JPH06306083A - Production of trialkoxysilane - Google Patents

Abstract

PURPOSE:To produce a trialkoxysilane from a metallic silicon and an alcohol in the presence of a copper alkoxide-based catalyst in high selectivity even under reactional temperature conditions for obtaining high reactional rate. CONSTITUTION:This method for producing a trialkoxysilane is carried out in the presence of a sulfur compound together with a copper alkoxide-based catalyst in the reaction system in reacting a metallic silicon with an alcohol in the presence of the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing trialkoxysilane useful as a raw material for silane coupling agents and the like.

[0002]

Trialkoxysilane has a highly reactive silicon-hydrogen bond and is easily added to various olefins or acetylenes. Therefore, compounds having various functions such as silane coupling agents can be produced. It is a compound useful as a raw material.

A method for producing trialkoxysilane is known, and it can be produced by reacting metallic silicon and alcohol in the presence of a catalyst. At that time, as the catalyst, copper chloride, or a copper alkoxide (Japanese Patent Application No. 354055) found by the present inventors is used.

However, when a copper chloride catalyst is used, it is necessary to react at a high temperature of 250 ° C. or higher in order to obtain an industrial reaction rate, which is an energy disadvantage. Moreover, the use of a copper chloride catalyst has a problem of increasing the amount of chlorine mixed in the product.

On the other hand, in the case of the copper alkoxide catalyst, the reaction rate is higher than that of the copper chloride catalyst at the same reaction temperature, but the selectivity tends to decrease as the reaction temperature increases. Therefore, under the reaction temperature conditions necessary to obtain a reaction rate that is industrially feasible, the selectivity becomes significantly low. There was a problem that the speed was not sufficient.

[0006]

Therefore, the present invention is to produce trialkoxysilane from metal silicon and alcohol with a high selectivity under the reaction temperature conditions for obtaining a high reaction rate which is industrially feasible. The purpose is to provide a method of doing.

[0007]

Means for Solving the Problems As a result of repeated studies on the improvement of the selectivity of trialkoxysilane in the case of using a copper alkoxide-based catalyst, the present inventors have found that when a sulfur compound is added to the reaction system, high reaction is achieved. The inventors have found that the desired trialkoxysilane can be obtained with a high selectivity even under the reaction temperature condition that the rate is obtained, and have reached the present invention.

That is, the present invention is a method for producing trialkoxysilane by reacting metallic silicon and alcohol in the presence of a catalyst, wherein a copper alkoxide catalyst is used as the catalyst and a sulfur compound is added to the reaction system. There is a method characterized by making it exist.

The alcohol used in the present invention is preferably a lower alkyl alcohol, particularly preferably methanol or ethanol. The alcohol is preferably supplied at 0.1 to 20 mol / hour, and more preferably 0.5 to 5 mol / hour with respect to 1 mol of metal silicon.

As the copper alkoxide catalyst used in the present invention, any of (a) copper alkoxide, (b) copper alkoxide and metal halide, or (c) alkoxy copper halide can be used.

(A) The copper alkoxide is preferably of the following formula
It is a copper alkoxide represented by Cu (OR) ₂ (wherein R represents an alkyl group having 1 to 10 carbon atoms). The alkyl group of R may be linear or branched. As such an alkyl group, for example, a methyl group,
Ethyl group, propyl group, butyl group, isobutyl group, sec-
Butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group,
A decyl group and the like can be mentioned.

