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[Lithium Bis(trimethylsilyl)amide]

Other Names:

Lithium hexamethyldisilazide

Hexamethyldisilazane lithium salt

General Information:


CAS Number: 4039-32-1

Molecular Weight: 167.33 g/mol

Appearance: Colorless crystalline solid

Melting Point: 70-72 C

Lithium bis(trimethylsilyl)amide (LiHMDS) is a sterically hindered strong base. It is commercially available as a solid and as a solution in a variety of solvents (ex. THF, 2Me-THF, toluene, hexane, and MTBE). Similar reagents include sodium bis(trimethylsilyl)amide (NaHMDS) and potassium bis(trimethylsilyl)amide (KHMDS).

Common Uses:

Strong base in Wittig reactions

Procedure excerpt:

LiHMDS (1.0 M in THF, 15 mL, 15 mmol) was added dropwise to a solution of methyl triphenylphosphonium bromide (5.36 g, 15 mmol) in THF (50 mL) at 0 C. . . .

[full procedure]


Lithium Bis(trimethylsilyl)amide (LiHMDS) is a flammable, moisture sensitive solid.


1) Patent Reference: WO2015129926, page 102, (21.5 MB)

2) Wikipedia: Lithium bis(trimethylsilyl)amide (link)

3) Lithium bis(trimethylsilyl)amide (link)

4) 42595 Lithium bis(trimethylsilyl)amide (link)

5) Reich, H. J.; Rigby, J. H.; Handbook of Reagents for Organic Synthesis, Acidic and Basic Reagents