Formation of 2,3,7,8-Tetrachlorodibenzodioxin by Thermal Decomposition of Sodium 2,4,5,-Trichlorophenate

IN the course of investigating an explosion which occurred in the Coalite Company's 2,4,5-trichlorophenol plant in 1968, a white crystalline solid of high melting point and extremely high toxicity was isolated which proved to be 2,3,7,8-tetrachlorodibenzodioxin. The manufacture of 2,4,5-trichlorophenol involves the hydrolysis of 1,2,4,5-tetrachlorobenzene using methanol and caustic soda at elevated pressure or ethylene glycol and caustic soda at atmospheric pressure. The plant in which the accident occurred used the latter process.