1-Bromopropane → Phosphonium, tetrapropyl-, bromide

In a 250 mL round bottom flask, n-propyl bromide (21.1 g, 171.5 mmol) (available from Sigma-Aldrich Canada) was dissolved in anhydrous acetonitrile (100 mL) under Ar-atmosphere, and tripropylphosphine (25 g, 156.0 mmol) (available from Sigma-Aldrich Canada) was added. The reaction mixture was heated at gentle reflux for 35 hrs. After cooling to room temperature, the solvent was removed under reduced pressure. The solid residue was suspended in toluene (50 mL) and the solvent was removed under reduced pressure. This process was repeated once. The solid residue was suspended in hexane (100 mL), filtered, washed with hexane (3×50 mL), and air-dried. The desired tetra (n-propyl)phosphonium bromide was obtained as colourless crystals (42.5 g, 96%).