JPS63313790A - Method for separating and purifying trialkoxysilane - Google Patents

Abstract

PURPOSE:To separate and purify a trialkoxysilane in good recovery ratio and high purity, by the coexistence of a specific amount of an organic halide in a reaction mixture containing an unreacted alcohol. CONSTITUTION:A trialkoxysilane is separated and purified from a reaction mixture containing an unreacted alcohol. In the process, an organic halide (preferably alkyl halide, alkenyl halide, aryl halide or quaternary ammonium halide) in an amount of 0.0001-20wt.%, preferably 0.01-6wt.% is added to coexist in the reaction mixture.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for separating and purifying trialkoxysilane, and more specifically, it stabilizes trialkoxysilane in a reaction mixture in which unreacted alcohol is present to produce trialkoxysilane. The present invention relates to a method for efficiently separating and purifying silane.

[Prior Art] Trialkoxysilane, in which three alkoxy groups and one hydrogen atom are bonded to one silicon atom, such as trimethoxysilane and triethoxysilane, is itself extremely reactive and has many Useful substances are produced by reactions such as addition, copolymerization, and cocondensation with organic compounds, and are used as raw materials for producing, for example, silane coupling agents, coating agents, heat-resistant paints, and the like.

As a method for producing such trialkoxysilane, for example, a method is known in which silicon metal and alcohol are directly reacted in the gas phase or liquid phase in the presence of a copper catalyst. However, in this method, the reaction rate of alcohol is low, and the reaction mixture contains, in addition to the target trialkoxysilane, tetraalkoxysilane, dialkoxysilane, dialkoxyalkylsilane, trialkoxyalkylsilane, or two of these. In addition to various alkoxysilanes such as trialkoxysilanes, a large amount of unreacted alcohol is contained, and this reaction mixture is produced by reacting the unreacted alcohol with the target trialkoxysilane during storage or during the purification operation. There is a problem in that tetraalkoxysilane is produced, resulting in a significant decrease in the yield of trialkoxysilane.

Therefore, in the past, there have been methods for storing the reaction mixture at a temperature below 0°C, or for stabilizing the reaction mixture by adding a predetermined amino acid to the reaction mixture (Japanese Unexamined Patent Application Publication No. 55-115). -72,197), a method of adding amines to adjust II to 2.0 to 7.0 (JP-A-57-118,592), a method of adding a trivalent organic phosphorus compound ( Tokuko Sho 61-21,
No. 478] and a method in which epoxides are present in the reaction mixture (Japanese Patent Laid-Open No. 1,694/1983) have been proposed.

[Problems to be Solved by the Invention] However, the method of preserving the reaction mixture at a temperature below O'C requires a refrigerator or freezer, which incurs a large storage cost. Since heating is required when rectifying and purifying the reaction mixture, there is a problem in that decomposition of trialkoxysilane cannot be prevented at this time, and amino acids, amines, and trivalent For methods using organic phosphorus compounds or epoxides, these stabilizers may be mixed as impurities into the purified trialkoxysilane obtained by distilling the reaction mixture, or the reaction between trialkoxysilane and unreacted alcohol may occur. In any case, they were not satisfactory, such as not necessarily having a sufficient effect of suppressing the reaction mixture, or having problems with the stabilizing effect when purifying trialkoxysilane by distilling the reaction mixture.

Therefore, an object of the present invention is to stabilize trialkoxysilane in the reaction mixture when separating and purifying trialkoxysilane from a reaction mixture containing unreacted alcohol, and to easily rectify the reaction mixture. The object of the present invention is to provide a method for separating and purifying trialkoxysilane, which can obtain highly pure trialkoxysilane in good yield.

[Means for Solving the Problems] That is, in the present invention, when separating and purifying trialkoxysilane from a reaction mixture containing unreacted alcohol, 0.0001 to 0.0001 of an organic halide is added to the reaction mixture.
This is a separation and purification method for trialkoxysilane in which 10% by weight is coexisting.

In the present invention, the reaction mixture containing unreacted alcohol may be a reaction mixture obtained by the reaction of trichlorosilane and alcohol, but from the viewpoint of the yield of trialkoxysilane, the presence of a copper catalyst is preferable. It is a reaction mixture obtained by directly reacting metallic silicon and alcohol in the gas phase or liquid phase.

In the direct reaction of metallic silicon and alcohol carried out in the presence of a copper catalyst, the metallic silicon used as a raw material may be a powder with a purity of 80% by weight or more and an average particle size of 200 μm or less, For example, an inexpensive general commercially available product manufactured by means such as a vibrating mill or a ball mill and having a purity of 80 to 99% by weight and an average particle size of 50 to 100 μm can be used as is.

In addition, as the alcohol used as a raw material, alkyl alcohol is usually used, preferably methyl alcohol, ethyl alcohol, n-propyl alcohol,
so-propyl alcohol, n-butyl alcohol, i
Lower alkyl alcohols having 1 to 6 carbon atoms such as butyl alcohol, alcohol, and amyl alcohol are used. For these alcohols, the purity is 98% by weight or more,
Preferably, the water content is 99.9% by weight or more, and the water content is 0.2% by weight or less, preferably 0.1% by weight or less. The amount of alcohol used is usually 3 to 10 moles per mole of metal silicon, but in order to improve the reaction rate of metal silicon, it is best to use it in excess of the metal silicon. , preferably 4 to 8 mol.