As the copper alkoxide in the copper alkoxide and the metal halide (b), the above-mentioned copper alkoxide can be similarly used. Further, the metal halide is, for example, MX _n (where M is the fourth group of the periodic table group 4 to group 16).
X is a halogen selected from F, Cl, Br and I, and n = 1 to 5, provided that when n is 2 or more, X may be the same or different). Indicated by. Specific examples of preferable metal halides include, for example, TiCl ₄ , VCl ₃ , CrCl ₃ and M.
nBr ₂ , FeCl ₂ , FeCl ₃ , CoBr ₂ , Co
Cl ₂ , CoI ₂ , NiCl ₂ , CuCl, CuC
l ₂ , ZnBr ₂ , GaCl ₃ , GeI ₄ , ZrC
l ₄ , NbCl ₅ , MoCl ₅ , MoBr ₃ , PdCl
₂ , CdCl ₂ , InCl ₃ , InF ₃ , SnCl ₂ ,
SnCl ₄ , SnI ₂ , SnF ₂ , SbCl ₃ , SbC
l ₅ , TeCl ₄ , BiCl ₃ , BiBr ₃ , OsCl
₃ , PbF ₂ , PbCl ₂ , PbI _{2 and the} like.
The metal halide may be a hydrate or an anhydride, but is preferably an anhydride.

Alkoxy copper halides are, for example, CuX
(OR) (where X and R are as defined above)
Indicated by. Such an alkoxy copper halide can be produced by the method described in, for example, Journal of Inorganic and Nuclea Chemistry (J. Inorg. Nucl. Chem.), Vol. 27, p. 59 (1965). The alkoxy copper halides can be used alone, but can also be used with the above-mentioned copper alkoxides or with the above-mentioned metal halides.

The ratio (molar ratio) of metal halide to copper alkoxide in the catalyst is preferably 0.001 to 10, more preferably 0.01 to 1 in the case of the above (b). In the case of (c) above, the ratio is necessarily 1 when the alkoxy copper halide is used alone. When using an alkoxy copper halide with a copper alkoxide,
1 mole of copper alkoxide for 1 mole of alkoxy copper halide
It is preferably used in an amount of up to 00 moles, and when an alkoxy copper halide is used with a metal halide, 20 moles of metal halide per mole of alkoxy copper halide.
It is preferably used in amounts up to molar.

The catalyst is used as a metal in an amount of preferably 0.001 to 0.1 mol, more preferably 0.005 to 0.05 mol, based on 1 mol of metal silicon.

The method of the present invention is characterized in that a sulfur compound is present together with the copper alkoxide catalyst in the reaction system. Examples of such sulfur compounds include R
SH, RSR 'or RSSR' (wherein R and R'may be the same or different and are a C _{1 to} C ₂₀ chain alkyl group, an optionally substituted phenyl group, a cyclohexyl group or a hydrogen atom) A compound represented by
Examples include cyclic sulfur-containing compounds. Alternatively, a metal complex having RS- as a ligand can also be used. Specifically, for example, methyl mercaptan, ethyl mercaptan, butyl mercaptan, phenyl mercaptan, cyclohexyl mercaptan, dimethyl sulfide, diethyl sulfide, diphenyl sulfide, dimethyl disulfide, diethyl disulfide, dicyclohexyl disulfide, diphenyl disulfide; ethylene sulfide, thiophene, benzothiophene And sulfur-containing heterocyclic compounds such as bis (4-methylthiophenol) copper (II). Such a sulfur compound is preferably used in an amount of 0.001 to 10 mol, more preferably 0.1 to 1 mol, based on 1 mol of copper of the copper alkoxide used as the catalyst. The method for adding such a sulfur compound to the system is not particularly limited, but for example, in the case of (1) a reaction in which alcohol is continuously supplied, a method of dissolving in alcohol and continuously charging, (2) When the sulfur compound is a solid at room temperature, it may be used by mixing it with a catalyst, or (3) adding an appropriate amount when the selectivity decreases (during the reaction).

