JPH08239476A - Production of low-molecular-weight organosilane or siloxane having silanol group - Google Patents

Abstract

PURPOSE: To obtain a low-molecular-weight linear organosilane or siloxane having silanol groups, a monomer diol, a dimer diol and a trimer diol in high yields. CONSTITUTION: An alkoxysilane or siloxane represented by the formula and having a chlorine content of 200ppm or below is mixed with water having an electric conductivity of 10<10> MΩ or above, sulfated zirconium oxide is added to the mixture, the alkoxysilane or siloxane is hydrolyzed, and the sulfated zirconium is removed from the reaction mixture. In the formula, R<1> is (un) substituted monovalent hydrocarbon group; R<2> is 1-4C lower alkyl; and m and n are numbers in the ragnes: m>=0, n>0, and m+n=2-4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a simple method for producing a low molecular weight organosilane or siloxane having a silanol group as a terminal group.

[0002]

BACKGROUND OF THE INVENTION Low molecular weight organopolysiloxanes having silanol groups in the molecule are useful as dispersants in the production of silicone rubber compounds, and various dispersants are widely used. Has been. In this case, the effect as a dispersant is proportional to the content of hydroxyl groups, polysiloxane with a large content of hydroxyl groups, that is, if a low molecular weight linear organotetrasiloxane having a silanol group at the terminal group is used, the addition amount is Although it is less necessary, and more effective when considering the processability of the silicone rubber compound, what is currently industrially used is a straight chain organopolysiloxane of organotetrasiloxane or higher, and a more effective monomer diol,
Few methods have been proposed for industrially obtaining a short-chain silanol group-containing organopolysilane or siloxane such as dimer diol or trimer diol.

That is, various studies have hitherto been made on methods for synthesizing short-chain hydroxysilanes and siloxanes. Laboratoryly known is a method of hydrolyzing an alkoxysilane solution in a neutral state using a buffer solution or the like, but this method is not suitable for practical use.
There is also a method in which dimethoxysilane is mixed with an excess of neutral distilled water and refluxed, but the yield of the target product is not so good.

Usually, in order to industrially obtain a low molecular weight linear organopolysiloxane having a silanol end group,
It is produced by hydrolyzing a linear organochlorosilane or chlorosiloxane having chlorine atoms at both ends in a weak alkaline aqueous solution so as not to form a cyclic body. However, in this method, the silanol group is unstable to an acid or an alkali, so that a condensation reaction occurs with HCl generated by hydrolysis, and in addition to the target organopolysiloxane, an organopolysiloxane having a higher molecular weight is used. There is a problem that by-products such as polysiloxane and cyclic polysiloxane are simultaneously produced. Therefore, with this method, it is difficult to synthesize the above-mentioned linear organopolysiloxane unless a method for strictly keeping the hydrolyzed water neutral.

Further, there is a method in which organochlorpolysiloxane is acetoxylated with acetic acid and then hydrolyzed.
In this method, it is difficult to completely hydrolyze, and the obtained organopolysiloxane is not preferable as a dispersant used for silicone rubber.

On the other hand, in US Pat. No. 3,925,285,
Hexamethylcyclotrisiloxane, methanol, formic acid and water are reacted to synthesize a low molecular weight linear organopolysiloxane having a silanol end group with some residual methoxy groups, but it is relatively expensive. The use of hexamethylcyclotrisiloxane is costly, and low molecular weight linear organopolysiloxanes with silanol end groups with less than ₃ D units [(CH ₃ ) ₂ SiO] cannot be formed. However, there is a problem that there is a limit in the hydroxyl group content because a product shorter than 1,5-dihydroxytrisiloxane cannot be produced in the reaction.

Further, in US Pat. No. 5,057,620,
A method of dropping the corresponding chlorosiloxane into an epoxy solvent such as propylene oxide containing water and butylene oxide is described, but this method also uses relatively expensive hexamethylcyclotrisiloxane.
If the solvent has a low boiling point, there was a safety problem such as electrostatic ignition.