Furthermore, examples of copper catalysts include metallic copper powder, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, and fluoride. Examples include copper compounds such as cuprous cuprous, copper formate, copper acetylacetonate, cuprous acetate, cupric acetate, cuprous oxide, cupric oxide, and the like. Regarding these metallic copper powders and copper compounds, only one type thereof may be used, or two or more types may be used in combination.

These copper catalysts are usually used in an amount of 0.0 per mole of metal silicon.
It is used in the range of 0.05 to 0.5 mol, preferably 0.01 to 0.1 mol, and if the amount used is less than 0.005 mol, there will be a problem of a decrease in the reaction rate of metal silicon, and
Even if the amount is more than 0.5 mol, no improvement in the reaction rate of metal silicon or the selectivity of trialkoxysilane is observed, which is rather uneconomical.

Further, the copper catalyst may be used after being mixed with the metal silicon and pulverized in advance, and activated by heat treatment at 200 to 600°C, preferably 200 to 400'C, in a nitrogen stream.

In addition, when carrying out the direct reaction of metallic silicon and alcohol in the presence of a copper catalyst in the liquid phase, the solvent used is one that is stable in the reaction system and can be raised to the specified reaction temperature. Various hydrocarbon compounds can be used, for example paraffinic hydrocarbons such as octane, decane, dodecane, tetrazocane, hexadecane, octadecane, ethylbenzene, ethylbenzene, trimethylbenzene, cymene, diethylbenzene, etc. Alkylbenzene hydrocarbons or their hydrides such as butylbenzene, butyltoluene, octylbenzene, dodecylbenzene, and didodecylbenzene; diphenyl hydrocarbons or their hydrides such as diphenyl, diphenyl ether, monoethyldiphenyl, diethyldiphenyl, and triethyldiphenyl; Examples include alkylnaphthalene hydrocarbons or their hydrides, triphenyl hydrocarbons or their hydrides, etc., and only one type thereof may be used, or two or more types may be used in combination. . Among these solvents, those that do not foam during the reaction and have a boiling point of 100 to 400'C1 at normal pressure are preferred.
Preferably it is 150 to 300°C.

When the direct reaction between metal silicon and alcohol in the presence of a copper catalyst is carried out in a liquid phase, the reaction is carried out, for example, in the following manner. That is, an alcohol introduction tube, a product distillation tube, and a thermometer are set in a reaction vessel equipped with a stirrer, and metal silicon, a copper catalyst, and a reaction solvent are charged into the reaction vessel, and if necessary, inert gas such as nitrogen gas or hydrogen While blowing gas, the reaction solvent is heated under stirring to the boiling point of the reaction solvent (usually within the range of 100 to 400°C), preferably 150 to 300°C, and then alcohol is poured into the reaction vessel from the alcohol inlet tube at a constant rate. The reaction mixture distilled out from the product distillation tube is cooled, condensed, and collected by a condenser connected to the outlet of the product distillation tube.

In addition, when the direct reaction of metallic silicon and alcohol in the presence of a copper catalyst is carried out in the gas phase, the reaction may be the same as the conventionally known method using a vertical reactor or a horizontal reactor.
The reactor filled with metal silicon and copper catalyst is usually 150 ~
While heating to 600°C, preferably 200 to 400°C, alcohol is introduced with or without dilution with an inert gas or hydrogen gas, and the distilled reaction mixture is poured into a cooler connected to the outlet of the reactor. Cool, condense and collect.

Preferably, an organic halide is immediately added to the reaction mixture obtained in this way, so that the organic halide coexists as a stabilizer at a predetermined ratio during storage or during the purification operation. . The organic halides used for this purpose may be those that can be easily separated and removed by distillation, such as methyl chloride, methyl bromide, methyl fluoride, methyl iodide, ethyl chloride, ethyl bromide, Alkyl halides such as ethyl fluoride, ethyl iodide, n-propyl chloride, n-propyl bromide, alkenyl halides such as dichloromethane and dichloroethane, aryl halides such as chlorobenzene and dichlorobenzene, and other chloroform , carbon tetrachloride, acetic chloride, etc., and preferably an alkyl halide having the same number of carbon atoms as the alkyl group of the trialkoxysilane. The amount of organic halide used in the reaction mixture is usually 0.0001 to 2.
0% by weight, preferably 0.001 to 10% by weight,
More preferably, it is 0.01 to 6% by weight. 0.000
If the amount is less than 1 mol, a sufficient stabilizing effect cannot be exhibited, and even if the amount is more than 20% by weight, no improvement in the stabilizing effect is observed, which is economically disadvantageous.

For reaction mixtures in which an organic halide coexists as a stabilizer, it is purified by distillation, and in particular, by using an organic halide that has a large boiling point difference with respect to trialkoxysilane, highly pure trialkoxysilane can be easily obtained. Can be done.

