JPH10330385A - Disproportionation of organosilanes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of industrially inexpensively producing an organosilane having hydrogen number larger than that of a monosilane or raw material silane as a result by subjecting the organosilane to disproportionation reaction by using a more inexpensive catalyst having high activity. SOLUTION: In a method for subjecting an organosilane having at least one or more Si-H bonds and represented by the formula; Hn Si(OR)4-n [(n) is 1, 2 or 3 and R is an alkyl group or an aryl group] to disproportionation reaction by bringing the organosilane into contact with a metal hydroxide represented by the formula; MOH or M(OH)2 [M is an alkali metal or an alkali earth metal], an operation for removing water content previously contained in a metal hydroxide is carried out and then used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compound represented by the general formula H_nRSi
(OR)_4-nOrganic silane having 1 to 3 hydrogen atoms represented by
Disproportionate to monosilane or raw material silanes
Also relates to a method for producing an organosilane having a large number of hydrogen atoms.
More specifically, the general formula H_nRSi (OR) _4-nRepresented by
Disproportionate organic silanes with 1 to 3 hydrogen atoms
More easily and more easily than monosilane or raw material silanes
The present invention relates to a method for producing organosilanes having many prime numbers.

[0002]

2. Description of the Related Art Monosilane gas has been widely applied to semiconductor substrates, solar cells, silicon epitaxial films, fine ceramics, etc. as a raw material for polycrystalline silicon, single crystal silicon, amorphous silicon, insulating films (silica) and the like. In particular, with the remarkable growth of the semiconductor industry in recent years, the demand has been rapidly increasing, and it is desired to develop a method for manufacturing the semiconductor device at a lower cost and in a larger quantity. In addition, organic silanes having a large number of hydrogens have recently been receiving attention as applications for semiconductor insulating films and sealants.

The above-mentioned industrial methods for producing monosilane gas include: 1) a method of reacting magnesium silicide with hydrochloric acid. Reaction formula example: Mg ₂ Si + 4HCl → SiH ₄ + 2MgCl ₂ ... [1] 2) Silicon tetrachloride Method for reacting with metal hydride Example of reaction formula: SiCl ₄ + 4LiH → SiH ₄ + 4LiCl... [2] 3) Method for disproportionation reaction of chlorosilane Reaction example of reaction: 4HSiCl ₃ → SiH ₄ + 3SiCl ₄ . 3].

[0004] Specifically, the problems of these methods are as follows.
Both methods involve a highly corrosive gas, that is, chlorosilane, which easily reacts with hydrochloric acid and atmospheric moisture to generate hydrochloric acid, and is economical because it requires the use of high-grade equipment and equipment. In addition to the disadvantages of
With regard to the method, the yield of monosilane is reduced due to by-products of higher silanes such as disilane and trisilane,
And the fact that the raw material metallic magnesium is expensive, so it is not economical, and the processing cost of the by-product MgCl ₂ is also generated,
In the method 2), high-purity monosilane can be obtained relatively easily, but on the other hand, the raw material lithium hydride is extremely expensive, which is economically problematic. However, due to the low equilibrium rate of monosilane due to the reaction equilibrium between trichlorosilane and other chlorosilanes, a large facility is required for industrial production.

[0005] On the other hand, as a method of producing monosilane relatively inexpensively from raw materials having low corrosivity, a general formula H _n S
A method of producing monosilane by disproportionating a silane represented by i (OR) _4-n has been attracting attention. As an example of the reaction, there is a disproportionation reaction of triethoxysilane as described in JP-B-51-20440 (formula [4]).

4HSi (OC ₂ H ₅ ) ₃ → SiH ₄ + 3Si (OC ₂ H ₅ ) ₄ .. [4] Starting with triethoxysilane, the general formula H _n Si (OR)
_The organic silanes represented by _4-n have been used for a long time.
No. 17967, Japanese Patent Publication No. 51-1692,
As described in JP-B-63-3869, a number of other patents and journals, etc., it can be easily produced by reacting metal silicon with a corresponding alcohol in the presence of a catalyst or a solvent.

