Both CFaCF2CCla and CFzClCFzCCla have been found to give reasonable yields of simple addition products with olefins in the presence of benzoyl peroxide. The products of dehydrohalogenatioris of the adducts are described. The preferred reaction of CClsCFZCFzBr is by cleavage of the C-Br bond rather than the C-C1 bond. Other telogens such as CFZBrCFzBr, CFaCFBrCFzBr and CFClBrClCFClBr react with ethylene to give 1: ...