH0188A - Method for producing dichlorosilanes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing dichlorosilanes.

[Prior Art] Dichlorodimethylsilane is currently produced in large quantities as a raw material for various silicones.

This conventional production method is based on Rochow's direct method (see "Chemistry of Organosilicon Compounds (Kagaku Dojin)", p. 9, 1972).

However, this method has the disadvantage that the product is complex, and dichlorodimethylsilane must be separated by distillation from a reaction mixture of more than 40 types, making it difficult to obtain a highly pure product. (Refer to "Chemistry of Organosilicon Compounds (Kagaku Doujin)," p. 9, 1972).In fact, permethylpolysilane produced from dichlorodimethylsilane obtained by this method is electronic due to the electronic nature of its 5i-3i bond. Although it was expected to be extremely useful as a material, in reality, due to its insoluble and infusible properties, it is currently only used to a limited extent as a silicon carbide fiber material.

In this way, permethylpolysilane is insoluble and infusible, and its molding process is timeless because the methyltrichlorosilane contained in dichlorodimethylsilane undergoes a crosslinking reaction. In order to solve the problem, solvent-soluble permethylpolysilane can be obtained by using high-purity dichlorodimethylsilane, which has been purified by precision distillation to reduce the methyltrichlorosilane content to about 20 ppm or less, as a raw material. is known [Journal of Polymer Science No. Polymer Chemistry ΦE Day-1 No. 17a, No. 9, 2
pp. 833-2843, 1979 (J, Polym.

Sci, Polym, Chem, Ed, 17
(9) 2833-2843. 1979) ]
.

However, in this method, it is necessary to use highly purified raw materials with a methyltrichlorosilane content of 300 ppm, the yield of dichlorodimethylsilane is extremely low at about 18%, and the dichlorodimethylsilane obtained However, there were still problems such as about 20 ppm of methyltrichlorosilane remaining.

[Purpose of the invention] This invention was made based on the actual situation described in #.

An object of the present invention is to provide a method for producing dichlorosilanes that can easily produce high-purity dichlorosilanes that do not contain trichlorosilane, which acts as a crosslinking agent, in a high yield.

[Means for Solving the Problems 1] As a result of extensive research in order to solve the above problems, the inventors discovered a specific compound called cyclopolysiloxane and a specific aromatic compound having a trichloromethyl group. We discovered that objective #2 can be easily achieved by using a novel reaction of reacting with a compound of
Based on this knowledge, we have completed this invention.

That is, the outline of the present invention for solving the above-mentioned problems is a method for producing dichlorosilanes, which is characterized by reacting cyclopolysiloxanes with an aromatic compound having a trichloromethyl group.

The cyclopolysiloxanes have the following general formula (I
) can be used.

In formula (r), R1 and R2 represent a methyl group or a phenyl group, and n is 1, usually an integer of 2 to 20, preferably an integer of 3 to 6, particularly preferably n=4. be.

Furthermore, in the method of this invention, hydrogen atoms of one or more methyl groups or phenyl groups of the compound represented by the general formula (I) as the cyclopolysiloxanes are substituents that do not substantially inhibit the reaction. Compounds substituted with can also be used.

Such substituents include, for example, halogen atoms such as fluorine and chlorine atoms; alkyl groups such as methyl, ethyl, propyl, and butyl; haloalkyl groups such as chloromethyl, fluoromethyl, and chloroethyl; Examples include heptalyl groups or aralkyl groups such as phenyl, tolyl, and xylyl; nitro; and nitroalkyl such as nitromethyl.

Specific examples of the compound represented by the general formula (I) include tetramethylcyclodisiloxane (n=2
), hexamethylcyclotrisiloxane (n=3), octamethylcyclotetrasiloxane (n=4), decamethylcyclopentasiloxane (n=5), dodecamethylcyclohexasiloxane (n=6), tetradecamethylhepta Siloxane (n = 7), hexadecamethylcyclooctasiloxane (n = 8), ophtadecamethylcyclononasiloxane (nR9), icosamethylcycloundecasiloxane (n = 10), docosamethylcycloundecasiloxane ( n = 11), tetracosacyclododecasiloxane (n = 12), hexaphenylcyclotricyclotriditetraxane (n = 3), octaphenylcyclotetrasiloxane (n = 4), trictyltriphenyltrisiloxane (n =3), tetramethyltetraphenyltrisiloxane (n=4), and the like.