Further, Japanese Patent Publication No. 64-5604 discloses that
A method for synthesizing short-chain silanols in which an alkoxysilane is hydrolyzed with a solid acid catalyst such as activated clay has been described, but this method requires complicated operations because it is necessary to neutralize the solid acid. . Moreover, this method produces a mixture of various short-chain silanols, and the yield of dimer diol is 50% or less. Further, regarding the monomer diol, as shown in Example 29, it was obtained at a yield of 84% by mol and a purity of 10% or less.

Incidentally, US Pat. No. 3,304,318 discloses that
A method for producing a resin having a high degree of polymerization by hydrolyzing an alkoxysilane using a cation exchange resin is disclosed. However, nothing is mentioned about the synthesis method and yield of short-chain silanols, especially monomer diols, dimer diols and trimer diols.

As described above, the silanol group-containing low-molecular-weight organosilane or siloxane has a low price as the application of silicone rubber expands, though the manufacturing process is complicated. It is desired to manufacture it inexpensively and easily.

The present invention has been made in view of the above circumstances.
An object of the present invention is to provide a method for producing a low-molecular-weight organosilane or organosiloxane having a silanol group, particularly a corresponding monomer diol, dimer diol, or trimer diol simply and at low cost.

[0012]

Means and Action for Solving the Problems The present inventors have
As a result of earnest studies to achieve the above object, as a result, an alkoxysilane or siloxane having a chlorine content of 200 ppm or less represented by the following general formula (1) and an electric conductivity of 10 are obtained.
By stirring with water of ¹⁰ MΩ or more and using sulfuric acid-treated zirconium oxide as a catalyst component, it is possible to slowly perform the reaction while the pH of the solution is kept near neutral during the reaction, After completion of the reaction, the sulfuric acid-treated zirconium oxide is simply removed from the system to stop the reaction without using a neutralizing agent such as an alkali, and the removed sulfuric acid-treated zirconium oxide is treated specially. It can be reused without any use, and therefore low molecular weight organosilanes or organosiloxanes having silanol groups, especially corresponding monomer diols, dimer diols, trimer diols, etc. can be easily obtained in high yields, It was found that the method is an industrially advantageous manufacturing method that can simplify the manufacturing process and greatly reduce the cost. Is that Tsu.

[0013]

Embedded image (In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and R ² represents a lower alkyl group having 1 to 4 carbon atoms.
m and n are numbers that satisfy m ≧ 0, n> 0, and m + n = 2 to 4. )

Therefore, according to the present invention, the alkoxysilane or siloxane represented by the above general formula (1) having a chlorine content of 200 ppm or less is mixed with water having an electric conductivity of 10 ¹⁰ MΩ or more, and this is treated with sulfuric acid to obtain zirconium oxide. And add
After stirring, the alkoxysilane or siloxane is hydrolyzed, the alkoxy group is converted into a hydroxyl group, and the sulfuric acid-treated zirconium oxide is removed. A low-molecular-weight organosilane having a silanol group, or A method for producing siloxane is provided.

The present invention will be described in more detail below. The method for producing a silanol group-containing low molecular weight organosilane or siloxane of the present invention is described by the following general formula (1).
Alkoxysilane or siloxane having a chlorine content of 200 ppm or less and water having an electric conductivity of 10 ¹⁰ MΩ or more are mixed, and sulfuric acid-treated zirconium oxide is added for hydrolysis to obtain a short-chain silanol. Is.

