Radical telomerization of 1,3‐butadiene with perfluoroalkyl iodides

The radical telomerization of 1,3-butadiene in the presence of 1-iodoperfluorohexane and 1-iodo-perfluorooctane (R F I) is presented. Experimental parameters (such as the nature of the radical initiaor, temperature, solvent and initial molar ratios of the reactants) were varied to increase both 1,3-butadiene and R F I conversions. Best conditions are reached at 140-150°C with di-ter-butyl peroxide as initiator and acetonitrile as solvent. According to different conditions, the monoadduct and higher order telomers were synthesized with average number molecular weights ranging from 250 to 4 000 as determined by 1 H NMR spectroscopy and elemental analysis. 80% of the 1,4-adducts were noted to lack a terminal iodine atom. The transfer constant of R F I towards 1,3-butadiene was determined to be C T = 2.59 at 145°C witch induces the formation of nonfunctional oligomers when a high [butadiene] 0 /[R F I] 0 molar ratio was used.