Reactivite comparee en catalyse redox de plusieurs telogenes halogenes vis-a-vis du butadiene

Using copper chloride as catalyst, we have achieved telomerization of butadiene with several different halogenated compounds as telogens. These telogens must have a CCl₃ group to be active as transfer agents. There is a linear relationship between log (telogen reactivity) and the σ¹ Taft constant of the R group. Using this relation, we have determined the values of the σ¹ constants for some halogenated substances. The reactivities of the telogens can be measured by this means. The results confirm those obtained earlier with styrene.