[0016]

[Chemical 4] (In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and R ² represents a lower alkyl group having 1 to 4 carbon atoms.
m and n are numbers that satisfy m ≧ 0, n> 0, and m + n = 2 to 4. )

In the formula (1), R ¹ is the same or different and is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, specifically, methyl group and propyl group. Group, butyl group, pentyl group, hexyl group, octyl group,
Alkyl groups such as decyl group and dodecyl group, aryl groups such as phenyl group and tolyl group, aralkyl groups such as β-phenylethyl group, and some or all of the hydrogen atoms in these hydrocarbon groups are halogen atoms or A group substituted with a cyano group or the like, for example, a 3,3,3-trifluoropropyl group or a cyanoethyl group. Of these, a methyl group, a vinyl group, a phenyl group and the like are preferable.

R ² is the same or different from each other and has 1 to 4 carbon atoms.
Of the above, specifically, a methyl group, an ethyl group, a propyl group, a butyl group and the like, among which a methyl group and an ethyl group are preferable.

As such an alkoxysilane or siloxane, the number of silicon atoms in the molecule is 1 to 5, especially 1.
The following general formula (2) is preferable.
Alkoxysilanes or siloxanes represented by (4) to (4) can be used. Specifically, dimethyldimethoxysilane, phenylmethyldimethoxysilane, methylvinyldimethoxysilane, dimethyldiethoxysilane, phenylmethylmethoxyethoxysilane, 1,3-dimethoxytetramethyldisiloxane, 1,1-dimethoxytetramethyldisiloxane, 1-methoxypentamethyldisiloxane, 1,5-dimethoxyhexamethyltrisiloxane, 1,7-dimethoxyoctamethyltetrasiloxane, 3-methoxyheptamethyltrisiloxane, 1,3
-Dimethoxy-1,3-divinyldimethyldisiloxane, 1,3-dimethoxy-1,3-diphenyldimethoxydisiloxane and the like can be mentioned, and among these, dimethyldimethoxysilane and dimethoxytetramethyldisiloxane are particularly preferable.

[0020]

Embedded image (However, in the formula, R ¹ and R ² represent the same groups as described above.)

The above-mentioned alkoxysilanes or siloxanes can be used alone or in admixture of two or more. However, when two or more kinds are mixed and used, the respective hydrolysis rates are different. Care should be taken as it may not react uniformly.

The alkoxysilane or siloxane of the above general formula (1) has a chlorine content of 200 ppm or less, preferably 1
The content is 00 ppm or less, more preferably 50 ppm or less. This is because the short-chain silanol, which is the target substance of the present invention, is very unstable under acid and alkaline conditions, so the system is kept neutral during the hydrolysis reaction and distillation under reduced pressure during the production of the short-chain silanol. Although necessary, alkoxysilanes or siloxanes are usually synthesized from the corresponding chlorosilanes, so there is a large amount of chlorosilanes in them. Since this chlorosilane reacts rapidly with water to generate hydrochloric acid, it is unavoidable that the reaction system becomes acidic when the chlorine content exceeds 200 ppm.
This may cause silanol condensation,
Therefore, in order to avoid such inconvenience, chlorine content is 20
It is necessary to use those of 0 ppm or less.

Next, water is an essential component for hydrolysis, and has an electric conductivity of 10 ¹⁰ MΩ or more, preferably ¹⁰ MΩ.
^Use ion-exchanged water or distilled water of ¹⁵ MΩ or more. Here, when water having an electric conductivity of less than 10 ¹⁰ MΩ is used,
Other cations such as Na, Ca, Mg contained in water undergo an ion exchange reaction with hydrogen ions in sulfuric acid-treated zirconium oxide as a catalyst to acidify the system and obtain short-chain silanol in high yield. However, there is a possibility that a large amount of chain-extended polysiloxane or cyclic polysiloxane will be produced.

The amount of water having an electric conductivity of 10 ¹⁰ MΩ or more is not particularly limited, but it is usually at least 1-fold the molar amount of the alkoxy group in the alkoxysilane or siloxane, and preferably the molar amount. It is preferable to use it in a molar amount of 1 to 5 times. Here, if the amount of water to the alkoxy group is too small, the hydroxyl group content is insufficient, the alkoxysilane or siloxane is not completely hydrolyzed, and if the amount of water is too large, water in the reaction product, methanol, etc. Is not recommended in terms of industrialization because it takes a long time to remove it during stripping.

