Synthesis of fluorinated telomers. Part 1. Telomerization of vinylidene fluoride with perfluoroalkyl iodides

Thermal and redox-induced telomerizations of vinylidene fluoride (VDF) with linear (n-C₄F₉I) or branched (i-C₃F₇I) perfluoroalkyl iodides have been performed. In both cases, thermal telomerizations led to telomeric-type distributions of the first five (from linear telogen) or the first three (from branched telogen) adducts produced, with better yields at higher temperatures. The redox-initiated telomerization was more selective since it led to the first two adducts only. For both reactions, mono- and di-adducts were isolated and characterized by ¹H and ¹⁹F NMR spectroscopy. Interestingly, both the diadducts were composed of two isomers (i.e. the expected telomer and R_FCH₂CF₂CF₂CH₂I). Two mechanisms are proposed and it is assumed that the products may be obtained either by chain propagation or by stepwise telomerization. In addition, attack of the electrophilic radical on the nucleophilic side of VDF is discussed.