In the method of the present invention, the reaction can be carried out in the gas phase or the liquid phase. When it is performed in the gas phase, for example, it is performed as follows. First, a touch body is prepared. As the method, for example, metal powder and a catalyst powder are physically mixed, or the catalyst is dissolved in a ketone solvent such as dimethyl ketone, and the metal silicon powder is added to the solution, followed by decompression. A method of evaporating to dryness can be mentioned. The thus-obtained contact body is usually at atmospheric pressure and under the condition of 130 to 300 ° C., several liters of an inert gas such as helium, hydrogen or a mixed gas of an alcohol used in the reaction and an inert gas such as helium. / Hour (normal temperature, atmospheric pressure conversion value) for several tens of minutes to several hours for pretreatment. The contact body is contacted with alcohol vapor. As the contact method, any of a fixed bed method, a moving bed method, a fluidized bed method, etc. can be adopted. In some cases, the alcohol vapor and the contact body can be brought into contact with each other in a batch manner. The contact time between alcohol vapor and contact is
At room temperature and pressure, gas space velocity (GHSV) 20,000-
1,000 hours- ¹ is preferred. The reaction temperature is preferably 100
~ 300 ° C, more preferably 150-220 ° C,
The reaction may be carried out under normal pressure or under pressure. The reaction temperature and pressure can be appropriately selected from the range in which the system can be kept in the gas phase.

When the reaction is carried out in the liquid phase, silicon metal and alcohol are reacted in a solvent in the presence of the above-mentioned catalyst. As the solvent, paraffin hydrocarbons such as decane, dodecane and pentadecane, and alkylbenzene hydrocarbons such as diethylbenzene and dodecylbenzene can be preferably used. It is preferable that alcohol is supplied at a reaction temperature of 100 to 250 ° C. at a rate of 0.1 to 5 mol / hour per 1 mol of metal silicon for the reaction.

The present invention will be described in more detail by the following examples.

[0020]

【Example】

Example 1 Metallic silicon (manufactured by Towa Kako Co., Ltd., purity 98.5%,
0.1 g of copper (II) methoxide (manufactured by Aldrich Co.) was added to 1.0 g of the material which had been sieved to 63 to 106 μm and washed with ion-exchanged water, and mixed sufficiently to obtain a contact body.

1.0 g of this contact body was filled in a Pyrex glass fixed bed reactor having an inner diameter of 10 mm, and then the reactor was set to 1
After heating to 30 ° C., helium gas was passed for 10 minutes at 1.0 liter / hour (normal temperature, atmospheric pressure conversion value). Then, the partial pressure of methanol was set to 56 kPa, and methanol containing 0.2 mol% of thiophene was fed to the reactor at a feed rate of 38 mmol / hour with a micro feeder, and the temperature was increased from 130 ° C. to about 30 minutes. The reactor at 190 ° C
And the touch body was pretreated.

Next, trimethoxysilane was produced in the gas phase. The reaction conditions are a reaction temperature of 190 ° C. and a reaction pressure of 1
It was atm. The reaction product was analyzed every 5 minutes by gas chromatography connected to the outlet of the reaction tube. As a result, the conversion of metal silicon was 75% and the selectivity of trimethoxysilane was 92% after 6 hours from the start of supplying the thiophene-containing methanol. The main product other than trimethoxysilane was tetramethoxysilane. The contact time with the methanol vapor of the contact body was 2,300 hours ^-1 in gas space velocity (GHSV) (normal temperature, normal pressure conversion value). Example 2 The reaction was carried out under the same conditions as in Example 1 except that cyclohexyl mercaptan was used instead of thiophene. As a result, the conversion rate of metallic silicon was 68% and the selectivity of trimethoxysilane was 91% 6 hours after the start of feeding the methanol containing cyclohexylmercaptan. The main product other than trimethoxysilane was tetramethoxysilane. Example 3 The reaction was performed under the same conditions as in Example 1 except that diethyl sulfide was used instead of thiophene. As a result, the conversion rate of metallic silicon was 71% and the selectivity of trimethoxysilane was 91% 6 hours after the start of feeding the methanol containing diethyl sulfide. The main product other than trimethoxysilane was tetramethoxysilane. Example 4 Example of Sulfur Compound Sequential Addition The reaction was performed under the same conditions as in Example 1 except that methanol was used instead of thiophene-containing methanol, but the products were sequentially traced by gas chromatography to select trimethoxysilane. Was lower than 60%, that is, 2 hours after starting the feeding of methanol, thiophene was injected from the upper part of the reactor by a microsyringe in an amount of 0.3 mol based on 1 mol of copper in the catalyst. The addition of thiophene restored the selectivity of trimethoxysilane to 90% or more. After continuing the reaction for a while, the selectivity of trimethoxysilane is 60.
When it fell below%, thiophene was added again in the same manner. This operation was repeated 5 times. As a result, 7 hours after the start of feeding methanol, the total amount of thiophene added was 2.3 mol based on 1 mol of the catalyst copper. At this time, the conversion rate of metal silicon was 81% and the selectivity of trimethoxysilane was 79%. The main product other than trimethoxysilane was tetramethoxysilane. Example 5 Example of mixing sulfur compound with catalyst Metallic silicon (similar to that used in Example 1) 1.0 g
To the above, 0.1 g of copper (II) methoxide (manufactured by Aldrich) and 0.04 g of diphenyl disulfide (0.25 mol per 1 mol of copper) were added and sufficiently mixed to obtain a contact body.

