In an alkyl halide, the halogen serves 2 functions that

Last updated: 8/3/2022

In an alkyl halide, the halogen serves 2 functions that render the alkyl halide reactive towards substitution and elimination processes. One is that halgens serve as leaving groups and substitution/elimination reactions can only occur when a leaving group is present. What is the other reason? The halogens have pką values above zero, making them weaker acids and more likely to participate in dissolution. The halogen repels electron density rendering the adjacent carbon atom nucleophilic and therefore subject to attack by an electrophile. The halogen is usually in an allylic postion and therefore does not participate in resonance, making it less stable and more likely to react. The halogen withdraws electron density rendering the adjacent carbon atom electrophilic and therefore subject to attack by a nucleophile.