| Boiling Point | 101°C |
| Melting Point | −59°C (lit.) |
| Density | 0.764 g/mL at 20°C (lit.) |
| Color | Colorless |
| Linear Formula | (CH3)3SiOSi(CH3)3 |
| Formula Weight | 162.38 |
| Physical Form | Liquid |
| Chemical Name or Material | Hexamethyldisiloxane |
| UN Number | 1993 |
| Molecular Weight | 162.38 g/mol |
| SMILES String | C[Si](C)(C)O[Si](C)(C)C |
| Refractive Index | n20/D 1.377 (lit.) |
| CAS Number | 107-46-0 |
| EC Number | 203-492-7 |
| NACRES | NA.22 |
| PubChem Substance ID | 24852329 |
| UNSPSC Code | 12352103 |
| MDL Number | MFCD00008265 |
| InChI | 1S/C6H18OSi2/c1-8(2,3)7-9(4,5)6/h1-6H3 |
| InChI Key | UQEAIHBTYFGYIE-UHFFFAOYSA-N |
| Beilstein/REAXYS Number | 1736258 |
| Quality Level | 200 |
| Reference Assay | ≥98% |
Hexamethyldisiloxane is the simplest linear siloxane, consisting of two trimethylsilyl groups joined through a single oxygen bridge. That symmetric, low-polarity structure gives it high volatility and low viscosity, along with the reactivity typical of organosilicon compounds — properties chemists exploit both as a reagent and as a coating-deposition precursor.
In organic synthesis, HMDSO serves as a mild silylating agent, useful for protecting hydroxyl groups or generating trimethylsilyl (TMS) derivatives. In materials science, it’s a common precursor gas for plasma-enhanced chemical vapor deposition of silicon-oxide barrier and adhesion-promoting coatings on packaging films and other substrates, and it has been used as a substitute for silane in silicon integrated-circuit technology. It also functions as a volatile, skin-feel-enhancing solvent in some cosmetic formulation research.
