JPH07102066A - Production of alkoxysilane - Google Patents

Abstract

PURPOSE:To produce a halogen-free alkoxysilane at a high yield while inhibiting side reactions. CONSTITUTION:An alkoxysilane of the general formula: R<1>aSi(OR<2>)4-a (wherein R<1> is an optionally substd. monovalent hydrocarbon group; R<2> is an optionally substd. alkyl group;.and a is 0, 1, 2, or 3) is reacted with a polysiloxane in the presence of a zirconium alkoxide or a chelate catalyst to produce an alkoxysilane of the general formula: R<3>bSiHc(OR<2>)4-(b+c) (wherein R<2> is the same as described above; R<3> is an optionally substd. monovalent hydrocarbon group; b is 1, 2, or 3; and c is 0, 1, or 2).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an alkoxysilane, which is one of the important intermediates in the silicone industry. More specifically, the objective alkoxysilane can be produced at a high yield by a halogen-free process. It relates to a method of manufacturing at a rate.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 1-132590 discloses that R ¹ _a Si (OR ² ) _4-a (wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, R 1 ² represents an alkyl group, and a represents 0, 1, 2 or 3) and an alkoxysilane represented by the general formula R ³ _b SiHc (OR ² ) is reacted with a polysiloxane. _{4- (b + c)} (wherein R ² is the same as above, R ³ is a substituted or unsubstituted 1
Represents a valent hydrocarbon group, b represents 1, 2 or 3, and c
Represents 0, 1 or 2) is disclosed. According to this method, for example, tetramethoxysilane and formula Me ₃ SiO- (MeH
SiO) ₄₀ -SiOMe ₃ can be reacted with polymethylhydrogensiloxane to obtain dimethoxymethylsilane, and tetraethoxysilane and octamethylcyclotetrasiloxane represented by the formula (Me ₂ SiO) ₄ can be obtained. Can be reacted to obtain diethoxydimethylsilane. In this method, the target alkoxysilane is produced by the cleavage of the Si-O bond of the polysiloxane by the titanium compound used as a catalyst and the insertion reaction (opening reaction) of the alkoxy group from the raw material alkoxysilane into that portion. It is said that.

[0003]

Since this method is a halogen-free process, it has the advantage that hydrogen chloride and chlorosilane are not by-produced, but there are many side reaction products, which lowers the yield of the target product and the purification. There was a problem that was complicated.

[0004]

The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for producing a desired alkoxysilane in a high yield. The inventors of the present application have studied various catalysts in order to achieve such an object, and as a result, when an alkoxysilane and a polysiloxane are reacted in the presence of a zirconium alkoxide or a chelate catalyst, a depolymerization reaction is mainly caused. Progressed, less by-products than the conventional method, it is possible to produce the desired alkoxysilane in high yield,
As a result, they have found that the separation from the by-products becomes easy, and have completed the invention of this application.

That is, the invention of the present application has the general formula R ¹ _a Si (OR ² ) _4-a (wherein R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and R ² represents an alkyl group). represents a radical, a is an alkoxysilane represented by the representative) 0, 1, 2 or 3, and a polysiloxane, characterized by reacting in the presence of a zirconium alkoxide or chelate catalyst, the general formula R ³ _b SiH _c (OR ² ) _{4- (b + c)} (wherein R ² is the same as above, R ³ is a substituted or unsubstituted 1
Represents a valent hydrocarbon group, b represents 1, 2 or 3, and c
Represents 0, 1 or 2. ) Is a method for producing an alkoxysilane. In the alkoxysilane used in the method of the present invention, examples of the alkoxy group represented by R ² O include a methoxy group, an ethoxy group, a propoxy group and a butoxy group. Of these, a methoxy group and an ethoxy group are preferable because they have high reactivity. Moreover, the number of bonds (4-a) of the alkoxy group may be 1 to 4. Of these, the number of bonds is 3 or 4
Those having high reactivity are preferable.

