JP3175548B2 - Method for producing hydrogen-containing cyclic siloxane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a compound represented by the following general formula (1), which has one or two Si—H bonds and three silicon atoms, which are useful as a basic material of a silicone resin. The present invention relates to a method for producing a cyclic siloxane having the formula (pentamethylcyclotrisiloxane or tetramethylcyclotrisiloxane).

[0002]

Embedded image (In the formula, n and m represent an integer of 1 or 2 that satisfies n + m = 3.)

[0003]

BACKGROUND OF THE INVENTION A cyclic siloxane having three silicon atoms in one molecule is obtained by reacting dichlorosilane with dihydroxydisiloxane in the presence of a dehydrochlorinating agent such as an amine. For example, JP-B-43-14720 discloses dimethyldichlorosilane and 1,3-dihydroxy-1,1,1.
A method is disclosed in which 3,3-tetramethyldisiloxane is reacted in the presence of pyridine to remove pyridine hydrochloride formed, followed by distillation to obtain hexamethylcyclotrisiloxane.

[0004] However, this method has a problem that a great deal of labor is required for filtration for removing the hydrochloride. In this case, instead of such a filtration step, water is added, washed with water to transfer the amine hydrochloride to the aqueous phase, which can be separated and removed, thereby eliminating the complexity of the filtration operation. it can.

However, in a similar manner, pentamethylcyclotrisiloxane in which one of the methyl groups of hexamethylcyclotrisiloxane is replaced by a hydrogen atom is converted into methyldichlorosilane and 1,3-dihydroxy-1,1,3,3. 3
-If it is intended to obtain by reaction with tetramethyldisiloxane, the Si-H group is hydrolyzed in the water washing step, and the yield of pentamethylcyclotrisiloxane is reduced. For example, Japanese Patent Publication No. 60-115592 discloses methyldichlorosilane and 1,3-dihydroxy-1,1,3,3.
The reaction with 3-tetramethyldisiloxane is described in Comparative Example 1, but the yield is as low as 6.7%. This is because the amine used to neutralize the hydrogen chloride formed during the reaction dissolves in water and becomes alkaline, so that Si—H
This is because the bond is hydrolyzed to form Si-OH.

Similarly, as a reaction for obtaining 1,1,3,5-tetramethylcyclotrisiloxane, dihydroxydimethylsilane and 1,3,3
When -dimethyl-1,3-dichlorodisiloxane is reacted, the yield of 1,1,3,5-tetramethylcyclotrisiloxane is low for the same reason.

The present invention has been made in view of the above circumstances, and is intended to produce a cyclotrisiloxane having one or two Si-H bonds in one molecule in a yield as high as about 10 times that of the conventional method. It is an object of the present invention to provide a method for producing a hydrogen-containing cyclic siloxane that can be produced.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have obtained a method for producing a cyclic siloxane represented by the above general formula (1). In the formula, when n = 1 and m = 2, that is, when pentamethylcyclotrisiloxane is produced, methyldichlorosilane and 1,3-dihydroxy-
When n = 2 and m = 1 in the formula, that is, when 1,1,3,5-tetramethylcyclotrisiloxane is produced, Dimethylsilane and 1,3-dimethyl-1,3-dichlorodisiloxane are allowed to react in the presence of an amine compound in an anhydrous state, respectively, and then represented by the structural formula MH ₂ PO ₄ (M represents Na or K). By adding an aqueous solution of the mono-alkali metal phosphate shown in the formula (1), the aqueous solution shows weak acidity, so that the Si-H bond of the generated cyclic siloxane can be stably retained without hydrolysis. The amine hydrochloride can be easily separated into an aqueous phase by suppressing the hydrolysis of the bond, and the above formula (1) having a Si—H bond can be used.
To be able to produce a high yield of cyclic siloxane,
The present invention has been accomplished.

