R3.4.2 – Nucleophilic substitution reactions
📌 Halogenoalkanes
- Halogenoalkanes are polar, causing the carbon to be slightly electron deficient (positive) and the halogen to be slightly electron rich (negative)
- Since nucleophiles are electron rich, they are attracted to the partially positive carbon in the halogenoalkane
- The nucleophile is then substituted in the position of the halogen
- The halogen then becomes the ‘leaving group’
- Halogens are good leaving groups because they form relatively weak bonds
- When the nucleophile is a neutral species (like water) the initial product is positively charged and deprotonates to form a neutral compound