In such an alkoxysilane, R
^The substituted or unsubstituted monovalent hydrocarbon group represented by ² is, for example, an alkyl group represented by R ¹ , a substituted alkyl group such as a chloromethyl group, an alkenyl group such as a vinyl group or an allyl group. And aryl groups such as phenyl group and tolyl group. Preferred alkoxysilanes include, for example, methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane,
Examples thereof include tetramethoxysilane and tetraethoxysilane. Among them, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane and tetraethoxysilane are preferable.

Examples of the alkoxysilane obtained by the method of the present invention include Si in the molecule of dimethylmethoxysilane, dimethylethoxysilane, methyldimethoxysilane, methyldiethoxysilane, methylvinylmethoxysilane, methylphenylmethoxysilane and the like. Examples thereof include alkoxysilane having no —H bond in the molecule, such as alkoxysilane having a —H bond, dimethyldimethoxysilane, dimethyldiethoxysilane, and dimethyldipropoxysilane.

In the invention of this application, when the desired alkoxysilane has a Si--H bond in its molecule, the polysiloxane used as a raw material is one having a Si--H bond in the molecule. To be The structure of such a polysiloxane may be linear, branched or cyclic, or may be a mixture thereof. In such a polysiloxane, as the organic group other than the hydrogen atom bonded to the silicon atom, an alkyl group as shown in the above R ¹ , a substituted alkyl group such as a chloromethyl group,
Examples thereof include an alkenyl group such as a vinyl group and an allyl group, and an aryl group such as a phenyl group and a tolyl group. Among them, methyl group, ethyl group and the like are preferable in terms of price. Examples of these polysiloxanes include the following.

[0009]

[Chemical 1] (However, p shows the integer of 0-100 and q shows the integer of 0-100.) Linear polyhydrogen siloxane represented.

[0010]

[Chemical 2] (However, p shows the integer of 1-100 and q shows the integer of 0-100.) Linear polyhydrogen siloxane represented.

[0011]

[Chemical 3] (However, m represents an integer of 1 to 6 and n represents an integer of 0 to 5).

The content of Si-H bond in such a polysiloxane is not particularly limited, but when the purpose is to produce an alkoxysilane having a Si-H bond in the molecule, the content of this bond is not limited. A larger amount is preferable because the yield of the desired alkoxysilane is improved. The following are more specific examples of the above polysiloxane.

[0013]

[Chemical 4]

[0014]

[Chemical 5] (CH ₃ ) ₂ HSiO consisting of _0.5 units and SiO ₂ units,
A branched polymethylhydrogensiloxane having a hydrogen atom content of 1.03% by weight and a viscosity at 25 ° C. of 24 cSt, and

[0015]

[Chemical 6] (N represents an integer of 3 to 8.) Among these, polymethyl hydrogen siloxane is preferable in terms of yield and cost.

In the invention of this application, when the desired alkoxysilane does not contain a Si-H bond in its molecule, the polysiloxane used as a raw material does not contain a Si-H bond in the molecule. Things are used. In such a polysiloxane, an organic group other than a hydrogen atom bonded to a silicon atom is an alkyl group,
Examples of the monovalent hydrocarbon group include an alkenyl group such as a vinyl group and an allyl group, an aryl group such as a phenyl group and a tolyl group, and the like. The monovalent hydrocarbon group may be a substituted hydrocarbon group, and examples thereof include a halogen-substituted hydrocarbon group such as a chloromethyl group. Moreover, the carbon number of the monovalent hydrocarbon group is preferably 10 or less, and more preferably 8 or less. Particularly, a methyl group, an ethyl group and the like are preferable in terms of cost.

The zirconium alkoxide or chelate used as a catalyst in the present invention is

[0018]

[Chemical 7] (R ² is the same as above, Y ¹ and Y ² are alkyl groups and alkoxy groups having 1 to 8 carbon atoms, and d is 0, 1, 2, 3 or 4). The most preferable zirconium alkoxide or chelate is zirconium tetraalkoxide represented by (R ² O) ₄ Zr), but a part or all of (R ² O) has a general formula.