In addition, examples of the cyclopolysiloxanes having the above-mentioned substituents include di(chloromethyl)dimethylcyclodisiloxane, tri(chloromethyl)trimethylcyclotrisiloxane, tetra(chloromethyl)tetramethylcyclotetrasiloxane, penta(chloromethyl)dimethylcyclodisiloxane, methyl)pentamethylcyclopentasiloxane, hexa(chloromethyl)hexamethylcyclohexasiloxane, octa(chloromethyl)cyclotetrasiloxane, tetraethyltetramethylcyclotetrasiloxane, octaethylcyclotetrasiloxane, tetraphenylmethyltetramethylcyclotetrasiloxane, Examples include tetrabutyltetramethylcyclotetrasiloxane and tetra(nitromethyl)tetramethylcyclotetrasiloxane.

Among these, hexamethylcyclotrisiloxane,
Octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane and the like are preferred, with octamethylcyclotetrasiloxane being particularly preferred.

Note that these various cyclopolysiloxanes may be used alone or in combination, such as by mixing two or more types.

The aromatic compound having a trichloromethyl group has a trichloromethyl group (-CCf) on the aromatic ring of the aromatic compound.
L3) is a compound in which at least one, usually 1 to 4, substitutions are made.

Examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring.

Among these, preferred is a benzene ring.

Note that these aromatic rings may be substituted with a substituent that does not inhibit the reaction. Examples of such substituents include a fluorine atom and a chlorine atom.

Halogen atoms such as bromine atoms: methyl group, ethyl group, n
- Straight chain, cyclic, or branched alkyl groups such as propyl, isopropyl, n-butyl, t-butyl, hexyl, cyclohexyl, octyl; phenyl, tolyl, xylyl, benzyl group, an aryl group such as a phenethyl group, or an aralkyl group.

Specific examples of the aromatic compound having the trichloromethyl group include benzochloride (α, α, α-trichlorotoluene), 0-chlorobenzotrichloride,
m-chlorobenzotrichloride, p-chlorobenzotrichloride, O-methylbenzotrichloride, m-methylbenzotrichloride, p-methylbenzotrichloride,
Ethylbenzotrichloride, dimethylbenzotrichloride, phenylbenzotrichloride, bis(trichloromethyl)benzene, tris(trichloromethyl)benzene, tetrakis(trichloromethyl)benzene, bis(
trichloromethyl)toluene, 1-)dichloromethylnaphthalene, 2-trichloromethylnaphthalene, 2,6-
Bis(trichloromethyl)naphthalene, l,4-bis(
trichloromethyl) naphthalene, l-ri° coromethyl-
Examples include 4-methylnaphthalene, 1-trichloromethylanthracene, and 2-trichloromethylanthracene. .

Among these, benzotrichlorides are particularly preferred because they are easily available, and benzotrichloride is particularly preferred.

In this invention method, dichlorosilanes are produced by reacting the cyclopolysiloxanes with the aromatic compound having a trichloromethyl group.

The ratio of the cyclopolysiloxane (A) and the aromatic compound (B) having a trichloromethyl group used in this reaction is not particularly limited, but the molar ratio of (^) to (B) is expressed as follows: 1: [k/ (2x j)] ~l
: (100xk/j), preferably 1: to/
It is preferable that j −1:L5 x (k/j).

However, above, k is one of the components (A) to be used.
represents the total number of moles of -0- units, and j is the number of moles used (B
) represents the total number of moles of reactive trichloromethyl groups directly bonded to the aromatic rings in the component, i.e., for example:
As component (A), a cyclopolysiloxane in which the number of 13i-0- units in one molecule is n is used alone, (B
) As a component, m(
When carrying out the reaction using an aromatic compound having i,
The usage ratio may be set within the range defined above as n=n and j=m.

When the proportion of component (B) used is less than the above range,
If the yield is significantly reduced, and on the other hand, the above range is exceeded, the effect of improving the yield may be reduced, and the amount of unreacted component (B) may increase, making the recovery process complicated.

In the method of this invention, it is usually desirable to use a catalyst in order to make the reaction proceed smoothly.

Lewis acids are suitable as this catalyst, and among them, commonly used metal halide Lewis acids are preferred.
Specifically, ferric chloride, antimony pentachloride, and the like are particularly preferred.

