CH33SiNHSiCH33

CH33SiNHSiCH33 is the condensed notation for hexamethyldisilazane (HMDS), a silicon–nitrogen compound widely used in organic and silicon chemistry. Its formula is (CH3)3Si-NH-Si(CH3)3, consisting of two trimethylsilyl groups linked by an NH bridge.

Structure and composition: The molecule features two identical silicon centers, each bearing three methyl groups, connected through an amine-like NH linkage. This disilazane framework gives HMDS both silicon and amide-like character, enabling it to engage in silylation and hydrolysis reactions.

Physical properties: HMDS is a colorless, volatile liquid at room temperature with a boiling point around 125–130°C. It is miscible with many organic solvents and is moisture-sensitive; contact with water leads to hydrolysis that yields ammonia and silanol species, which condense to silica. It is flammable and should be stored in a dry, well-ventilated area, away from moisture and incompatible materials.

Production and handling: Industrial HMDS is typically produced by condensation of chlorosilane derivatives in the presence of ammonia, followed by purification. In the laboratory, it is handled under inert, dry conditions and used under a fume hood to control exposure to fumes.

Applications: HMDS is a versatile silylating agent, often used to convert alcohols, amines, and carboxylic acids into their trimethylsilyl derivatives for protection and subsequent manipulation. It serves as a drying agent for moisture-sensitive reagents and glassware and as a surface treatment in microfabrication to render substrates hydrophobic and to promote photoresist adhesion. It also acts as a precursor for certain silicon-containing polymers and thin-film materials.

Safety: HMDS releases ammonia upon hydrolysis and can irritate skin, eyes, and the respiratory tract. It is flammable and reacts with strong oxidizers. Handle with appropriate PPE in a well-ventilated area and store dry.