KR20040040133A - Method for preparing alkylalkoxysilane with high purity - Google Patents

Abstract

PURPOSE: A method for preparing alkylalkoxysilane with high purity is provided, thereby environment-friendly treating chloric acid as a by-product, and improving the purity of alkylalkoxysilane by removing remaining chloric acid. CONSTITUTION: A method for preparing alkylalkoxysilane with high purity comprises the steps of: adding dropwise of 3 to 5 mole of alcohol into 1 mole of alkylchlorosilane in the presence of inert solvent at 0 to 60 deg. C for 0.1 to 10 hours; introducing 3 to 10 mole of ammonia gas into chloric acid as a by-product in situ to precipitate ammonium chloride; and filtering the solution to remove the precipitated ammonium chloride and distilling the filtered solution to remove solvent, wherein the inert solvent is pentane, hexane, decane, dodecane or a mixture thereof; the alkylchlorosilane is methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, ethyltrichlorosilane or diethyldichlorosilane; and the alcohol is methanol, ethanol or alcohol having carbon number of 10 or less.

Description

Process for preparing high purity alkylalkoxysilane {Method for preparing alkylalkoxysilane with high purity}

The present invention relates to a method for producing a high purity alkylalkoxysilane, and more particularly, the reaction of alkylchlorosilane and alcohol in an inert solvent, and by-produced hydrochloric acid is treated with ammonia in an environmentally friendly and efficient manner, while purifying pure alkylalkoxysilane It relates to a method for producing a high purity alkylalkoxysilane obtainable in a tub.

Alkoxyalkoxysilanes are used in various fields such as adhesion promoters, crosslinking agents, paint additives, fiber or leather coating agents, fillers and pigment surface modifiers. In addition, various studies are being conducted to minimize residual chlorine content or maximize product purity.

For example, as a synthesis method, US Pat. No. 3,792,071 and US Pat. No. 4,039,567 disclose a continuous reaction, and US Pat. No. 4,173,576 and US Pat. No. 4,228,092 disclose a batch production method. In particular, U.S. Patent No. 4,228,092 describes a method for synthesizing high purity, high yield alkylalkoxysilanes by dividing alcohol into alkylchlorosilanes in three steps, but does not mention treatment of hydrochloric acid as a byproduct.

In addition, according to the advancement of the industry, in order to use it as an intermediate in the electronic field, there is a demand for a high-quality product having high purity, that is, a chlorine content of several ppm or less. Removal of residual chlorine in the product has been studied in various ways. First, US Pat. No. 4,298,753 describes the removal of hydrochloric acid by distillation. However, a disadvantage of this method is that the remaining hydrochloric acid reacts with the alkylalkoxysilane to form siloxanes in the distillation process, thereby lowering the purity of the product. Second, European Patent No. 282,846 uses alkali metal alkoxide as a neutralizing agent, which has a disadvantage in that the product decomposes during the reaction and the color of the product decreases. Third, in US Pat. No. 6,117,584, magnesium particles were used to reduce the residual chlorine content to several tens of ppm without decomposition of the product, but it was unsuitable for products requiring chlorine content of less than 5 ppm. Fourth, U.S. Patent No. 6,150,550 uses a polar solvent in which hydrochloric acid and an unreacted substance are dissolved and a nonpolar solvent in which the product is dissolved to prevent residual chlorine from attacking the product to reduce its purity. This method can obtain a high purity and yield product, but by using two solvents, it has a disadvantage that a lot of time and energy is consumed because it has to go through a complex distillation process for separation and purification.

The methods disclosed in the above-mentioned patents refer only to the treatment of residual chlorine in the product and not to the treatment of large amounts of hydrochloric acid discharged out of the production equipment. Since hydrochloric acid is a highly corrosive and toxic substance, special materials or containers should be used for storage and transportation, and special care and handling skills are required because it causes large environmental problems.

Accordingly, in the present invention, extensive research has been conducted to solve the problems described above. When the alkylalkoxysilane is prepared by reacting an alkylchlorosilane with an alcohol in the presence of an inert solvent, hydrochloric acid by-produced during the reaction is ammonia gas. React in situ to produce and remove ammonium chloride to prevent hydrochloric acid from leaving the reactor.

The method according to the present invention synthesizes a high purity product having a residual chlorine content of 1 ppm or less and simultaneously stores a large amount of hydrochloric acid in-situ in a reactor with ammonia in storage to store and store hydrochloric acid. It solved the environmental and safety problems of expensive facilities and spills caused by transportation.

Accordingly, an object of the present invention is to prepare in-situ high purity alkylalkoxysilanes having an chlorine content of 1 ppm or less remaining in the alkylalkoxysilanes while treating the corrosive and toxic hydrochloric acid produced by the production of alkylalkoxysilanes in an eco-friendly and economical manner. To provide a way to do this.

