Diphenylsilane
[CAS# 775-12-2]

Identification

• Classification: Chemical reagent >> Organic reagent >> Silane
• Name: Diphenylsilane
• Molecular Formula: C₁₂H₁₂Si
• Molecular Weight: 184.31
• CAS Registry Number: 775-12-2
• EC Number: 212-271-4
• SMILES: C1=CC=C(C=C1)[Si]C2=CC=CC=C2

Properties

• Density: 0.993 g/mL (Expl.)
• Melting point: 79 º°C (solv: pentane) (Expl.)
• Boiling point: 218.6 °C 760 mmHg (Calc.)^*, 235.9 - 238.5 °C (Expl.)
• Flash point: 98.3 °C (Calc.)^*, 98 °C (Expl.)
• Refraction index: 1.579 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319
• Safety Statements: P264-P264+P265-P280-P302+P352-P305+P351+P338-P321-P332+P317-P337+P317-P362+P364

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

Diphenylsilane (C₁₂H₁₂SiH₂) is an organosilicon compound composed of a silicon atom bonded to two phenyl groups and two hydrogen atoms. It is a colorless, flammable liquid with a distinctive odor, used mainly as a reagent in organic synthesis. The two Si–H bonds in diphenylsilane are reactive and serve as a source of hydride in a variety of chemical transformations.

The compound was first prepared in the mid-20th century during the expansion of organosilicon chemistry, which followed early developments in Grignard and organolithium chemistry. A typical synthetic route involves the reaction of phenylmagnesium bromide or phenyllithium with dichlorosilane, producing diphenylsilane after hydrolysis. Redistribution reactions between phenylsilanes under the influence of catalysts can also yield diphenylsilane.

Diphenylsilane is valued for its role as a selective reducing agent. In the presence of suitable transition metal catalysts, such as rhodium, iridium, or palladium complexes, it participates in hydrosilylation reactions with alkenes and alkynes to produce organosilicon derivatives. It can also reduce carbonyl compounds, imines, and certain organic halides through hydride transfer, often under milder conditions than traditional reducing agents. These properties make it particularly useful in synthetic organic chemistry, including the preparation of fine chemicals and pharmaceuticals.

The steric bulk of the two phenyl groups influences both the reactivity and selectivity of diphenylsilane. Compared with simpler silanes like phenylsilane or trialkylsilanes, diphenylsilane is generally less prone to uncontrolled side reactions, which can be advantageous in selective reductions. In catalytic transformations, the electron-withdrawing effect of the phenyl substituents modifies the Si–H bond polarity, affecting the reaction rate and product distribution.

Beyond its role in organic synthesis, diphenylsilane can serve as a precursor to silicon-containing polymers, resins, and coatings. The incorporation of phenyl groups imparts enhanced thermal stability and oxidation resistance to the resulting materials. Such properties are beneficial in applications where resistance to heat and chemical degradation is required, including specialty adhesives and protective surface treatments.

Diphenylsilane is moisture-sensitive and should be stored under an inert atmosphere to prevent hydrolysis, which can release flammable hydrogen gas. While it has relatively low acute toxicity compared to some other reactive silanes, appropriate precautions such as handling in a fume hood and avoiding ignition sources are necessary to ensure safe laboratory use.

References

2006. Diphenylsilylene. Journal of the American Chemical Society, 128(42).
DOI: 10.1021/ja0653223
URL: https://pubmed.ncbi.nlm.nih.gov/17090011

2005. Silicon-containing polyoxadiazoles—synthesis and perspectives. Advances in Colloid and Interface Science, 118(1-3).
DOI: 10.1016/j.cis.2005.03.006
URL: https://pubmed.ncbi.nlm.nih.gov/16188217

2010. Facile and Efficient Reduction of Ketones in the Presence of Zinc Catalysts Modified by Phenol Ligands. Chemistry - An Asian Journal, 5(9).
DOI: 10.1002/asia.201000317
URL: https://pubmed.ncbi.nlm.nih.gov/20635378