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.Preparation
In the laboratory, phenylacetylene can be prepared by elimination of hydrogen bromide from styrene dibromide using sodium amide in ammonia:
It can also be prepared by the elimination of hydrogen bromide from bromostyrene using molten potassium hydroxide.Reactions
- Phenylacetylene can be reduced by hydrogen over Lindlar catalyst to give styrene.
- It undergoes a metal catalyzed trimerization to give 1,2,4- and 1,3,5-triphenylbenzene:
- 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:
- It undergoes a hydration reaction, catalyzed by gold or mercury, to give acetophenone.
