Radical telomerization of 1,3-butadiene with perfluoroalkyl iodides

The radical telomerization of 1,3-butadiene in the presence of 1-iodoperflu orohexane and 1-iodoperfluorooctane (RFI) is presented. Experimental parame ters (such as the nature of the radical initiator, temperature, solvent and initial molar ratios of the reactants) were varied to increase both 1,3-bu tadiene and RFI conversions. Best conditions are reached at 140-150 degrees C with di-tert-butyl peroxide as initiator and acetonitrile as solvent. Ac cording to different conditions, the monoadduct and higher order telomers w ere synthesized with average number molecular weights ranging from 250 to 4 000 as determined by H-1 NMR spectroscopy and elemental analysis. 80% of th e 1,4-adducts were noted to lack a terminal iodine atom. The transfer const ant of RFI towards 1,3-butadiene was determined to be C-T = 2.59 at 145 deg rees C which induces the formation of nonfunctional oligomers when a high [ butadiene](0)/[RFI](0) molar ratio was used.