JPS60252488A - Method for purifying trialkoxysilane - Google Patents

Abstract

PURPOSE:To separate and purify a trialkoxysilane efficiently without using a neutralizing agent, by treating a mixture containing the trialkoxysilane and an alcohol with a specific extractant. CONSTITUTION:A mixture containing a trialkoxysilane and an alcohol is extracted with an extractant consisting of an organic solvent, preferably a (di) alkylbenzene or mineral spirit, capable of forming two phases from the above- mentioned mixture and/or an organopolysiloxane, preferably chain dimethylpolysiloxane to give the aimed trialkoxysilane. The extractant preferably has <=1,000 cSt kinematic viscosity.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for purifying trialkoxysilane, and more specifically, a method for efficiently separating and purifying trialkoxysilane from a mixture of trialkoxysilane and alcohol. It's about how to do it.

[Conventional technology]

Trialkoxysilane is usually obtained by reacting trichlorosilane with an alcohol or by directly reacting silicon metal with an alcohol using a copper salt as a catalyst (Japanese Unexamined Patent Publications No. 117723/1982, No. 3944/1983)
Publication No. 2). These methods yield mixtures of trialkoxysilanes containing hydrogen chloride and alcohol. Since trialkoxysilane is not stable in the mixture and decomposes sequentially, it is necessary to efficiently separate and purify trialkoxysilane. Conventionally, as a separation and purification method, there is a method in which a neutralizing agent is added and then distilled (Japanese Patent Application Laid-open No. 54-4
No. 4619, Japanese Patent Application Laid-open No. 47931, Pl.
asticheskie Massy 125 (196
3)). In this method, depending on the combination of l-realkoxysilane and alcohol, it may not be possible to purify it to a certain concentration by distillation alone due to the formation of an azeotrope, or the decomposition of the trialkoxysilane may be accelerated due to heating. There is a problem.

[Problem that the invention seeks to solve]

As a result of research aimed at solving these problems and establishing a method for efficiently separating and purifying trialkoxysilane from a mixture containing trialkoxysilane and alcohol, the present inventor found that a certain shaft side was used. The present inventors have discovered that trialkoxysilane can be separated not only from alcohol but also from hydrogen chloride without using a neutralizing agent, exhibiting an excellent extraction effect.

[Means to solve the problem]

That is, the object of the present invention is to extract trialkoxysilane from a mixture containing at least trialkoxysilane and alcohol using the shaft side consisting of an organic solvent or organopolysiloxane or a mixture thereof that forms two phases with the mixture. This is achieved by extracting the .

The configuration and effects of the present invention will be specifically explained below.

In the present invention, a mixture containing at least trialkoxysilane and alcohol refers to a reaction mixture obtained by reacting trichlorosilane and alcohol, particularly a reaction mixture obtained by reacting 3 or more equivalents of alcohol with 1 equivalent of trichlorosilane. There are also mixtures obtained by directly reacting silicon metal and alcohol using a copper salt as a catalyst. These mixtures often contain hydrogen chloride, tetraalkoxysilane, etc. in addition to trialkoxysilane and alcohol. Alternatively, it may be a mixture containing trialkoxysilane recovered in a form containing alcohol from a reaction solution using trialkoxysilane.

When extracting a mixture containing at least trialkoxysilane and alcohol, the higher the concentration of trialkoxysilane in the mixture, the higher the extraction efficiency.
It is preferably 5 wt% or more.

The shaft side used in the present invention is an organic solvent or an organopolysiloxane, which forms a liquid phase under the conditions of the extraction operation and forms a two-phase with a mixture containing at least trialkoxysilane and alcohol. It is a mixture of

Any organic solvent or organopolysiloxane can be used as long as it forms two phases with the mixture containing at least trialkoxysilane and alcohol; however, in actual use, the amount of trialkoxysilane in the mixture It is necessary to select appropriately depending on the type and content t, and the type and content of alcohol.

Specific examples of the organic solvent and organopolysiloxane are detailed below.

Examples of organic solvents include chain or cyclic saturated and unsaturated aliphatic hydrocarbons, and aromatic hydrocarbons having a chain or cyclic aliphatic hydrocarbon group in their side chains. Further, they may have characteristic groups such as fluoro, chloro, hydroxyl, alkoxy, cyano, and nitro in their molecules.