Accordingly, the present invention provides a method for preparing methyldichlorosilane and 1,3-dihydroxy-1,1,3,3-tetramethyldisiloxane, or dihydroxydimethylsilane and 1,3-dimethyl-1,3-dichlorodisiloxane. After reacting siloxane with an anhydrous compound in the presence of an amine compound,
_After adding an aqueous solution of a mono alkali metal phosphate represented by ₂ PO ₄ (M represents Na or K) to transfer the amine hydrochloride from the reaction mixture to the aqueous solution, and then separating the aqueous phase, the organic phase was separated. Provided is a method for producing a hydrogen-containing cyclic siloxane (pentamethylcyclotrisiloxane or tetramethylcyclotrisiloxane) represented by the following general formula (1), which is characterized by performing distillation.

[0010]

Embedded image (In the formula, n and m represent an integer of 1 or 2 that satisfies n + m = 3.)

Hereinafter, the present invention will be described in more detail. The method for producing a hydrogen-containing cyclic siloxane of the above formula (1) according to the present invention comprises the steps of: when n = 1 and m = 2, methyldichlorosilane and 1,1; When n = 2 and m = 1 in the formula, dihydroxydimethylsilane and 1,3-dimethyl-
1,3-dichlorodisiloxane is reacted with each other in an anhydrous state in the presence of an amine compound. As shown in the following reaction formulas A and B, a dehydrochlorination reaction between a Si-OH group and a Si-Cl group is performed. is there.

[0012]

Embedded image

The molar ratio of methyldichlorosilane to 1,3-dihydroxy-1,1,3,3-tetramethyldisiloxane is preferably 1: 1-2, more preferably 1: 1.01-1.0. 1.5, the molar ratio of dihydroxydimethylsilane to 1,3-dimethyl-1,3-dichlorodisiloxane is preferably 1: 1-2, more preferably 1: 1.
The pair is 1.01 to 1.5.

Here, the reaction proceeds even in the presence of a hydrochloric acid-free scavenger, but if hydrochloric acid generated by the reaction is present, a double reaction such as a ring-opening reaction of the formed cyclic siloxane occurs. An amine compound is added.

As the amine compound, a tertiary amine can be particularly preferably used, and specific examples thereof include triethylamine, tributylamine, pyridine and picoline. It is effective to use one or more equivalents of these amine compounds with respect to the generated hydrochloric acid. If the amount of the amine compound added is less than 1 equivalent relative to the generated hydrochloric acid, the generated hydrochloric acid may remain in the system, and the remaining hydrochloric acid may cause a side reaction such as ring opening of the generated cyclic siloxane. . If the amine compound is excessive, the amine compound remains unreacted in the reaction system, and the aqueous solution becomes alkaline in the water washing step described later, and the yield of the cyclic siloxane is reduced due to hydrolysis of the Si-H group of the generated cyclic siloxane. There is a risk. For this reason, the amount of the amine compound exceeds 1.0 times mol of the Si—Cl group in the raw material,
A range of 1.2 moles or less is preferred.

The reaction represented by the above reaction formulas A and B is as follows:
Since the reaction between the Si—Cl group and the Si—OH group in the molecule is included, methyldichlorosilane and 1,3-dihydroxy-1,1,3,3-tetramethyldisiloxane (A)
Alternatively, the reaction is carried out by simultaneously dropping dihydroxydimethylsilane and 1,3-dimethyl-1,3-dichlorodisiloxane (B). Usually, an amine compound is dissolved in a solvent as a hydrochloric acid scavenger, and methyldichlorosilane and 1,3-dihydroxy-1,1,3,3-tetramethyldisiloxane are dissolved in the solvent, respectively.
Alternatively, the reaction is carried out by simultaneously adding dropwise a mixture of dihydroxydimethylsilane and 1,3-dimethyl-1,3-dichlorodisiloxane dissolved in a solvent.

Here, as the solvent, dihydroxydimethylsilane and 1,3-dihydroxy-1,1,3,3
Since tetramethyldisiloxane generally does not dissolve in a nonpolar solvent, a polar solvent or a mixed solvent of a polar solvent and a nonpolar solvent is used. Also, 1,3-dimethyl-1,3-
The solvent for dichlorodisiloxane and methyldichlorosilane may be a non-polar solvent, a polar solvent, or a mixed solvent thereof. Further, the solvent for the amine compound may be either a non-polar solvent or a polar solvent, and when the amount of the amine compound is large, the solvent may not be used.

