Synthesis of Phenylacetylene

Set up a 2-neck RBF with a thermometer, with vigorous stirring, add 40 g of sodium hydroxide and 250 mL of dry warm glycerine, start heating the mixture. When the temperature has raised to 125°C add 66 g of (1,2-dibromoethyl)benzene and set up a simple distillation, vigorous stirring is important. The phenylacetylene starts to distill off at about 144°C. When the temperature rises to about 200°C not much of the phenylacetylene distills off anymore, so stop the heating. Then transfer the distillate to a separatory funnel and rise the distillate flash with 20 mL of diethyl ether, shake and discard the lower aqueous layer, wash with 30 mL of water. Then transfer the cloudy bottom layer to a beaker and add some dry magnesium sulfate to dry the phenylacetylene. Then filter the magnesium sulfate out. Add 20 mL of diethylene glycol, and set up for a vacuum fractionating distillation apparatus. The ether comes off at 34°C, phenylacetylene at 80°C, when the temperature starts to vigorously raise from the 80°C stop the distillation and store the pure phenylacetylene fraction. Store the phenylacetylene in a freezer.


Distillation of the solution

The crude product

Diethyl ether was added to the mixture and it was shaken

Washing the crude phenylacetylene with water

Set up for a vacuum fraction distillation apparatus


The pure product

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