Thereafter, the contact body was treated in the same manner as in Example 1, and then reacted with methanol under the same conditions. As a result, the conversion rate of metallic silicon was 62% and the selectivity of trimethoxysilane was 9% after 7 hours from the start of supplying methanol.
It was 2%. The main product other than trimethoxysilane was tetramethoxysilane. Example 6 Example in which sulfur compound was mixed with catalyst First, bis (4-methylthiophenol) was prepared from 4-methylthiophenol sodium salt and cupric chloride by a conventional method.
Copper (II) was synthesized. The elemental analysis value (%) is C 5
3.96, H 4.51, S 20.58 and Cu
20.95 (theoretical value: C 54.26, H
4.55, S 20.69 and Cu 20.5).

Next, to 1.0 g of metallic silicon (similar to that used in Example 1), 0.1 g of copper (II) methoxide (manufactured by Aldrich) and bis (4-methylthiophenol) copper (synthesized above) II) 0.024 g (0.1 mol per 1 mol of copper) was added and mixed sufficiently to obtain a contact body.

Thereafter, the contact body was treated in the same manner as in Example 1, and then reacted with methanol under the same conditions. As a result, the conversion of metallic silicon was 68% and the selectivity for trimethoxysilane was 8 after 7 hours from the start of supplying methanol.
It was 5%. The main product other than trimethoxysilane was tetramethoxysilane. Comparative Example 1 The reaction was carried out under the same conditions as in Example 1 except that methanol was used instead of thiophene-containing methanol. As a result, the conversion rate of metallic silicon after 6 hours from the start of supplying methanol was 94%.
And the selectivity of trimethoxysilane was 20%. The main product other than trimethoxysilane was tetramethoxysilane. Comparative Example 2 The reaction was carried out under the same conditions as in Comparative Example 1 except that the reaction temperature was changed from 190 ° C to 180 ° C. As a result, the conversion rate of metallic silicon was 50% and the selectivity of trimethoxysilane was 92% after 6 hours from the start of supplying methanol. The main product other than trimethoxysilane was tetramethoxysilane.

[0026]

Industrial Applicability According to the method of the present invention, trialkoxysilane can be produced in the presence of a copper alkoxide catalyst with a high selectivity even under a reaction temperature condition for obtaining a high reaction rate. Further, since no chlorine-based catalyst is used, there is no problem of chlorine being mixed in the product. Therefore, the method of the present invention is industrially highly useful.

Claims (1)

[Claims] 1. A method for producing trialkoxysilane by reacting metallic silicon and alcohol in the presence of a catalyst, wherein a copper alkoxide catalyst is used as the catalyst, and a sulfur compound is present in the reaction system. How to characterize.