In the present invention, sulfuric acid-treated zirconium oxide is used as a catalyst during hydrolysis. This sulfuric acid-treated zirconium oxide is an essential component for slowly proceeding the reaction while maintaining the pH of the system in the vicinity of neutrality, and this one has an acid strength higher than 100% sulfuric acid and is excellent in hydrolysis. Since the catalytic activity is obtained, the short-chain silanol can be obtained in good yield. Further, the hydrolysis of the short-chain silanol formation can be easily stopped simply by removing the sulfuric acid-treated zirconium oxide, which can also suppress the condensation of the short-chain silanol, so that the neutralizing agent etc. No need for the reaction terminator, and the sulfuric acid-treated zirconium oxide after removal can be reused as a catalyst without any special treatment, so workability and cost during industrial production are reduced. It can be reduced significantly.

[0026] As zirconium oxide is treated sulfuric acid, zirconium oxide containing sulfate ions (SO ^_2-4
/ ZrO ₂ ) is preferable, and one containing 1 to 5% by weight, and preferably 2 to 3% by weight as a sulfate ion is particularly preferable. In order to obtain such a sulfuric acid-treated zirconium oxide, a known method can be adopted,
For example, it can be obtained by adding dilute sulfuric acid to zirconium hydroxide as described in JP-B-59-6181, filtering and then calcining this. Further, commercially available products may be used, and for example, trade name zirconia sulfate (manufactured by Japan Energy Co.) and the like can be preferably used.

The amount of the above-mentioned sulfuric acid-treated zirconium oxide used is not particularly limited and may be appropriately selected depending on the amount of the alkoxysilane or siloxane and water.
0.0001 to 30 parts by weight, particularly 0.
1 to 1 part by weight is preferable. If the amount added is more than 30 parts by weight, the condensation of the generated silanol may proceed and short-chain silanol may not be obtained in good yield. If it is less than 0.0001 parts by weight, sufficient catalytic activity during hydrolysis may not be obtained. In some cases, the alkoxy group in the alkoxysilane or siloxane remains unreacted without being obtained, and a sufficient silanol group may not be provided to the target composition. Further, sulfuric acid-treated zirconium oxide has a strong catalytic activity, and when it is contained in a solution consisting of the above-mentioned alkoxysilane or siloxane and water for a long time after being hydrolyzed, the reaction proceeds further, resulting in a short-chain silanol produced. May be condensed into a long-chain / cyclic structure, so add it to the solution only for the time required to form short-chain silanols, and after the formation of short-chain silanols, quickly remove the sulfuric acid-treated zirconium oxide. Is recommended.

In order to obtain the silanol group-containing low molecular weight organosilane or organosiloxane of the present invention, the above-mentioned alkoxysilane or siloxane, water, or sulfuric acid-treated zirconium oxide is used for treatment. A method in which a sulfuric acid-treated zirconia oxide is packed in a packed column, and the alkoxysilane or siloxane and water are stirred well by a mixer such as a dynamic mixer, and the flow rate is adjusted to continuously feed the resulting mixture for hydrolysis. Alternatively, a method may be mentioned in which siloxane and water are thoroughly stirred, sulfuric acid-treated zirconium oxide is added and mixed therein to hydrolyze, and then the sulfuric acid-treated zirconium oxide is removed by filtration.

In the production method of the present invention, the reaction time, reaction temperature and the like are appropriately selected depending on the amount of materials used, the production process and the like, and these are not particularly limited, but the reaction time is usually 3 hours. It is preferably within the range, and it is recommended that the sulfuric acid-treated zirconium oxide be removed immediately after the reaction to stop the reaction. If the reaction time exceeds 3 hours, condensation of the generated silanol occurs, and short-chain silanol may not be obtained. Further, the reaction temperature is 80 ° C. or lower, preferably 50 ° C. or lower, and if it is higher than 80 ° C., condensation of the silanol produced is likely to occur.