Although various solvents can be used as the solvent, alcohols having active hydrogen include methyldichlorosilane, 1,3-dimethyl-
It cannot be used because it reacts with 1,3-dichlorodisiloxane. Specific examples of the solvent include diethyl ether, tetrahydrofuran, ethers such as dioxane, methylene chloride, chlorinated solvents such as dichloroethane, acetone, ketone solvents such as methyl ethyl ketone, pentanes, aliphatic hydrocarbon solvents such as hexane, It is possible to use aromatic solvents such as benzene and toluene. In this case, as described above, methyldichlorosilane and 1,3-dimethyl-1,3-dichlorodisiloxane are dissolved in the solvents exemplified above.
Dihydroxy-1,1,3,3-tetramethyldisiloxane hardly dissolves in solvents such as hexane and methylene chloride.
It is necessary to use or use a polar solvent such as tetrahydrofuran or acetone. On the other hand, a large amount of the amine compound does not require a solvent. In addition, when the above silane and disiloxanes are simultaneously dropped from the upper dropping container,
The solvent which should be present in the lower reaction vessel in advance is not particularly limited, and examples thereof include the above-mentioned solvents.

With respect to the amount of the solvent used, when the amount of the solvent is small, the amine hydrochloride formed as the reaction proceeds does not dissolve in these solvents, so that the salts are sequentially precipitated as solids, which makes stirring difficult. Become. Conversely, if the amount of the solvent is too large, it is economically disadvantageous. Therefore, the amount of the solvent used is methyldichlorosilane, 1,3-
The total amount of dihydroxy-1,1,3,3-tetramethyldisiloxane or dihydroxydimethylsilane,
1.5 to 100 times the weight of the total amount of 1,3-dimethyl-1,3-dichlorodisiloxane, more preferably 2 to 20 times
Double weight.

The temperature condition of the reaction is -30 ° C.
It is preferable to carry out the operation within a range of from 50 ° C to 50 ° C. However, when the reaction (A) is carried out at normal pressure, the reaction is preferably carried out at 41 ° C or lower, which is the boiling point of methyldichlorosilane, particularly at -20 ° C to 40 ° C. Recommended. The reaction time is usually 2 to 5 hours.

In the present invention, after the above reaction, an aqueous solution of a mono alkali metal phosphate represented by MH ₂ PO ₄ (M represents Na or K) is added to the reaction mixture to convert the amine hydrochloride from the reaction mixture. After transferring to an aqueous solution and then separating the aqueous phase, the organic phase is distilled.

That is, after completion of the reaction, a large amount of amine hydrochloride is formed, and an aqueous solution of a mono alkali metal phosphate represented by MH ₂ PO ₄ is added for separation from the product.
The amine hydrochloride dissolves in this aqueous solution and separates into an aqueous phase and an organic phase. The siloxane product is dissolved in the organic phase and can be easily separated by liquid separation. When the washing is carried out with mere water, the aqueous solution becomes alkaline by the amine, and the Si—H group is hydrolyzed and the yield deteriorates. However, the aqueous MH ₂ PO ₄ solution shows weak acidity, and under this condition, the Si—H The group is relatively stable and can suppress the hydrolysis reaction of the Si-H group that occurs under alkaline conditions.

Here, the amount of water to be used is an amount that completely dissolves the amine hydrochloride to be produced. In particular, the amount of water to be added is 5 to 5 of the amines used as the dehydrochlorinating agent. The weight is preferably 100 times, more preferably 10 to 20 times the weight.

The monoalkali metal phosphate represented by MH ₂ PO ₄ is used in an amount of 0.01 to 10 times, more preferably 0.05 to 1 times the weight of the amine used as the dehydrochlorinating agent. Is preferred. If the amount is less than this, the aqueous phase becomes alkaline due to the amine present in excess, and an undesirable hydrolysis reaction of the Si-H group may proceed to lower the yield.

