Final answer:
Propene undergoes allylic bromination when reacted with N-bromosuccinimide in the presence of light or peroxides, resulting in a brominated alkene.
Step-by-step explanation:
When propene is reacted with N-bromosuccinimide (NBS) in the presence of light or peroxides, a halogenation reaction occurs. This reaction involves the substitution of one of the hydrogen atoms on the allylic position (the carbon atom next to the double bond) of propene with a bromine atom. The presence of light or peroxides initiates a free radical chain mechanism. In this process, the light or peroxide acts as an initiator by generating bromine radicals from NBS, which then abstracts a hydrogen atom from the allylic position of propene, forming a free radical. This allylic radical can then react with another molecule of N-bromosuccinimide, resulting in the formation of the brominated product and another bromine radical to propagate the reaction.
The product of this reaction is an alkane, more specifically, a brominated alkene having the same carbon skeleton as the propene starting material. This type of allylic bromination reaction is commonly used in organic synthesis to functionalize molecules for further reactions, as the allylic bromide is a versatile intermediate.