Reaction of elemental fluorine with bromofluoroalkanes

Abstract There have been few reports of reactions of elemental fluorine with bromo derivatives and we now find that bromine in bromofluoroalkanes may be replaced by fluorine and, in some cases, in very high yields. For example, fluorination of Br(C 2 ClF 3 ) 3 Br, n = 1-5, with elemental fluorine diluted with 50% nitrogen gives the corresponding Br(C 2 ClF 3 ) n F and F(C 2 ClF 3 ) n F at room or 0°C temperature in high yields. The terminal CBrClF groups are more reactive than CBrF 2 ones, e.g.: CBrClFCBrF 2 → CBrF 2 CClF 2 (80%) + CClF 2 CF 3 (20%) Under similar conditions CF 3 CBrFCBrF 2 yields CF 3 CBrFCF 3 as the main products. The mechanism for the reaction is presumed to be free radical with a moderating effect of bromine (respective bromine fluorides) that was displaced. The utility of the reaction in interpretation of complex 19 F NMR spectra of isomeric mixtures introduced above will be described.