Prepn: Baeyer, Ann. 130, 129 (1864). Manuf: Gresham, Schweitzer, US 2402134 (1946 to du Pont); White, Wysong, US 2663713 (1953 to Dow). Review: J. H. Bateman in Kirk-Othmer Encyclopedia of Chemical Technology vol. 12 (Wiley-Interscience, New York, 3rd ed., 1980) pp 692-711.