JPH0730097B2 - Method for producing chlorosilanes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for producing chlorosilanes from disiloxanes.

Chlorsilanes are important compounds used in a wide range of industrial fields as major intermediates for organosilicon products such as silicone rubber, silicone oil, and silicone resin, and as raw materials for the production of organic chemicals such as pharmaceuticals, agricultural chemicals, and dyes. .

<Prior Art> As a method for producing chlorosilanes from disiloxanes, (a) a method of reacting disiloxanes with sulfuric acid and ammonium chloride (J. Amer. Chem. Soc., 70 , 433, 445 (1948)) ( (B) Method of reacting disiloxane with hydrogen chloride (JP-A-52-144628 and JP-A-55-92392) (C) Reaction of disiloxane with thionyl chloride in the presence of a strong inorganic acid Method (JP-B-56-19355) (D) A method (JP-B-57-7639) of reacting with dimethylhalogenosilane in the presence of an inorganic iron compound is known.

<Problems to be Solved by the Invention> However, in the above-mentioned known method, the reaction temperature is a high temperature or a low temperature, which is not only a reaction under industrially disadvantageous conditions, but also an unnecessary by-product is produced. It is unsatisfactory because of environmental problems such as the treatment of waste liquid generated in the post-treatment of the reaction.

In view of such circumstances, the inventors of the present invention have earnestly studied a method for industrially producing chlorosilanes from disiloxanes, and as a result, by reacting disiloxanes with phosgene, they are extremely selective under mild conditions. It was found that chlorosilanes can be produced in high yield, and the present invention has been completed.

<Means for Solving Problems> That is, the present invention provides a general formula The method for producing chlorosilanes is characterized by reacting phosgene with a disiloxane represented by

Examples of disiloxanes used in the present invention include hexamethyldisiloxane, hexaethyldisiloxane, bischlorotetramethyldisiloxane, triethyltripropyldisiloxane, bischloromethyltetramethyldisiloxane, bisethynyltetramethyldisiloxane,
Examples thereof include, but are not limited to, dibutyltetramethyldidyloxane.

These disiloxanes are readily available, and disiloxanes by-produced from chlorosilanes used for protecting or activating functional groups in the production of organic chemicals can also be used.

The amount of phosgene used for the reaction with disiloxanes must be 1 equivalent or more per 1 equivalent of silicon-oxygen bonds in order to convert all silicon-oxygen bonds in disiloxanes into silicon-chlorine bonds. Is. Since excess phosgene remains unreacted after the reaction, it is not preferable to use more than necessary because a great amount of labor is required for the recovery operation. When it is inconvenient for phosgene to remain, the amount can be 1 equivalent or less. In this case, all of the phosgene used in the reaction is consumed to produce the desired product. Usually, about 0.7 to 3 equivalents of phosgene are used for one equivalent of silicon-oxygen bond in disiloxanes.

This reaction is generally carried out in the presence of a solvent, but it can also be carried out without a solvent.

Examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene, monochlorobenzene, and dichlorobenzene, cyclohexane, hexane, n-heptane, n-
Aliphatic hydrocarbons such as octane, methylcyclohexane and isooctane, ethers such as diethyl ether and dibutyl ether, esters such as ethyl acetate and butyl acetate, acid amides such as N, N-dimethylformamide and N-methyl-N-phenylformamide , Chloroform, 1,
2-dichloroethane, 1,1,1-trichloroethane, 1,1,2
And lower halogenated hydrocarbons such as trichloroethane and tetrachloroethylene.

The reaction is generally about 0 ° C to 200 ° C, preferably 40 ° C to 150 ° C.
Carried out at a temperature of. When the reaction temperature exceeds about 200 ° C., phosgene causes thermal decomposition, which is not preferable. When the reaction temperature is lower than 0 ° C., the reaction rate becomes slow and it takes a long time to complete the reaction, which is not preferable.

The reaction pressure may be increased or decreased, and there is no difference in level, but it is usually carried out at around normal pressure.

The reaction method may be a continuous system, a semi-continuous system or a batch system.

The reaction is usually carried out by introducing phosgene into the disiloxanes, or optionally into a mixture of the disiloxanes premixed with a solvent. It is also carried out by adding disiloxanes to a mixture in which phosgene is previously introduced into a solvent. It can also be carried out by introducing phosgene and disiloxanes into the reactor at the same time.

The chlorosilanes can be easily separated from the starting disiloxanes and phosgene, by-products or solvents by a known method such as distillation from the reaction solution obtained by the above reaction method.

(Effect of the Invention) The method for reacting phosgene with the disiloxanes of the present invention enables the reaction under mild conditions and can produce chlorosilanes in high yield. Furthermore, since by-products can be easily separated by an operation such as distillation, high-purity chlorosilanes can be easily produced. Further, the present invention is useful for recovering chlorosilanes from disiloxanes by-produced from chlorosilanes used for protecting functional groups in the production of organic chemicals.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 A glass reactor equipped with a gas inlet tube, a reflux condenser, a thermometer, and a stirrer was charged with 81.1 g (0.5 mol) of hexamethyldisiloxane and 306 g of 1,2-dichloroethane, while stirring the mixture. Phosgene 98.9g (0.748mol) at a temperature of 50-55 ℃
Introduced over time.

After the completion of the introduction, stirring was continued for another 3 hours at the same temperature, and then the reaction mixture was distilled to remove trimethylchlorosilane.
56.0 g (boiling point; 56-57 ° C., yield 51.5%) was obtained.

Example 2 Hexaethyldisiloxane 6 was added to the same reactor as in Example 1.
1.6 g (0.25 mol) and 300 g of o-dichlorobenzene were charged, and 39.6 g (0.4 mol) of phosgene was added to this with stirring.
Introduced at ~ 135 ° C for 7 hours.

After completion of the introduction, stirring was continued for 2 hours at the same temperature, and then the reaction mixture was distilled to give triethylchlorosilane 5
3.7 g (boiling point; 144-145 ° C., yield 71.3%) was obtained.

Example 3 A reactor similar to Example 1 was charged with 1,3-di-t-butyl-1,1,
2,3-Tetramethyldisiloxane 24.7 g (0.1 mol), o
100 g of dichlorobenzene were charged and 29.7 g (0.3 mol) of phosgene were introduced into this with stirring at 115 to 120 ° C. over 7 hours. After the introduction was completed, stirring was continued for 4 hours at the same temperature, and then the reaction mixture was distilled to give 19.7 g of t-butyldimethylchlorosilane (boiling point; 124 to 126 ° C., yield 65.2).
%) Was obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhisa Masumoto 5-1, Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Co., Ltd. (72) Inventor, Katsuta Kamoda 5-5, Sokai-cho, Niihama-shi Sumitomo Chemical Co., Ltd. Incorporated (56) References Chemical Abstracts, 91 (1979), 140988.

Claims (2)

[Claims] 1. A general formula A method for producing chlorosilanes, which comprises reacting phosgene with a disiloxane represented by: 2. The disiloxanes are hexamethyldisiloxane, hexaethyldisiloxane and 1,3-di-t-butyl-1,1,3,3-tetramethyldisiloxane. A method for producing the described chlorosilanes.