JPH0859834A - Production of organopolysiloxane with low degree of polymerization - Google Patents

Abstract

PURPOSE: To selectively produce an organopolysiloxane with a low degree of polymn. by subjecting a trialkylchlorosilane and a linear polysiloxane having both of the molecular ends blocked with chlorine to hydrolysis using an aq. soln. of an org. oxygen compd. CONSTITUTION: A trialkylchlorosilane and a linear polysiloxane having both of the molecular ends blocked with chlorine shown at the left side of the formula (wherein R<1> to R<5> are each 1-18C alkyl or aryl; and n is 1- -9) are hydrolyzed using an aq. soln. of an org. oxygen compd. to give an organopolysiloxane with a low degree of polymn. as shown at the right side of formula. This method is useful for producing a dimethylpolysiloxane oligomer esp. widely used. The oxygen compd. is exemplified by an alcohol and a ketone, pref. examples being acetone, 1,4-dioxane. and tetrahydrofuran, which are not reactive with an SiCl bond, and is used in an amt. of 50-200wt.% of the sum of the silane and the polysiloxane shown at the left side of the formula. Water is used pref. in an equivalent ratio to SiCl bond of 0.25-2.

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 a low degree of polymerization organopolysiloxane, and in particular, a trialkylchlorosilane and a chlorinated linear polysiloxane having both ends blocked,
The present invention relates to a method for producing an organopolysiloxane having a high degree of selectivity and a low degree of polymerization by hydrolysis using an aqueous solution containing an oxygen-containing organic compound.

[0002]

2. Description of the Related Art Conventionally, a low-polymerization degree dimethylpolysiloxane (hereinafter sometimes referred to as "dimethylpolysiloxane oligomer") has been prepared by using hexamethyldisiloxane and octamethylcyclotetrasiloxane with sulfuric acid as a catalyst. There are known methods including an equilibration reaction (US Pat. No. 2,469,888) and a hydrolysis reaction of trimethylchlorosilane and dimethyldichlorosilane (US Pat. No. 2,398,672).

However, in these production methods, the desired dimethylpolysiloxane oligomer cannot be selectively produced due to the nature of the above reaction, so that the yield and pot yield are low, and as a result, the desired dimethylpolysiloxane oligomer is obtained. The time required for distillation purification for separating the dimethylpolysiloxane oligomer is long, and this is not a cost-effective method. Moreover, in recent years, as the applications of dimethylpolysiloxane oligomers have expanded in various industrial fields such as detergents for machine parts, reduction of oligomer production cost and stable supply have been demanded.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors
As a result of extensive studies on a selective and highly efficient production method of dimethylpolysiloxane having a low degree of polymerization, as a result, a mixture of trimethylchlorosilane and linear dimethylpolysiloxane having both ends blocked by chlorine was hydrolyzed in the presence of a specific organic compound. If this is the case, the desired dimethylpolysiloxane oligomer can be produced selectively and in high yield, and it is also advantageous in terms of cost. Furthermore, this production method replaces the methyl group with another alkyl group or aryl group. The present invention has been found to be applicable to the case where Therefore, an object of the present invention is to provide a production method by which an organopolysiloxane having a low degree of polymerization can be selectively obtained in a high yield.

[0005]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
According to the reaction formula shown in Chemical formula 7 below, the trialkylchlorosilane shown in Chemical formula 4 and the linear polysiloxane having both ends blocked by chlorine shown in Chemical formula 5 below are hydrolyzed using an aqueous solution containing an oxygen-containing organic compound. From the reaction solution,
It was achieved by separating and purifying a low degree of polymerization organopolysiloxane represented by

[Chemical 4]

[Chemical 5]

[Chemical 6]

[Chemical 7] In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different alkyl groups having 1 to 18 carbon atoms or aryl groups, and n is an integer of 1 to 9.

In the trialkylchlorosilane represented by the above formula 4 used in the present invention, the alkyl group having 1 to 18 carbon atoms or the aryl group of R ¹ , R ² and R ³ does not impair the effects of the present invention. As long as it is not particularly limited, for example, as an alkyl group, a methyl group, an ethyl group,
A phenyl group etc. are mentioned as an aryl group, such as a decyl group. R ¹ , R ² and R ³ may be the same or different, and different examples include C ₁₀ H ₂₁ M
eSiCl (in the formula, Me represents a methyl group; the same applies below) and the like.

