JP2803358B2 - Method for producing siloxane having Si-Si bond - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a siloxane having a Si—Si bond from a disilane mixture, and more particularly to a method for producing a siloxane having a high boiling point produced during chlorosilane synthesis by a direct method. The present invention relates to a method for producing the above-mentioned siloxane, which is effectively employed for converting disilanes into siloxanes having a Si-Si bond.

[Problems to be solved by conventional technology and invention]

In the silicone industry, the production of chlorosilanes by the direct method is a very important route, and now a large amount of chlorosilane is produced by the direct method every year.

However, at this time, a high-boiling fraction can be obtained by collecting chlorosilane by distillation, and the high-boiling fraction contains disilanes and the like having close boiling points which are difficult to separate by distillation. It was difficult to effectively use the boiling point fraction.

That is, the high-boiling fraction at the time of the production of chlorosilane by the direct method focuses on disilane, and is classified into the following 3 based on the boiling point.
Divided into two fractions.

Low boiling point: C ₆ H ₁₈ Si ₂ , C ₅ H ₁₅ ClSi ₂ , C ₄ H ₁₂ Cl ₂ Si ₂ Medium boiling point: C ₃ H ₉ Cl ₃ Si ₂ , C ₂ H ₆ Cl ₆ Si ₂ High boiling point : CH ₃ Cl ₅ Si ₂ , Cl ₆ Si _{2 In} this case, even if represented by the same composition formula, for example, C ₄
H ₁₂ Cl ₂ Si ₂ is a 1,2-chloro form (Me ₂ ClSi—SiClMe ₂ ),
Structural isomers such as 1-chloro form (MeCl ₂ Si-SiMe ₃ ) (M
e represents a methyl group. same as below. ), And Other than disilane.

In fact, high-boiling fractions, when analyzed by gas chromatography, show a very complicated pattern as shown in Table 1 below, and therefore high-boiling fractions are industrially useful having Si-Si bonds. Despite the fact that it contains a major compound as a main component, the boiling points of chloro and methyl structural isomers are close to each other, so there is no effective separation method, and there is a problem in effective utilization.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a siloxane that is effectively employed to obtain a siloxane having a Si-Si bond from a high-boiling fraction generated during chlorosilane synthesis. I do.

Means and Action for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have found that it is effective to react cyclotrisiloxane with a disilane mixture.

That is, the present inventors first studied the reactivity between chlorosilanes and cyclotrisiloxane, and found that when chlorosilanes and an excess mole of cyclotrisiloxane were reacted at a low temperature in a polar solvent having no proton, Silane with only one chloro atom on Si does not react at all with cyclotrisiloxane, but silane with two or more chloro atoms on one Si is formed by inserting cyclotrisiloxane between Si-Cl. It was found that the reaction continued until the Si having two or more chloro atoms disappeared (see the following reaction formula).

(However, D ₃ in the above formula is And HMPA indicates hexamethylphosphoryltriamide. Furthermore, the present inventors applied the above reaction to disilanes. For example, when cyclotrisiloxane was reacted with the above structural isomer of C ₄ H ₁₂ Cl ₂ Si ₂ , The 1,2-dichloro form in which only one atom is bonded to each atom does not react at all, but the 1,1-dichloro form reacts with cyclotrisiloxane to give, for example, the following formula The compound (1) having a boiling point greatly different from that of the 1,2-dichloro compound and being separable from each other;
Moreover, in this case, it has been found that the obtained compound (1) becomes a mixture of the following formulas (2) and (3) by hydrolysis.

In this case, even if Me ₃ Cl ₃ Si ₂ is mixed with Me ₄ Cl ₂ Si ₂ , the compound of the formula (4) can be obtained by, for example, the following reaction. By hydrolyzing, a compound of the formula (5) having a high boiling point was obtained, and it was found that these compounds could be easily separated, and the present invention was accomplished.

