JP3119110B2 - Co-production method of dimethylchlorosilane and trimethylchlorosilane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrially advantageous method for co-producing dimethylchlorosilane and trimethylchlorosilane, which can easily obtain dimethylchlorosilane and trimethylchlorosilane simultaneously under mild conditions using inexpensive raw materials. Things.

[0002]

2. Description of the Related Art Dimethylchlorosilane is a monomer material occupying an important position in the silicone industry, for example, silicone oil or silicone resin having a Si--H bond at one end or in the main chain. It is known as an important compound that is used as a raw material or as an intermediate for synthesizing organosilicon compounds such as various silylating agents.

Conventionally, as a method for producing dimethylchlorosilane, when dimethylchlorosilane is obtained by a direct method, there is a method in which dimethylchlorosilane is isolated by rectification from by-products obtained together with hydrocarbons and the like in low-boiling components. Are known. However, this method has the disadvantage that the process time is long and that only a small amount of dimethylchlorosilane can be obtained.

[0004] A production method using tetramethyldisiloxane as a raw material has also been proposed. However, tetramethyldisiloxane is obtained by cracking an oil containing a Si-H bond, so that the process time becomes longer and Si cracking occurs during cracking.
-There is a risk of H-bond cleavage.

Further, a method of reacting pentamethylchlorodisilane with dry hydrogen chloride at a high temperature for synthesis (Industrial Scientific Magazine 60, 1395 (1957)), or irradiating polydimethylsilane with ultraviolet light while passing hydrogen chloride through A method of synthesizing dimethylsilane by reacting hydrogen chloride with dimethylsilane (Chem. Comm., 507 (1970)) has been reported, but these methods are expensive in raw materials and not industrially common. .

Further, JP-A-53-95922 discloses that dialkyldichlorosilane can be converted to sodium borohydride or sodium in N, N, N ', N', N ", N" -hexamethylphosphortriamide. Reduced with borohydride and sodium hydride,
A method for obtaining dialkylmonochlorosilane has been proposed, but in recent years, it has been revealed that N, N, N ', N', N ", N" -hexamethylphosphortriamide is a potent carcinogen. Therefore, it has become industrially impossible to adopt this method.

In addition, a method of hydrogen-decomposing chlorine in the Si—Cl bond of chlorosilane using a hydrogenolysis reagent for lithium aluminum hydride can be considered. However, even if dialkyldichlorosilane is reduced using such a reducing agent, All two chlorine atoms are hydrogen-decomposed into dialkylsilane, and dialkylmonochlorosilane cannot be obtained.

As a method for obtaining dimethylchlorosilane from methyldichlorosilane as a raw material, a method of methylating a Si—Cl bond by using a Grignard reagent is generally considered. It is impossible to selectively obtain only dimethylchlorosilane, and a complicated operation of separating and purifying from various methylsilanes after completion of the reaction is required.

On the other hand, as a method for obtaining trimethylchlorosilane, other than the direct method, a method of synthesizing dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane using a Grignard reagent is generally used. Since by-products of tetramethylsilane are large, it is impossible to selectively obtain only trimethylchlorosilane, and a complicated operation of separating and purifying from various methylsilanes after completion of the reaction is required.

Further, Z. Anorg. Allgem. C
hem. According to 287, 273 (1956), methylation reaction of tetrachlorosilane or methyltrichlorosilane is attempted using methylaluminum sesquichloride, but this method is obtained as a mixture of various methylsilanes, and only trimethylchlorosilane is selectively obtained. Not obtained as a single component.

Further, methyl hydrogen dichlorosilane and methyl chloride are mixed with metallic
It is known that trimethylchlorosilane can be obtained at a composition ratio of 81.7% by passing at 450 ° C. (Japanese Patent Publication No. 57-30114). However, this method requires high temperature conditions, and furthermore has a drawback with a great danger that aluminum chloride as a by-product is easily clogged in a flow system.

Further, a method of obtaining trimethylchlorosilane by passing hydrogen chloride gas from tetramethylsilane as a raw material in the presence of a Friedel-Crafts catalyst (Japanese Patent Application Laid-Open No.
No. 92895) and a method of obtaining trimethylchlorosilane by a distribution reaction using tetramethylsilane and dimethyldichlorosilane as raw materials in the presence of a Friedel-Crafts catalyst (Japanese Patent Laid-Open No. 55-61195). In order to obtain tetramethylsilane, it is necessary to perform a synthesis reaction in a previous step, and therefore, a combination of two synthesis steps is required, resulting in poor production efficiency.

The present invention has been made in view of the above circumstances, and is an industrially advantageous dimethyl compound which can synthesize dimethylchlorosilane and trimethylchlorosilane simultaneously and inexpensively and easily without a risk. An object of the present invention is to provide a method for co-production of chlorosilane and trimethylchlorosilane.

