Chemistry:Diphenylacetylene
Diphenylacetylene is the chemical compound C6H5C≡CC6H5. The molecule consists of two phenyl groups attached to a C2 unit. A colorless solid, it is used as a building block in organic synthesis and as a ligand in organometallic chemistry.
Preparation and structure
In one preparation for this compound, benzil is condensed with hydrazine to give the bis(hydrazone), which is oxidized with mercury(II) oxide.[1] Alternatively stilbene is brominated, and the resulting dibromodiphenylethane is subjected to dehydrohalogenation.[2] Yet another method involves the coupling of iodobenzene and the copper salt of phenylacetylene in the Castro-Stephens coupling. The related Sonogashira coupling involves the coupling of iodobenzene and phenylacetylene.
Diphenylacetylene is a planar molecule. The central C≡C distance is 119.8 picometers.[3]
Derivatives
1,2,3,4-Tetraphenylbutadiene is prepared by reductive coupling of diphenylacetylene using lithium metal followed by hydrolysis of the resulting 1,4-dilithiobutadiene:[4]
- 2 PhC≡CPh + 2 Li → LiCPh=CPh–CPh=CPhLi (Ph = C6H5)
- LiCPh=CPh–CPh=CPhLi + 2 H
2O → PhCH=CPh–CPh=CHPh + 2 LiOH
Reaction of diphenylacetylene with tetraphenylcyclopentadienone results in the formation of hexaphenylbenzene in a Diels–Alder reaction.[5]
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Dicobalt octacarbonyl catalyzes alkyne trimerisation of diphenylacetylene to form hexaphenylbenzene.[6]
Reaction of Ph2C2 with benzal chloride in the presence of potassium t-butoxide affords 3-tert-butoxy-1,2,3-triphenylcyclopropene, which converts to 1,2,3-triphenylcyclopropenium bromide after the elimination of tert-butoxide.[7]
References
- ↑ Cope, A. C.; Smith, D. S.; Cotter, R. J. (1954). "Diphenylacetylene". Organic Syntheses 34: 42. doi:10.15227/orgsyn.034.0042.
- ↑ Lee Irvin Smith; M. M. Falkof (1942). "Diphenylacetylene". Organic Syntheses 22: 50. doi:10.15227/orgsyn.022.0050.
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedXray - ↑ Leavitt, F. C.; Manuel, T. A.; Johnson, F.; Matternas, L. U.; Lehman, D. S. (1960). "Novel Heterocyclopentadienes. II". Journal of the American Chemical Society 82 (19): 5099–5102. doi:10.1021/ja01504a021. Bibcode: 1960JAChS..82.5099L.
- ↑ Fieser, L. F. (1966). "Hexaphenylbenzene". Organic Syntheses 46: 44. doi:10.15227/orgsyn.046.0044.
- ↑ Vij, V.; Bhalla, V.; Kumar, M. (8 August 2016). "Hexaarylbenzene: Evolution of Properties and Applications of Multitalented Scaffold". Chemical Reviews 116 (16): 9565–9627. doi:10.1021/acs.chemrev.6b00144.
- ↑ Xu, Ruo; Breslow, Ronald (1997). "1,2,3-Triphenylcyclopropenium Bromide". Organic Syntheses 74: 72. doi:10.15227/orgsyn.074.0072.
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