JPH072876A - Production of hexamethyldisiloxane - Google Patents

Abstract

PURPOSE:To efficiently obtain hexamethyldisiloxane in a short reactional time and high yield by reacting a dimethylcyclopolysiloxane with methyl Grignard in the presence of a fluorine-containing salt compound. CONSTITUTION:Dimethylcyclopolysiloxane of the formula (n is 3-10) are made to react with methyl Grignard in the presence of preferably 0.01-10mol% (based on dimethylcyclopolysiloxane) of a fluorine-containing salt compound such as NaF or KF to provide the objective compound.

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 hexamethyldisiloxane, and more particularly to a method for obtaining hexamethyldisiloxane in a short reaction time and in good yield.

[0002]

2. Description of the Related Art Conventionally, trimethylsilanol and its ethers have been synthesized by directly reacting a hydrolyzate of dimethyldichlorosilane with methyl Grignard without using a catalyst [J. Amer. Chem. Soc. , 66
1707 (1944)]. Therefore, when hexamethyldisiloxane is synthesized by utilizing the above reaction, not only is it necessary to react for a long time, but also the disadvantage that the yield is extremely poor because a large amount of by-products are generated. It was

[0003]

DISCLOSURE OF THE INVENTION The present inventors have made diligent studies to solve the above-mentioned drawbacks and produce hexamethyldisiloxane on an industrial scale, and as a result, dimethylcyclopolysiloxane was easily prepared by a fluorine-containing salt compound. It was found that hexamethyldisiloxane can be produced in a short time in a high yield by ring-opening into a ring and by reacting it with methyl Grignard, and reached the present invention. Therefore, an object of the present invention is to provide a method for obtaining hexamethyldisiloxane in a short time in good yield.

[0004]

The above objects of the present invention are as follows.
This is achieved by a method for producing hexamethyldisiloxane, which comprises reacting dimethylcyclopolysiloxane represented by the following chemical formula 2 with methyl Grignard in the presence of a fluorine-containing salt compound.

[Chemical 2] In the formula, n is an integer of 3 to 10.

The fluorine-containing salt compound used in the present invention is
It is a catalyst that promotes the ring-opening reaction of dimethylcyclopolysiloxane shown in Chemical formula 2 above and facilitates the reaction with the Grignard reagent, and specific examples thereof include LiF and N.
Alkali metal salts such as aF, KF, RbF, CsF, B
alkaline earth metal salts such as eF ₂ , MgF ₂ , CaF ₂ , SrF ₂ and BaF ₂ , BF ₃ , AlF ₃ , GaF ₃ ,
Metal salts of Group III elements such as InF ₃ and TlF ₃ , L
aF ₃ , CeF ₃ , PrF ₃ , NdF ₃ , SmF ₃ , E
uF ₃ , GdF ₃ , TbF ₃ , DyF ₃ , HoF ₃ , E
Lanthanoid metal salts such as rF ₃ , CuF ₂ , ZnF
Metal salts such as ₂ , SnF ₂ , PbF ₂ , SbF ₃ and YF ₃ ;

NH ₄ F, (NH ₄ ) ₂ SiF ₆ , H ₂ S
iF ₆ , Na ₂ SiF ₆ , K ₂ SiF ₆ , (CH ₃ ) ₄
NF, (CH ₃ CH ₂ ) ₄ NF, (CH ₃ CH ₂ C
H ₂ ) ₄ NF, (CH ₃ CH ₂ CH ₂ CH ₂ ) ₄ NF,
Examples thereof include fluorine-containing salt compounds such as C ₆ H ₅ CH ₂ N (CH ₃ ) ₃ F. Among these fluorine-containing salt compounds, NaF and K are particularly preferable from the viewpoint of activity and economical efficiency.
F and the like can be preferably used.

The amount of this catalyst added is preferably in the range of 0.01 to 10 mol%, particularly preferably in the range of 0.1 to 5 mol%, based on the dimethylsiloxane unit. When the amount of the catalyst added is less than 0.01 mol%, the ring-opening reaction of dimethylcyclopolysiloxane cannot be promoted, and when it exceeds 10 mol%, the stirring efficiency and the separability after hydrolysis decrease.