The A-isomers include n-pentane, n-hexane, n-decane, n-hexadecane, cyclohexane, methylcyclohexane, cyclooctane, l-decene, l-hexadecene, n-hexylbenzene, dihexylbenzene, lauryl. Examples include compounds such as benzene, cyclohexylbenzene, hexyldiphenyl, and lauryldiphenyl, but these compounds need not be a single compound, and include petroleum ether, ligroin, kerosene, mineral spirits, liquid paraffin, etc. Mixtures of various compounds such as mixtures mainly composed of aliphatic hydrocarbons and alkylbenzene mixtures and dialkylbenzene mixtures having linear and cyclic aliphatic hydrocarbon groups in their side chains are used. The molecule may contain characteristic groups such as fluoro, chloro, hydroxyl, alkoxy, cyano, and nitro.

Particularly preferred are aromatic hydrocarbons having linear or cyclic aliphatic hydrocarbon groups in their side chains, such as alkylbenzenes, dialkylbenzenes, alkyldiphenyls, laurylbenzenes, and mixtures thereof, mineral spirits, liquid paraffins, etc. Mention may be made of mixtures consisting primarily of aliphatic hydrocarbons.

As the organopolysiloxane, the most commonly used chain dimethylpolysiloxane having a trimethylsilyl group at the end is preferably used. Further, cyclodimethylpolysiloxane in which the siloxane skeleton forms a ring, and dimethylpolysiloxane in which the siloxane skeleton is chain-like and has branches in the siloxane skeleton can also be used. Furthermore, in addition to methyl groups, the organic group bonded to silicon is a hydrocarbon group such as an ethyl group, octyl group, vinyl group, or aryl group, or a carbonization group having a heteroatom such as a trifluoroalkyl group or a polyalkyleneoxyalkyl group. Provisions for hydrogen groups can also be used.

Specifically, linear and cyclic dimethylpolysiloxane,
diluted and cyclic methylphenylpolysiloxane, diluted and cyclic diphenylpolysiloxane, chain dimethylpolysiloxane having a trifluoroalkyl group in the side chain,
Examples include chain dimethylpolysiloxane having an alkylaralkyl polyether group in its side chain, and chain dimethylpolysiloxane having a polyether group in its side chain.

Particularly preferred are dimethylpolysiloxane and chain dimethylpolysiloxane having a trifluoroalkyl group in the side chain.

It is also preferable to use a mixture of these organopolysiloxanes and the above-mentioned organic solvents in an appropriate ratio.

The organic solvent, organopolysiloxane, or mixture thereof used as an extraction agent should not have a viscosity that is too high for the purpose of extraction, and the kinematic viscosity at 20°C is preferably 10,000<S+ or less, particularly preferably. 1,
000 cst or less.

The amount of oil used in the present invention can be selected as appropriate, but is 0.1 to 10.0 parts by weight per 1 part by weight of the mixture containing at least motorkoxysilane and alcohol in one extraction. It is appropriate to use 1 part by weight, and more preferably 0.25 to 4.0 parts by weight.

As for extraction operation methods, it is advantageous to use methods such as multiple extraction and countercurrent extraction.In particular, if a more efficient method such as countercurrent extraction is used, multiple extractions can be performed with a smaller amount of plowing agent used. The same efficiency can be obtained, which is advantageous when processing large quantities industrially.

In the extraction operation in the present invention, a wide range of conditions can be selected within the range in which the trialkoxysilane, alcohol, and extractant are in a liquid state.

For example, operation under reduced pressure and high pressure, high temperature by heating,
Operation at low temperatures by cooling can also be carried out. However, from the viewpoint of ease of operation and simplicity of equipment, operation at room temperature and around normal pressure is advantageous.

In the present invention, it is preferable to add inorganic and organic salts as salting-out agents to the extraction system, which has the effect of improving the trialkoxysilane/alcohol ratio in the extraction phase. Various salts can be used as salting out agents, but at 20°C
If the concentration of the saturated solution in alcohol is Q, l w
t% or more, specifically lithium chloride, lithium bromide, lithium iodide, sodium chloride,
Sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, ammonium chloride, ammonium bromide, ammonium iodide, ammonium nitrate, cesium chloride, magnesium chloride, magnesium bromide, sodium formate, potassium formate, sodium acetate , potassium acetate, sodium propionate, potassium propionate, sodium butyrate, potassium butyrate, sodium benzoate, potassium benzoate, ammonium acetate, and sodium benzenesulfonate. When the specialized trialkoxysilane is trimethoxysilane and the alcohol is methanol, sodium bromide, sodium iodide, and potassium iodide are preferred, and the trimethoxysilane/methanol-iV ratio is significantly improved.

The salting-out agent can be used in any amount, but even if it is added in an amount greater than the saturated dissolution amount in the extraction system, there is no further effect, and it is preferable to use an amount near or below the saturated dissolution amount.