[0007] In the method using these organic silanes as raw materials, it is natural that it is necessary to take measures against leakage and to sufficiently cope with environmental problems. However, the method has extremely low corrosiveness as compared with chlorosilane. Even carbon steel is economically advantageous because it can sufficiently withstand use. Further, unlike the above-described disproportionation reaction of chlorosilane, monosilane can be easily generated by the reaction, which is advantageous in terms of the apparatus scale. For this reason, studies on catalysts and reaction modes for obtaining monosilane rationally from organic silanes have been widely conducted.

[0008]

The general formula H _n Si (O
R) A base catalyst is advantageous as a catalyst for disproportionating the organosilane represented by _4-n . However, the elucidation of the reaction mechanism is still insufficient, and the development of highly active catalysts has been promoted from various viewpoints.

For example, Japanese Patent Publication No. Sho 51-20040 discloses a method using a metal alcoholate catalyst.
No. 8769 discloses a method using cobalt, nickel, platinum group metals or compounds thereof, and Japanese Patent Publication No. 6-887.
No. 70 discloses a method using an anion exchange resin, Japanese Patent Application Laid-Open No. 63-195107, and Japanese Patent Publication No. 8-29926.
Japanese Patent Publication No. Hei 8-29927 discloses a method in which an oxide of a metal belonging to the third to sixth cycles is used to cause a reaction in a gas phase. The use of these catalysts, the general formula _{H n Si (OR) 4-} n in organic silanes was allowed disproportionation reaction represented, often organic silanes of the number of hydrogen than monosilane or raw silanes prepared can do.

However, metal alcoholates and anion exchange resins are expensive, and the desired products cannot be produced at low cost depending on the reaction activity and catalyst life. Also,
There is also a problem that the thermal conditions are not sufficient, and the reaction conditions are narrowed.

The present invention provides a less expensive and more active catalyst.
Using the general formula H_nSi (OR) _4-nYes represented by
Silanes disproportionate, resulting in industrially cheap
Has a higher hydrogen number than monosilane or raw material silanes.
To provide a method for producing organic silanes
It is in.

[0012]

Means for Solving the Problems The present inventors have focused on metal hydroxides as inexpensive strong bases and conducted research. Sodium hydroxide and potassium hydroxide have been proposed to some extent in the past and are considered to have low activity, and are not currently industrially used as disproportionation catalysts for organosilanes. However, the present inventors have conducted intensive studies to use metal hydroxide as a catalyst for disproportionation of organic silanes, and have obtained new findings.

When a metal hydroxide is used as it is as a catalyst and is brought into contact with an organic silane, the catalytic activity is certainly low, and an organic silane having a higher number of hydrogen atoms than the monosilane or the starting silane is produced with a high yield. Cannot be performed, and when the experiment is performed for a long time, a phenomenon occurs in which the device is blocked.

However, when this phenomenon was further studied, it was clarified that the cause was caused by moisture unavoidably contained in the metal hydroxide, and if an operation for removing this moisture was performed in advance, The present inventors have found that the catalyst activity can be kept high and that organic silanes having a larger number of hydrogen atoms than monosilane or raw material silanes can be produced in good yield, and the present invention has been completed.