Although the washing step is carried out at an arbitrary temperature, it is usually preferable to carry out the step at a temperature of 0 to 50 ° C.

After washing with water, liquid separation is performed by a conventional method, and a neutral desiccant such as anhydrous sodium sulfate or anhydrous magnesium sulfate is added to the separated organic phase to remove water dissolved in the organic phase. Can be.

Next, distillation is performed. The distillation can be performed under normal pressure or under reduced pressure. By performing the distillation, the solvent used for the water separation during the reaction can be easily removed, and the intended cyclic trisiloxane having a Si—H group can be obtained.

[0028]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to the following Examples.

Example 1 1,1,3,3,5-pentamethylcyclotrisiloxa
Down with a thermometer, a dropping funnel two stirrer and 1000 ml, into 5000ml flask purged with nitrogen, diethyl ether 900 g, triethylamine 199.8g
(1.975 mol) was added and stirred.

1,3-dihydroxy-1,1,3,3-
153.0 g of tetramethyldisiloxane (0.920 m
ol) and diethyl ether was added and dissolved.
0 ml solution and 108.9 methyldichlorosilane
g (0.947 mol), diethyl ether was added and dissolved, and the solution having a total volume of 600 ml was added to each solution.
Put it in a 000 ml dropping funnel and take the same amount for 140 minutes,
The solution was dropped into the flask while keeping the liquid temperature at 0 to 10 ° C. After the dropping was completed, stirring was continued at 20 ° C for 30 minutes.

After completion of the reaction, 27.0 g of KH ₂ PO ₄ (0.
198 mol) in 2000 ml of water was added to the flask. As a result, triethylamine hydrochloride precipitated in the reaction mixture was dissolved in water, and the upper layer was separated into an ether phase, and the lower layer was separated into an aqueous phase.

The ether phase was separated, and saturated saline solution 1000
After washing twice with ml, 50 g of Na ₂ SO ₄ was added, dehydration was performed, and distillation was performed to obtain 131.4 g of 1,1,3,3,5-pentamethylcyclotrisiloxane (0.658 mol).
1) was obtained. The yield was 68.5%.

Example 2 1,1,3,3,5-pentamethylcyclotrisiloxa
In a 2000 ml flask equipped with a nitrogen thermometer, a stirrer, and two 100 ml dropping funnels, dichloromethane 600 g and triethylamine 39.2 g (0.3
87 mol) and stirred.

Acetone was added to and dissolved in 30.0 g (0.180 mol) of 1,3-dihydroxytetramethyldisiloxane to make the total amount 80 ml, and dichloromethane was added to 21.4 g (0.186 mol) of methyldichlorosilane. Add and dissolve the solution to a total volume of 80 ml, put each in a separate 100 ml dropping funnel, and add
Over a period of 0 minutes, the solution was dropped into the flask while maintaining the liquid temperature at 0 to 10 ° C. After the completion of the dropping, stirring was continued at 20 ° C for 30 minutes.

After the completion of the reaction, 5.3 g of KH ₂ PO ₄ (0.0 g
44 mol) in 800 ml of water was added to the flask. As a result, triethylamine hydrochloride precipitated in the reaction mixture was dissolved in water, and the lower layer was separated into a dichloromethane phase, and the upper layer was separated into an aqueous phase.

The dichloromethane phase was separated, and saturated saline 8
After washing twice with 00 ml, 10 g of Na ₂ SO ₄ was added,
After dehydration, the mixture was distilled to obtain 24.1 g (0.116 g) of 1,1,3,3,5-pentamethylcyclotrisiloxane.
mol). The yield was 64.2%.

Example 3 of 1,1,3,5-tetramethylcyclotrisiloxane
550 g of diethyl ether and 121.0 g of triethylamine were placed in a 5000 ml flask equipped with a production thermometer, a stirrer, and two 1000 ml dropping funnels and purged with nitrogen.
(1.196 mol) was added and stirred.

