Acetylene → 1-Bromo-trans-1-octen-3-one

A mixture of 300 g. of aluminum bromide and 250 ml. of 1,2-dibromoethane, cooled in an ice bath and protected from moisture, is saturated with acetylene. To the mixture is added with ice cooling 150 g. of hexanoyl bromide (Example 991) over a period of 20 minutes and the resulting mixture is treated with acetylene until gas uptake ceases. The reaction mixture is poured onto 500 ml. of saturated brine and 500 g. of ice. The resulting mixture is extracted twice with 500 ml. of ether. The combined organic extracts are washed twice with 500 ml. of saturated brine and dried with anhydrous sodium sulfate. To the organic phase is added 5 g. of hydroquinone and the solvent is evaporated in vacuo to yield the crude 1-bromo-trans-1-octen-3-one.