Further, the above chemical formula 5 used in the present invention
In the linear polysiloxane with both ends chlorinated represented by, the alkyl group or aryl group having 1 to 18 carbon atoms of R ⁴ and R ⁵ is not particularly limited as long as the effects of the present invention are not impaired. Examples thereof include a methyl group, ethyl group and decyl group, and examples of the aryl group include phenyl group. R ⁴ and R ⁵ may be the same or different. The amount of the trialkylchlorosilane represented by the above chemical formula 4 is 2 to 20 with respect to the linear polysiloxane having both ends chlor-blocked represented by the above chemical formula 5.
Equivalent times is suitable, but it is 4 to 1 from the viewpoint of yield and economy.
It is particularly preferable to be 5 equivalents.

Examples of the oxygen-containing organic compound include alcohols such as methanol and ethanol, ketones such as acetone, cyclic ethers such as 1,4-dioxane and tetrahydrofuran, and ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and ethylene. Examples thereof include ethers such as glycol diethyl ether and diethylene glycol diethyl ether, but from the viewpoint of not reacting with SiCl bond,
Acetone, 1,4-dioxane and tetrahydrofuran are preferred.

The amount of the oxygen-containing organic compound used is 10 to 400% by weight based on the total amount of the trialkylchlorosilane represented by the above Chemical formula 4 and the linear polysiloxane having both ends chlorinated represented by the Chemical formula 5. Although it is suitable, it is preferably 50 to 200% by weight from the viewpoint of yield and economy. The amount of water used for hydrolysis is appropriately 0.1 to 5.0 times the total amount of SiCl bonds contained in the trialkylchlorosilane and the linear polysiloxane having chlorinated ends at both ends, From the viewpoint of yield and pot yield, it is preferably 0.25 to 2.0 equivalent times.

Examples of the low-polymerization degree organopolysiloxane represented by the above chemical formula 6 which is the object compound of the present invention include Me (Me ₂ SiO) ₄ SiMe ₃ (in the chemical formula 6, R ¹ , R ² , R ³ and R ⁴ And R ⁵ is Me and n is 3), Ph (Me ₂ SiO) ₃ SiMe ₂ Ph
(In chemical formula 6, R ¹ is Ph (phenyl group), R ² ,
R ³ , R ⁴ and R ⁵ are Me and n is 2), C ₁₀
H ₂₁ (Me ₂ SiO) ₃ SiMe ₂ C ₁₀ H ₂₁ (in the formula 6, R ¹ is C ₁₀ H ₂₁ , R ² , R ³ , R ⁴ and R ⁵ are M
e and n is 2).

In the production method of the present invention, a chlorosilane solution consisting of the trialkylchlorosilane represented by the above chemical formula 4 and the linear polysiloxane having both ends chlorinated and represented by the chemical formula 5 is hydrolyzed with an aqueous solution containing an oxygen-containing organic compound. The desired low polymerization degree organopolysiloxane is separated and purified from the reaction solution.

In this case, the hydrolysis reaction is preferably carried out by dropping an aqueous solution containing an oxygen-containing organic compound into the chlorosilane solution under normal pressure or reduced pressure. The generated hydrochloric acid gas is removed from the reaction system to give a yield. It is preferable to carry out under reduced pressure, especially at 10 to 450 mmHg, since The temperature during the hydrolysis reaction is suitably 5 to 50 ° C, but it is preferably 5 to 25 ° C in order to suppress the decomposition of the SiCl bond by hydrochloric acid. Further, it is advantageous to make the dropping rate as slow as possible so that the yield can be improved, but economically, it is preferable to drop at 0.3 to 2.0 g / min with respect to 100 g of the chlorosilane solution.