The method for producing an alkylalkoxysilane according to the present invention for achieving the above object is prepared according to the following Scheme 1, 3 to 5 with respect to 1 mol of alkylchlorosilane in the presence of 0 to 60 ℃ temperature and 3 to 10 mol of inert solvent. Molar alcohol is added dropwise for 0.1 to 10 hours to synthesize an alkylalkoxysilane; Adding 3 to 10 moles of ammonia gas in-situ to hydrochloric acid, which is a by-product generated in the synthesis step, during the dropping time of alcohol and reacting to precipitate ammonium chloride; And removing the precipitate by filtration, and then removing the solvent in the filtrate through distillation to obtain an alkylalkoxysilane.

RaSiCl4-a + (4-a) R'OH + (4-a) NH3-> RaSi (OR ') 4-a + (4-a) NH4Cl

In the above formula, a is an integer of 1 to 3, and R and R 'are the same or different alkyl groups having 1 to 10 carbon atoms.

Hereinafter, the present invention will be described in more detail.

As described above, the present invention is in situ hydrochloric acid by-produced during the reaction when the alkyl alkoxysilane is prepared by reacting the alkylchlorosilane with an alcohol in an inert solvent such as pentane, hexane, decane, dodecane, etc. The present invention relates to a method for producing a pure alkylalkoxysilane having a residual chlorine content of 1 ppm or less while being treated environmentally and economically by precipitation and removal of ammonium chloride using ammonia gas.

Scheme 1

RaSiCl4-a + (4-a) R'OH + (4-a) NH3-> RaSi (OR ') 4-a + (4-a) NH4Cl

In the above formula, a is an integer of 1 to 3, and R and R 'are the same or different alkyl groups having 1 to 10 carbon atoms.

According to the present invention, in order to treat the corrosive and toxic hydrochloric acid which is a by-product of the production of alkylalkoxysilanes in an eco-friendly and efficient manner, ammonia gas is supplied to remove hydrochloric acid in situ during the reaction. In other words, alkylchlorosilane is added in the presence of an inert solvent, and the alcohol is added dropwise for 0.1 to 10 hours to synthesize an alkylalkoxysilane, and ammonia gas is injected simultaneously with the dropwise addition of alcohol to react with by-product hydrochloric acid to react with ammonium chloride salt. Precipitate to separate and remove by filtration.

As the alkylchlorosilane which can be used in the present invention, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, ethyltrichlorosilane or diethyldichlorosilane is preferable.

In addition, the inert solvent used in the present invention is a solvent which is easy to be separated from the final product, and a solvent having a temperature difference of at least 10 ° C. above the breaking point of the alkylalkoxysilane should be selected to be easily separated during distillation to obtain an alkylalkoxysilane. Pentane, hexane, decane, dodecane or mixtures thereof may be used. In this case, the amount of the inert solvent is preferably 3 to 10 moles with respect to 1 mole of the alkylchlorosilane, and when the amount is less than 3 moles, ammonium chloride salt is not dispersed well, so it is difficult to control the exotherm generated during stirring and reaction, and ammonia Hydrochloric acid gas may be emitted because the gas is not evenly dispersed. Exceeding 10 moles consumes a lot of time and energy to remove the solvent from the product and reduces the productivity of the product.

Alcohols used in the present invention include methanol, ethanol and alcohols having 10 or less carbon atoms, and the amount of the alcohol is preferably 3 to 5 moles based on 1 mole of the alkylchlorosilane, and when the amount is less than 3 moles, the alcohol does not react with the alcohol. Unreacted chloroalkoxysilanes are present, resulting in poor product yields, and exceeding 5 moles consumes a lot of time and energy to react and recycle the excess alcohol remaining from the product.

On the other hand, in order to maximize the yield and purity of the alkyl alkoxysilane, the reaction product of the present invention, and to minimize side reactions, the reaction temperature is preferably carried out at 0 ~ 60 ℃. At this time, if the reaction temperature is less than 0 ℃ slow the reaction rate, a lot of energy is consumed to maintain the low temperature reaction temperature. On the other hand, if the temperature exceeds 60 ° C., the amount of side reactions generated during the reaction increases, thereby reducing the purity and yield of the product, and causing hydrochloric acid to be discharged out of the reaction system.

In addition, by enlarging the particles of ammonium chloride produced above, stirring and reaction temperature control during the reaction are easy, and workability during filtration is improved. The size of the ammonium chloride particles can be appropriately adjusted according to the temperature and stirring speed in the reactor and the amount of ammonia added.

The ammonia is added in an amount of 2 to 5 moles per 1 mole of alkylchlorosilane during the dropping time of the alcohol. After the dropwise addition of alcohol, ammonia is continuously added for 0.1 to 2 hours to have a aging process.

Meanwhile, the ammonium chloride salt is separated through the filtration process, and the filtrate is distilled at a temperature of 20 to 200 ° C. and a vacuum condition of 1 to 760 torr to recover a solvent or an alkylalkoxysilane, thereby obtaining 97 to 99% purity and 85 to 95% yield. Alkyl alkoxysilanes can be obtained. At this time, the residual chlorine content in the product is 1 ppm or less. On the other hand, the recovered solvent can be reused in the next reaction.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.

