video tutorial Methylpropiophenone synthesis via Friedel-Crafts acylation with James Earl Jones

Summary

• Objective: Friedel–Crafts acylation of toluene using propionyl chloride generated in situ from propionic acid and phosphorus trichloride.
• Preparation: dry propionic acid, set up with a water bath, carefully dried glassware, and monitor temperature; generate propionyl chloride by adding phosphorus trichloride to the acid with stirring and ventilation; separate and wash the product to isolate crude propionyl chloride.
• Reaction setup: assemble a 500 mL two‑neck flask with a drying tube and addition funnel for propionyl chloride; use toluene (75 mL) as solvent (slightly excess) and freshly prepared aluminum chloride catalyst (about 36 g AlCl3 from a ZnCl2/Al mixture, 5:1 weight ratio); maintain vigorous stirring and cooling; slowly add propionyl chloride over ~30 minutes; gas (HCl) evolves and the mixture changes color from brown to green.
• Workup: quench with a cold ice/HCl mixture to prevent aluminum hydroxide formation; separate organic layer, extract aqueous layer with additional toluene, combine organics, dry and remove water.
• Purification and isolation: distill to remove toluene; crude product (methylpropiothenone) distills at >200°C; steam distillation attempted due to high boiling point but caused dangerous bumping; anti-bumping precautions advised; salvage first portion via dichloromethane extraction from steam distillate.
• Yield and purity: obtained 2.3 g of product (about 6% yield) believed to be pure methylpropionone with possible ortho isomer; bisulfite adduct formation failed, making another purification route unavailable; high-boiling ketone would require vacuum distillation for higher purity.
• Safety notes: handling reagents (propionyl chloride, AlCl3, HCl) and steam distillation hazards emphasized; warnings about extreme bumping and explosions during steam distillation.