JPS63238088A - Production of chlorosilanes - Google Patents

Abstract

PURPOSE:To readily obtain the titled silanes useful as a raw material producing organic chemicals, such as an intermediate for an organosilicon products and agricultural chemicals in high purity and high yield, by reacting a specific silanols with phosgene in the presence of an amide. CONSTITUTION:(A) Silanols expressed by the formula (R1 represents 1-18C alkyl; R2 and R3 represent 1-3C alkyl) (e.g. t-butyldimethylsilanol) are reacted with (C) phosgene in the presence of (B) a tertiary amide, for example at 20-70 deg.C. As for the component (B), N,N-dimethylformamide or N-methyl-N- phenylformamide is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing chlorosilanes from silanols.

Chlorsilanes are important compounds used in a wide range of industrial fields as 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> The following method is known as a method for obtaining chlorosilanes from silanols.

(1) Method of reacting silanols with hydrogen chloride [Chemical Abstract
ct) Volume 74, 58908W) (2) Method of reacting silanols with phosphorus pentachloride [Journal of Organometallic Chemistry (Journal of Organon+etal)
lic Che-sistry) Volume 275, 01-0
Page 4 (1984)] (Problems to be Solved by the Invention) However, in the above-mentioned known methods, it is necessary to carry out the reaction at a low temperature below zero, and the reaction may be carried out under industrially disadvantageous conditions. Moreover, it is not always satisfactory, as it produces unnecessary by-products and, in some cases, causes problems in terms of environmental protection, such as the treatment of waste liquid generated during post-treatment of the reaction.

In view of these circumstances, the present inventors investigated an industrially advantageous method for producing chlorosilanes from silanols, and found that chlorosilanes can be produced under mild conditions by reacting silanols with phosgene in the presence of a tertiary amide. It was discovered that chlorosilanes can be produced selectively and in high yields, leading to the completion of the present invention.

Namely, the present invention is a method for producing chlorosilanes, which is characterized by reacting silanols represented by the general formula [% formula %] with phosgene in the presence of a tertiary amide. .

The silanols used in the present invention include triethylsilanol, trimethylsilanol, tributylsilanol, tripropylsilanol, ethyldimethylsilanol, diethylmethylsilanol, t-butyldimethylsilanol, diethylpropylsilanol, hexyldimethylsilanol, decyldimethylsilanol, and tetradecyl. Examples include dimethylsilanol, octadecyldimethylsilanol, and the like, but are not limited to these.

These silanols can be easily produced manually, and silanols produced by-product from chlorosilanes used for protecting or activating functional groups in the production of organic drugs can also be used.

The tertiary amide used in the present invention is N.

N-disubstituted carboxylic acid amides are commonly used. 'N,N-dimethylformamide, N,N-diethylformamide, N-methyl-N-phenylformamide, N
, N-diphenylformamide, N,N-dimethylacetamide, and polymers having these acid amides in their side chains.

Since the reaction rate is high, N,N-dimethylformamide and N-methyl-N-phenylformamide are preferably used, and N,N-dimethylformamide is particularly preferably used.

The tertiary amide is generally about 0.001 mol or more per silicon-oxygen bond in the silanol, preferably 0.0 mol or more.
It is used in an amount of 1 mol or more, particularly preferably 0.02 mol or more.

Since the tertiary amide also functions as a solvent, the upper limit is not particularly limited.

If the amount of tertiary amide used is less than about 0.001 mole, it is not preferable because it takes a long time to complete the reaction.

It is usually used in an amount of about 0.01 to 0.2 mol just to promote the reaction.

The amount of phosgene used for reaction with silanols is:
In order to convert all the silicon-oxygen bonds in the silanols into silicon-chlorine bonds, 1 equivalent or more is required per 1 equivalent of silicon-oxygen bonds.

Excess phosgene remains unreacted after the reaction, so
It is not preferable to use more than necessary because the recovery operation requires a lot of effort.

If it is inconvenient for phosgene to remain, the amount can be reduced to 1 equivalent or less.

In this case, all of the phosgene used in the reaction is consumed to produce the target product.

Usually, about 0.8 to 1.2 equivalents of the chlorinating agent are used per equivalent of silicon-oxygen bonds in the silanols.

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

Such carriers include benzene, toluene, xylene,
Aromatic hydrocarbons such as monochlorobenzene and dichlorobenzene, cyclohexane, hexane, n-hebutane, 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, N,N-dimethylformamide, N-methyl-N
- Acid amides such as phenylformamide, chloroform, 1,2-dichloroethane, 1,1,1-trichloroethane, 1. l.

2- To! J Examples include lower halogenated hydrocarbons such as chloroethane and tetrachloroethylene.

The reaction is generally carried out at a temperature of about 0°C to 100°C, preferably 20°C to
It is carried out at a temperature of 70°C.

If the reaction temperature exceeds about 100°C, the yield will decrease due to decomposition of the tertiary amide, and if it is lower than 0°C, the reaction rate will be slow and it will take a long time to complete the reaction, which is not preferred.

Although the reaction pressure may be increased or decreased, it is usually carried out at around normal pressure.

The reaction method can be carried out continuously, semi-continuously or batchwise.

