Radical telomerization of 1,3‐butadiene with perfluoroalkyl iodides in the presence of potassium carbonate

The radical telomerization of 1,3-butadiene with perfluoroalkyl iodides (C6F13I or merely C8F17I) initiated by di-tert-butyl peroxide was studied in the presence of various amounts of potassium carbonate at 145 °C in acetonitrile. The influence of this salt on both the kinetics and the telomer characteristics (color, molar mass, and functionality) was established. First, the determination of the chain-transfer constant of C8F17I led to a value (2.52) similar to that obtained under the same conditions without any K2CO3 (2.59). Second, 1,3-butadiene conversion was much faster, and the molar mass/time profiles were also quite different, revealing the formation of high molar mass polymers at the end of conversion, which was not observed in previous studies without any K2CO3. Moreover, great improvements in the functionality of the fluorinated telomers were achieved (closer to unity). The products were also not as colored as before (black in the absence of K2CO3), and this allowed valuable application tests. With electronic microscopy, K2CO3 was shown to neutralize hydrogen iodide (HI) produced in the course of the reaction, which caused major drawbacks (e.g., low functionality and dark color). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3743–3756, 2002