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skeletal formula of phenylsilane
ball-and-stick model of the phenylsilane molecule
Other names
3D model (JSmol)
ECHA InfoCard 100.010.703
Molar mass 108.22 g·mol−1
Appearance Colorless liquid
Density 0.878 g/cm3
Boiling point 119 to 121 °C (246 to 250 °F; 392 to 394 K)
Safety data sheet MSDS
R-phrases (outdated) R11-R14/15-R20/22-R36/37/38
S-phrases (outdated) S16-S43
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

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.

Synthesis and reactions[edit]

Phenylsilane is produced in two steps from Si(OEt)4. In the first step, phenylmagnesium bromide is added to form Ph-Si(OEt)3 via a Grignard reaction. Reduction of the resulting Ph-Si(OEt)3 product with LiAlH4 affords phenylsilane.[1]

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


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 configuration at the phosphine. For example, cyclic chiral tertiary phosphine oxides can be reduced to cyclic tertiary phosphines.[2]

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%.[3]


  1. ^ 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
  2. ^ Weber, W. P. Silicon Reagents for Organic Synthesis. Springer-Verlag: Berlin, 1983. ISBN 0-387-11675-3.
  3. ^ Fleck, T. J. Encyclopedia of Reagents for Organic Synthesis doi:10.1002/047084289X.rp101