Methyltriacetoxysilane
[CAS# 4253-34-3]

Identification

• Classification: Chemical reagent >> Organic reagent >> Silane
• Name: Methyltriacetoxysilane
• Synonyms: Methylsilanetriyl triacetate; Triacetoxy(methyl)silane
• Molecular Formula: C₇H₁₂O₆Si
• Molecular Weight: 220.25
• CAS Registry Number: 4253-34-3
• EC Number: 224-221-9
• SMILES: CC(=O)O[Si](C)(OC(=O)C)OC(=O)C

Properties

• Density: 1.2±0.1 g/mL, Calc.^*, 1.20 g/mL (Expl.)
• Melting point: 40-45 °C (Expl.)
• Index of Refraction: 1.424, Calc.^*, 1.52-1.522 (Expl.)
• Boiling Point: 221.3 °C (760 mmHg), Calc.^*, 246.9-248.2 °C (Expl.)
• Flash Point: 85.0 °C, Calc.^*, 84 °F (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H302-H314-H315-H318-H319-H335
• Safety Statements: P260-P261-P264-P264+P265-P270-P271-P280-P301+P317-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P351+P338-P305+P354+P338-P316-P317-P319-P321-P330-P332+P317-P337+P317-P362+P364-P363-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Skin corrosion	Skin Corr.	1B	H314
Skin corrosion	Skin Corr.	1C	H314
Serious eye damage	Eye Dam.	1	H318
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Respiratory sensitization	Resp. Sens.	1	H334
Skin sensitization	Skin Sens.	1	H317
Eye irritation	Eye Irrit.	2	H320
Skin corrosion	Skin Corr.	1	H314
Acute toxicity	Acute Tox.	1	H302

Discovery and Applications

Methyltriacetoxysilane (MTAS) is an organosilicon compound with the chemical formula CH₃Si(OCOCH₃)₃. It is a colorless liquid that is commonly used as a silane coupling agent and crosslinking agent. MTAS was first introduced in the 1960s as part of the development of silane chemistry, which has since been widely adopted in various industrial applications.

The compound consists of a silicon atom bonded to three acetoxy groups (–OCOCH₃) and one methyl group (–CH₃). The acetoxy groups are hydrolyzed in the presence of water to form acetic acid, leading to the formation of reactive silanol groups (–SiOH) that can further bond with substrates, such as glass, metal, and organic materials. This reactivity allows MTAS to act as a surface modifier and adhesive promoter, enhancing the bonding of organic and inorganic materials.

Methyltriacetoxysilane is primarily used in the formulation of sealants, adhesives, coatings, and paints. It is especially valuable in applications requiring improved adhesion to glass, metal, and ceramics. Its ability to form strong covalent bonds with silica surfaces makes it a key ingredient in the production of glass fibers and reinforced composite materials. In the automotive and construction industries, MTAS is used to create durable, water-resistant adhesives that improve the performance of various components.

In addition to its use as a coupling agent, MTAS is also employed in the production of silicone rubber and other silicone-based materials. It serves as a crosslinking agent in the curing process, improving the thermal stability, elasticity, and mechanical strength of silicone products. Methyltriacetoxysilane is a critical component in the manufacturing of products such as gaskets, seals, and automotive parts that require resistance to high temperatures and environmental factors.

Another significant application of MTAS is in the field of surface treatment. The compound is used to modify the surface properties of substrates such as glass, ceramics, and metals, improving their wettability, corrosion resistance, and adhesion properties. This makes it useful in a wide range of applications, including the production of coatings for electronic devices, optical fibers, and medical equipment. Additionally, MTAS is used in the preparation of hydrophobic and anti-fouling surfaces, which find use in industries like marine coatings and water treatment.

MTAS is also employed in the synthesis of various other silane compounds, which are used as intermediates in the production of specialty chemicals and materials. Its versatility and reactive nature have made it an essential building block in silane chemistry, which underpins numerous industrial processes.

While methyltriacetoxysilane is generally safe to handle when proper precautions are followed, it can be hazardous if not used properly. The compound is known to release acetic acid when hydrolyzed, which can cause irritation to the eyes, skin, and respiratory system. Therefore, it is important to work with MTAS in well-ventilated areas and to use appropriate protective equipment to avoid exposure.

In summary, methyltriacetoxysilane is a key organosilicon compound with widespread applications in adhesives, coatings, sealants, and surface treatment. Its ability to promote adhesion between inorganic and organic materials has made it indispensable in industries ranging from automotive and construction to electronics and medical devices. Its discovery and use have had a lasting impact on materials science, particularly in the development of durable and high-performance products.

References

2015. Two-cationic 2-methylbenzothiazole derivatives as green light absorbed sensitizers in initiation of free radical polymerization. Colloid and Polymer Science, 293(7).
DOI: 10.1007/s00396-015-3572-1

2022. Photoinduced free radical-releasing systems and their anticancer properties. Photochemical & Photobiological Sciences, 21(7).
DOI: 10.1007/s43630-022-00231-1

2023. Sensitive photoresists for high-speed two-photon lithography. Nature Nanotechnology, 18(12).
DOI: 10.1038/s41565-023-01518-9