Wurtz reaction and Allylic bromination by N-Bromosuccinimide
(A) Wurtz reaction - Ethyl bromide on treatment along with metallic sodium forms butane, ethane and ethylene by including free radical mechanism.
(B) Allylic bromination by NBS (N-Bromosuccinimide) - NBS (N-Bromosuccinimide) is a selective brominating agent and it generally brominates the ethylenic compounds in the allylic (CH2 = CH - CH2-) position. This form of reaction including substitution at the alpha carbon atom along with respect to the double bond is known as Allylic replacement. It is as well need for benzylic bromination.