[0019]

[Chemical 8] You may use the compound substituted by the group represented by.

Specifically, zirconium tetrabutoxide, zirconium tetraisopropoxide, zirconium tetramethoxide, zirconium tributoxide monoacetylacetonate, zirconium dibutoxide bisacetylacetonate, zirconium monobutoxide trisacetylacetonate, zirconium tributoxide. Examples thereof include monoethyl acetoacetate, zirconium dibutoxide bisethyl acetoacetate, zirconium monobutoxide trisethyl acetoacetate, zirconium tetraacetyl acetonate, zirconium tetraethyl acetoacetate and the like. The zirconium alkoxide is particularly preferably zirconium butoxide.

These zirconium alkoxides or chelates may be used as they are, or may be used by dissolving them in a suitable solvent such as alcohol, ketone or hydrocarbon.

The reaction temperature of the present invention is selected within a temperature range where the desired reaction product can be easily distilled. Low or high pressures may be used for this purpose, but it is generally preferred to carry out the process at normal pressure.
The reaction temperature is generally about 60 to 300 ° C, preferably 100 to 200 ° C.

As a method of adding each raw material in the invention of this application, a part of alkoxysilane and zirconium alkoxide or chelate catalyst are mixed and heated in advance, and the mixture of the balance of alkoxysilane and polysiloxane is added dropwise thereto. Alternatively, all of the alkoxysilane and zirconium alkoxide or chelate catalyst may be mixed and heated in advance, and polysiloxane may be added dropwise to the mixture for reaction. Alternatively, the alkoxysilane, the polysiloxane, and the zirconium alkoxide or the chelate catalyst may be mixed and then heated and reacted. In either case, it is particularly desirable to distill off the reaction product rapidly in order to suppress side reactions.

The amount of the catalyst used in the invention of this application can be variously selected according to the desired reaction rate. Generally, it will be in the range of about 0.1 to 10% by weight (based on the starting compound), preferably about 0.5 to 5% by weight.

In the invention of this application, the reaction may be carried out in the presence of a solvent. For example, in order to suppress an increase in the viscosity of the reaction mixture, a boiling point which is inert and higher than that of the desired alkoxysilane is used. A solvent having such as toluene or xylene is preferably used. The invention of this application does not produce hydrogen chloride or chlorosilane as a by-product and has a small amount of undesirable side reaction products, so that a halogen-free alkoxysilane can be produced in a high yield.

[0026]

EXAMPLES Next, the invention of the present application will be specifically described with reference to Examples and Comparative Examples. Example 1 Tetramethoxysilane (10.00 g) (0.066 mol Shin-Etsu) was placed in a four-necked flask having a capacity of 300 ml equipped with a thermometer, a mechanical stirrer, a dropping funnel, a rectification tube (Raschig ring filling, length 30 cm), and a distillation head. Chemical Co., Ltd.) and zirconium tetrabutoxide 0.8
6 g (0.0023 mol, Matsumoto Pharmaceutical Co., Ltd.) was added.
The contents of the flask were heated to 117 ° C. with stirring, and 31.04 g (0.204 mo) of tetramethoxysilane was added thereto.
l) and the formula Me ₃ SiO- (MeHSiO) ₄ O-
SiOMe ₃ polymethyl hydrogen siloxane 1
A mixture of 7.30 g (0.270 mol in terms of Si—H bond, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise over about 1 hour. After the dropping, the temperature of the flask contents was raised to about 180 ° C. and stirring was continued for 2 hours. From the start of dropping to the end of heating and stirring, the fraction in the boiling point range of 40 to 62 ° C was 23.37.
g was obtained. As a result of gas chromatography and ¹ H NMR analysis of the fraction and the residue of the flask, the yield based on the Si—H group in the raw polysiloxane was Me (Me
O) ₂ SiH 74%, Me (MeO) SiH ₂ 2%,
(MeO) ₃ SiH 3%, MeSi (OMe) ₃ 4
%, And unreacted Si (OMe) ₄ was 0%. The residual Si—H group in the residue analyzed by the alkali decomposition method was 4% (based on the Si—H group in the raw material polysiloxane).