The proportion of the catalyst to be used is not particularly limited, but is usually 10-5 to 1 mol, preferably 10-3 to 0.05 mol, per 1 mol of the cyclopolysiloxane.

A solvent can be used in the reaction, if necessary. As long as the cyclopolysiloxane used is liquid under the reaction conditions, no solvent is particularly required. If a solvent is used as desired, it can be used that does not interfere with the reaction. Specific examples of such solvents include alkanes such as hexane, heptane, decane, and dodecane; cycloalkanes such as dichlorohexane; halogenated hydrocarbons such as carbon tetrachloride; nitro compounds such as nitrobenzene and nitromethane. ; Examples include carbon disulfide.

The reaction temperature is usually 1 θ to 150°C, preferably 3
A range of 0 to 80° C. is suitable. 0. If the reaction temperature is too low, the reaction rate will be slow and the time taken to complete the reaction will be long; 11. On the other hand, if the reaction temperature is too high, the yield may decrease.

If the reaction temperature is higher than the boiling point (70.7°C) of the product dichlorodimethylsilane, a reflux condenser or a distillation head should be attached to the reactor to reduce the dichlorodimethylsilane produced. It is desirable to employ a method in which the silane is refluxed or distilled off.

There is no particular restriction on the reaction pressure, and either increased pressure or reduced pressure can be used as required, but it is usually preferable to carry out the reaction at atmospheric pressure since no additional equipment is required.

There are no particular restrictions on the reaction method, and continuous methods can be used.

A semi-continuous method or a batch method can be used, and there is no particular limit to the order in which the raw materials are added, but since the reaction is a one-exothermic reaction, a method of carrying out the reaction while adding one of the raw materials dropwise, etc. It is preferable to employ 0. Usually, a method can be preferably adopted in which the cyclopolysiloxane and the catalyst are charged into a reactor, and then the aromatic compound having a trichloromethyl group is added dropwise. At this time, it is desirable that the dropping rate be adjusted to 2:1 as appropriate to maintain the desired reaction temperature.

The reaction time is usually 10 minutes to 30 hours, preferably 30 minutes to 3 hours after the completion of supplying the predetermined reaction raw materials.

Note that the reaction is preferably performed under stirring.

In the manner described above, the target product, dichlorosilanes, can be obtained in high yield. The dichlorosilanes can be separated and purified by various known methods, but the method of distilling the reaction mixture is simple and suitable.

Dichlorosilanes separated by very rough distillation may contain a small amount of hydrogen chloride, but in such cases, if necessary, extremely high purity dichlorosilanes that do not contain hydrogen chloride can be obtained by distilling again. Obtainable.

In the reaction of this invention method, aromatic carbonyl chlorides are obtained as by-products in addition to dichlorosilanes. These acyl chlorides and unreacted raw materials and solvents can be recovered by ordinary separation and purification methods such as distillation.

The recovered unreacted raw materials and solvent can be used again in the reaction as they are or after further purification if necessary.

Furthermore, the obtained acyl chlorides can be suitably used in various fields of organic synthesis, such as intermediates for fragrances.

The dichlorosilanes recovered as described above have extremely high purity and do not substantially contain methyltrichlorosilanes, and can be used for non-crosslinked homopolymers, copolymers, branched polymers, etc. Among them, it can be suitably used as a raw material for oligomers suitable for use in the field of electronic materials such as semiconductors and conductive materials, or as a raw material for other organic and inorganic syntheses that require high purity.

This invention method has been explained in detail above, but next,
As an example of the application of high-purity dichlorosilanes produced by the method of this invention, polysilanes such as linear or cyclic polysilanes that do not have a crosslinked or branched structure by polymerizing dichlorosilanes obtained by the method of this invention An example of the manufacturing method will be described.

In the following, a case is shown in which high-purity dichlorodimethylsilane produced by the method of the present invention is used as the polymerization monomer, but if desired, other dichlorosilanes obtained by the method of the present invention may be used. It can be done in the same way.