[0014]

The present inventors have made intensive studies to achieve the above object, and as a result, have found that methyldichlorosilane and dimethyldichlorosilane can be combined with methyl chloride in the presence of metallic aluminum or an aluminum alloy. The inventors have found that dimethylchlorosilane and trimethylchlorosilane can be co-produced with good yield simply and without danger by the reaction, and the present invention has been accomplished.

Accordingly, the present invention provides a method for co-production of dimethylchlorosilane and trimethylchlorosilane, which comprises reacting methyldichlorosilane and dimethyldichlorosilane with methyl chloride in the presence of aluminum metal or an aluminum alloy. .

Hereinafter, the present invention will be described in more detail. As methyldichlorosilane and dimethyldichlorosilane used as raw materials in the method of the present invention, those obtained by a known method can be used. What is easily obtained as can be used.

On the other hand, as metal aluminum and aluminum alloy, for example, Al, AlMgSi, AlCu
Mg and the like can be mentioned. The aluminum alloy preferably contains aluminum in an amount of 85% by weight or more.

In this case, the metal aluminum and the aluminum alloy react sufficiently even if they are used as they are without being activated, but they are usually activated in advance because their surfaces are usually covered with an oxide film. Is preferred. As a method for the activation, a method of flowing anhydrous hydrogen chloride gas at about 60 to 150 ° C., or a method of heating by mixing with iodine pieces is preferable. In addition, ethyl bromide or bromide dispersed in raw material chlorosilane is preferable. A method of activating by adding ethylene, iodine or the like can also be employed.

The amount of the above-mentioned methyldichlorosilane to be used is preferably 0.25 to 1.5 mol, more preferably 0.5 to 1.2 mol, per 1 mol of dimethyldichlorosilane. If the amount of methyldichlorosilane used is less than 0.25 mol, unreacted raw materials may remain in large quantities, and if it is more than 1.5 mol, trimethylsilane by-products may increase.

The amount of the metal aluminum or aluminum alloy used is preferably 0.7 to 2.5 mol, particularly preferably 1.0 to 1.5 mol, per mol of dimethyldichlorosilane. If the amount is less than 0.7 mol, the amount of unreacted raw materials will increase, and if it exceeds 2.0 mol, trimethylsilane by-product may increase.

The above reaction can be usually carried out by introducing metallic aluminum or an aluminum alloy into a mixed solution of dimethyldichlorosilane and methyldichlorosilane, and feeding methyl chloride in an autoclave. Alternatively, metal aluminum or an aluminum alloy may be introduced into dimethyldichlorosilane, methyl chloride may be fed in an autoclave, and then methyldichlorosilane may be introduced and stirred. The reaction temperature in this case is preferably 30 to 150 ° C, particularly preferably 50 to 100 ° C. The reaction time is usually 5 to 20 hours.

In the production method of the present invention, the reaction may be carried out at normal pressure or in an autoclave using a solvent. Examples of the solvent used in this case include toluene, ethyl acetate, decane, o-xylene and the like. be able to.

After completion of the reaction, dimethylchlorosilane and trimethylchlorosilane can be obtained by distilling the reaction solution directly or by distilling after filtering. The thus obtained dimethylchlorosilane and trimethylchlorosilane can be separated by a conventional method. In addition, the still residue or the filter cake after filtration is directly distilled,
Aluminum chloride and a small amount of unreacted aluminum. The aluminum chloride can be recovered by sublimation, and the unreacted aluminum can be treated with acid or alkaline water.

[0024]

According to the method for co-producing dimethyl chlorosilane and trimethyl chlorosilane of the present invention, it is a simple production method using inexpensive raw materials, and furthermore, dimethyl chloro silane and trimethyl chloro silane are highly safe with high yield. At the same time, which is industrially advantageous.

[0025]

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

[Example 1] Dimethyldichlorosilane 12 was placed in a pressure-resistant reaction vessel to which a stirrer, a thermometer and a distilling tube were connected.
9.0 g were charged, and 36 g of metallic aluminum and 2.0 g of ethyl bromide were further introduced. The reaction system was closed by disconnecting the distillation tube, and 111.1 g of methyl chloride was used.
Was fed at 80 ° C. for 5 hours, and 115 g of methyldichlorosilane was introduced over 30 minutes. Next, the content liquid was distilled out by connecting to a distilling pipe. As a result, 86.8 g (80.1% yield) of trimethylchlorosilane and 72.3 g (76.5% yield) of dimethylchlorosilane were obtained. Was.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mikio Endo 28-1 Nishifukushima, Kazagusuku-mura, Nakakubijo-gun, Niigata Shin-Etsu Chemical Co., Ltd. Synthetic Technology Research Laboratory (56) References B1) (58) Investigated field (Int. Cl. ⁷ , DB name) C07F 7/12 B01J 21/02 CASREACT (STN)

Claims (1)

(57) [Claims] 1. A method for co-production of dimethylchlorosilane and trimethylchlorosilane, comprising reacting methyldichlorosilane and dimethyldichlorosilane with methyl chloride in the presence of aluminum metal or an aluminum alloy.