tert-Butylchlorodiphenylsilane
[CAS 58479-61-1]

Identification

• Classification: Chemical reagent >> Organic reagent >> Silane
• Name: tert-Butylchlorodiphenylsilane
• Synonyms: tert-Butyldiphenylchlorosilane; tert-Butyldiphenylsilyl chloride
• Molecular Formula: C₁₆H₁₉ClSi
• Molecular Weight: 274.86
• CAS Registry Number: 58479-61-1
• EC Number: 261-282-0
• SMILES: CC(C)(C)[Si](C1=CC=CC=C1)(C2=CC=CC=C2)Cl

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*, 1.072 g/mL (Expl.)
• Boiling point: 334.4±11.0 °C 760 mmHg (Calc.)^*, 461 °C (Expl.)
• Flash point: 143.3±9.2 °C (Calc.)^*, 112 °C (Expl.)
• Index of refraction: 1.547 (Calc.)^*, 1.568 (Expl.)

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

Safety Data

• Hazard Symbols: GHS05 Danger
• Risk Statements: H314
• Safety Statements: P260-P264-P280-P301+P330+P331-P302+P361+P354-P304+P340-P305+P354+P338-P316-P321-P363-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Specific target organ toxicity - single exposure	STOT SE	3	H335
Serious eye damage	Eye Dam.	1	H318
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Skin corrosion	Skin Corr.	1	H314

• Transport Information: UN 2987

Discovery and Applications

tert-Butylchlorodiphenylsilane is an organosilicon compound widely used as a protecting-group reagent in synthetic organic chemistry. It consists of a silicon atom bonded to a tert-butyl group, two phenyl groups, and one chlorine atom. The compound belongs to the family of chlorosilanes and is commonly abbreviated as TBDPS-Cl, reflecting its role as the precursor of the tert-butyldiphenylsilyl (TBDPS) protecting group.

The molecule contains a tetravalent silicon center in an approximately tetrahedral arrangement. Silicon is bonded to three carbon-containing substituents and one chlorine atom. The silicon–chlorine bond is strongly polarized because chlorine is more electronegative than silicon, creating an electrophilic silicon center that is highly susceptible to nucleophilic attack. This bond is the principal reactive feature of the compound.

The tert-butyl substituent contributes substantial steric bulk around the silicon atom. This group consists of a quaternary carbon attached to three methyl groups and provides strong steric shielding. The two phenyl rings further increase molecular size and contribute aromatic character. Together, these substituents make the silicon center significantly more sterically hindered than in simpler chlorosilanes such as trimethylsilyl chloride.

Because of this steric protection, tert-butyldiphenylsilyl groups introduced from tert-butylchlorodiphenylsilane often exhibit greater resistance to hydrolysis and deprotection conditions than smaller silyl protecting groups. This property has made the reagent particularly useful in multistep synthesis where selective protection and later removal of alcohol functionalities are required.

The principal application of tert-butylchlorodiphenylsilane is the conversion of alcohols into tert-butyldiphenylsilyl ethers. In a typical reaction, an alcohol oxygen acts as a nucleophile and attacks the electrophilic silicon center, displacing chloride and generating a silyl ether. A base is commonly used to neutralize the hydrogen chloride generated during the reaction. The resulting silyl ethers are frequently employed because they remain stable under many reaction conditions.

The reagent was developed as part of broader efforts in synthetic chemistry to create protecting groups with differing levels of stability. Earlier silyl protecting groups such as trimethylsilyl and tert-butyldimethylsilyl groups offered useful properties, but the increased steric hindrance of the tert-butyldiphenylsilyl group provided enhanced selectivity and durability in complex synthetic sequences.

From a physicochemical standpoint, tert-butylchlorodiphenylsilane is relatively hydrophobic due to the presence of two aromatic rings and the bulky hydrocarbon substituent. The phenyl groups contribute π-electron character and increase compatibility with organic solvents. The polarized silicon–chlorine bond introduces localized electrophilicity but does not dominate the overall hydrophobic nature of the molecule.

Chemically, chlorosilanes are moisture sensitive because water can act as a nucleophile toward silicon. Exposure to moisture leads to hydrolysis of the silicon–chlorine bond, forming silanol species and releasing hydrogen chloride. For this reason, tert-butylchlorodiphenylsilane is commonly handled under dry conditions.

Overall, tert-butylchlorodiphenylsilane is a sterically hindered chlorosilane reagent whose significance lies in its use as a precursor to the tert-butyldiphenylsilyl protecting group. Its combination of an electrophilic silicon center and bulky aromatic substituents makes it a valuable tool for selective alcohol protection in synthetic organic chemistry.

References

2026. Synthesis and Study of the Optical Properties of a New Green Fluorescent Protein Chromophore Analogue with an sp-Hybridized Carbon Fragment. Russian Journal of Bioorganic Chemistry.
DOI: 10.1134/s1068162025603076

2025. Iodine-doped reduced graphene: efficient acetylation catalyst for the protection of hydroxyl group in carbohydrates, alcohols, and phenols. Journal of the Iranian Chemical Society.
DOI: 10.1007/s13738-025-03233-9