Phenylacetylene

Phenylacetylene is an alkyne hydrocarbon containing a phenyl group. It exists as a colorless, viscous liquid. In research, it is sometimes used as an analog for acetylene; being a liquid, it is easier to handle than acetylene gas.

Phenylacetylene
Names
IUPAC name
Ethynylbenzene
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.007.861
UNII
Properties
C8H6
Molar mass 102.133 g/mol
Density 0.93 g/cm3
Melting point −45 °C (−49 °F; 228 K)
Boiling point 142 to 144 °C (288 to 291 °F; 415 to 417 K)
Acidity (pKa) 28.7 (DMSO),[1]
23.2 (aq, extrapolated)[2]
-72.01·10−6 cm3/mol
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

Preparation

In the laboratory, phenylacetylene can be prepared by elimination of hydrogen bromide from styrene dibromide using sodium amide in ammonia:[3]

It can also be prepared by the elimination of hydrogen bromide from bromostyrene using molten potassium hydroxide.[4]

Reactions

  • Choosing a rhodium catalyst leads to the cyclotrimerization producing both the 1,2,4- and 1,3,5- isomers along with substantial quantities of acyclic enyne dimer products:[6]

See also

References

  1. Bordwell, F.G. Acc. Chem. Res. 1988, 21, 456-463.
  2. Streitwieser, A.,Jr.; Ruben, D.M.E; J. Am. Chem. Soc. 1971., 93, 1794-1795.
  3. Kenneth N. Campbell, Barbara K. Campbell (1950). "Phenylacetylene". Organic Syntheses. 30: 72. doi:10.15227/orgsyn.030.0072.
  4. John C. Hessler (1922). "Phenylacetylene". Organic Syntheses. 2: 67. doi:10.15227/orgsyn.002.0067.
  5. Gerhard Hilt; Thomas Vogler; Wilfried Hess; Fabrizio Galbiati (2005). "A simple cobalt catalyst system for the efficient and regioselective cyclotrimerisation of alkynes". Chemical Communications. 2005 (11): 1474–1475. doi:10.1039/b417832g. PMID 15756340.
  6. Ardizzoia, G. A.; Brenna, S.; Cenini, S.; LaMonica, G.; Masciocchi, N.; Maspero, A. (2003). "Oligomerization and Polymerization of Alkynes Catalyzed by Rhodium(I) Pyrazolate Complexes". Journal of Molecular Catalysis A: Chemical. 204–205: 333–340. doi:10.1016/S1381-1169(03)00315-7.
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