Bis(trimethylsilyl)acetylene

Bis(trimethylsilyl)acetylene
IUPAC name Bis(trimethylsilyl)acetylene
Other names BTMSA
Identifiers
CAS number	14630-40-1
PubChem	84564
ChemSpider	76286
Jmol-3D images	{{#if:C(#C[Si](C)(C)C)[Si](C)(C)C|Image 1
SMILES C(#C[Si](C)(C)C)[Si](C)(C)C
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
Properties
Molecular formula	C8H18Si2
Molar mass	170.40 g mol−1
Appearance	Colorless to white Liquid
Density	0.791 g/cm3
Melting point	26 °C
Boiling point	134.6 ± 8.0 °C
Solubility in water	0.031 g/L
Hazards
Main hazards	Flammable, Irritant
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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

References