Bis(trimethylsilyl)acetamide

Bis(trimethylsilyl)acetamide (BSA) is an organosilicon compound with the formula MeC(OSiMe3)NSiMe3 (Me = CH3). It is a colorless liquid that is soluble in diverse organic solvents, but reacts rapidly with moisture and solvents containing OH and NH groups. It is used in analytical chemistry to increase the volatility of analytes, e.g., for gas chromatography.[1] It is also used to introduce the trimethylsilyl protecting group in organic synthesis.[2] A related reagent is N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA).

Bis(trimethylsilyl)acetamide
Structural formula of (E)-bis(trimethylsilyl)acetamide
Ball and stick model of (E)-bis(trimethylsilyl)acetamide
Names
Preferred IUPAC name
Trimethylsilyl N-(trimethylsilyl)ethanecarboximidate
Other names
N,O-Bis(trimethylsilyl)acetamide
Identifiers
3D model (JSmol)
Abbreviations BSA
1306669
ChemSpider
ECHA InfoCard 100.030.799
EC Number
  • 233-892-7
MeSH N,O-bis(trimethylsilyl)acetamide
RTECS number
  • AK3000000
UNII
UN number 2920
  • InChI=1S/C8H21NOSi2/c1-8(9-11(2,3)4)10-12(5,6)7/h1-7H3
    Key: SIOVKLKJSOKLIF-UHFFFAOYSA-N
  • InChI=1/C8H21NOSi2/c1-8(9-11(2,3)4)10-12(5,6)7/h1-7H3/b9-8+
  • CC(=N[Si](C)(C)C)O[Si](C)(C)C
  • CC(O[Si](C)(C)C)=N[Si](C)(C)C
Properties
C8H21NOSi2
Molar mass 203.432 g·mol−1
Appearance Liquid
Density 0.832 g cm−3
Melting point 24 °C (75 °F; 297 K)
Boiling point 71 to 73 °C (160 to 163 °F; 344 to 346 K) at 35mmHg
Hazards
GHS labelling:
GHS02: FlammableGHS05: CorrosiveGHS07: Exclamation mark
Danger
H226, H302, H314
P210, P233, P240, P241, P242, P243, P260, P264, P270, P280, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P330, P363, P370+P378, P403+P235, P405, P501
Related compounds
Related Amides
 Dimethylacetamide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Synthesis and reactions

BSA is prepared by treating acetamide with trimethylsilyl chloride in the presence of a base (Me = CH3, Et = C2H5):[2]

MeC(O)NH2 + 2 SiMe3Cl + 2 Et3N→ MeC(OSiMe3)NSiMe3 + 2 Et3NHCl

The reaction of BSA with alcohols gives the corresponding trimethylsilyl ether, together with acetamide as a byproduct (Me = CH3):[3]

2 ROH + MeC(OSiMe3)NSiMe3 → MeC(O)NH2 + 2 ROSiMe3

References
  1. Blau, Karl; J. M. Halket (1993). Handbook of Derivatives for Chromatography (2nd ed.). John Wiley & Sons. ISBN 0-471-92699-X.
  2. Harry Heaney, Jian Cui, “N,O-Bis(trimethylsilyl)acetamide” Encyclopedia of Reagents for Organic Synthesis Copyright © 2007 John Wiley & Sons. doi:10.1002/047084289X.rb208.pub2.
  3. Young, Steven D.; Buse, Charles T.; Heathcock, Clayton H. (1985). "2-Methyl-2-(Trimethylsiloxy)pentan-3-one". Organic Syntheses. 63: 79. doi:10.15227/orgsyn.063.0079.
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