That is, the present invention relates to the general formula H _n Si (OR)
_{4-n wherein} n is 1, 2 or 3, and R represents an alkyl group or an aryl group.
Contacting an organosilane having at least one Si—H bond with a metal hydroxide represented by the general formula: MOH or M (OH) ₂ [where M represents an alkali metal or an alkaline earth metal] The present invention relates to a method for disproportionation of organosilanes, which is performed after an operation of removing water contained in a metal hydroxide in advance and then used.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Disproportionation raw materials used in the present invention have the general formula _H n Si (OR)
Organic silanes having at least one or more Si-H bond represented by _4-n . Here, in the formula, n is 1, 2 or 3, and R represents an alkyl group or an aryl group. Specifically, trimethoxysilane [HSi (OC
H ₃ ) ₃ ], dimethoxysilane [H ₂ Si (OCH ₃ )
₂ ], triethoxysilane [HSi (OC
₂ H ₅ ) ₃ ], diethoxysilane [H ₂ Si (OC ₂ H
₅ ) ₂ ], triphenoxysilane [HSi (OC
₆ H ₅ ) ₃ ], diphenoxysilane [H ₂ Si (OC ₆
H ₅ ) ₂ ] and the like, but are not limited thereto.

The catalyst is represented by the general formula MOH or M
A metal hydroxide represented by (OH) ₂ is used. Here, M represents an alkali metal or an alkaline earth metal. Specifically, LiOH, NaOH, KOH, M
g (OH) ₂ , Ca (OH) ₂ , Ba (OH) _{2, and the} like.
It is preferable to use OH, KOH, Ca (OH) ₂ or the like.

The reaction is an operation of bringing an organosilane into contact with a metal hydroxide. For example, a fixed layer type, that is, a method in which liquid or gaseous organic silanes are circulated in a layer filled with solid metal hydroxide, or a tank type, that is, metal hydroxide is dispersed in a liquid dispersion medium. Can be widely adopted such as a method of supplying raw material organic silanes in
It is not particularly limited to the reaction type. Therefore, the reaction temperature, pressure, residence time, type of solvent, and the like are not particularly limited, and conditions can be freely selected according to the purpose.

In the present invention, the metal hydroxide used as a catalyst is subjected to an operation for removing moisture contained in advance. Generally, even a grade of a special grade reagent contains several percent to several tens percent of water in a metal hydroxide. Therefore, if a metal hydroxide is used as a disproportionation catalyst for organic silanes without performing this operation, reaction products such as raw material organic silanes or monosilane are decomposed by moisture originally contained to produce silica. Therefore, the target product cannot be obtained with an apparently high yield. Although the details are not clear, the loss of the active site due to the generated silica adhering to the surface of the metal hydroxide seems to be one of the causes of the low catalytic activity of the metal hydroxide.

Hereinafter, a method for removing water contained in the metal hydroxide in advance so as not to affect the disproportionation of the organosilane will be specifically disclosed. 1) Simple heating method Simply heating at the boiling point of water, that is, 100 ° C. or higher, does not achieve the object. To remove moisture in metal hydroxide, 2
It is necessary to heat at 00 ° C. or more for 10 minutes or more, preferably 30 minutes or more. The atmosphere at that time is not particularly limited, but it goes without saying that the use of dry air or dry nitrogen is more effective.

2) A method of dispersing a metal hydroxide in an organic solvent that forms a minimum azeotrope with water, followed by drying The metal hydroxide is dispersed in an organic solvent, and the mixture is stirred for several tens minutes to several hours. . At this time, the metal hydroxide does not necessarily need to be dissolved in the organic solvent. Drying refers to an operation of evaporating and removing an organic solvent by heating. For example, if the metal hydroxide does not dissolve in the organic solvent, a method of heating in a dry gas stream after filtration and a method of dissolving the metal hydroxide in a dry gas stream atmosphere are also used. Removed as an object. Organic solvents that form the lowest azeotrope with water include alcohols such as ethanol and propanol,
There are many paraffins such as pentane and hexane, and aromatic hydrocarbons such as benzene and toluene.However, it is needless to say that inexpensive ones are preferable, and also because water and organic substances form a two-liquid phase, it is difficult to handle. In particular, ethanol, propanol and butanol are mentioned as particularly preferred organic solvents. Here, propanol and butanol are generic terms including structural isomers.