Therefore, the present invention is represented by the following composition formula [I] (CH ₃ ) _n Si ₂ Cl _6-n ... [I] (where n is an integer of 6 to 0) A disilane mixture containing at least one disilane having two or more chlorine atoms bonded thereto is represented by the following formula [II] (Where R represents a hydrogen atom or a monovalent hydrocarbon group which is the same or different from each other).
Among two or more Si—Cl bonds of a disilane in which two or more chlorine atoms are bonded to one silicon atom, OSiR _{2 3} (excluding one Si—Cl bond between other Si—Cl bonds) , R
Has the same meaning as described above). A process for producing a siloxane having a Si—Si bond is provided.

 Hereinafter, the present invention will be described in more detail.

In the method for manufacturing a siloxane having a Si-Si bond of the present invention, although the starting material is a disilane mixture represented by the following formula [I] _{Me n Si 2 Cl 6-n} ... [I], to the mixture disilane in which two or more chlorine atoms attached to one silicon atom, for example, _{MeCl 2 SiSiMe 3, MeCl 2 SiSiClMe} 2, Cl 3 SiS
It is necessary to include at least one kind of iCl ₃ or the like. As such a disilane mixture, a high-boiling fraction produced in the production of chlorosilane by a direct method is suitably used.

On the other hand, cyclotrisiloxane to be reacted with this disilane mixture is represented by the following formula [II] It is shown by. In this case, R is a hydrogen atom or a monovalent hydrocarbon group which is the same or different from each other, and preferably has 1 to 10 carbon atoms, such as methyl, phenyl, trifluoropropyl and vinyl. You.
Among them, hexamethylcyclotrisiloxane is particularly preferably used.

The amounts of the chloromethyldisilane mixture and the cyclotrisiloxane used are appropriately selected. The number of silicon atoms having two or more chloro atoms in the mixture and two chloro atoms are bonded to silicon atoms, but three Although it depends on whether they are combined, the latter is usually 0.5 to 33 parts per 100 parts by weight of the former.
The range is 0 parts by weight.

The reaction between the chloromethyldisilane mixture and the cyclotrisiloxane is carried out in a polar solvent having no proton, for example, hexamethylphosphoryltriamide (HMPA), dimethylsulfoxide (DMSO), dimethylformamide (DMF)
And the like as a solvent. Of these, HMPA is particularly preferred. The amount used is preferably from 0.1 to 10% by weight, especially from 0.5 to 3% by weight, based on cyclotrisiloxane. If it is less than 0.1%, the reaction rate may be slow. If it exceeds 10%, the reaction of monochlorosilane may start to occur.

Reaction conditions are also appropriately selected, but the reaction temperature is 30 ° C or less,
In particular, the temperature is preferably from 0 to 30 ° C. If the temperature exceeds 30 ° C, a silicon atom having only one chlorine atom may start reacting with cyclotrisiloxane. Although the reaction is possible even at a temperature lower than 0 ° C., the reaction rate is reduced when the temperature is too low. The reaction time is usually 1 to 5 hours.

In this reaction, the Cl ₂ M in the disilane mixture was
It is preferable that the component of e ₄ Si ₂ is concentrated by pre-distillation or the like.

Thus, in the present invention, cyclotrisiloxane acts on disilane in which two or more chlorine atoms are bonded to one silicon atom in the disilane mixture by this reaction,
Leaving one of the pieces more Si-Cl bonds, introduces OSiR _{2 3} between the other Si-Cl bonds, for example, the following (i), (i
The siloxane of i) is obtained.

The siloxane thus obtained can be easily separated by distillation due to a difference in boiling point, and if the obtained siloxane is hydrolyzed by a conventional method, the hydrolyzate can be more easily separated by distillation. Can be.

Therefore, according to the method for producing a siloxane according to the present invention, a siloxane that can be easily separated by distillation can be produced from a high-boiling fraction generated at the time of chlorosilane synthesis by a direct method, and a high-boiling fraction with low utility value can be produced. Can be used effectively.

