Diphenylacetylene

Diphenylacetylene is the chemical compound C₆H₅C≡CC₆H₅. The molecule consists of phenyl groups attached to both ends of an alkyne. It is a colorless crystalline material that is widely used as a building block in organic and as a ligand organometallic chemistry.

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Preparation

Several preparations for this compound exist:

• one being from benzil which is condensed with hydrazine to give the bis(hydrazone) that in turn suffers oxidation with mercury oxide.^[1]
• The compound is usually prepared from stilbene by bromination dehydrohalogenation sequence, but the product can be contaminated with stilbene, which is difficult to remove.
• One methods starts from iodobenzene and the copper salt of phenylacetylene in the Castro-Stephens coupling

Interesting derivatives

• Reaction of Ph₂C₂ with tetraphenyl substituted cyclopentadienone results in the formation of hexaphenylbenzene.^[2]
• Reaction of Ph₂C₂ with benzal chloride in the presence of potassium t-butoxide affords the 3-alkoxycyclopropene which coverts to the cyclopropenium ion.^[3]

References

1. ^ Cope, A. C.; Smith, D. S.; Cotter, R. J.. "Phenylacetylene". Org. Synth.; Coll. Vol. 4: 377. 
2. ^ Fieser, L. F.. "Hexaphenylbenzene". Org. Synth.; Coll. Vol. 5: 604. 
3. ^ Xu, R. Breslow, R.. "1,2,3-Triphenylcyclopropendium Bromide". Org. Synth.; Coll. Vol. 9: 730.