Hydrochloric Acid → P-Chloroacetophenone

Participants

Reaction Conditions

Reaction Steps

A 100-mL round-bottom flask was equipped with a magnetic stir bar, reflux condenser, thermometer, nitrogen inlet, and heating mantle attached to a temperature controller. The flask was charged with 2,4-dichloroacetophenone (5.0 g, 26.5 mmol) and copper powder (0.84 g, 13.2 mmol). The flask was purged with nitrogen for 0.5 hour. Meanwhile, a separate flask was charged with acetic acid (30 g) and triethylamine (30 g). The resulting solution was degassed by bubbling nitrogen through the solution for 0.5 hour. A portion of the degassed solution (20 mL) was charged to the reaction flask by syringe and the resulting mixture was heated to 135° C. Additional copper (0.17 g, 2.65 mmol) was added after 2 hours in order to complete the dehalogenation. The reaction was monitored by GC analysis and was judged to be complete when the starting material was no longer detectable (5 hours). The reaction mixture was cooled to room temperature and poured into a 250-mL Erlenmeyer flask; toluene (50 mL) and 2M hydrochloric acid solution (50 mL) were added. The resulting mixture was filtered, and the solids were washed with toluene. The resulting brown organic layer was washed with 2M hydrochloric acid solution (50 mL), water (50 mL), and 5% sodium hydroxide solution (50 mL). Solids precipitated during the base wash. The mixture was filtered through a pad of Florisil® (magnesium silicate), which was rinsed with additional toluene. The filtrates were combined to give a yellow solution. The solvent was removed by evaporation under reduced pressure. The residue was dried under vacuum, yielding 3.38 g of 4-chloroacetophenone as a brown oil.

Provenance & Evidence