Example 1

The interior of the five-necked reactor, equipped with a nitrogen supply, reflux condenser, dropping funnel, thermometer, cooler and gas inlet tube, was made into a dry nitrogen atmosphere. First, 866 g (12 moles) of n-pentane was introduced into the reactor, and 300 g (2 moles) of methyltrichlorosilane was added thereto and stirred while maintaining the temperature of the reactant at a temperature of 5 to 30 ° C. 205 g (6.4 mol) of methyl alcohol was added dropwise for 2 hours using a dropping funnel, and ammonia gas was added thereto using a gas inlet tube. At this time, the ammonia gas was flowed at 1000-1500 ml / min, and the reaction proceeded while precipitating hydrochloric acid generated during the reaction with ammonium chloride. After completion of the reaction, ammonium chloride was separated and removed by filtration, and the filtrate was fractionally distilled under a temperature of 20 to 100 ° C. and a vacuum condition of 760 to 1 torr to remove n-pentane from the filtrate. Purity of the methyltrimethoxysilane obtained from this was 98.5%, yield 90%, the residual chlorine content in the product was 1ppm.

Example 2

The same reactor as in Example 1 was installed, and the inside of the reactor was made into a dry nitrogen atmosphere. First, 1550 g (18 moles) of n-hexane was added to the reactor, and 450 g (3 moles) of methyltrichlorosilane was added thereto and stirred while maintaining the temperature of the reactant at a temperature of 5 to 50 ° C. 442 g (9.6 mol) of ethyl alcohol was added dropwise for 2 hours using a dropping funnel, and ammonia gas was added thereto using a gas inlet tube. At this time, the ammonia gas was allowed to flow at 1300 to 2000 ml / min while the hydrochloric acid generated during the reaction was precipitated with ammonium chloride. After completion of the reaction, high-purity methyltriethoxysilane (purity 97.5%, yield 87%, residual chlorine content 1ppm) was obtained through filtration and distillation.

Example 3

The same reactor as in Example 1 was installed, and the inside of the reactor was made into a dry nitrogen atmosphere. First, 3400 g (20 mol) of n-dodecane were added to the reactor, and 600 g (4 mol) of methyl trichlorosilane was added thereto while stirring the temperature of the reactant at a temperature of 5 to 60 ° C. 400 g (12.4 mol) of methyl alcohol was added dropwise for 2 hours using a dropping funnel, while ammonia gas was added using a gas inlet tube. At this time, the ammonia gas was allowed to flow at 2000 to 2700 ml / min while the hydrochloric acid generated during the reaction was precipitated with ammonium chloride. After completion of the reaction, filtration and distillation yielded methyltrimethoxysilane having a purity of 99%, a yield of 92%, and a residual chlorine content of 0 ppm.

Example 4

Synthesis was carried out in the same manner using n-dodecane recovered in Example 3. Filtration and distillation gave a high purity methyltrimethoxysilane (99% purity, 90% yield, 0 ppm residual chlorine).

As described above, the process according to the present invention, compared to the conventional methods, reacts firstly with by-products of hydrochloric acid, which can cause corrosiveness, toxicity and hazards in handling and environmental problems on spillage without using ammonia to discharge it out of the reactor. It is advantageous in that it can be environmentally treated by precipitation and removal of ammonium chloride in situ in the aircraft. Second, if hydrochloric acid remains in the alkylalkoxysilane, the purity of the alkylalkoxysilane is reduced by increasing the high boiling point components. In the method, ammonia gas precipitated and removed all residual chlorine with ammonium chloride in situ, thereby obtaining a high-purity alkylcoccisilane having a high boiling point component of 2% or less. Third, the distilled alkylalkoxysilane required no further purification with a residual chlorine content of 1 ppm or less. Therefore, the method of the present invention can produce a high purity alkylalkoxysilane through an environmentally friendly process.

Claims (6)

It is prepared according to Scheme 1 below. Synthesizing the alkylalkoxysilane by dropwise addition of 3 to 5 moles of alcohol for 0.1 to 10 hours to 1 mole of alkylchlorosilane in the presence of 0 to 60 ° C. and 3 to 10 moles of inert solvent; Adding 3-10 moles of ammonia gas in-situ to hydrochloric acid, which is a by-product generated in the synthesis step, during the alcohol dropping time and reacting to precipitate ammonium chloride; And After the precipitate is filtered off, the method of preparing an alkylalkoxysilane of high purity, comprising the step of removing the solvent in the filtrate through distillation to obtain an alkylalkoxysilane: Scheme 1 RaSiCl4-a + (4-a) R'OH + (4-a) NH3-> RaSi (OR ') 4-a + (4-a) NH4Cl In the above formula, a is an integer of 1 to 3, and R and R 'are the same or different alkyl groups having 1 to 10 carbon atoms. The method of claim 1 wherein the method further comprises recovering and reusing the removed solvent. The method of claim 1 wherein the inert solvent is a solvent having a temperature difference of at least 10 ° C. or more compared to the breaking point of the alkylalkoxysilane. The method of claim 1 or 3, wherein the inert solvent is pentane, hexane, decane, dodecane or mixtures thereof. The method of claim 1, wherein the alkylchlorosilane is methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, ethyltrichlorosilane or diethyldichlorosilane. The method of claim 1, wherein the alcohol is methanol, ethanol or an alcohol having 10 or less carbon atoms.