Preparation
Currently, in industry, methyltrichlorosilane and acetic anhydride are commonly used as raw materials for acylation reactions to synthesize methyltriacetoxysilane products. The content can reach over 95%, and the total chlorine content is ≤100ppm. The reaction formula is as follows: CH3SiCl3 + 3C4H6O3 → (CH3CO2)3SiCH3 + 3C2H3ClO. The production process is as follows: Using methyltrichlorosilane and acetic anhydride as raw materials, the materials are added to the synthesis reactor in a certain proportion for the acylation reaction. The temperature is first raised to 80℃ for atmospheric pressure reflux reaction, and acetyl chloride is collected while refluxing at 80~95℃ until the flow is stopped. The semi-finished methyltriacetoxysilane in the synthesis reactor is transferred to a crude synthesis tank. The semi-finished product is then pumped to an acetyl chloride vacuum thin-film evaporator, where the feeding temperature is controlled at 100℃ to distill off acetic anhydride and acetyl chloride. The material is then pumped to an acetic anhydride vacuum thin-film evaporator, where the feeding temperature is controlled at 105-115℃ to obtain the finished methyltriacetoxysilane. Material containing a large amount of acetic anhydride is extracted from both vacuum thin-film evaporators and returned to the synthesis reactor. The finished methyltriacetoxysilane is then decolorized in a decolorization reactor using activated carbon at 70℃. After decolorization, the material is filtered through a candle filter into a modification reactor to obtain pure methyltriacetoxysilane.
Chemical Properties
Methyltriacetoxysilane (MTAC) is a clear to yellowish liquid with acrid odor of acetic acid (vinegar). It hydrolyzes in the presence of moisture (acetic acid is released) to form silanols, which can react with themselves to pro-duce siloxanes or bind to inorganic substrates.
Uses
Methyltriacetoxysilane is used as a silane coupling agent.
Flammability and Explosibility
Not classified
Toxics Screening Level
The initial threshold screening level (ITSL) for methyltriacetoxysilane (CASRN 4253-34-3) remains at 0.1 μg/m3 based on an annual averaging time.