The effect of the extraction according to the present invention is that not only can trialkoxysilane be separated from alcohol, but if the mixture contains hydrogen chloride, it can be separated by extraction as in Example 4 without adding a neutralizing agent.

The trialcoxin run fraction 11i from the phase phase is easily achieved by known methods such as distillation. In particular, when the trialkoxysilane has a low boiling point and the extractant has a significantly high boiling point, the separation is preferably carried out by distillation under reduced pressure.

The extractant from which the trialkoxysilane has been separated can be recycled and reused without any treatment or after an appropriate treatment.

〔Effect of the invention〕

According to the present invention, trialkoxysilane can be efficiently separated and purified from a mixture containing trialkoxysilane and alcohol.

EXAMPLES The present invention will be specifically described below with reference to examples, but the following examples are intended to explain some examples of the present invention and are not intended to limit the scope of the claims.

〔Example〕

Example 1 A 35 wt% methanol solution of trimethoxysilane 3y and an extractant 6f shown in Table 1 were placed in a test tube with a capacity of 30 ml, and a shaker (trade name: PT Shaker manufactured by Ikemoto Rika Kogyo Co., Ltd.) was prepared.
was shaken vigorously for 3 minutes. After being allowed to stand for 2 hours after shaking, the extract phase and raffinate phase were separated, and trimethoxysilane and methanol in the extract phase were analyzed by gas chromatography. The results are shown in Table 1.

Table 1 *Product name 5) 1200 Kinematic viscosity 100cS (25℃)
1.-Re Silicone C Wa Seicha 2 Commercial Electric 3 Commercial Thread 4 Commercial *5 Product Name Sum-S 800 // 20 // (2
0°C) Nippon Steel Chemical Example 2 7 wt%, 15 wt%, 25 wt% and 3.5 wt%
A methanol solution of trimethoxysilane was prepared, 3 f of each was added to a 30 g/capacity test tube, and 6 f of extractant dialkylbenzene was added, and the solution was shaken, allowed to stand, separated, and analyzed in the same manner as in Example 1. The results are shown in Table 2.

Table 2 Example 3 Four systems were extracted using dialkylbenzene and laurylbenzene as extraction agents, using the same preparation as in Example 1, and adding 0.3f and 0.91 of sodium iodide, respectively. The results are shown in Table 3.

Table 3 Example 4 Methanol solution of 38wt96 trimethoxysilane containing hydrogen chloride (719F) 3f' x volume 30 ml
In addition to the above test tubes, six extractants shown in Table 4 were added to each test tube, and the extraction phase was analyzed in the same manner as in Example 1. The amount of hydrogen chloride in the extraction phase was analyzed by potentiometric titration 88 using a 25/100 OON silver nitrate aqueous solution. The results are shown in Table 4.

Table 4 ※※A, Chemical analysis vol 41A by Lee Sm1th
Analysis of 5ilicones Job
VVily & 5ons (1974) See page 133 Example 5 Add 30F methanol solution of 35.6 wt% trimethquinsilane and dialkylbenzene 601 to a 100 ml separatory funnel, shake vigorously for 7 minutes, and rest for 3 hours after shaking. After standing, the extraction phase and raffinate phase were separated. The extracted phase was added to a heart-shaped distillation flask with a capacity of 100 ml, and the distillation receiver was distilled at 10 mHf for 20 minutes at room temperature while cooling the distillation receiver to -78°C with dry ice-acetone, and then further distilled at 2 f.
Distilled at fHf for 60 minutes and analyzed the distillate by gas chromatography, it was found that trimethoxysilane was 5.551 (52.0% of the charge) and methanol L was 54f (the ratio of trimethoxysilane/methanol in the distillate was 78.3/
2L7).

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Scope of Claims] (1) Trialkoxysilane is extracted from a mixture containing at least trialkoxysilane and alcohol using an extractant consisting of an organic solvent that forms two phases with the mixture, organopolysiloxane, or a mixture thereof. A method for purifying trialkoxysilane, which is characterized by extracting. (2) The method for purifying trialkoxysilane according to claim (1), wherein the trialkoxysilane is trimethoxysilane or dinosilane. (3) The method for purifying trialkoxysilane according to claim II (1), wherein the alcohol is methanol. (4) The method for purifying trialkoxysilane according to claim (1), wherein the trialkoxysilane is trimethoxysilane and the alcohol is methanol. (6) Claim No. 1 in which the organic solvent is a hydrocarbon
) The method for purifying trialkoxysilane described in section 2.