Question

The following compound contains two bromine atoms. Which bromine will be more reactive in an SN2 reaction and why? Br -Br

Answer 1

B By Cup is psómaviy carbon. Cz is tertiary carbon.

In SN2 (Substitution Nucleophilic Bimolecular Reaction) reaction, both bond breaking and bond formation occur in the same step. Both attacking and leaving group are involved in the same rate-determining step. In SN2 reaction, as both groups are involved in the same step, therefore, requires more space on the reacting (attacking) carbon. The steric hindrance is less on primary carbon than that of the secondary and tertiary carbon atoms in a given reactant. Thus, the bromine atom attached to primary carbon (Carbon-4) is more reactive towards SN2 reaction. The order of carbon atom for SN2 reaction thus becomes primary > secondary > tertiary. On the other hand, the order becomes reverse in the SN1 reaction i.e. tertiary > secondary > primary.