3) Method of contacting with a hydrolyzable substance Examples of the method include dispersing a metal hydroxide in the hydrolyzable substance and flowing the hydrolyzable substance through a fixed layer of the metal hydroxide. . Organic metals are generally hydrolyzable substances, but from the viewpoint of relatively easy handling, the general formula Mt (OR) _m [where Mt is a metal and m is a positive number indicating the valence of the metal. , R represents an alkyl group or an aryl group]. Also, from the purpose of the reaction, if another kind of metal remains after the operation of removing water, it may become an impurity.
It is particularly preferable to use an organic silane represented by (OR) _{4 wherein} R represents an alkyl group or an aryl group.

As can be said in common with the methods 1) to 3), since alkali metal hydroxides such as NaOH and KOH have deliquescence, care must be taken not to bring them into contact with the atmosphere after the operation of removing water. is necessary. As described above, three methods have been disclosed as methods for removing water in a metal hydroxide in advance and preparing a catalyst having high activity as a catalyst for disproportionation of organosilanes. If a metal hydroxide subjected to any of these operations is used as a catalyst, it exhibits extremely high activity with respect to disproportionation of organosilanes and can maintain it.
That is, organic silanes having a larger number of hydrogen atoms than monosilane or raw material silanes can be produced inexpensively and with high yield.

[0024]

The present invention will be described below in detail with reference to examples. Example 1 Wako Pure Chemical's special grade potassium hydroxide (A) [KOH] reagent (pellet) was crushed into a SUS304 tube having an inner diameter of 15 mm and a length of 200 mm and formed into granules of 1 to 2 mm in the center of the tube. 8 cc and 5.7 g were filled, and the upper and lower sides were sandwiched between silica wools (a) to prepare a fixed bed reactor 1. A sheath heater (C) is wrapped around the fixed layer, about 300 ° C.
Temperature. Also, a raw material tank 2 and a plunger pump 3 are attached so that the raw material liquid can flow from the lower part of the tube, and the gas outlet 4 and the liquid outlet 5 are provided on the upper part.
The liquid was piped so that the gas could enter the gas chromatograph (GC-8A, manufactured by Shimadzu) 6 together with the carrier gas, so that an apparatus as shown in FIG. 1 was produced. 50 cc of nitrogen gas from the lower part of the fixed bed reactor 1
/ Min while flowing at a rate of 21 min / min.
After elevating the temperature to 0 to 230 ° C., the operation was left for 1 hour to remove water in KOH.

A trimethoxysilane [HSi (OCH ₃ ) ₃ ] reagent and a tetramethoxysilane [Si (OCH ₃ ) ₄ ] reagent manufactured by Tokyo Chemical Industry Co., Ltd.
300 g of a raw material mixed so as to give a ratio of 5:65 was charged. After setting the temperature of the KOH layer to 80 ° C., the raw material was introduced into the fixed-bed reactor 1 by the plunger pump 3 at 0.5 g / min.
, And a disproportionation reaction of trimethoxysilane was performed. Immediately upon contact between the raw material and KOH, the reaction proceeded and gas was generated. As a result of gas chromatography 6 analysis, it was confirmed that the gas was silane gas. The liquid at the outlet of the reactor was analyzed by gas chromatography (GC-
As a result of 8A), it was confirmed that the mixture was a mixture of trimethoxysilane and tetramethoxysilane. About one hour after the start of the reaction, the state almost reached a steady state. At this time, the composition of each gas and liquid was analyzed. As a result, the conversion of trimethoxysilane was about 85%, and the generation rate of silane gas was about 7 cc / min.
Met. The reaction was continued for 6 hours, during which the reaction proceeded stably without increasing the pressure in the fixed-bed reactor 1. As a result of the measurement after completion of the reaction, the total weight of the raw material supplied, the total weight of the recovered liquid, and the production The sum of the converted weights of silane gas, that is, the so-called weight balance, was almost the same. In addition, under nitrogen flow to the KOH layer,
After performing a drying operation at 30 ° C. for 1 hour, KOH was taken out.
There was no significant change in the appearance, and the weight was measured to be 5.4 g, indicating a slight weight loss.

