Lithium bis(trimethylsilyl)amide Property

Melting point:

73°C

Boiling point:

55-56 °C

Density 

0.860 g/mL at 25 °C (lit.)

refractive index 

n20/D 1.425(lit.)

Flash point:

48 °F

storage temp. 

Store below +30°C.

solubility 

hydrolysis

form 

Powder

color 

White

Specific Gravity

0.716

Water Solubility 

hydrolysis

Sensitive 

Air & Moisture Sensitive

Hydrolytic Sensitivity

8: reacts rapidly with moisture, water, protic solvents

BRN 

3567910

Exposure limits

ACGIH: TWA 50 ppm; STEL 100 ppm (Skin)
OSHA: TWA 200 ppm(590 mg/m3)
NIOSH: IDLH 2000 ppm; TWA 200 ppm(590 mg/m3); STEL 250 ppm(735 mg/m3)

InChIKey

YNESATAKKCNGOF-UHFFFAOYSA-N

CAS DataBase Reference

4039-32-1(CAS DataBase Reference)

EPA Substance Registry System

Silanamine, 1,1,1-trimethyl-N-(trimethylsilyl)-, lithium salt (4039-32-1)

Safety

Hazard Codes 

F,C,N

Risk Statements 

11-34-48/20-63-65-67-51/53-35-20-62-14-40-37-19

Safety Statements 

9-16-26-29-33-36/37/39-45-61-62-57-43

RIDADR 

UN 2925 4.1/PG 2

WGK Germany 

3

F 

10-23

TSCA 

Yes

HazardClass 

4.3

PackingGroup 

II

HS Code 

29319090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H228Flammable solid

H251Self-heating; may catch fire

H314Causes severe skin burns and eye damage

Precautionary statements

P210Keep away from heat/sparks/open flames/hot surfaces. — No smoking.

P235Keep cool.

P260Do not breathe dust/fume/gas/mist/vapours/spray.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P303+P361+P353IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

Lithium bis(trimethylsilyl)amide Chemical Properties,Usage,Production

Chemical Properties

light yellow to yellow crystalline powder

Physical properties

distillable low-melting solid; mp 70–72 °C, bp 115 °C/1mmHg. LHMDS is a cyclic trimer in the solid state,3 whereas in benzene solution it exists in a monomer–dimer equilibrium. LHMDS exists as a tetramer-dimer mixture in hydrocarbons and as a dimer-monomer mixture in THF and ether. Treatment of LHMDS with trialkylamines increases the monomer concentration, whereas the use of diamines affords exclusively the corresponding chelated monomer. LHMDS is less soluble, less basic, more stable, and much less sensitive to air compared to lithium diisopropylamide. pKa 29.5 (THF, 27 °C).

Uses

Lithium bis(trimethylsilyl)amide is used as nonnucleophilic base to generate kinetic ketone and ester enolates. It is considerably more selective than LDA and undesired reductions (e.g., of nonenolizable ketones observed in the case of LDA) can be avoided by using LHMDS.

Uses

Lithium Hexamethyldisilazide is widely used as strong nonnucleophilic base

Uses

Lithium bis(trimethylsilyl)amide is a base used in preparation of dienes and enolates. It is used to catalyze the addition of phosphine P-H bonds to carbodiimides leading to phosphaguanidines. Lithium bis(trimethylsilyl)amide is also used in a novel three-step synthesis of disubstituted 1,2,5-thiadiazoles.

Preparation

It is conveniently prepared by the reaction of hexamethyldisilazane with n-butyllithium in hexane. For most uses the hexane is then evaporated and replaced with THF.

General Description

This product, 0.5 M in 2-methyltetrahydrofuran aligns with Safer Solvents and Auxiliaries, Use of Renewable Feedstocks and Inherently Safer Chemistry for Accident Prevention.

Flammability and Explosibility

Highly flammable