JP3567034B2 - Purification method of alkoxysilane - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for reducing impurities contained in alkoxysilane.
[0002]
Technical background of the invention and its problems
In alkoxysilanes used as materials for semiconductor industry, it has become clear that traces of halides, such as halogenated organic compounds, contained as impurities therein attack semiconductor substrates and cause material problems.
As a method for reducing impurities in the alkoxysilane, JP-A-63-238091 describes a method using a metal alcoholate in excess of the chemical equivalent of a chlorine compound contained as an impurity. However, there is a problem that the organic compound is not sufficiently removed. Japanese Patent Application Laid-Open No. 63-77887 discloses a method of contacting an organosilicon compound with an organomagnesium compound for purification, but the preparation of the organomagnesium compound is industrially difficult. However, since the alkoxy group reacts with the organic residue of the organomagnesium compound, there is also a problem that the yield of alkoxysilane is reduced. Further, JP-A-2-23587 discloses a method of removing chlorine in an alkoxysilane by contacting it with an organometallic compound comprising a metal belonging to Group IA, IIA, or IIB of the periodic table. Examples of the compound include an organic lithium compound, an organic sodium compound, an organic potassium compound, an organic magnesium compound, an organic calcium compound, and an organic zinc compound. However, this method has the same problem as the invention described in the above-mentioned publication, and also has the problem that the halogenated organic compound as an impurity is insufficiently removed. In addition, the present applicant has proposed a method of using a specific organic zinc compound as a method for purifying alkoxysilane (Japanese Patent Application Laid-Open No. 4-26694). It is further desired to raise.
[0003]
[Object of the invention]
An object of the present invention is to provide a method for simply and efficiently separating a halide as an impurity from alkoxysilane and purifying the same.
[0004]
Configuration of the Invention
The present inventors have conducted intensive studies to solve the disadvantages of the prior art, and as a result, have found that, in a method for purifying alkoxysilane using a metal alcoholate, by performing purification under pressure, the halide content is significantly reduced. As a result, the present invention has been completed.
That is, the method for purifying an alkoxysilane of the present invention is characterized by comprising contacting an alkoxysilane containing a halide with a metal alcoholate under pressure, and then separating the alkoxysilane.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
In the present invention, as an alkoxysilane to be purified, trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, trimethylisopropoxysilane, trimethylbutoxysilane, triphenylmethoxysilane, triphenylethoxysilane, dimethyl-t-butyl Monoalkoxysilanes such as methoxysilane and dimethylphenylmethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diphenyldimethoxysilane, dialkoxy such as diphenyldiethoxysilane, methylphenyldimethoxysilane and methylphenyldiethoxysilane Silanes, metritrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, phenyltrimethoxy Silane, trialkoxy silanes such as phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, etc. tetraalkoxysilanes such as tetra-isopropoxy silane.
[0006]
Examples of the halide removed by the method of the present invention include methyl chloride, methyl bromide, chlorobenzene, bromobenzene, chlorobiphenyl, halogenated organic compounds such as bromobiphenyl, and hydrogen chloride and chlorosilane compounds. It is not limited, and includes all halides as impurities contained in the alkoxysilane other than these.
[0007]
Examples of the metal alcoholate used in the present invention include methylates such as sodium, potassium, magnesium, aluminum, titanium, and zirconium, ethylates, isopropylate, n-propylate, n-butyrate, and the like. Alcoholates of similar metals are used, particularly preferably potassium and sodium alcoholates, more preferably sodium alcoholates. Specifically, metal methylates such as sodium methylate, potassium methylate, magnesium methylate, aluminum methylate, magnesium methylate, sodium ethylate, potassium ethylate, magnesium ethylate, aluminum ethylate, magnesium ethylate, etc. Examples include metal ethylates, metal isopropylates such as aluminum isopropylate and titanium tetraisopropylate, and metal n-butylates such as zirconium tetra-n-butylate. From the type of alcohol, methylate and ethylate are preferred.
The amount of the metal alcoholate to be used is preferably 1.0 to 10.0 equivalents to 1 equivalent of chlorine of the halide as an impurity. If the amount used is small, the removal of the halide may be insufficient, so it is preferable to use 1.0 equivalent or more. In addition, when the alkoxysilane is continuously treated, since a reaction product of the metal alcoholate and the halide or the metal alcoholate itself is often a solid, if a large amount of the metal alcoholate is used, many residues after purification will be generated. Since the number of times of removing the residue is required, the purification efficiency is reduced. Therefore, it is preferable that the amount used is 10.0 equivalents or less. Particularly preferably, 1.0 to 3.0 equivalents are used.
Since metal alcoholates are generally solid in many cases, they may be used as solutions of alcohols such as methanol, ethanol and isopropanol and organic solvents such as toluene and xylene for easy handling.
[0008]
In the method for purifying an alkoxysilane of the present invention, the alkoxysilane and the metal alcoholate are brought into contact with each other under pressure, and then the alkoxysilane is separated. In general, the contact between the alkoxysilane and the metal alcoholate may be performed by adding the metal alcoholate to the alkoxysilane and stirring the mixture. The present invention is characterized in that the contact is performed under pressure, and the contact is performed under pressure so that the difference (gauge pressure) from the atmospheric pressure is preferably 0.01 to 10 kg / cm ² . 0.01 kg / cm is less than ² not sufficient effect of removal of halide by the pressure, the greater than 10 kg / cm ^2, the control of the design and the pressure of the apparatus is complicated. Particularly preferably, pressure is applied in a range of 1.0 to 3.0 kg / cm ² .
