JP7491258B2 - Method for producing purified (organooxymethyl)organooxysilane - Google Patents

Description

The present invention relates to a method for producing purified (organooxymethyl)organooxysilane.

(Alkoxymethyl)alkoxysilanes are widely known for their ability to accelerate curing, and are therefore used as crosslinking agents in elastic sealants and adhesives whose main raw material is polysiloxanes containing silanol or alkoxysilyl groups.

Here, (alkoxymethyl)alkoxysilane can be obtained by adding an excess amount of sodium alkoxide to (chloromethyl)alkoxysilane, reacting them in the presence of an alcohol solvent, removing the by-product salt, and then purifying them by distillation (Patent Document 1).

JP 2009-513734 A

However, in the case of the manufacturing method described in Patent Document 1, since there are no regulations regarding the temperature or degree of vacuum during distillation, the higher the internal temperature of the distillation still is, the more likely disproportionation occurs when distilling (alkoxymethyl)alkoxysilane. When disproportionation occurs, the target product changes into low-boiling impurities and high-boiling impurities, respectively, and since these impurities have similar boiling points, they are likely to be mixed into the main distillate, making it difficult to obtain the target product with high purity. Not only that, but the amount of the target product decreases, making it difficult to obtain it in high yield. In particular, when the purity of the target product is low, it is considered that the desired effect will not be achieved when used as a curing agent, etc.
On the other hand, if distillation is performed under conditions where the degree of pressure reduction is increased and the internal temperature of the still is too low, the boiling point becomes lower, which can result in a large loss due to evaporation.

The present invention has been made in consideration of the above circumstances, and aims to provide a method for producing purified (organooxymethyl)organooxysilane with high purity and high yield by suppressing disproportionation during distillation.

As a result of extensive research into achieving the above object, the inventors discovered that when distilling (organooxymethyl)organooxysilanes, particularly (alkoxymethyl)alkoxysilanes, by setting the internal temperature of the distillation still to a predetermined temperature and adjusting the degree of vacuum so that the pressure is a predetermined pressure, it is possible to suppress disproportionation of (organooxymethyl)organooxysilanes such as (alkoxymethyl)alkoxysilanes during distillation, and to obtain the desired product with high purity and high yield, which led to the completion of the present invention.

That is, the present invention provides
1. The following general formula (1)
( ^R1OCH2 ) _mSi ( _OR2 ^{) nR34} _{-mn (} 1)
(In the formula, R ¹ , R ² and R ³ are each independently an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and m and n are integers of 1 to 3, and m+n≦4 is satisfied.)
in the presence of a metal organooxide, by adjusting the internal temperature of a distillation still to less than 100° C. and the degree of reduced pressure to less than 9 kPa;
2. The method for producing a purified (organooxymethyl)organooxysilane according to 1, wherein the purified (organooxymethyl)organooxysilane is (methoxymethyl)trimethoxysilane or (ethoxymethyl)triethoxysilane.

According to the present invention, in the production of (organooxymethyl)organooxysilanes, particularly (alkoxymethyl)alkoxysilanes, it is possible to obtain purified (organooxymethyl)organooxysilanes, particularly purified (alkoxymethyl)alkoxysilanes, with high purity and high yield without causing disproportionation during distillation.

The present invention will be specifically described below.
In the present invention, the (organooxymethyl)organooxysilane is represented by the following general formula (1).
( ^R1OCH2 ) _mSi ( _OR2 ^{) nR34} _{-mn (} 1)

In general formula (1), R ¹ , R ² and R ³ are each independently an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, and more preferably 1 to 3 carbon atoms.
The monovalent hydrocarbon groups of R ¹ , R ² , and R ³ may be linear, branched, or cyclic, and specific examples thereof include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, and n-pentyl; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, and thexyl; cyclic alkyl groups such as cyclopentyl and cyclohexyl; alkenyl groups such as vinyl, allyl, butenyl, and pentenyl; alkynyl groups such as ethynyl, propynyl, butynyl, and pentynyl; aryl groups such as phenyl and tolyl; and aralkyl groups such as benzyl and phenethyl.