The siloxane obtained in the present invention can be copolymerized with a cyclic siloxane in the presence of an alkali or acid catalyst to give a polymer having a trimethylsilyl group or the like in a side chain. (M. Ishikawa et al, J. Polym. Sci., Polymn. Letter, 21, 6
57 (1983)] [Effect of the Invention] According to the invention, it is possible to easily and reliably obtain a siloxane having a Si-Si bond which can be easily separated from a disilane mixture and which is difficult to obtain by other methods. It is advantageously employed to produce a siloxane having a Si-Si bond by a simple treatment from a high-boiling fraction at the time of chlorosilane synthesis, which had no utility value until now.

 Hereinafter, the present invention will be described specifically with reference to examples.

〔Example〕

The simple distillation of 1 kg of the high boiling fraction at the time of chlorosilane production
400 g of a 6060 ° C./60 mmHg distillate was collected. This fraction was analyzed by gas chromatography. As shown in Table 1, this fraction contained Me ₃ SiSiMe ₃ 14.3% and MeSiSiMe ₂ Cl24.
It contained disilanes of 8% and Me ₄ Si ₂ Cl ₂ 11.1%, and also contained various silanes having boiling points close to each other.

Next, 400 g of hexamethylcyclotrisiloxane and 4 g of hexamethylphosphoryltriamide were added to 400 g of the above fraction, and the mixture was stirred at 0 ° C. for 1 hour. During this period, the solid hexamethylcyclotrisiloxane was gradually reacted and dissolved, and after 1 hour, a completely homogeneous solution was obtained.

The solution was heated to 70 ° C. at 2 mmHg to remove unreacted hexamethylcyclotrisiloxane and chlorosilanes, and then distilled under reduced pressure through a short distillation column to obtain 93 to 95 ° C./2
95 g of mmHg fraction was collected.

The fraction was analyzed by ¹ H-NMR, ²⁹ Si-NMR, IR and GC-MASS, and as a result, the following formula (1) was obtained. Was found. The drawing shows the infrared absorption spectrum of this compound (1). Further, the (n ^{25 ° C.} _D ) of this compound (1) was 1.4139.

(Reference example)

Next, the compound (1) was dissolved in 190 g of diethyl ether, added to water, and hydrolyzed. The hydrolyzate is washed with water, dried, stripped and distilled.
A fraction at 7878 ° C./2 mmHg was isolated. This was subjected to ¹ H-NMR, IR, GC
Analysis by -MASS, UV absorption measurement in cyclohexane, and confirmation of the presence of Si-Si bonds by absorption at 213 nm. As a result, a mixture of the following (2) and (3) (almost 1: 2 ratio) Was found.

[Brief description of the drawings]

The drawing is an infrared absorption spectrum of the compound (1) obtained by the method of the present invention.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiko Tobita 100-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Shin-Etsu Chemical Co., Ltd. Corporate Research Center (72) Inventor Shigeru Mori Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 100-1 Shin-Etsu Chemical Co., Ltd. Corporate Research Center (56) References JP-A-58-194892 (JP, A) JP-A-54-119417 (JP, A) JP-A-53-7625 (JP, A) A) JP-A-58-180494 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07F 7/12 CA (STN) REGISTRY (STN) CAOLD (STN) BEILSTEIN (STN) WPIDS (STN)

Claims (1)

(57) [Claims] 1. A compound represented by the following composition formula [I] (CH ₃ ) _n Si ₂ Cl _6-n ... [I] (wherein n is an integer of 6 to 0). A disilane mixture containing at least one disilane having two or more chlorine atoms bonded thereto is represented by the following formula [II] (Where R represents a hydrogen atom or a monovalent hydrocarbon group which is the same or different from each other).
Among two or more Si—Cl bonds of a disilane in which two or more chlorine atoms are bonded to one silicon atom, OSiR _{2 3} (excluding one Si—Cl bond between other Si—Cl bonds) , R
Has the same meaning as described above). A process for producing a siloxane having a Si—Si bond.