When a molecular weight regulator is not used, this polymerization reaction is formally carried out using the following reaction formula (i) CCH3)2src12x-+5i(CH3)2+;Y
(1) (However, in formula (i), M represents an alkali metal,
x, Y represent H or C1, p is.

gla of 2 or more, q usually represents an integer of 4 or more)
In addition, when chlorotrimethylsilane is used as the 5-molecule Fit jii m agent, formally, for example, the following reaction formula (ii) (CH3)zsi
cuz + (ChhSi C standing - m - → (where the formula (
In ii), M, P and q have the same meanings as in formula (i) above. ).

In this polymerization reaction, lithium,
Alkali metals such as sodium and potassium are used. This alkali metal may be used as a dispersion thereof or as an alloy such as a sodium-potassium alloy. Either of these can be suitably used, but potassium poses a risk of ignition. Highly sexual,
Also, since lithium is expensive, it is usually particularly preferred to use sodium.

This polymerization reaction may be carried out as described above, if desired, by adding 2 g of molecules M.
l FJ agent can be used. Simply write the molecular weight as a
For the purpose of (2) Both ends of the polymer button can be made into methyl groups.

For the purpose of (1) above, chlorotrimethylsilane may be used in combination with monomer dichlorodimethylsilane, and the larger the amount of chlorotrimethylsilane used, the lower the polysilane with a molecular weight can be obtained. In the case of (2) above, the objective can be achieved by first reacting dichlorodimethylsilane and an alkali metal, then adding chlorotrimethylsilane, and further reacting.

By using these two methods simultaneously, a polysilane having a low molecular weight and having methyl groups at both ends of the polymer chain can be obtained.

In terms of stoichiometry, this polymerization reaction is completed by an amount of alkali metal equal to the total number of moles of chlorine atoms in the raw materials used.

The amount of alkali metal used is 0.7 to 3.1 of the normal stoichiometry.
A suitable value is 0 times, preferably 1.0 to 1.5 times. If the amount of alkali metal is too small, the yield of polysilane will be low and the molecular weight will be extremely small;
If the amount is too large, the amount of alkali metal remaining after one reaction will increase, and it will take time to decompose it.

In addition, when chlorotrimethylsilane is added after the polymerization reaction and further reacted, the first polymerization reaction is carried out under conditions where the alkali metal is in excess, preferably 1.0% of the stoichiometry.
A preferred method is to react at a ratio of about 5 to 1.2 times, and to add chlorotrimethylsilane in an equimolar amount or more than the excess amount of alkali metal.

Although this polymerization reaction can be carried out without a solvent, a solvent is usually used. Examples of this solvent include aliphatic hydrocarbons such as hexane, heptane, decane, dodecane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and ethers such as diethyl ether, tetrahydrofuran, dimethoxyethane, and dioxane. can be used.

This solvent can be appropriately selected depending on the type and form of the alkali metal used. For example, when using metallic sodium, dodecane, toluene, xylene, etc., which have a boiling point higher than the melting point of sodium, which can prepare a sodium dispersion at normal pressure, are suitable; when using metallic lithium, Ether solvents are preferred from the viewpoint of increasing the reaction rate.

Note that it is preferable to use a dry solvent.

The reaction temperature of this polymerization is desirably adjusted appropriately depending on the boiling point of the heptamine used.

Since the boiling point of dichlorodimethylsilane at normal pressure is 70.7°C, the appropriate reaction temperature is 10 to 70°C, and when chlorotrimethylsilane (boiling point 56.7°C) is added and reacted. The appropriate reaction temperature is 10 to 65°C.

If the reaction temperature is less than 10° C., the reaction progresses slowly and one reaction may take a long time. Note that this polymerization reaction can be performed at a higher temperature than the above by performing it under pressure.

In this polymerization reaction, there is no particular limitation on the order in which the components are added, but from the viewpoint of ease of reaction operation, it is usually preferable to add the solvent, alkali metal, and dichlorodimethylsilane in this order. Depending on the conditions, strong heat may be generated, but with the above addition order, the addition rate of dichlorodimethylsilane should be J! Heat generation can be controlled by 1m.

When carrying out this polymerization reaction, it is desirable to previously purify the reaction vessel with an inert gas such as nitrogen or argon, and it is preferable to stir strongly during one reaction.

The reaction time for this polymerization reaction varies depending on other conditions such as temperature, but is usually 1 to 200 hours.
Preferably it is about 5 to 50 hours.