Combinations of organooxymethyl groups and organooxy groups in general formula (1) include a methoxymethyl group and a methoxy group, a methoxymethyl group and an ethoxy group, an ethoxymethyl group and a methoxy group, an ethoxymethyl group and an ethoxy group, a propoxymethyl group and a propoxy group, a vinyloxymethyl group and a methoxy group, a vinyloxymethyl group and an ethoxy group, a phenoxymethyl group and a methoxy group, and a phenoxymethyl group and an ethoxy group.
Among these, preferred combinations are a methoxymethyl group and a methoxy group, and an ethoxymethyl group and an ethoxy group.

In general formula (1), m and n are integers from 1 to 3, and satisfy m+n≦4. Preferably, m is 1 and n is 3.

Specific examples of the (organooxymethyl)organooxysilane represented by the general formula (1) include (methoxymethyl)trimethoxysilane, bis(methoxymethyl)dimethoxysilane, tris(methoxymethyl)methoxysilane, (methoxymethyl)methyldimethoxysilane, bis(methoxymethyl)methylmethoxysilane, (methoxymethyl)ethyldimethoxysilane, bis(methoxymethyl)ethylmethoxysilane, (methoxymethyl)triethoxysilane, bis(methoxymethyl)diethoxysilane, tris(methoxymethyl)ethoxysilane, (methoxymethyl)methyldiethoxysilane, bis(methoxymethyl)methylethoxysilane, (methoxymethyl)ethyldiethoxysilane, bis(methoxymethyl)ethylethoxysilane, (ethoxymethyl)trimethoxysilane, , bis(ethoxymethyl)dimethoxysilane, tris(ethoxymethyl)methoxysilane, (ethoxymethyl)methyldimethoxysilane, bis(ethoxymethyl)methylmethoxysilane, (ethoxymethyl)ethyldimethoxysilane, bis(ethoxymethyl)ethylmethoxysilane, (ethoxymethyl)triethoxysilane, bis(ethoxymethyl)diethoxysilane, tris(ethoxymethyl)ethoxysilane, (ethoxymethyl)methyldiethoxysilane, bis(ethoxymethyl)methylethoxysilane, (ethoxymethyl)ethyldiethoxysilane, bis(ethoxymethyl)ethylethoxysilane, (propoxymethyl)tripropoxysilane, bis(propoxymethyl)dipropoxysilane, tris(propoxymethyl)propoxysilane, (propoxymethyl)meth Tyldipropoxysilane, bis(propoxymethyl)methylpropoxysilane, (propoxymethyl)ethyldipropoxysilane, bis(propoxymethyl)ethylpropoxysilane, (vinyloxymethyl)trimethoxysilane, bis(vinyloxymethyl)dimethoxysilane, tris(vinyloxymethyl)methoxysilane, (vinyloxymethyl)methyldimethoxysilane, bis(vinyloxymethyl)methylmethoxysilane, (vinyloxymethyl)ethyldimethoxysilane, bis(vinyloxymethyl)ethylmethoxysilane, (phenoxymethyl)trimethoxysilane, bis(phenoxymethyl)dimethoxysilane, tris(phenoxymethyl)methoxysilane, (phenoxymethyl)methyldimethoxysilane, bis(phenoxymethyl)methylmethoxysilane, (phenoxymethyl) ethyl)ethyldimethoxysilane, bis(phenoxymethyl)ethylmethoxysilane, (vinyloxymethyl)triethoxysilane, bis(vinyloxymethyl)diethoxysilane, tris(vinyloxymethyl)ethoxysilane, (vinyloxymethyl)methyldiethoxysilane, bis(vinyloxymethyl)methylethoxysilane, (vinyloxymethyl)ethyldiethoxysilane, bis(vinyloxymethyl)ethylethoxysilane, (phenoxymethyl)triethoxysilane, bis(phenoxymethyl)diethoxysilane, tris(phenoxymethyl)ethoxysilane, (phenoxymethyl)methyldiethoxysilane, bis(phenoxymethyl)methylethoxysilane, (phenoxymethyl)ethyldiethoxysilane, bis(phenoxymethyl)ethylethoxysilane, and the like.
Among these, (methoxymethyl)trimethoxysilane and (ethoxymethyl)triethoxysilane are particularly preferable.