In the present invention, when the contact is carried out under pressure, it is preferred to heat, preferably to 50 to 200 ° C, particularly preferably 90 to 150 ° C. By heating in this way, the halides, which are impurities in the alkoxysilane, are decomposed to generate, for example, HCl, and by further increasing the pressure, the reaction between HCl and the metal alcoholate proceeds favorably. The result appears to be good removal of halide. The contact under pressure in the present invention is preferably performed for 0.5 to 10 hours, particularly preferably 2 to 5 hours. Further, at the time of contact under pressure, or before and after the contact under pressure, treatment with activated carbon may be used in combination to reduce halides, and it is particularly preferable to use the treatment simultaneously with or after the contact. The treatment with activated carbon may be performed by adding activated carbon powder to alkoxysilane and stirring the mixture.
[0009]
After the contact treatment, the alkoxysilane may be separated by a known method such as distillation, decantation, or filtration.For example, the alkoxysilane may be distilled as it is or after filtration under normal pressure or reduced pressure by a conventional method. To obtain the desired purified alkoxysilane.
[0010]
【The invention's effect】
According to the method of the present invention, halides as impurities in the alkoxysilane can be efficiently removed, and furthermore, the amount of metal alcoholate used can be reduced, so that the number of treatments of the residue after purification can be reduced. It has the feature that it can be manufactured and is excellent in productivity.
[0011]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, parts and% indicate parts by weight and% by weight, respectively, unless otherwise specified, and the viscosity indicates a value at 25 ° C.
The method of quantifying impurities in the examples was performed by fluorescent X-rays, and the electric conductivity was also measured.
[0012]
Example 1
150 g of methyltrimethoxysilane having a chlorine content of 150 ppm (including HCl content of 1.3 ppm) and an electric conductivity of 15 μs / cm was placed in a container, and 2.5 g of powdery sodium methylate was added thereto. The mixture was stirred at 110 ° C. for 3.5 hours under a pressure of 0.0 kg / cm ² (gauge pressure). After stirring, the mixture was distilled under normal pressure to obtain 142 g of methyltrimethoxysilane. Its chlorine content was 8 ppm (HCl content was not detected), and its electrical conductivity was 1.1 μs / cm.
[0013]
Example 2
The same treatment as in Example 1 was performed except that the pressure was changed to 2.5 kg / cm ² (gauge pressure) to obtain 143 g of methyltrimethoxysilane. The chlorine content (and HCl content) was not detected, and the electric conductivity was 0.3 μs / cm.
[0014]
Example 3
The same treatment as in Example 1 was performed except that 10 g of a 25% methanol solution of sodium methylate was used to obtain 144 g of methyltrimethoxysilane. The chlorine content thereof was 5 ppm (HCl content was not detected), and the electric conductivity was 0.8 μs / cm.
[0015]
Example 4
Treatment was performed in the same manner as in Example 1 except that dimethyldimethoxysilane having a chlorine content of 110 ppm (of which HCl content was 1.0 ppm) and an electric conductivity of 12 μs / cm was used, and 1.0 g of sodium ethylate was added. Was carried out to obtain 143 g of dimethyldimethoxysilane. The chlorine content was 7 ppm (HCl content was not detected), and the electrical conductivity was 1.0 μs / cm.
[0016]
Example 5
150 g of methyltriethoxysilane having a chlorine content of 80 ppm (of which the HCl content is 0.8 ppm) and an electric conductivity of 10 μs / cm was placed in a container, and 10 g of a 25% methanol solution of potassium methylate was added thereto. The mixture was stirred at 120 ° C. for 5.0 hours under a pressure of 0.0 kg / cm ² (gauge pressure). After stirring, the mixture was distilled under normal pressure to obtain 136 g of methyltriethoxysilane. The chlorine content (and HCl content) was not detected, and the electric conductivity was 0.3 μs / cm.
[0017]
Comparative Example 1
The same treatment as in Example 1 was carried out except that stirring was performed at 100 ° C. under normal pressure without pressurization, to obtain 140 g of methyltrimethoxysilane. Its chlorine content was 29 ppm (HCl content was not detected), and its electrical conductivity was 10.6 μs / cm.
[0018]
Comparative Example 2
A treatment was carried out in the same manner as in Example 1, except that 10 g of a 25% methanol solution of sodium methylate was used and stirring was performed at 82 ° C. without applying pressure, to obtain 142 g of methyltrimethoxysilane. . Its chlorine content was 22 ppm (HCl content was not detected), and its electrical conductivity was 9.4 μs / cm.
[0019]
Comparative Example 3
The same treatment as in Example 1 was carried out except that reflux was carried out at about 102 ° C. at normal pressure without pressurization without using sodium methylate, to obtain 136 g of methyltriethoxysilane. Its chlorine content was 150 ppm (HCl content was 50 ppm) and its electrical conductivity was 15.1 μs / cm.

Claims (5)

A method for purifying alkoxysilane, comprising contacting an alkoxysilane containing a halide with a metal alcoholate under pressure, and separating the alkoxysilane. Method of purifying alkoxysilanes according to claim 1, wherein a 0.01 to 10 / cm ² to the pressing pressure is atmospheric pressure. The method for purifying an alkoxysilane according to claim ² , wherein the pressure is 1.0 to 3.0 kg / cm2 with respect to the atmospheric pressure. The method for purifying an alkoxysilane according to any one of claims 1 to 3, wherein the metal alcoholate is a potassium or sodium alcoholate. The method according to any one of claims 1 to 4, wherein the contact under pressure is performed at 90 to 150 ° C for 2 to 5 hours.