Iodobenzene (100 g, 0.49 mol) was placed in a dry 1 L three-necked flask fitted with an N2 inlet and 200 mL of carbon disulfide (CS2) was added to it. The reaction mixture was cooled to 0-5 °C, followed by the addition of anhydrous aluminum trichloride (AlCl3, 80 g, 0.6 mol) in batches, followed by the slow dropwise addition of propionyl chloride (60 g, 0.64 mol) while the reaction temperature was controlled to be maintained at 5-10 °C. The reaction mixture was stirred at room temperature for 24 hours. Upon completion of the reaction, the mixture was slowly poured into a 5 L plastic beaker containing 1 L of 10% hydrochloric acid (HCl) and 1 kg of crushed ice. The reaction mixture was extracted with 1 L of ethyl acetate and the organic layer was separated and washed sequentially with 2 x 500 mL of water and 500 mL of saturated saline. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure at 40 °C to give 4'-iodopropiophenone (48 g, 38% yield). The product was characterized by 1H NMR (500 MHz, CDCl3): δ 7.82 (d, 2H), 7.67 (d, J = 8.30 Hz, 2H), 2.96 (q, J = 7.00 Hz, 2H), 1.22 (t, J = 7.32 Hz, 3H).
