Its main uses are: ① as a chain extender for organosilicon polymers; ② Organic silicone resin as a modifier to improve the flexibility of the resin; ③ And as important raw materials for vinyl sealing agents; ④ Organosilicon structure control agent for mixed rubber to improve its mixing performance; ⑤ Used to treat the surface of white carbon black, fiberglass, pigments, fillers, and hygroscopic inorganic compounds, improving their hydrophobicity and anti adhesion.

The present invention proposes a preparation method for dimethyl dimethoxysilane to address the shortcomings. The preparation method enables the reaction to be carried out at room temperature, reduces the concentration of hydrogen chloride in the reaction system, and shortens the process flow.
In order to achieve the above invention objectives, the present invention provides the following technical solution: a method for preparing dimethyl dimethoxysilane, including adding a hydrogen chloride absorbent to the reaction of dimethyl dichlorosilane and methanol.
The preferred process for adding hydrogen chloride absorber is to add dimethyl dichlorosilane and hydrogen chloride absorber into the reactor, and add methanol dropwise under stirring; The molar ratio of dimethyl dichlorosilane, hydrogen chloride absorbent, and methanol is 1:2-2.5:2-2.8; The reaction pressure is -200-0 millimeters of mercury, the temperature is 40-60 ℃, and the time is 2-4 hours; Let it stand for layering and take the upper layer product.
Preferably, the molar ratio of dimethyl dichlorosilane, hydrogen chloride absorbent, and methanol is 1:2:2.2.
Preferably, the hydrogen chloride absorbent is urea, ammonia, amine, or alkaline earth metal.
To remove hydrogen chloride as much as possible, the preparation method also includes the step of removing hydrogen chloride from the upper product.
Preferably, the step of removing hydrogen chloride is to add a neutralizing agent that reacts with hydrogen chloride to the upper product, and the reaction product is solid.
Preferably, the neutralizing agent is sodium alcohol, potassium alcohol, alkaline earth metal, ammonia or amine. [0019] The preparation method also includes rectifying the clear liquid after removing hydrogen chloride.
Compared with the prior art, the present invention adopts a hydrogen chloride absorber, which allows the reaction to take place at room temperature and minimizes the concentration of hydrogen chloride in the system, thereby preventing the occurrence of side reactions and shortening the process flow and reducing investment The reaction is easy to control and the operating cost is reduced; ③ The yield has significantly increased, reducing production costs.
Due to the fact that the hydrogen chloride absorbent is not miscible with the target product of the present invention (i.e. dimethyldimethoxysilane) after absorbing hydrogen chloride, it is easy to separate and separate, preventing the solid by-product from encapsulating the crude product. This is easy to operate and can improve the yield of crude products.
Due to the fact that hydrogen chloride absorbers are easily soluble in the absorbed product system, the contact between hydrogen chloride in the target product system and the absorbent is not very good, resulting in a small amount of hydrogen chloride and a small amount of non alcoholysis products of the second chlorine in the target product system. So further reaction is needed. At this point, continuing to add an absorbent is not effective, so a substance that is easier to absorb hydrogen chloride and the reaction is more thorough is used. In the present invention, neutralizing agents such as potassium alcohol, sodium alcohol, magnesium powder, aluminum powder, etc. that do not produce water can be used, and the solid precipitates generated can be accumulated and filtered for slag removal.