Benzoyl Chloride: Benzoic Acid Heated with Phosphorus Pentachloride, then Fractionated (Thorpe 1912)

Phosphorus pentachloride swaps the OH of benzoic acid for chlorine, giving benzoyl chloride, phosphorus oxychloride and hydrogen chloride gas. Distilling separates the two liquids. Result: benzoyl chloride, a colourless liquid boiling at about 197-199 °C, plus phosphorus oxychloride. Source: Thorpe, Dictionary of Applied Chemistry, vol. 1 (1912), Benzoyl chloride. Not given: heating time, column. Danger: hydrogen chloride gas; the vapour brings tears. Picture drawn by Youblob.