Bis(trimethylsilyl)acetylene

Bis(trimethylsilyl)acetylene
Names
	IUPAC name Bis(trimethylsilyl)acetylene
	Other names BTMSA
Identifiers
CAS Number	14630-40-1 ;
3D model (JSmol)	Interactive image;
ChemSpider	76286 ;
ECHA InfoCard	100.035.141
PubChem CID	84564;
CompTox Dashboard (EPA)	DTXSID3065798 ;
	InChI InChI=1S/C8H18Si2/c1-9(2,3)7-8-10(4,5)6/h1-6H3 Key: ZDWYFWIBTZJGOR-UHFFFAOYSA-N ; InChI=1/C8H18Si2/c1-9(2,3)7-8-10(4,5)6/h1-6H3 Key: ZDWYFWIBTZJGOR-UHFFFAOYAF;
	SMILES C(#C[Si](C)(C)C)[Si](C)(C)C;
Properties
Chemical formula	C8H18Si2
Molar mass	170.402 g·mol−1
Appearance	Colorless to white Liquid
Density	0.791 g/cm3
Melting point	26 °C (79 °F; 299 K)
Boiling point	134.6 ± 8.0 °C
Solubility in water	0.031 g/L
Hazards
Main hazards	Flammable, Irritant
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Bis(trimethylsilyl)acetylene (BTMSA) is an organosilicon compound with the formula C₂(Si(CH₃)₃)₂. It is a colorless liquid that is soluble in organic solvents. This compound is used as a surrogate for acetylene.

BTMSA is prepared by treating acetylene with butyl lithium followed by addition of chlorotrimethylsilane:[1][2]

Li₂C₂ + 2 (CH₃)₃SiCl → [(CH₃)₃Si]₂C₂ + 2 LiCl

Applications

BTMSA is used as a nucleophile in Friedel-Crafts type acylations and alkylations and a precursor to lithium trimethylsilylacetylide. The TMS groups can be removed with tetra-n-butylammonium fluoride (TBAF) and replaced with protons. BTMSA is also a useful reagent in cycloaddition reactions. Illustrating its versatility, BTMSA was used in a concise total synthesis of (±)-estrone.[3] A key step in this synthesis was the formation of the steroidal skeleton, catalyzed by CpCo(CO)₂.

BTMSA also serves as a ligand in organometallic chemistry. For example, it forms stable adducts with metallocenes.[4]

Cp₂TiCl₂ + Mg + Me₃SiC≡CSiMe₃ → Cp₂Ti[(CSiMe₃)₂] + MgCl₂

BTMSA is also used in the total synthesis of epibatidine (and analogs), and also in the synthesis of iclaprim.

References

Holmes, A.; Sporikou, C.; Org. Synth. 1993, Coll. Vol. 8, 606.
Walton, D. R. M.; Waugh, F., J. Organomet. Chem. 1972, 37, 45. doi:10.1016/S0022-328X(00)89260-8
Curtain, M. L.; Wang, C. Bis(trimethylsilyl) acetylene. e-EROS.
Rosenthal, U.; Burlakov, V. V.; Arndt, P.; Baumann, W.; Spannenberg, A. Organometallics 2003, 22, 884. doi:10.1021/om0208570

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[1] Holmes, A.; Sporikou, C.; Org. Synth. 1993, Coll. Vol. 8, 606.

[2] Walton, D. R. M.; Waugh, F., J. Organomet. Chem. 1972, 37, 45. doi:10.1016/S0022-328X(00)89260-8

[3] Curtain, M. L.; Wang, C. Bis(trimethylsilyl) acetylene. e-EROS.

[4] Rosenthal, U.; Burlakov, V. V.; Arndt, P.; Baumann, W.; Spannenberg, A. Organometallics 2003, 22, 884. doi:10.1021/om0208570