Question

Give examples for allylic halides.

Answer 1

Allylic halides:-

1. These are the compounds where the halogen group is attached to a ${\mathrm{sp}}^3$hybridised carbon atom next to the carbon which is already in a double bond with another carbon atom.
2. In both ${\mathrm{S}}_{\mathrm{N}}1$and ${\mathrm{S}}_{\mathrm{N}}2$ mechanisms, these halides are reactive.
3. Some common examples are 1-chlorobut-2-ene $({\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_2-\mathrm{Cl})$, 1-bromohex-2-ene $({\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_2-\mathrm{Br})$, etc.

Therefore, 1-chlorobut-2-ene $({\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_2-\mathrm{Cl})$ is an example of allylic halides.