Phenylsilane

Chembox new
Name = Phenylsilane
ImageFileL1 = Phenylsilane.png ImageSizeL1 = 80 px
ImageNameL1 = skeletal formula of phenylsilane
ImageFileR1 = Phenylsilane-3D-vdW.png ImageSizeR1 = 120 px
ImageNameR1 = ball-and-stick model of the phenylsilane molecule
OtherNames = Silylbenzene
Section1 = Chembox Identifiers
CASNo = 694-53-1

Section2 = Chembox Properties
Formula = C6H8Si
MolarMass = 108.22 g/mol
Appearance = Colorless liquid
Density = 0.878 g/cm³
Solubility in water = N/A (very reactive with water)
MeltingPt = N/A
BoilingPt = 119-121 °C (433-394 K)

Section3 = Chembox Hazards
MSDS = [http://www.sigmaaldrich.com/cgi-bin/hsrun/Suite7/Suite/HAHTpage/Suite.HsSigmaAdvancedSearch.formAction]
RPhrases = 11-14/15-20/22-36/37/38
SPhrases = 16-43

Phenylsilane, also known as silylbenzene, a colorless liquid, is one of the simplest organosilanes with the formula C6H5SiH3. It is structurally related to toluene, with a silyl group replacing the methyl group. Both of these compounds have similar densities and boiling points due to these similarities. Phenylsilane is soluble in organic solvents.

ynthesis and reactions

Phenylsilane is produced in two steps from Si(OEt)4. In the first step magnesium bromobenzene is added to form Ph-Si(OEt)3. The approach of using a magnesium-bromine reagent is called a Grignard reaction. Reduction of the resulting Ph-Si(OEt)3 product with LiAlH4 affords phenylsilane [Minge, O.; Mitzel, N. W.; and Schmidbaur, H. Synthetic Pathways to Hydrogen-Rich Polysilylated Arenes from Trialkoxysilanes and Other Precursors. Organometallics 2002, 21, 680-684. DOI 10.1021/om0108595.] .

Ph-MgBr + Si(OEt)4 → Ph-Si(OEt)3 + MgBr(OEt)

4 Ph-Si(OEt)3 + 3 LiAlH4 → 4 Ph-SiH3 + 3 LiAl(OEt)4

Uses

Phenylsilane can be used to reduce tertiary phosphine oxides to the corresponding tertiary phosphine.

P(CH3)3O + PhSiH3 --> P(CH3)3 + PhSiH2OH

The use of phenylsilane proceeds with retention of the configuration at the phosphine. For example, cyclic chiral tertiary phosphine oxides can be reduced to cyclic tertiary phosphines [Weber, W. P. "Silicon Reagents for Organic Synthesis". Springer-Verlag: Berlin, 1983. ISBN 0387116753.] .

Phenylsilane can also be combined with cesium fluoride. In aprotic solvents, it becomes a nonnucleophilic hydride donor. Specifically, phenylsilane-caesium fluoride has been shown to reduce 4-oxazolium salts to 4-oxazolines. This reduction gives yields of 95% [Fleck, T. J. "Encyclopedia of Reagents for Organic Synthesis" DOI 10.1002/047084289X.rp101] .

References


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