The reaction of isopropylbenzene with bromine under light is a radical reaction. The light initially reactions with the bromine in the initiation step to form the bromine radicals:
Br₂ + hv → 2Br·
The next step is the first propagation step where a bromine radical reacts with the isopropylbenzene to abstract the hydrogen from the tertiary carbon in the isopropyl group:
We have now formed a radical in the benzylic position of the isopropylbenzene structure. Now this radical will react with another molecule of bromine in a second propogation step to form the final brominated product:
The bromine radical can terminate in a reaction with another bromine radical or the benzylic radical to give more of the final product. The final product is shown and is called (2-bromopropan-2-yl)benzene.
