JPH085899B2 - Method for producing alkoxysilane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a method for producing a trialkoxysilane, and more specifically, a reaction of silicon and an aliphatic alcohol in a solvent to give a high yield of trialkoxysilane. The present invention relates to a manufacturing method.

(3) Prior art Regarding the production method of alkoxysilane, 1) a method of synthesizing from chlorosilane and alcohol SiH _4-x Cl _x + _x ROH → SiH _4-x (OR) _x + xHCl (x = 1,2,3, 4) 2) Method of reacting silicon and alcohol in the presence of copper catalyst Si + ROH → SiH ₃ (OR) + SiH ₂ (OR) ₂ + SiH (OR) ₃ + Si (OR) ₄ + H ₂ is known. However, in the method 1), the by-product hydrochloric acid is corrosive, so that an expensive corrosion-resistant material is required, and chlorosilane as a raw material is easily hydrolyzed to liberate hydrochloric acid, which makes handling difficult. The method 2) allows reaction in the gas phase and liquid phase, but in the gas phase, SiH is considered to be useful because Si (OR) ₄ is preferentially produced among the various alkoxysilanes produced. It has the disadvantage that the yield of (OR) ₃ is low. On the other hand, in the liquid phase system, the selectivity of SiH (OR) ₃ is improved, but there is a drawback that the reaction rate of silicon is low and the reaction rate is slow.

(3) Problems to be Solved by the Invention Almost all of the production of alkoxysilanes in a liquid phase system uses copper, especially cuprous chloride as a catalyst, but the catalyst alone is active and the trialkoxysilane is selected. There is a problem that the rate is low. Co-catalysts have also been investigated in order to increase the activity and the selectivity of trialkoxysilane, but the examples are few and very limited. As an example of the cocatalyst, there is known a method of using a metal of zinc, aluminum or iron in a gas phase reaction (Japanese Patent Publication No. Sho 37-17967). It is only disclosed under the conditions described below. On the other hand, a method of using a metal or a metal compound of a subgroup element as a catalyst in a liquid phase reaction in some cases (Japanese Patent Publication No. 44-25768) is disclosed, but in principle, the reaction does not require addition of a catalyst And only the use of the catalyst alone is disclosed, not the combination of catalyst and cocatalyst.

This invention solves the problem that the catalyst alone has low activity and low selectivity to trialkoxysilane in a method for producing trialkoxysilane by reacting silicon and alcohol in a solvent in the presence of a copper catalyst. The purpose is to do.

(4) Means for Solving the Problems As a result of various studies on methods for obtaining trialkoxysilane with high activity and high selectivity, the present inventors have found that silicon and alcohol in a solvent in the presence of a copper catalyst. In the method of reacting, a copper catalyst, a periodic table, a first group, a second group, and a third group are used.
It was found that the presence of one or more of halogens, sulfuric acid, nitric acid, and phosphates of metals selected from the group greatly improves the activity and the selectivity of trialkoxysilane as compared with the reaction using the catalyst alone. The present invention has been completed. Silicon as a starting material in the method of the present invention has a purity of 80% or more and an average particle size of 1,000μ or less, preferably 500μ.
There is no particular limitation as long as it is crushed to the following average particle size, and a commercially available product may be used.

The aliphatic alcohol preferably contains an alkyl group having 1 to 5 carbon atoms, such as methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol, and among them, methyl alcohol and ethyl alcohol are preferable.

The copper catalyst used to carry out this reaction may be of the known type and may include metallic copper, cuprous chloride, cupric chloride.
Copper, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, copper formate, copper acetylacetonate, cuprous acetate,
Examples include copper compounds such as cupric acetate and cuprous oxide.
The copper catalyst is used in the range of 0.001 to 0.5 times mol per mol of silicon.

On the other hand, as a solvent, what is important is that it has high thermal stability and that finely divided silicon is dispersed in the solvent. For this purpose, polycyclic aromatic hydrocarbons, aryl methane compounds, Hydrogenated triphenyl, cyclic or chain polyether, dodecylbenzene, diphenyl ether organosilicon compound and the like are used as appropriate, and the amount used is in the range of 1 ml to 10 l per 1 g of silicon metal.