[Example] Hereinafter, the method of the present invention will be specifically explained based on Examples, Comparative Examples, and Test Examples.

Example 1 500 g of silicon metal with an average particle size of 200 μm and 2 cuprous chlorides
5 g was pulverized and mixed in a magnetic ball mill for 2 hours, filled in a quartz tube, and heat-treated in an electric furnace at 600° C. in a nitrogen gas stream for 3 hours.

Next, the heat-treated metal silicon and cuprous chloride were placed in a stainless steel reactor with a diameter of 10 cm and a height of 23 cm equipped with an alcohol inlet tube, a nitrogen gas inlet tube, a product distillation tube, and a thermometer. A mixture and an alkylbenzene hydrocarbon with a boiling point of 280°C (product name: AB-HL manufactured by Mitsubishi Yuka)
>1,000.11, reaction temperature 170-180
30ml of methyl alcohol with a purity of 99°C or more 9% by weight
/hr and nitrogen gas at a rate of 20 ml/min, the reaction was allowed to proceed for 80 hours, and the reaction mixture 2.
2809 were recovered. Analysis of this reaction mixture by gas chromatography revealed that its composition was methanol 13.3
% by weight, 60.8% by weight of trimethoxysilane, 21.5% by weight of tetramethoxysilane, and 4.4% by weight of others, the reaction rate of metal silicon is 81.9% by weight, and the selectivity of trimethoxysilane is 77% by weight. It was .9% by weight.

The reaction mixture thus obtained was divided into two parts, 23 g (corresponding to about 2% by weight) of methyl chloride was added to one part (A), and nothing was added to the other part (B). Distillation was carried out for each reaction mixture (A> and (B), and the initial distillation up to a boiling point range of 60°C, the water distillation with a boiling point range of 79 to 81°C, the after-distillation with a boiling point range of 120 to 122°C, and the bottom residue. The composition of each fraction was investigated by gas chromatography.The results of fractional distillation are shown in Table 1, and the results of gas chromatography analysis are shown in Table 2.

Table 1 Table 2 (Note) TMS Nitrimethoxysilane QMS: Tetramethoxysilane Example 2 Methyl chloride was added to the reaction mixture obtained in the same manner as in Example 1 above, and 50% by weight of trimethoxysilane and tetramethoxysilane were added. 20% by weight of silane, 2% of unreacted methyl alcohol
The reaction mixture had a composition of 5% by weight, 1.5% by weight of methyl chloride, and 3.5% by weight of others.

This reaction mixture was filled into a stainless steel container with a calcium chloride pipe attached to the gas outlet and left at room temperature of 15 to 20°C, and gas chromatography analysis was performed every 20 days to determine whether trimethoxysilane and tetramethoxysilane were detected. Changes in the content over time were investigated. The results are shown in Table 3.

Test example l l11! 32 g of methyl alcohol and 4.6 g of methyl chloride (2,
9% by weight) and mixed to prepare a sample mixture.

Regarding this sample mixture, changes over time in the contents of trimethoxysilane and tetramethoxysilane were investigated in the same manner as in Example 2 above. The results are shown in Table 3.

Test Example 2 A sample mixture was prepared in the same manner as in Test Example 1 above, except that methyl chloride was not added, and changes over time in the contents of trimethoxysilane and tetramethoxysilane were investigated. The results are shown in Table 3.

= 15- Test Example 3 46 tj of ethyl alcohol and 6.39 ethyl chloride (2,9
% by weight> and mixed to prepare a sample mixture. Regarding this sample mixture, changes over time in the content of triethoxysilane and tetraethoxysilane were investigated in the same manner as in Example 2 above. The results are shown in Table 3.

Test Example 4 A sample mixture was prepared in the same manner as in Test Example 3 above, except that ethyl chloride was not added, and changes in the contents of triethoxysilane and tetraethoxysilane over time were investigated. The results are shown in Table 3.

Table 3 (Note) TMS Cotrimethoxysilane QMS: Tetramethoxysilane TES Nitriethoxysilane QES: Tetraethoxysilane [Effects of the Invention] According to the method of the present invention, trialkoxysilane in the reaction mixture containing unreacted alcohol can be The stability is significantly improved, and the recovery rate is significantly improved when distilling this to separate and purify trialkoxysilane, and it is also possible to easily obtain high-purity trialkoxysilane in good yield by distilling the reaction mixture. Can be done.

Claims (3)

[Claims] (1) Separation of trialkoxysilane characterized by allowing 0.0001 to 20% by weight of an organic halide to coexist in the reaction mixture when separating and purifying trialkoxysilane from a reaction mixture containing unreacted alcohol. Purification method. (2) The organic halide according to claim 1, wherein the organic halide is one or a mixture of two or more selected from alkyl halides, alkenyl halides, aryl halides, and quaternary alkylammonium halides. Separation and purification method for alkoxysilane. (3) the organic halide is an alkyl halide,
3. The method for separating and purifying trialkoxysilane according to claim 1 or 2, wherein the alkyl group is the same as the alkyl group of the trialkoxysilane.