Example 2 Approximately 20 g of sodium hydroxide reagent manufactured by Wako Pure Chemical in the form of granules of 1 to 2 mm was dispersed in about 200 cc of tetramethoxysilane manufactured by Tokyo Chemical Industry, and allowed to stand with stirring for about 2 hours.
An operation for removing water in OH was performed. After completion of the operation, the mixture was filtered in a nitrogen box, and then the tube used in Example 1 was filled with about 8 cc of NaOH. Then, Example 1
A fixed-bed reactor was manufactured in the same manner as described above, and the raw materials were supplied under the same conditions. About one hour after the start of the reaction, the state almost reached a steady state. At this time, the composition of each gas and liquid was analyzed. As a result, the conversion of trimethoxysilane was about 88%, and the generation rate of silane gas was about 7 cc / min. there were. The reaction was continued for 6 hours, but proceeded smoothly, and the weight balance after the reaction was almost the same. After performing the same drying operation as in Example 1, NaOH was removed, but there was no significant change in appearance.

Comparative Example 1 A fixed-bed reactor filled with 5.5 g of a KOH reagent was produced in the same manner as in Example 1, and the same conditions as in Example 1 were used without performing the operation for removing water in KOH. A disproportionation reaction was performed. Immediately upon contact between the raw material and KOH, the reaction proceeded and gas was generated. As a result of gas chromatography analysis, a peak of hydrogen gas was detected together with silane gas. The reaction was continued as it was, but after about 30 minutes, the pressure in the fixed bed reactor began to rise, and at 36 minutes, the pressure exceeded 1 kg / cm ² G, so the supply of the raw material was stopped.
After draining the liquid in the fixed bed reactor, the KOH layer was dried under nitrogen at 130 ° C. for 1 hour, and then KOH was taken out. Had a white powder that appeared to be silica. In addition, the blockage point is K
It was silica wool above the OH layer, and was in the form of a sponge with white powder that appeared to be silica involved.

Example 3 Approximately 20 g of a potassium hydroxide reagent manufactured by Wako Pure Chemical in the form of granules of 1 to 2 mm was weighed to about 200 c of special grade ethanol manufactured by Wako Pure Chemical.
After dispersing and stirring for about 2 hours, ethanol was evaporated to dryness using an evaporator, and an operation of removing water in KOH was performed. After completion of the operation, Example 1 was placed in a nitrogen box.
Was filled with about 8 cc and 5.7 g of KOH. Thereafter, a fixed-bed reactor was manufactured in the same manner as in Example 1, and the raw materials were supplied under the same conditions. About one hour after the start of the reaction, the state almost reached a steady state. At this time, the composition of each gas and liquid was analyzed. As a result, the conversion of trimethoxysilane was about 91%, and the generation rate of silane gas was about 7 cc.
/ Min. The reaction was continued for 6 hours, but proceeded smoothly, and the weight balance after the reaction was almost the same. After performing the same drying operation as in Example 1, KO
H was taken out, but there was no significant change in the appearance, and the weight remained 5.7 g.

Example 4 10 g of a potassium hydroxide reagent manufactured by Wako Pure Chemical was dissolved in 90 g of water, and γ-alumina manufactured by Sumitomo Chemical Co., Ltd.
mm) and left at room temperature for 10 hours to impregnate γ-alumina with KOH. After the γ-alumina was separated by filtration and dried in a nitrogen stream at 120 ° C. for 2 hours, about 20 g of water was removed from KOH in the same manner as in Example 2. Γ-alumina-supported KOH filtered after operation, about 8c
c was filled in the tube used in Example 1, a fixed-bed reactor was produced by the same operation as in Example 1, and the raw materials were supplied under the same conditions. About one hour after the start of the reaction, the state almost reached a steady state. At this time, the composition of each gas and liquid was analyzed. As a result, the conversion of trimethoxysilane was about 88%, and the generation rate of silane gas was about 7 cc / min. there were. Reaction 6
The reaction was continued for a long time, but progressed smoothly, and the weight balance after the completion of the reaction was almost the same. After performing the same drying operation as in Example 1, KOH was taken out, but there was no significant change in appearance.