The (organooxymethyl)organooxysilane used in the present invention can be produced by a conventional method, for example, by a substitution reaction between a (halogenated methyl)organooxysilane such as a (chloromethyl)alkoxysilane and a metal organooxide such as an alkali metal alkoxide.

Specific examples of the (halogenated methyl)organooxysilane include (chloromethyl)trimethoxysilane, bis(chloromethyl)dimethoxysilane, tris(chloromethyl)methoxysilane, (chloromethyl)methyldimethoxysilane, bis(chloromethyl)methylmethoxysilane, (chloromethyl)ethyldimethoxysilane, bis(chloromethyl)ethylmethoxysilane, (chloromethyl)triethoxysilane, bis(chloromethyl)diethoxysilane, tris(chloromethyl)ethoxysilane, (chloromethyl)methyldiethoxysilane, bis(chloromethyl)methylethoxysilane, (chloromethyl)ethyldiethoxysilane, bis(chloromethyl)ethylethoxysilane, and (chloromethyl)tripropoxysilane. Bis(chloromethyl)dipropoxysilane, tris(chloromethyl)propoxysilane, (chloromethyl)methyldipropoxysilane, bis(chloromethyl)methylpropoxysilane, (chloromethyl)ethyldipropoxysilane, bis(chloromethyl)ethylpropoxysilane; (bromomethyl)trimethoxysilane, bis(bromomethyl)dimethoxysilane, tris(bromomethyl)methoxysilane, (bromomethyl)methyldimethoxysilane, bis(bromomethyl)methylmethoxysilane, (bromomethyl)ethyldimethoxysilane, bis(bromomethyl)ethylmethoxysilane, (bromomethyl)triethoxysilane, bis(bromomethyl)diethoxysilane, tris(bromomethyl)ethoxysilane, (bromomethyl) (bromomethyl)methyldiethoxysilane, bis(bromomethyl)methylethoxysilane, (bromomethyl)ethyldiethoxysilane, bis(bromomethyl)ethylethoxysilane, (bromomethyl)tripropoxysilane, bis(bromomethyl)dipropoxysilane, tris(bromomethyl)propoxysilane, (bromomethyl)methyldipropoxysilane, bis(bromomethyl)methylpropoxysilane, (bromomethyl)ethyldipropoxysilane, bis(bromomethyl)ethylpropoxysilane; (iodomethyl)trimethoxysilane, bis(iodomethyl)dimethoxysilane, tris(iodomethyl)methoxysilane, (iodomethyl)methyldimethoxysilane, bis(iodomethyl)methylmethoxysilane, (iodometyl)methyldiethoxysilane, bis(bromomethyl)ethylethoxysilane, (bromomethyl)tripropoxysilane, bis(bromomethyl)dipropoxysilane, tris(iodomethyl)propoxysilane, (bromomethyl)methyldipropoxysilane, bis(bromomethyl)ethylpropoxysilane; Examples of such silane include bis(iodomethyl)ethyldimethoxysilane, bis(iodomethyl)ethylmethoxysilane, (iodomethyl)triethoxysilane, bis(iodomethyl)diethoxysilane, tris(iodomethyl)ethoxysilane, (iodomethyl)methyldiethoxysilane, bis(iodomethyl)methylethoxysilane, (iodomethyl)ethyldiethoxysilane, bis(iodomethyl)ethylethoxysilane, (iodomethyl)tripropoxysilane, bis(iodomethyl)dipropoxysilane, tris(iodomethyl)propoxysilane, (iodomethyl)methyldipropoxysilane, bis(iodomethyl)methylpropoxysilane, (iodomethyl)ethyldipropoxysilane, and bis(iodomethyl)ethylpropoxysilane.
Among these, (chloromethyl)trimethoxysilane and (chloromethyl)triethoxysilane are particularly preferable.

Examples of metal species constituting the metal organooxide include alkali metals such as lithium, sodium, and potassium.
Specific examples of the metal organooxide include lithium methoxide, lithium ethoxide, lithium propoxide, lithium vinyl oxide, lithium phenoxide, sodium methoxide, sodium ethoxide, sodium propoxide, sodium vinyl oxide, sodium phenoxide, potassium methoxide, potassium ethoxide, potassium propoxide, potassium vinyl oxide, potassium phenoxide, and alcohol solutions of these in alcohols such as methanol and ethanol.