LiCl, NaCl, KCl, RbCl, NaBr, Nal, CaCl ₂ , AlCl ₃ as one or more metal halides, sulfates, nitrates, and phosphates that coexist with the copper catalyst.
Etc., sulfates such as K ₂ SO ₄ , Na ₂ SO ₄ , CaSO ₄ etc., nitrates such as Al (NO ₃ ) ₃ etc. as phosphates NaH ₂ PO ₄ , KH ₂ PO ₄ etc. However, the present invention is not limited to this. The halides, sulfates, nitrates and phosphates of these metals are
It may be allowed to be present in the reaction system in advance, or it is added by a method of being accompanied by feed alcohol. Furthermore, the amount used is 0.0001 to 0.2 mol per 1 mol of catalyst.
Preferably, it is appropriately determined from the range of 0.001 to 0.03 mol.

The reaction is carried out in the temperature range of 100 to 300 ° C. under reduced pressure, normal pressure or increased pressure.

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

(5) Examples Example 1 A 100 ml reactor equipped with a distilling pipe having a condenser, an alcohol introducing pipe, a stirrer and a thermometer was used to obtain silicon metal powder (purity: 9
8%) 20.0 g, cuprous chloride 1.0 g, and 40 ml of dimethyldiphenylsilane as a solvent were charged, and then when the internal liquid temperature reached 230 ° C by heating the reactor, methyl alcohol was added at a rate of 15 ml / hr. Was introduced at the same time, sodium chloride was simultaneously entrained in methanol, and the reaction was carried out at a reaction temperature of 228 to 232 ° C. After reacting for 5 hours, 69.30 g of distillate was obtained. From the analysis results, this was 28.56 g of methanol and 37.00 g of trimethoxysilane (53.4 g).
wt%) and 3.74 g (5.4 wt%) of tetramethoxysilane. The selectivity of trimethoxysilane was 92.5%, and the production rate was 0.18 g / ml · hr. The total amount of sodium chloride added after 5 hours was 0.015m per 1mol of cuprous chloride.
was ol.

Comparative Example 1 62.7 g of a distillate was obtained when the same apparatus as in Example 1 was used and the reaction was carried out for 5 hours under the same conditions except for the addition of sodium chloride. Based on the analysis results, this contained 42.90 g of methanol, 13.41 g (21.36 wt%) of trimethoxysilane, and 6.48 g (10.32 wt%) of tetramethoxysilane. The selectivity of trimethoxysilane was 66.9% and the production rate was 0.07 g. / ml ・ hr
Met.

Example 2 Except for changing the methyl alcohol of Example 1 to ethyl alcohol, the same reaction as in Example 1 was carried out. 5h
The reaction result after r shows that the selectivity of triethoxysilane is 94.5.
%, The production rate was 0.18 g / ml · hr.

Comparative Example 2 Example 1 except that the methyl alcohol of Example 1 was changed to ethyl alcohol and the addition of sodium chloride was omitted.
After reacting for 5 hours in the same manner as above, the selectivity of triethoxysilane was 63.2%, and the production rate was 0.07 g / ml · hr.

Examples 3 to 13 The same reaction conditions as in Example 1 were carried out except that the sodium chloride of Example 1 was changed to various metal salts shown in Table 1. The amount of the cocatalyst used was 0.015 mol per 1 mol of cuprous chloride as in Example 1, and the results after 5 hours of reaction are shown in Table 1.

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Claims (1)

[Claims] 1. A method of reacting silicon with an aliphatic alcohol in a solvent, wherein a copper catalyst and one or more selected from halogen, sulfuric acid, nitric acid and phosphoric acid are selected from the groups 1 and 2 of the periodic table. A method for producing a trialkoxysilane, which comprises reacting in the presence of a metal salt of a metal selected from Group 3 and Group 3.