1,2-Dibromotetrachloroethane (DBTCE) is an organohalide with the chemical formula . It is a crystalline solid that emits lachrymatory (tear-producing) vapours. Dibromotetrachloroethane can be used as a fungicide,Dewayne Torgeson, Agricultural and Industrial Applications Environmental Interactions: An Advanced Treatise (2012), p. 333 flame retardantRichard Montgomery Stephenson, Stanisław Malanowski, Handbook of the Thermodynamics of Organic Compounds (2012), p.20 and a source for bromine in the laboratory.B. Iddon, Basil John Wakefield, D. Price, Bromine Compounds: Chemistry and Applications (1988) Because the 1,1-dibromotetrachloroethane isomer is rare, 1,2-dibromotetrachloroethane is frequently referred to as simply dibromotetrachloroethane.
Reactions and synthesis Dibromotetrachloroethane decomposes to Tetrachloroethylene and bromine when heated. Reacted with potassium sulphide, it gives tetrachloroethylene, potassium bromide and sulphur:
Dibromotetrachloroethane, when reacted with aniline at 140 to 150 °C, gives pure tetrachloroethylene.E. Burgoin, Preparation of Perchlorethylene (1870)
When reacted with compounds like cyclohexene, 2,2,4-trimethylpentene, 1-hexene, 1-octene, 2-methyl-1-butene and 2,2,4-trimethyl-2-pentene, it yields allylic monobromides via bromination. Dibromotetrachloroethane loses both of its bromine atoms, leaving tetrachloroethylene and hydrogen bromide.G. H. Williams Advances in Free-radical Chemistry (1972), p. 186
Dibromotetrachloroethane was discovered by the Italian chemist Faustino Malaguti in 1846.Faustino Malaguti, Recherches sur Éthers Chlorés, Annales de Chimie et de Physique, 16-3, p. 24 Malaguti exposed a mixture of Tetrachloroethylene (then known as chloréthose) and bromine to sunlight. It was named Bromure de chloréthose ("bromide of chlorethose") after its synthesis method.Edmond Frémy, Paul Louis Chastain, Encyclopédie Chimique (1883) p. 235 Similar to Malaguti's method, modern synthesis of dibromotetrachloroethane uses bromine dissolved in carbon tetrachloride on tetrachloroethylene.
References