Hexamethyldisiloxane
From Wikipedia, the free encyclopedia
| Hexamethyldisiloxane | |
|---|---|
 |
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| IUPAC name | Hexamethyldisiloxane |
| Other names | HMDS HMDSO Bis(trimethylsilyl) ether Bis(trimethylsilyl) oxide |
| Identifiers | |
| CAS number | [107-46-0] |
| RTECS number | JM9237000 |
| SMILES | CSi(C)(C)OSi(C)(C)C |
| Properties | |
| Molecular formula | C6H12OSi2 |
| Molar mass | 162.38 g/mol |
| Appearance | colorless liquid |
| Density | 0.764 g/cm3 |
| Melting point |
−59 °C |
| Boiling point |
101 °C |
| Solubility in water | low |
| Solubility in other solvents | all organic solvents |
| Refractive index (nD) | 1.377 |
| Hazards | |
| Main hazards | flammable |
| R-phrases | 11 |
| S-phrases | 16 |
| Related compounds | |
| Related compounds | Tetramethylsilane Dimethyl ether Bis(trimethylsilyl)amine |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Hexamethyldisiloxane is a chemical compound with the formula O[Si(CH3)3]2. This volatile liquid is used as a solvent and as a reagent. The species arises by the hydrolysis of trimethylsilyl chloride. The molecule is the protypical silyl ether and can be considered a subunit of polydimethylsiloxane.
[edit] Uses
It is primarily used as source of the trimethylsilyl functional group (-Si(CH3)3) in organic synthesis. For example, in the presence of acid catalyst, it converts alcohols and carboxylic acids into the silyl ethers and silyl esters, respectively.[1]
HMDS is used as an internal standard for calibrating chemical shift in1H NMR spectroscopy. It is more easily handled since it is less volatile than the usual standard tetramethylsilane but still displays only a singlet near 0 ppm.
HMDS has even poorer solvating power than alkanes. It is therefore sometimes employed to crystallize highly lipophilic compounds.
It is also used in liquid bandages (spray on plasters) like in cavilon spray used on the body to protect damaged skin from irritation from other bodily fluids.
[edit] Safety
Like most siloxanes, hexamethyldisiloxane is fairly innocuous.
[edit] References
- ^ Pfeifer, J. "Hexamethyldisiloxane" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
