Potassium bis(trimethylsilyl)amide Property

Melting point:

194-195°C

Boiling point:

111 °C

Density 

0.877 g/mL at 25 °C

vapor density 

3.2 (vs air)

vapor pressure 

54 mm Hg ( 25 °C)

refractive index 

1.4920

Flash point:

45 °F

storage temp. 

Refrigerator

solubility 

Miscible with terahydrofuran, ether, benzene and toluene.

form 

Liquid

Specific Gravity

0.877

color 

clear to slightly hazy yellow

Water Solubility 

Reacts with water.

Hydrolytic Sensitivity

8: reacts rapidly with moisture, water, protic solvents

Sensitive 

Moisture Sensitive

BRN 

4006754

CAS DataBase Reference

40949-94-8(CAS DataBase Reference)

EPA Substance Registry System

Silanamine, 1,1,1-trimethyl-N-(trimethylsilyl)-, potassium salt (1:1) (40949-94-8)

Safety

Hazard Codes 

C,F,Xn

Risk Statements 

14-34-67-65-63-48/20-11-40-36/37/38-19-37

Safety Statements 

26-36/37/39-45-62-43-46-16-36/37

RIDADR 

UN 3263 8/PG 3

WGK Germany 

3

F 

1-3-10

TSCA 

No

HazardClass 

3

PackingGroup 

II

HS Code 

29319090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H314Causes severe skin burns and eye damage

Precautionary statements

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

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

P301+P330+P331IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.

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.

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

Chemical Properties

Colorless to amber solution

Uses

Potassium Hexamethyldisilazide is widely used as a Sterically Hindered Base for Enolate Generation in Selective Formation of Linear Conjugated Dienolates and Alkyl (Z)-3-Alkenoates.

Uses

Potassium Bis(trimethylsilyl)amide (1M in THF) is used in the preparation of 5-azacytidine, an antineoplastic drug. Also applied in the preparation of β3-AR agonists used in anti-stress formulations. It is also used as a reagent in the preparation of lanthanide complexes employed in selective cyclization reactions.

Uses

Potassium bis(trimethylsilyl)amide is a strong base used in the alkylation carbonyl compounds.1

Preparation

Potassium Hexamethyldisilazide is prepared and isolated by the procedure of Wannagat and Niederpruem. A more convenient in situ generation from potassium hydride and hexamethyldisilane is described by Brown.

General Description

This product, 1.0 M in 2-methyltetrahydrofuran aligns with "Safer Solvents and Auxiliaries", "Use of Renewable Feedstocks" and "Inherently Safer Chemistry for Accident Prevention".

Synthesis

Potassium bis(trimethylsilyl)amide is an important non-nucleophilic base widely used in organic synthesis. The main method for its preparation is are interaction of hexamethyldisilazane with potassium amide) potassium hydride, potassium metal, mad styrene, isoprene, or naphthalene as electron acceptors.
An oven-dried 100 ml round-bottom flask was charged with KH (3.22 g, 20.1 mmol, 25 wt. 96 in oil) and flushed with argon. The hydride was then washed with hexane (4x5 ml). To the flask was fitted, a reflux condenser was made, and then THF (20 ml) and bis(trimethylsi1yl)amine (3.81 ml, 18.1 mmol) were added. The resultant slurry was sonicated until the hydrogen gas evolution had ceased, and almost all the potassium hydride had been consumed (3.25 h). The slurry was allowed to settle, and the supernatant was then cannulated into a Schlenk flask. Titration4 for the amide base concentration showed it to be 0.80 M, while the concentration of the total base was 0.86 M[1-2].

References

[1] I. V. Magedov. “Convenient method for the preparation of a solution of potassium bis(trimethylsilyl)amide.” Russian Chemical Bulletin 44 11 (1995): 2197–2198.
[2] J. Ahman, P. Somfai. “An Efficient Preparation of Potassium Bis (Trimethylsilyl) Amide (KHMDS).” Synthetic Communications 25 1 (1995): 2301–2303.