Further, the alkoxysilane or siloxane and water may be separated into two phases simply by mixing them.
On the other hand, sulfuric acid-treated zirconium oxide does not elute in the solution, and the reaction is carried out on the solid surface of this catalyst. Therefore, it is necessary to add sulfuric acid-treated zirconium oxide with sufficient stirring so that the solution does not separate. However, after a while after the hydrolysis reaction is started, the reaction system is homogenized by the production of methanol and the like. In order to make the reaction system uniform, a polar organic solvent may be added if necessary, and for example, alcohols such as methanol and ethanol, tetrahydrofuran, acetone and the like can be used. In this case, if the addition amount of the polar solvent is too large, it takes time to remove it. Therefore, the addition amount of the alkoxysilane or siloxane and the water is preferably the minimum amount, and the addition amount of the same amount as the alkoxysilane or siloxane is sufficient. is there.

The above reaction product is preferably stripped at any temperature and pressure to remove by-products such as methanol and residual water. In this case, the temperature during stripping is preferably 80 ° C. or lower, particularly 50 ° C. or lower, and if it is higher than 80 ° C., silanol condensation may occur.

[0032]

EXAMPLES Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. As the sulfuric acid-treated zirconium oxide, zirconia sulfate manufactured by Japan Energy Co., Ltd. was used. In the following examples,% is% by weight
Indicates.

[Example 1] A stirrer and a thermometer were used, and N ₂
In a replaced 200 ml flask, 85.5 g (0.71) of dimethyldimethoxysilane (containing chlorine content 5 ppm) was added.
1 mol), 30.0 g (1.67 mol) of ion-exchanged water having an electric conductivity of 10 ¹⁵ MΩ was added and stirred,
Further, 0.093 g of zirconium oxide treated with sulfuric acid was added, and the mixture was stirred at 20 ° C. for 30 minutes. In this case, the solution in the flask was initially separated into two phases, but after 15 minutes, it became a homogeneous solution. Next, the sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 20 ° C., 5 m
By-product methanol, water and the like were removed under the condition of mHg, and 51.7 g of white plate crystals were obtained. The white plate crystals were dissolved in tetrahydrofuran and analyzed by gas chromatography to find that dihydroxydimethylsilane 74.7% and 1,3-dihydroxytetramethyldisiloxane 17.1% were contained.

Example 2 A stirrer and a thermometer were used, and N ₂
In a replaced 200 ml flask, 28.5 g (0.23 g of dimethyldimethoxysilane (containing chlorine content 5 ppm) was added.
7 mol), 10.0 g (1.557 mol) of ion-exchanged water having an electrical conductivity of 10 ¹⁰ MΩ was added and stirred, and 0.031 g of zirconium oxide treated with sulfuric acid was further added.
After adding, the mixture was stirred at 20 ° C. for 5 hours. In this case, the solution in the flask was initially separated into two phases, but after 15 minutes, it became uniform. Next, the sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 20 ° C., 5 m
When methanol and water produced as by-products under mHg conditions were removed, 22.5 g of a colorless transparent oily substance was obtained. When this colorless transparent oily matter was analyzed by gas chromatography, it was found that dihydroxydimethylsilane 19.9% 1,3-dihydroxytetramethyldisiloxane 41.7% 1,5-dihydroxyhexamethyltrisiloxane 18.4% 1, It contained 4.6% of 7-dihydroxyoctamethyltetrasiloxane.