[0013]

According to the production method of the present invention, an organopolysiloxane having a low degree of polymerization can be produced selectively and in a high yield.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Example 1. A 200 ml flask was charged with Me ₃ SiCl (71
g, 0.66 mol) and ClMe ₂ SiOSiMe ₂ Cl
(23 g, 0.11 mol), and at room temperature of 20 ° C.,
The pressure was reduced to 150 mmHg, and an aqueous solution of water (8.0 g, 0.44 mol) and 1,4-dioxane (94 g) was added dropwise over 2 hours while stirring the reaction solution. After completion of the dropping, wash the reaction solution with 100 g of water once and wash it 6 times.
After H7, dimethylpolysiloxane oligomer Me ₃ SiO (Me ₂ SiO) ₂ SiMe _{3 was obtained} by vacuum distillation.
Was obtained 22.2 g (yield 65%).

Example 2. Me ₃ S in a 200 ml flask.
iCl (71 g, 0.66 mol) and Cl (Me ₂ Si
O) ₂ SiMe ₂ Cl (30 g, 0.11 mol) was added, the pressure was reduced to 150 mmHg at room temperature of 20 ° C., and water (8.0 g, 0.44 mol) and 1,4-dioxane (51 g) were added. An aqueous solution consisting of 2 while stirring the reaction solution.
It dripped over time. After the dropping is completed, the reaction liquid is 100 g /
After washing with water once for 6 times to adjust the pH to 7, dimethylpolysiloxane oligomer Me ₃ SiO was obtained by vacuum distillation.
25.4 g of (Me ₂ SiO) ₃ SiMe ₃ (yield 60
%)Obtained.

Comparative Example 1. Hexamethyldisiloxane (100 g, 0.62 mol), octamethylcyclotetrasiloxane (137 g, 0.46 mol) and 7.1 g of concentrated sulfuric acid were placed in a 300 ml flask, and the mixture was cooled to room temperature at 20 ° C. under,
The equilibration reaction was performed for 8 hours. Then the reaction solution
It was washed 6 times with water (00 g / 1 time) to adjust the pH to 7, and then dimethylpolysiloxane oligomer Me ₃ S was obtained by vacuum distillation.
23.7 g (yield 10%) of iO (Me ₂ SiO) ₃ SiMe ₃ was obtained.

Comparative Example 2. Me ₃ SiCl (47 g, 0.
44 mol) and Me ₂ SiCl ₂ (83.6 g, 0.65
Water (314 g, 17.4 mol) was added to the solution with (mol. After washing with 100 g of water / water 6 times until pH becomes 7, dimethylpolysiloxane oligomer Me ₃ SiO (Me ₂ SiO) _{3 was obtained} by vacuum distillation.
8.5 g (yield 10%) of SiMe ₃ was obtained.

Claims (5)

[Claims] 1. A method of hydrolyzing a trialkylchlorosilane represented by the following chemical formula 1 and a linear polysiloxane having both ends blocked by chlorine represented by the following chemical formula 2 with an aqueous solution containing an oxygen-containing organic compound. A method for producing a low polymerization degree organopolysiloxane represented by the following chemical formula 3; Embedded image [Chemical 3] In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ may be the same or different and are an alkyl group having 1 to 18 carbon atoms or an aryl group, and n is an integer of 1 to 9. . 2. The low polymerization degree organopolysiloxane according to claim 1, wherein the oxygen-containing organic compound is at least one selected from the group consisting of 1,4-dioxane, tetrohydrofuran and acetone. Method. 3. The amount of water in the aqueous solution containing an oxygen-containing organic compound is 0.25 to 2.0 equivalent times with respect to the total amount of SiCl bonds contained in Chemical formulas 1 and 2. Process for the production of the described low degree of polymerization organopolysiloxanes. 4. The method for producing a low degree of polymerization organopolysiloxane according to claim 1, wherein the hydrolysis is performed under a pressure of 10 to 760 mmHg. 5. An aqueous solution containing an oxygen-containing organic compound is added dropwise to a chlorosilane solution consisting of the trialkylchlorosilane represented by the above chemical formula 1 and the linear polysiloxane having both ends blocked by chlorination represented by the above chemical formula 2. 4. The method for producing an organopolysiloxane having a low degree of polymerization described in any one of 4 above.