The amount of the metal organooxide used is preferably more than 1 mole and not more than 5 moles, more preferably more than 1 mole and not more than 2 moles, and even more preferably more than 1 mole and not more than 1.5 moles, per mole of the (halogenated methyl)organooxysilane.
In the above reaction, since a molar excess of the metal organooxide is used relative to the (halogenated methyl)organooxysilane, the metal organooxide remains unreacted after the reaction is completed. In the present invention, the distillation can be carried out in the presence of the metal organooxide by distilling the (organooxymethyl)organooxysilane together with the remaining metal organooxide.

In the above substitution reaction, a solvent can be used as necessary. Specific examples of solvents that can be used are any solvent that does not inhibit the reaction, and include alcohol solvents such as methanol and ethanol; hydrocarbon solvents such as hexane, toluene, and xylene; ether solvents such as tetrahydrofuran and dioxane; and aprotic polar solvents such as acetonitrile and N,N-dimethylformamide. These solvents may be used alone or in combination of two or more.
When a solvent is used, the amount added is preferably 10 to 300 parts by mass, and more preferably 50 to 200 parts by mass, per 100 parts by mass of the total of the (halogenated methyl)organooxysilane and the metal organooxide.

The reaction conditions may be appropriately selected from known conditions. For example, the reaction temperature is preferably 50 to 100°C, and the reaction time is preferably 1 to 10 hours.

The salts generated during the production process of the (organooxymethyl)organooxysilane can be distilled even if they remain, but it is preferable to remove them from the viewpoint of ease of post-treatment after distillation. The removal of the salts is preferably carried out by filtration, centrifugation, or a combination thereof, from the viewpoint of the hydrolysis property of the (organooxymethyl)organooxysilane.
When a solvent is used, the (organooxymethyl)organooxysilane used in the present invention may be isolated by removing the solvent after removing the salt, but may also be in the form of a solution. In the present invention, in view of the fact that distillation is performed in the presence of the remaining metal organooxide, it is preferable that the (organooxymethyl)organooxysilane is dissolved in a solvent together with the remaining metal organooxide. After removing the salt, the solution in which the (organooxymethyl)organooxysilane and the metal organooxide are dissolved can be used as is for the subsequent distillation.

The internal temperature of the still during distillation is below 100°C, preferably 30 to 90°C, and more preferably 35 to 85°C. If the temperature is above 100°C, disproportionation of (organooxymethyl)organooxysilane is likely to occur during distillation, leading to a decrease in purity and yield.

The pressure during distillation is less than 9 kPa, preferably 0.1 to 8 kPa, and more preferably 0.2 to 7 kPa. If the pressure is 9 kPa or more, the internal temperature of the distillation still must be increased accordingly, which makes it easier for disproportionation of (organooxymethyl)organooxysilane to occur during distillation, leading to a decrease in purity and yield. In addition, high temperatures are required during distillation, which leads to high energy consumption and is inefficient in production.

The degree of vacuum can be adjusted by opening and closing the valve, for example, by providing a device for checking the degree of vacuum, such as a manometer, and a valve between the distillation apparatus and the pressure reducing apparatus.

The distillation method can be either single-shot distillation or distillation using a rectification column, but from the perspective of purification, distillation using a rectification column is preferred.

In the production method of the present invention, a solvent may not be used, but as described above, a solvent may be already mixed in the process before distillation. Examples of the solvent include the same ones as those described above.
When a solvent is present, the solvent may be removed in advance at a reduced pressure of, for example, 9 kPa or more, and then the interior of the distillation still may be adjusted to the reduced pressure and temperature described above for distillation, to distill the desired (organooxymethyl)organooxysilane.