Comparative Example 2 A tube was filled with 7.2 g of γ-alumina-supported KOH, which had not been subjected to an operation for removing water in advance, and then Example 4 was performed.
The reaction was performed in the same manner as described above. At the beginning of the reaction, the peak of hydrogen gas was detected together with the silane gas in the same manner as in Comparative Example 1. Approximately 2 hours after the start of the reaction, it reached a nearly steady state,
As a result of composition analysis of each liquid, the conversion of trimethoxysilane was about 84%, and the generation rate of silane gas was about 7c.
c / min. The reaction proceeded smoothly for 6 hours, but after the reaction was completed, the weight balance was measured and calculated. As a result, it was found that the silane weight conversion value was about 83% of the theoretical value. After performing the same drying operation as in Example 1, KO
Although H was taken out, a white powder like silica was adhered to the surface, and the weight was slightly increased to 7.5 g.

[0031]

According to the present invention, by preliminarily performing the operation of removing the water content of the metal hydroxide, the organic silane exhibits extremely high activity against disproportionation and can maintain the activity. That is, in Comparative Examples outside the scope of the present invention, the entire metal hydroxide was fused in a candy-like manner, or a silica-like white powder was adhered to the surface, causing clogging in the fixed-bed reactor and pressure. Rise, and a long-term reaction cannot be maintained.
In contrast, embodiments within the scope of the present invention have all of these performances. Further, by implementing the present invention, monosilane or an organic silane having a larger number of hydrogen atoms than the raw material silane can be efficiently produced with an inexpensive catalyst, so that the effect is large.

[0032]

[Brief description of the drawings]

FIG. 1 shows an example of an apparatus for confirming the effects of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed-bed reactor 2 Raw material tank 3 Plunger pump 4 Gas outlet 5 Liquid outlet 6 Gas chromatography (A) Metal hydroxide (A) Silica wool (U) Sheath heater (D) Thermocouple thermometer

Claims (7)

[Claims] 1. At least one Si represented by the general formula H _n Si (OR) _{4-n wherein} n is 1, 2 or 3, and R represents an alkyl group or an aryl group.
An organosilane having an —H bond is brought into contact with a metal hydroxide represented by the general formula: MOH or M (OH) ₂ [wherein M represents an alkali metal or an alkaline earth metal], resulting in unevenness. A method for disproportionation of organic silanes, which is performed after an operation of removing water contained in a metal hydroxide in advance. 2. The method for disproportionation of organosilanes according to claim 1, wherein the operation of removing moisture contained in the metal hydroxide in advance is an operation of heating at 200 ° C. or more for 10 minutes or more. 3. The operation for previously removing water contained in the metal hydroxide is an operation of dispersing the metal hydroxide in an organic solvent that forms a minimum azeotrope with water and then drying. The method for disproportionation of organosilanes according to the above. 4. The method for disproportionation of organosilanes according to claim 1, wherein the operation of previously removing water contained in the metal hydroxide is an operation of bringing the metal hydroxide into contact with a hydrolyzable substance. 5. The organic solvent which forms the lowest azeotrope with water is one of ethanol, propanol and butanol.
4. The method for disproportionation of organosilanes according to claim 3, wherein the method is a combination of two or more species. 6. The hydrolyzable substance has a general formula Mt (O
R) _m [where Mt is a metal, m is a positive number representing the valence of the metal, and R represents an alkyl group or an aryl group], and is a metal alkoxide represented by the formula: Disproportionation method. 7. The hydrolyzable substance represented by the general formula Si (O
The method for disproportionation of organosilanes according to claim 4, wherein the organosilanes are represented by R) _{4 wherein} R represents an alkyl group or an aryl group.