Question

10.48 When butane reacts with Br2 in the presence of Cl2, both bro- minated and chlorinated products are obtained. Under such conditions the usual selectivity of bromination is not observed. In other words, the ratio of 2-bromobutane to 1-bromobutane is very similar to the ratio of 2-chlorobutane to 1-chlorobutane. Can you offer an explanation as to 1 why we do not observe the normal selectivity expected for bromination? ra st

Answer 1

The reaction occurs in a radical pathway and both the chlorine radical (Cl^.) and bromine radical (Br^.) are equally reactive.

Hence, the ratio of 2-bromobutane to 1-bromobutane is very similar to that of 2-chlorobutane to 1-chlrobutane.

The mechanism is shown as follows.