[Embodiment 3] A stirrer and a thermometer are provided, and N ₂
In a replaced 50 ml flask, 10.0 g of dimethoxyvinylmethylsilane (containing chlorine content 10 ppm) (0.
756 mol), 3.6 g (0.2 mol) of ion-exchanged water having an electric conductivity of 10 ¹⁵ MΩ was added and stirred.
Further, 0.0109 g of zirconium oxide treated with sulfuric acid was added, and the mixture was stirred at 20 ° C. for 45 minutes. Next, the sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 40 ° C., 5 m
When methanol and water produced as by-products under mHg conditions were removed, 6.4 g of white crystals were obtained. The white crystals were dissolved in tetrahydrofuran and analyzed by gas chromatography to find that dihydroxydivinylmethylsilane 73.3% and 1,3-dihydroxy-1,3-divinyldimethylsilane 15.1% were contained.

[Embodiment 4] A stirrer and a thermometer were used, and N ₂
Add 1,3-dimethoxytetramethyldisiloxane (containing chlorine content: 10 ppm) to a replaced 50 ml flask.
0.0 g (0.514 mol) was added, and 2.0 g (0.111 mo) of ion-exchanged water having an electric conductivity of 10 ¹⁵ MΩ was added.
l) The mixture was added and stirred, and 0.015 g of zirconium oxide treated with sulfuric acid was further added, followed by stirring at 20 ° C. for 60 minutes.
Next, the sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 40 ° C., 5 m
When the by-product methanol and water were removed under mHg conditions, 7.6 g of white crystals were obtained. When this white crystal was dissolved in tetrahydrofuran and analyzed by gas chromatography, it contained 1,2.6 dihydroxytetramethyldisiloxane (82.6%).

[Embodiment 5] A stirrer and a thermometer were used, and N ₂
In a replaced 50 ml flask, 10.0 g (0.372 mol) of 1,5-dimethoxyhexamethyltrisiloxane (containing chlorine content 10 ppm) was placed, and 2.0 g of ion-exchanged water having an electric conductivity of 10 ¹⁵ MΩ was added thereto. (0.111m
ol) was added and stirred, and 0.015 g of zirconium oxide treated with sulfuric acid was further added, followed by stirring at 20 ° C. for 75 minutes. Next, the sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 40 ° C., 5 m
When the by-product methanol and water were removed under the condition of mHg, 8.0 g of a colorless transparent liquid was obtained. The colorless transparent liquid was analyzed by gas chromatography and found to contain 85.2% of 1,5-dihydroxyhexamethyltrisiloxane.

Example 6 A stirrer and a thermometer were used, and N ₂
Add 1,1-dimethoxytetramethyldisiloxane (containing chlorine content 10 ppm) to a replaced 50 ml flask.
0.0 g (0.514 mol) was added, and 2.0 g (0.111 mo) of ion-exchanged water having an electric conductivity of 10 ¹⁵ MΩ was added.
l) The mixture was added and stirred, and 0.015 g of zirconium oxide treated with sulfuric acid was further added, followed by stirring at 20 ° C. for 60 minutes.
Next, the sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 40 ° C., 5 m
When methanol and water produced as by-products under mHg conditions were removed, 75.7 g of white crystals were obtained. The white crystals were analyzed by gas chromatography and found to contain 75.7% of 1,1-dihydroxytetramethyldisiloxane.

[Embodiment 7] A stirrer and a thermometer were used, and N ₂
In a replaced 50 ml flask, 1-methoxypentamethyldisiloxane (containing chlorine content 10 ppm) was added 10.0.
g (0.561 mol) was added and the electric conductivity was 10 ¹⁵
1.1 g (0.062 mol) of ion-exchanged water of MΩ was added and stirred, and zirconium oxide was treated with sulfuric acid 0.1.
After adding 015 g, the mixture was stirred at 20 ° C. for 70 minutes. next,
The sulfuric acid-treated zirconium oxide was removed by filtration to terminate the reaction.

From the obtained hydrolysis product, 40 ° C., 5 m
When the by-product methanol and water were removed under the condition of mHg, 82.4 g of a colorless transparent liquid was obtained. When this colorless transparent liquid was analyzed by gas chromatography, it contained 84.2% of 1-hydroxypentamethyldisiloxane.

