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, which is oxidized with mercury(II) oxide. Alternatively stilbene is brominated, and the resulting dibromodiphenylethane is subjected to dehydrohalogenation. 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.

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:
Reaction of diphenylacetylene with tetraphenylcyclopentadienone results in the formation of hexaphenylbenzene in a Diels–Alder reaction.
Dicobalt octacarbonyl catalyzes alkyne trimerisation of diphenylacetylene to form hexaphenylbenzene.
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.