The reaction of the present invention is preferably carried out in an inert gas atmosphere as in the case of a general Grignard reaction, and the solvent is a high boiling ether such as tetrahydrofuran, dibutyl ether, diphenyl ether, ethylene glycol dimethoxy ether. Classes are preferred. The reaction temperature is preferably in the range of 40 to 180 ° C, particularly preferably in the range of 70 to 150 ° C. When the reaction temperature is lower than 40 ° C, the conversion rate is lowered, and there is no suitable solvent even when trying to raise the temperature to 180 ° C or higher. This reaction may be carried out under pressure, if desired.

[0009]

INDUSTRIAL APPLICABILITY The method for producing hexamethyldisiloxane according to the present invention is suitable as an industrial method since the desired product can be obtained in a good yield in a short reaction time.

[0010]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Embodiment 1. In a 3 liter reactor equipped with a cryogenic trap, a gas introduction tube, a thermometer and a dropping funnel, M
26.4 g and 770 g of dibutyl ether were added, and CH was added under a nitrogen atmosphere until Mg was absent.
₃ Cl was added. Next, after the temperature inside the flask was raised to 100 ° C. for aging, 0.21 g of NaF as a catalyst was added, and a dibutyl ether solution in which 74 g of octamethylcyclotetrasiloxane was dissolved was added dropwise.

After completion of the dropping, the mixture was stirred for 10 hours while refluxing with dibutyl ether, and then the reaction solution was cooled and then 1
1500 ml of regular hydrochloric acid was added to make the reaction system acidic. Next, the organic layer is separated and purified from the reactor, and the boiling point is 1
61 g of a colorless and transparent fraction having a temperature of 00.5 ° C. was obtained. When the nuclear magnetic resonance spectrum, the infrared absorption spectrum and the gas chromatographic mass spectrum of the obtained fraction were measured,
The following features have become clear.

¹ H-NMR (δ, CCl ₄ ): 0.15
ppm [S, Si (C H ₃ ) ₃ ] IR (KBr): 1066 cm ^-1 (S
i-O-Si) GC-MS: A peak of parent ion minus 15 was confirmed at m / e = 147. From the above analysis results, it was confirmed that the obtained compound was hexamethyldisiloxane [(CH ₃ ) ₃ SiOSi (CH ₃ ) ₃ ]. Further, when analyzed by gas chromatography, its purity was 98.5% and its yield was 75%.

Example 2. When the reaction was carried out in the same manner as in Example 1 except that 74 g of hexamethylcyclotrisiloxane was used instead of the octamethylcyclotetrasiloxane used in Example 1, hexamethyldihexene having a purity of 99% was obtained. The siloxane could be obtained in a yield of 90%.

Example 3. The reaction was carried out in the same manner as in Example 1 except that 74 g of decamethylcyclopentanesiloxane was used instead of the octamethylcyclotetrasiloxane used in Example 1, and hexamethyldiene having a purity of 98% was obtained. The siloxane could be obtained in a yield of 50%.

Example 4. The reaction was carried out in the same manner as in Example 1 except that 74 g of the hydrolyzate of dimethyldichlorosilane was used instead of the octamethylcyclotetrasiloxane used in Example 1, and the purity was 98.5%.
Hexamethyldisiloxane could be obtained in a yield of 70%.

Comparative Example 1. Hexamethyldisiloxane was synthesized in the same manner as in Example 1 except that NaF used in Example 1 was not added, and the purity was 98.5.
%, But the yield was 33%, which was low compared to the examples.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Norio Shinohara Inventor No. 1 Hitomi, Osamu Matsuida-cho, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Shoji Ichinohe Matsui, Usui-gun, Gunma Prefecture Tamachi Daiji Hitomi 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology Laboratory

Claims (3)

[Claims] 1. The following chemical formula 1 in the presence of a fluorine-containing salt compound:
A method for producing hexamethyldisiloxane, which comprises reacting dimethylcyclopolysiloxane represented by: with methyl Grignard. [Chemical 1] In the formula, n is an integer of 3 to 10. 2. The method for producing hexamethyldisiloxane according to claim 1, wherein the amount of the fluorine-containing salt compound added is in the range of 0.01 to 10 mol% with respect to the dimethylsiloxane unit. 3. The fluorine-containing salt compound is NaF and / or K.
The method for producing hexamethyldisiloxane according to claim 1 or 2, which is F.