RADICAL-ADDITION OF IODINE MONOCHLORIDE TO TRIFLUOROETHYLENE

The addition of iodine monochloride to trifluoroethylene (TrFE) leadin g to a ClCF2CFHI (I)/ClCFHCF2I (II) mixture is described. Four differe nt ways of initiation (thermal, photochemical, presence of radical ini tiator, or redox catalyst) were used and all of them led to a high amo unt (> 89%) of isomer (I). The amounts of (I) and (II) isomers were de termined by H-1 and F-19 NMR and also they were deduced from those of ClCF2CFH2 and ClCFHCF2H obtained by selective reduction of the iodine atom of the former mixture, in the presence of tributylstannane. The r eactivity of ICl to TrFE and the high proportion of isomer (I) were in terpreted by means of a thermodynamical approach from the enthalpy of formation of (I) and (II), respectively, determined by semi-empirical computations. In addition, heats of formation of both isomers and inte ractions between SOMO of radicals and HOMO of fluoro-olefin enable to show that the mechanism of such a reaction occurs via the addition of I-. to the less fluorinated side of TrFE. (C) 1998 Elsevier Science S. A. All rights reserved.