Example 2 Using the same apparatus as in Example 1, 15.0 g of tetramethoxysilane (0.099 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.86 g of zirconium tetrabutoxide were placed in the flask.
(0.0023 mol, manufactured by Matsumoto Pharmaceutical Co., Ltd.) was added. The contents of the flask were heated to 117 ° C. with stirring, to which 46.6 g (0.306 mol) of tetramethoxysilane and the formula Me ₃ SiO— (MeHSiO) ₄₀ —SiOMe _{3 were} added.
Polymethyl hydrogen siloxane 17.30g
A mixture of (0.270 mol in terms of Si-H bond, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise over about 1 hour. After the dropping, stirring was continued for 2 hours while raising the temperature of the flask contents to about 180 ° C. From the start of dropping to the end of heating and stirring, 32.11 g of a fraction having a boiling point range of 40 to 62 ° C. was obtained. As a result of gas chromatography and ¹ H NMR analysis of the fraction and the residue of the flask, the yield based on the Si—H group in the raw material polysiloxane was Me (MeO) ₂ S.
81% iH, 2% Me (MeO) SiH ₂ , (Me
O) ₃ SiH was 5%, MeSi (OMe) ₃ was 4%, and unreacted Si (OMe) ₄ was 42%. The residual Si—H group in the residue analyzed by the alkali decomposition method was 4% (based on the Si—H group in the raw material polysiloxane).

Example 3 Using the same apparatus as in Example 1, 8.95 g of methyltrimethoxysilane (0.066 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.98 g of zirconium dibutoxide bisacetylacetonate (0. 0023 mol) was added. The contents of the flask were heated to 100 ° C. with stirring, and 27.70 g of methyltrimethoxysilane was added thereto.
(0.204mol) and the formula Me ₃ SiO- (MeH
SiO) ₄ O-SiOMe ₃ polymethyl hydrogen siloxane 17.30 g (0.27 in terms of Si-H bond)
0 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise over about 1 hour. After the dropping, stirring was continued for 2 hours while raising the temperature of the flask contents to about 180 ° C. From the start of dropping to the end of heating and stirring, 23.41 g of a fraction having a boiling point range of 40 to 62 ° C. was obtained. As a result of gas chromatography and ¹ H NMR analysis of the fraction and the residue of the flask, the yield based on the Si—H group in the raw material polysiloxane was 77% for Me (MeO) ₂ SiH and Me (MeO) ₂ SiH.
O) SiH ₂ was 3%, (MeO) ₃ SiH was 3%, and unreacted MeSi (OMe) ₃ was 4%. The residual Si—H group in the residue analyzed by the alkali decomposition method was 0% (based on the Si—H group in the raw material polysiloxane).

Example 4 Using the same apparatus as in Example 1, 13.4 g of methyltrimethoxysilane (0.099 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.98 g of zirconium dibutoxide bisacetylacetonate (0. 0023 mol) was added. The contents of the flask were heated to 100 ° C. with stirring, and 41.62 g of methyltrimethoxysilane was added thereto.
(0.306mol) and the formula Me ₃ SiO- (MeH
SiO) ₄ O-SiOMe ₃ polymethyl hydrogen siloxane 17.30 g (0.27 in terms of Si-H bond)
0 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise over about 1 hour. After the dropping, stirring was continued for 2 hours while raising the temperature of the flask contents to about 180 ° C. From the start of dropping to the end of heating and stirring, 41.03 g of a fraction having a boiling point range of 40 to 62 ° C. was obtained. As a result of analysis by gas chromatography and ¹ H NMR of the fraction and the residue of the flask, the yield based on the Si—H group in the raw material polysiloxane was 86% for Me (MeO) ₂ SiH and Me (MeO).
SiH ₂ 3%, (MeO) ₃ SiH 4%, unreacted Me
Si (OMe) ₃ was 46%. The residual Si—H group in the residue analyzed by the alkali decomposition method was 1% (based on the Si—H group in the raw material polysiloxane).

