Summary: The text describes a lab procedure to synthesize propiothinone via Friedel–Crafts acylation of benzene with propionic acid using aluminum chloride (AlCl3) and phosphorus pentoxide (P2O5). The setup includes a moisture-controlled, vented system with a drying tube, slow dropwise addition of propionic acid under reflux, and a two-hour reaction. Workup yields two phases, and distillation gives 8.1 g of propiothinone (about 30% yield relative to propionic acid), a pale yellow product. The author notes yields are lower than a standard Friedel–Crafts ethylation, but potential improvements could increase yields with better quenching and workup or alternative setup.
