Benzyl Bromide → 7-Phenylhept-5-ynoic acid

Participants

Reaction Conditions

Reaction Steps

A solution of hex-5-ynoic acid (1 mmole) in dimethylformamide (50 ml) is treated with sodium hydride (2 mmole; 50% dispersion in oil) first at room temperature, then at 60° C. A copious evolution of hydrogen occurs. Then, the solution is cooled and benzyl bromide (1.5 mmole) is added. The reaction mixture is heated to 80° C. and maintained thereat until then layer chromatography indicates the consumption of all the hex-5-ynoic acid. After cooling, the solution is poured onto a 10% sodium hydroxide solution and extracted with ethyl ether to remove unreacted benzyl bromide. The aqueous layer is then acidified to pH2 with concentrated hydrochloric acid, and extracted with chloroform. Removal of the solvent from the chloroform layer affords a residue which is distilled under reduced pressure to give the desired title product, 7-phenylhept-5-ynoic acid.

Provenance & Evidence