The reaction is usually carried out by introducing phosgene into a premixed mixture of silanols and tertiary amide, or optionally a solvent.

Chlorosilanes can be easily separated from the raw materials silanols, phosgene, tertiary amides, by-products, or solvents from the reaction solution obtained by the above reaction method by a known method such as distillation.

Furthermore, the separated tertiary amide and solvent can be used repeatedly in the reaction.

<Effects of the Invention> According to the method of the present invention in which phosgene is reacted with silanols in the presence of a tertiary amide, the reaction can be carried out under milder conditions than in conventional methods, and chlorosilanes can be produced in high yield. be able to.

Furthermore, since by-products can be easily separated by operations such as distillation, highly pure chlorosilanes can be easily produced.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present 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 66.1 g of t-butyldimethylsilanol.
g (0,5 mol), 265 g of 4,2-dichloroethane and 18.3 g of N,N-dimethylformamide (0,
25 mol) and add phosgene 7 to this while stirring.
4.0 g (0,748 mol) were introduced over a period of 2 hours at a temperature of 40-45°C. After the introduction is complete, the reaction mixture is distilled to yield 72% of t-butyldimethylchlorosilane.
4 g (boiling point 124-126°C, yield 96°0%) was obtained.

Example 2 In a reactor similar to Example 1, triethylsilanol 66
．． 2g (0.5 mol), 1,2-dichloroethane 250
g and N, N-dimethylformamide 3.65 g
(0.05 mol) was charged, and 54.4 g (0.55 mol) of phosgene was introduced thereinto at 40-45° C. over 2 hours while stirring. After the introduction was completed, the same operation as in Example 1 was performed to obtain 71.6 g of triethylchlorosilane (boiling point 144-145°C, yield 95%).

Example 3 In a reactor similar to Example 1, 66.1 g (0.5 mol) of t-butyldimethylsilanol, 950 g (7 mol) of 1,2-dichloroethane and 6.76 g (0.5 mol) of N-methyl-N-phenylformamide were added. , 0.05 mol), and 54.4 g (0.55 mol) of phosgene was added to it while stirring.
The introduction was carried out over a period of 2 hours at 0-45°C. After the installation is complete,
After continuing stirring at the same temperature for 3 hours, the same operation as in Example 1 was performed to obtain 69.3 g of t-butyldimethylchlorosilane (
tA point 124-125°C, yield 92%).

Example 4 In a reactor similar to Example 1, 40.1 g (0.25 mol) of hexyldimethylsilanol, 160 g of 1,2-dichloroethane and 1.83 g of N,N-dimethylformamide were added.
g (0,025 mol) and 27.2 g (0,275 mol) of phosgene was added into the mixture while stirring.
The introduction was carried out for 2 hours at 45°C. After the introduction, the same operation as in Example 1 was performed to obtain 40.7 g of hexyldimethylchlorosilane (boiling point 77-80°C/16 To
rr yield of 91%) was obtained.

Example 5 In a reactor similar to Example 1, 54.1 g (0.25 mol) of decyldimethylsilanol, 215 g of 1,2-dichloroethane and 1.83 g of N,N-dimethylformamide were added.
g (0,025 mol) and 27.2 g (0.2'15 mol) of phosgene was added into the mixture while stirring.
The introduction was carried out for 2 hours at 45°C. After the introduction was completed, the same operation as in Example 1 was performed to obtain 51.7 g of decyldimethylchlorosilane <boiling point 103-106°C/l To
rr yield of 88%) was obtained.

Example 6 In a reactor similar to Example 1, 82.2 g (0.25 mol) of octadecyldimethylsilanol was added.

330 g of 2-dichloroethane and 1.83 g (0,025 mol) of N,N-dimethylformamide were charged,
27.2 g of phosgene (0,27
5 mol) was introduced over a period of 2 hours at 40-45°C.

After the introduction, the same operation as in Example 1 was carried out to obtain 75.5 g of octadecyldimethylchlorosilane (boiling point 184-18
6° C., 10.2 Torr, yield 87%).

Comparative Example Into the same reactor as in Example 1, 66.1 g (0.5 mol) of t-butyldimethylsilanol and 265 g of 1.2-dichloroethane were charged, and 98.9 g (1.5 mol) of phosgene was added to the reactor while stirring. 0 mol) was introduced over a period of 10 hours at a temperature of 60°C. After the introduction was completed, stirring was continued for an additional 8 hours at the same temperature. Analysis of the reaction mixture using gas chromatography revealed that t-butyldimethylchlorosilane 8
．． 38 (yield 11%) was produced.

Claims (3)

[Claims] (1) General formula ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_1 represents an alkyl group having 1 to 18 carbon atoms, and R_2 and R_3 represent the same or different alkyl groups having 1 to 3 carbon atoms. ] A method for producing chlorosilanes, which comprises reacting silanols represented by the following with phosgene in the presence of a tertiary amide. (2) The method for producing chlorosilanes according to claim 1, wherein the tertiary amide is N,N-dimethylformamide or N-methyl-N-phenylformamide. (3) The method for producing chlorosilanes according to claim 1, wherein the silanol is t-butyldimethylsilanol.