Benzoyl Peroxide: Benzoyl Chloride Shaken with Cold 10 % Hydrogen Peroxide and Lye (Pechmann & Vanino 1894)

Benzoyl chloride shaken with cold hydrogen peroxide and lye joins two benzoyl groups through an oxygen-oxygen bridge. Benzoyl peroxide crystallises out and is what starts acrylic and other plastics polymerising. Result: colourless prisms melting at 104-105 °C, about 70 % of theory. Source: Pechmann & Vanino, Berichte 27 (1894) 1511, as given in Vanino, Handbuch der präparativen Chemie, vol. 2. Not given: amounts, lye strength. Danger: the dry peroxide flares up when heated. Picture drawn by Youblob.