video tutorial Methylpropiophenone synthesis via Friedel-Crafts acylation

Summary

• Goal: perform a Friedel–Crafts isolation reaction to acylate toluene with propionyl chloride, yielding a methylpropiothenone–type ketone.
• Propionyl chloride prepared in situ from propionic acid and phosphorus trichloride under strictly dry conditions; temperature monitored; HCl fumes present.
• Catalyst prepared in situ by heating a 5:1 weight ratio of zinc chloride to aluminium powder to form anhydrous aluminium chloride; used with dry toluene (75 ml; excess).
• Reaction: slow addition of propionyl chloride to the toluene/AlCl3 mixture; process generates HCl; color changes observed (brown to green); after addition, mixture stirred for ~2 hours.
• Workup: quench with ice and concentrated HCl to prevent aluminium hydroxide precipitation; separate organic phase, wash and dry; distill to remove toluene; product obtained as an orange viscous oil (crude methylpropiothenone).
• Purification: attempted distillation; steam distillation used due to high boiling point (~240°C) but caused dangerous bumping/superheating; accident occurred, but some material (2.3 g) recovered.
• Yield: about 6% (2.3 g) of product; purification via bisulfite adduct not successful; vacuum distillation recommended for higher purity; otherwise product remains impure.
• Hazards: HCl gas evolution, exotherms, severe bumping during steam distillation; dangerous reactor conditions emphasized.