51.4 g of dihydroxydimethylsilane
(0.557 mol) was added and dissolved in diethyl ether to make a total volume of 700 ml, and 100.0 g (0.5%) of 1,3-dimethyl-1,3-dichlorodisiloxane.
71 mol), and dissolved in diethyl ether. The total volume of the resulting solution (700 ml) was placed in separate 1000 ml dropping funnels, and the same amount was added over 120 minutes.
While maintaining the temperature at 0 ° C, the solution was dropped into the flask, and after completion of the dropping, stirring was continued at 20 ° C for 30 minutes.

After completion of the reaction, 30.0 g of KH ₂ PO ₄ (0.
22 mol) in 1500 ml of water was added to the flask. As a result, triethylamine hydrochloride precipitated in the reaction mixture was dissolved in water, and the upper layer was separated into an ether phase, and the lower layer was separated into an aqueous phase.

The ether phase was separated, and saturated saline solution 1000
After washing twice with ml, 30 g of Na ₂ SO ₄ was added, dehydration was performed, and distillation was performed to obtain 57.5 g (0.230 mol) of 1,1,3,5-tetramethylcyclotrisiloxane.
I got The yield was 53.0%.

Example 4 Instead of KH ₂ PO ₄ , Na
Except for using H ₂ PO ₄ performs the same operation as in Example 1 to obtain a 1,1,3,3,5- pentamethyl cyclotrisiloxane in 66.2% yield.

Comparative Example 1 The procedure of Example 1 was repeated, except that 2000 ml of water was used instead of the aqueous solution of KH ₂ PO ₄ , to prepare 1,1,3,3,5-pentamethylcyclotrisiloxane. However, the yield was very low at 6.2%.

Comparative Example 2 The procedure of Example 1 was repeated, except that 2000 ml of a saturated saline solution was used in place of the aqueous KH ₂ PO ₄ solution, and 1,1,3,3,5-pentamethylcyclotriethyl was used. The siloxane was obtained, but the yield was as low as 6.0%.

Comparative Example 3 The procedure of Example 3 was repeated, except that 1500 ml of water was used instead of the aqueous KH ₂ PO ₄ solution, to obtain 1,1,3,5-tetramethylcyclotrisiloxane. However, the yield was very low at 1.0%.

Comparative Example 4 The procedure of Example 3 was repeated, except that 1500 ml of a saturated saline solution was used instead of the aqueous KH ₂ PO ₄ solution, to obtain 1,1,3,5-tetramethylcyclotrisiloxane. However, the yield was very low at 1.5%.

[0046]

According to the process for producing a hydrogen-containing cyclic siloxane of the present invention, 1,1,3,3,5-pentamethylcyclotrisiloxane and 1,1,3,5-tetramethylcyclotrisiloxane can be prepared at a high level. It can be obtained in yield.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Sato 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Inside Silicone Electronics Materials Research Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Masaharu Takahashi Matsui, Usui-gun, Gunma Prefecture Hitomi Tamachi 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) References JP-A-7-324090 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) C07F 7/21 C08G 77/06 C08G 77/12 C08G 77/32

Claims (2)

(57) [Claims] 1. A reaction between methyldichlorosilane and 1,3-dihydroxy-1,1,3,3-tetramethyldisiloxane in the presence of an amine compound in an anhydrous state.
An aqueous solution of a mono alkali metal phosphate represented by H ₂ PO ₄ (M represents Na or K) was added to transfer the amine hydrochloride from the reaction mixture to the aqueous solution, and then the aqueous phase was separated. 1,1,3, characterized by distilling
A method for producing 3,5-pentamethylcyclotrisiloxane. 2. Dihydroxydimethylsilane and 1,3-
After reacting dimethyl-1,3-dichlorodisiloxane in the presence of an amine compound in an anhydrous state, MH ₂ PO
₄ Add an aqueous solution of a monoalkali metal phosphate salt (M represents Na or K) to transfer the amine hydrochloride from the reaction mixture to the aqueous solution, then separate the aqueous phase and distill the organic phase A process for producing 1,1,3,5-tetramethylcyclotrisiloxane.