Comparative Example 1 Using the same apparatus as in Example 1, 10.00 g of tetramethoxysilane (0.066 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.2 parts of titanium tetrabutoxide monomer were placed in the flask.
3 g (0.00068 mol, Wako Pure Chemical Industries, Ltd.) was added. Heat the contents of the flask to 110 ° C with stirring,
To this, 31.04 g (0.204 g) of tetramethoxysilane
mol) and the formula Me ₃ SiO- (MeHSiO) ₄ O-
SiMe ₃ polymethyl hydrogen siloxane 1
A mixture of 7.30 g (0.270 mol in terms of Si—H bond, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise over about 1 hour. After dropping, stirring was continued for 2 hours while raising the temperature of the flask contents to about 170 ° C. A fraction having a boiling point range of 40 to 62 ° C. is 22. from the start of dropping to the end of heating and stirring.
43 g were obtained. Gas chromatography and ¹ H NM
As a result of analysis by R, Si-H in the raw polysiloxane
The yield based on the group is 68 for Me (MeO) ₂ SiH.
%, 5% Me (MeO) SiH ₂ and (MeO) ₃ SiH
Was 3% and MeSi (OMe) ₃ was 1%. The residual Si—H group in the residue analyzed by the alkali decomposition method was 8% (based on the Si—H group in the raw material polysiloxane).

Comparative Example 2 Using the same apparatus as in Example 1, 8.95 g of methyltrimethoxysilane (0.066 mol, manufactured by Shin-Etsu Chemical Co., Ltd.) and titanium tetrabutoxide monomer 0.1.
23 g (0.00068 mol, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Heat the contents of the flask to 110 ° C with stirring,
27.70 g of methyltrimethoxysilane (0.2
04mol) and the formula Me ₃ SiO- (MeHSiO) ₄
17.30 g of polymethyl hydrogen siloxane of O-SiOMe ₃ (0.270 mo in terms of Si-H bond)
1, a product of Shin-Etsu Chemical Co., Ltd.) was added dropwise over about 1 hour. After dropping, stirring was continued for 2 hours while raising the temperature of the flask contents to about 190 ° C. From the start of dropping to the end of heating and stirring, 30.84 g of a fraction having a boiling point range of 40 to 62 ° C. was obtained. With gas chromatography ¹
As a result of 1 H NMR analysis, the yield based on the Si—H group in the raw material polysiloxane was Me (MeO) ₂ SiH.
68%, Me (MeO) SiH ₂ 17%, (Me
O) ₃ SiH is 0%, unreacted MeSi (OMe) ₃ is 26
%Met. Residual S in the residue analyzed by alkali decomposition method
The i-H group was 0% (Si in the raw polysiloxane
-H group basis).

[0032]

[Table 1]

[0033]

As described above, the present invention suppresses by-products such as hydrogen chloride and chlorosilane by reacting an alkoxysilane with a polysiloxane in the presence of a zirconium alkoxide or a chelate catalyst, It is possible to obtain the excellent effect of producing the desired alkoxysilane in a high yield.

Claims (2)

[Claims] 1. A general formula R ¹ _a Si (OR ² ) _4-a (wherein R ¹ is a monovalent substituted or unsubstituted hydrocarbon group, R ²
Is a substituted or unsubstituted alkyl group, a is 0, 1, 2 or 3) and a polysiloxane is reacted with a polysiloxane in the presence of a zirconium alkoxide or a chelate catalyst. ³ _b SiH _c (OR ² ) _{4- (b + c)} (wherein R ² is the same as above, R ³ is a substituted or unsubstituted 1
A valent hydrocarbon group, b represents 1, 2 or 3 and c represents 0, 1 or 2. The manufacturing method of the alkoxysilane shown by these. 2. The method for producing an alkoxysilane according to claim 1, wherein the polysiloxane has a Si—H bond in the molecule.