As described above, by using dichlorolatenes which are highly purified and do not contain methyltrichlorosilanes, etc., which cause crosslinking and branching reactions, obtained by the method of this invention, various molecular weights without crosslinking or branching can be obtained. polysilanes can be produced. The polysilanes such as the obtained polysilane are soluble in solvents and therefore have excellent processability, so they can be expected to be suitably applied to, for example, electronic materials such as semiconductors and conductive materials.

[Effects of the invention] According to this invention, since a new reaction using specific raw material compounds is used, the purity is significantly higher than that of conventional methods.
In addition, when used in monopolymerization reactions, etc., dichlorosilanes (7) that do not contain methyltrichlorosilanes, which cause crosslinking and branching reactions, can be easily obtained in high yields, and with precision It is possible to provide a novel method for producing dichlorosilanes that is extremely useful in the chemical industry and the like.

[Example] (Example 1) 74.14 g (0.25 mol) of octamethylcyclotetrasiloxane and anhydrous dichloromethane were added to a 500-cup four-bottle flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer. Two irons 8.10. (0,050 mol) was added,
It was heated to 50°C using an oil bath. While stirring, 205.3 g (1.05 mol) of benzotrichloride was added dropwise from the dropping funnel over 2 hours. The temperature inside the flask is 5
After the 0-drop addition was completed at 5 to 60°C, 30 batches were heated at 80°C and stirring was continued. Thereafter, the iW condenser and dropping funnel were removed from the flask, and a new distillation head with a condenser was attached. p! The temperature of the oil bath was raised while stirring to obtain 123 g (0,953 mol) of dichlorodimethylsilane.

The yield is based on octamethylcyclotetrasiloxane.
It was 95.3 mol%.

The reaction mixture from which dichlorodimethylsilane had been distilled off was distilled under reduced pressure to obtain 122 g of benzyl chloride (0.8E18
mole) was obtained.

The yield was 83 mol% based on benzotrichloride.

The proton nuclear magnetic resonance spectrum of dichlorodimethylsilane obtained by the above method was measured. No peak corresponding to methyltrichlorosilane could be observed. (Reference Example 1) Nitrogen was added to a 200-cup glass four-loop flask equipped with a stirrer, a calcium chloride tube reflux condenser, and a dropping funnel thermometer with a nitrogen introduction tube. While introducing nitrogen gas from the inlet tube, 40 ml of dry toluene and 11.
4 g (0.50 mol) were added.

The sodium dispersion was prepared by heating the flask to 110° C. with an oil bath, removing the oil bath and cooling the flask while stirring vigorously.

Heat the flask to 60° C. with an oil bath and under stirring.

25.8 g of dichlorodimethylsilane obtained in Example 1 above
(0.20 mol) 5.43 g of chlorotrimethylsilane
(0,050 mol) and 40 mjL of dry toluene was added dropwise from the dropping funnel over 1 hour.

After the dropwise addition was completed, heating and stirring were continued at BO°C for 40 hours. Chlorotrimethylsilane 5.43g (0,050mol)
was added from the dropping funnel, and the mixture was heated and stirred at 60°C for 5 hours.

The reaction mixture was cooled to room temperature, 50 ml of toluene was added, and methanol was added little by little while stirring.

After decomposition of unreacted metallic sodium, 10 m of water
After distilling off a portion of methanol, water, and toluene by heating, the residue was filtered under reduced pressure while hot. ii! The residual solution was washed four times with 100 mJl of hot toluene each time.

After drying this filtration residue under reduced pressure, the resulting powder was washed with hot water until it became neutral, and then dried under reduced pressure to obtain white powdery linear and cyclic permethylpolysilane polymer 8.
．． 20g was obtained.

On the other hand, the toluene solution obtained by filtration was concentrated to obtain 3.39 g of a white wax-like linear and cyclic permethylpolysilane oligomer.

Claims (4)

[Claims] (1) A method for producing dichlorosilanes, which comprises reacting cyclopolysiloxanes with an aromatic compound having a trichloromethyl group. (2) The method for producing dichlorosilane according to claim 1, wherein the cyclopolysiloxane is permethylcyclopolysiloxane. (3) The method for producing dichlorosilanes according to claim 1 or 2, wherein the cyclopolysiloxanes are cyclopolysiloxanes having 3 to 6 silicon atoms. (4) The method for producing dichlorosilanes according to any one of claims 1 to 3, wherein the aromatic compound having a trichloromethyl group is benzotrichloride.