Example 8 Hydrolysis was carried out under the conditions of Example 1, filtered zirconia sulfate was added to the product again, the same operation was repeated 10 times, and then the zirconia sulfate was removed.

From the obtained hydrolysis product, 20 ° C., 5 m
Remove by-product methanol, water, etc. under mHg condition,
The obtained white crystals were dissolved in tetrahydrofuran and analyzed by gas chromatography to find that dihydroxydimethylsilane 72.7% and 1,3-dihydroxytetramethyldisiloxane 15.1% were contained.

[Comparative Example 1] A stirrer and a thermometer were used, and N ₂
In a replaced 50 ml flask, 20.0 g (0.16 of chlorine content of 10 ppm) of dimethyldimethoxysilane was added.
6 mol) was added, and 6.58 g (0.366 mol) of hydrochloric acid water adjusted to pH 4.2 was added thereto, the temperature was raised to 40 ° C., and a uniform solution was obtained. Then, after continuing stirring for 5 minutes, 0.2 g of magnesium oxide (0.00496 m
ol) and 15 g of magnesium sulfate (0.125 mo)
1) was added and the mixture was further stirred for 3 hours. Then, the obtained hydrolysis product was filtered and stripped under the conditions of 20 ° C. and 5 mmHg.
5 g was obtained.

When this colorless transparent liquid was analyzed by gas chromatography, it was found that dihydroxydimethylsilane 1.0% 1,3-dihydroxytetramethyldisiloxane 27.8% 1,5-dihydroxyhexamethyltrisiloxane 21.9%. It contained 1,7-dihydroxyoctamethyltetrasiloxane 15.3% and 1,9-dihydroxydecamethylpentasiloxane 6.6%, which confirmed that condensation of silanol groups had occurred and confirmed that dimethyldihydroxy It was found that no silane was obtained.

Comparative Example 2 Hydrolysis was carried out in the same manner as in Comparative Example 1 except that sulfuric acid water adjusted to pH 4.0 was used instead of hydrochloric acid water adjusted to pH 4.2. 11.8 g was obtained.

When this colorless transparent liquid was analyzed by gas chromatography, it was found that 1,3-dihydroxytetramethyldisiloxane 20.8% 1,5-dihydroxyhexamethyltrisiloxane 29.1% 1,7-dihydroxyoctamethyl Tetrasiloxane 17.9% 1,9-dihydroxydecamethylpentasiloxane 8.0% was contained, which confirmed that condensation of silanol groups had occurred, and that dimethyldihydroxysilane could not be obtained. Admitted.

[0053]

According to the production method of the present invention, short-chain silanols, particularly monomer diols, dimer diols and trimer diols can be obtained in high yield easily and at low cost.

Claims (4)

[Claims] 1. The following general formula (1): (In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and R ² represents a lower alkyl group having 1 to 4 carbon atoms.
m and n are numbers that satisfy m ≧ 0, n> 0, and m + n = 2 to 4. ), The electrical conductivity of the alkoxysilane or siloxane having a chlorine content of 200 ppm or less is 10 ¹⁰ M
Mixing water of Ω or more, adding sulfuric acid-treated zirconium oxide thereto, stirring and hydrolyzing the alkoxysilane or siloxane to convert the alkoxy group into a hydroxyl group, and then treated with the sulfuric acid. A method for producing a low molecular weight organosilane or siloxane having a silanol group, which comprises removing zirconium oxide. 2. The production method according to claim 1, wherein the sulfuric acid-treated zirconium oxide is removed, and then stripping is performed to remove volatile components. 3. The production method according to claim 1, wherein the alkoxysilane or siloxane is one of the following general formulas (2) to (4). Embedded image (However, in the formula, R ¹ and R ² represent the same groups as described above.) 4. The method according to claim 3, wherein the alkoxysilane or siloxane is dimethyldimethoxysilane or dimethoxytetramethyldisiloxane.