Radiation-Initiated Dehalogenation of Organofluorine Compounds in Aqueous Solutions

The γ-radiolysis of 2-fluoroethanol-1, 2,2,2-trifluoroethanol-1, 3-fluoropropanol-1, and 4,4,4- trif luorobutanol-1 in aqueous solutions in an inert atmosphere or in the presence of oxygen has been studied. It has been found that the dehalogenation of hydroxyl-containing organic compounds is induced by •ОН and Н• radicals rather than hydrated electrons. The carbon-centered α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH are def luorinated much more efficiently than α-fluoroalkyl radicals, both vicinal (F–•CHCH2OH) and nonvicinal (F–•CHCH2CH2OH). In the absence of oxygen, α-fluoroalkyl radicals
eliminate fluoride ions by the mechanism of nucleophilic substitution, and this process is enhanced in the presence of alkali. In an oxygenated medium, the dehalogenation of α-fluoroalkyl radicals occurs via the addition of oxygen molecules to them and the subsequent disproportionation of resulting peroxyl radicals. The dehalogenation of the α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH is inhibited by oxygen through their oxidation.