According to the present invention, the purity of the purified (organooxymethyl)organoxysilane can be increased to 98.0% or more, preferably 98.5% or more, and more preferably 99.0% or more.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
A 1L four-neck glass flask was fitted with a Dimroth condenser, a thermometer and a stirrer, and the inside of the flask was replaced with nitrogen. 408.6 g of a 21% by mass ethanol solution of sodium ethoxide (1.26 mol of sodium ethoxide) was charged into the flask, and 255.4 g (1.20 mol) of (chloromethyl)triethoxysilane was added dropwise over 1 hour while controlling the internal temperature of the reactor to 70-85°C, and the mixture was aged at the same temperature for 6 hours. Thereafter, the reaction solution was filtered to remove the by-produced sodium chloride.
Next, 559.0 g of the obtained filtrate was charged into a 1 L flask (stillage still) of a distillation charging vessel equipped with a pressure reducing device, a rectification column, a fractionation head equipped with a cooling device, and a thermometer, and room temperature water was passed through the cooling device. The solvent ethanol was removed under 14.3 to 51.3 kPa, and then the pressure was reduced while maintaining the internal temperature of the still at 75 to 85°C, and the main fraction was distilled under 0.4 to 1.4 kPa.
As a result, purified (ethoxymethyl)triethoxysilane with a purity of 99.4% was obtained in an isolated yield of 70.7%.

[Example 2]
A 1L four-neck glass flask was fitted with a Dimroth condenser, a thermometer and a stirrer, and the inside of the flask was replaced with nitrogen. 300.0 g of a 28% by mass methanol solution of sodium methoxide (1.56 mol of sodium methoxide) was charged into the flask, and 252.9 g (1.48 mol) of (chloromethyl)trimethoxysilane was added dropwise over 1 hour while controlling the internal temperature of the reactor to 60-70°C, and the mixture was aged for 6 hours at the same temperature. Thereafter, the reaction solution was filtered to remove the by-produced sodium chloride.
Next, 440.0 g of the filtrate was charged into a 1 L flask (stillage still) equipped with a pressure reducing device, a rectification column, a distillation head equipped with a cooling device, and a thermometer, and room temperature water was passed through the cooling device. The solvent methanol was removed under 14.3 to 51.3 kPa, and then the pressure was reduced while maintaining the internal temperature of the still at 60 to 70°C, and the main fraction was distilled under 0.4 to 4.0 kPa.
As a result, purified (methoxymethyl)trimethoxysilane with a purity of 99.4% was obtained in an isolated yield of 65.0%.

[Comparative Example 1]
559.6 g of the filtrate obtained in the same manner as in Example 1 was charged into a 1 L flask (stillage still) equipped with a pressure reducing device, a rectification column, a fractionation head equipped with a cooling device, and a thermometer, and water at room temperature was passed through the cooling device. The solvent ethanol was removed under 8.0 to 50.8 kPa, and then the main fraction was distilled out at an internal temperature of 110 to 138°C and a pressure of 8.0 kPa.
As a result, purified (ethoxymethyl)triethoxysilane with a purity of 97.9% was obtained in an isolated yield of 37.8%.

[Comparative Example 2]
440.0 g of the filtrate obtained in the same manner as in Example 2 was charged into a 1 L flask (stillage still) equipped with a pressure reducing device, a rectification column, a fractionating head equipped with a cooling device, and a thermometer, and water at room temperature was passed through the cooling device. The solvent methanol was removed under 8.0 to 50.8 kPa, and then the main fraction was distilled out at an internal temperature of 95 to 115°C and a pressure of 8.0 kPa.
As a result, purified (methoxymethyl)trimethoxysilane with a purity of 97.0% was obtained in an isolated yield of 35.0%.

Claims (2)

The following general formula (1)
( ^R1OCH2 ) _mSi ( _OR2 ^{) nR34} _{-mn (} 1)
(In the formula, R ¹ , R ² and R ³ are each independently an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and m and n are integers of 1 to 3, and m+n≦4 is satisfied.)
in the presence of a metal organooxide, while adjusting the internal temperature of a distillation still to 30 to 90°C and the degree of reduced pressure to 0.1 to 4.0 kPa . The method for producing purified (organooxymethyl)organooxysilane according to claim 1, wherein the purified (organooxymethyl)organooxysilane is (methoxymethyl)trimethoxysilane or (ethoxymethyl)triethoxysilane.