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Hexamethyldisiloxane

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Names

  

Preferred IUPAC name

Hexamethyldisiloxane

  

Other names

Bis(trimethylsilyl) ether

Bis(trimethylsilyl) oxide

  

Identifiers

  

CAS Number

107-46-0 

Abbreviations

HMDSO, (TMS)2O

Beilstein Reference

1736258

ChEBI

CHEBI:78002 

ChemSpider

23150 

EC Number

203-492-7

InChI[show]

  

Jmol interactive 3D

Image

MeSH

Hexamethyldisiloxane

PubChem

24764

RTECS number

JM9237000

SMILES[show]

  

UNII

D7M4659BPU 

UN number

1993

Properties

  

Chemical formula

C6H18OSi2

Molar mass

162.38 g·mol1

Appearance

Colourless liquid

Density

0.764 g cm3

Melting point

59 °C (74 °F; 214 K)

Boiling point

100 to 101 °C (212 to 214 °F; 373 to 374 K)

Solubility in water

930.7±33.7 ppb (23 °C) [1]

Vapor pressure

43 hPa (20 °C) [2]

Refractive index (nD)

1.377

Hazards

  

Main hazards

Highly flammable liquid and vapour

Causes serious eye irritation

EU classification (DSD)

F

R-phrases

R11

S-phrases

S16

NFPA 704

4

1

0

Flash point

-1(1) °C

Related compounds

  

Related compounds

Disiloxane

Tetramethylsilane

Dimethyl ether

Bis(trimethylsilyl)amine

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

  

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Infobox references

  

Hexamethyldisiloxane

Hexamethyldisiloxane (HMDSO) is an organosilicon compound with the formula O[Si(CH3)3]2. This volatile colourless liquid is used as a solvent and as a reagent in organic synthesis. It is prepared by the hydrolysis of trimethylsilyl chloride. The molecule is the protypical disiloxane and resembles a subunit of polydimethylsiloxane.

Synthesis and reactions[edit]

Hexamethyldisiloxane can be produced by hydrolysis of trimethylsilyl chloride:

2 Me3SiCl + H2O 2 HCl + O[Si(CH3)3]2

It also results from the hydrolysis of silylethers and other silyl-protected functional groups. HMDSO can be converted back to the chloride by reaction with Me2SiCl2.[3]

Hexamethyldisiloxane is mainly 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.[4]

It reacts with rhenium(VII) oxide to give the silanoate complex:[5]

Re2O7 + O[Si(CH3)3]2 2 O3ReOSi(CH3)3

Niche uses[edit]

HMDSO 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.

HMDSO has even poorer solvating power than alkanes. It is therefore sometimes employed to crystallize highly lipophilic compounds.

It is used in liquid bandages (spray on plasters) such as cavilon spray, to protect damaged skin from irritation from other bodily fluids. It is also used to soften and remove adhesive residues left by medical tape and bandages, without causing further skin irritation.

HMDSO is being studied for making low-k dielectric materials for the semi-conductor industries by PECVD (plasma-enhanced chemical vapor deposition).

HMDSO has been used as a reporter molecule to measure tissue oxygen tension (pO2). HMDSO is highly hydrophobic and exhibits high gas solubility, and hence strong nuclear magnetic resonance spin lattice relaxation rate (R1) response to changes in pO2. Molecular symmetry provides a single NMR signal. Following direct injection into tissues it has been used to generate maps of tumor and muscle oxygenation dynamics with respect to hyperoxic gas breathing challenge.[6]

References[edit]

  1. Jump up ^ Sudarsanan Varaprath, Cecil L. Frye, Jerry Hamelink (1996). "Aqueous solubility of permethylsiloxanes (silicones)". Environmental Toxicology and Chemistry 15 (8): 1263–1265. doi:10.1002/etc.5620150803.
  2. Jump up ^ Record of CAS RN 107-46-0 in the GESTIS Substance Database of the IFA, accessed on March 11, 2015.
  3. Jump up ^ Röshe, L.; John, P.; Reitmeier, R. "Organic Silicon Compounds" Ullmann's Encyclopedia of Industrial Chemistry. John Wiley and Sons: San Francisco, 2003. doi:10.1002/14356007.a24_021.
  4. Jump up ^ Pfeifer, J. "Hexamethyldisiloxane" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
  5. Jump up ^ Schmidt, M.; Schmidbaur, H., "Trimethylsilyl perrhenate", Inorg. Synth. 1967, 9, 149-151. doi:10.1002/9780470132401.ch40
  6. Jump up ^ Kodibagkar VD, Cui W, Merritt ME, Mason RP. A novel 1H NMR approach to quantitative tissue oximetry using hexamethyldisiloxane. Magn Reson Med 2006;55:743–748 and Kodibagkar VD, Wang X, Pacheco-Torres J, Gulaka P, Mason RP. Proton Imaging of Siloxanes to map Tissue Oxygenation Levels (PISTOL): a tool for quantitative tissue oximetry. NMRBiomed 2008;21:899-907.

   

출처: <https://en.wikipedia.org/wiki/Hexamethyldisiloxane>

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