One-electron reduction of halothane and formation of halide ions in aqueous solutions

Formation of Br^? and, under certain conditions also F^? ions has been observed in the radiation chemically induced one-electron reduction of the anesthetic halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) in aqueous solutions. The initial step is the release of Br^? and formation of the 2-chloro-1,1,1-trifluoroethyl radical. The latter can react via competing pathways including H-atom abstraction, addition of molecular oxygen and further reduction by an antioxidant. All of these three competitive routes lead to different product patterns. High yields of F^? ions are observed under anaerobic conditions in the presence of antioxidants such as ascorbate, propylgallate, etc. The fluoride elimination is strongly pH-dependent and seems to occur in various steps after initiation through reduction of the (CF₃CHCl) radical. The implication for biochemical studies on the metabolism of halothane under different oxygen concentrations is discussed.