Markovnikov’s rule is a simple guideline used in addition reactions of alkenes.
It says:
When HX (like HCl, HBr, HI) adds to an unsymmetrical alkene,
- Hydrogen (H) goes to the carbon that already has more hydrogens.
- The halogen (X) goes to the carbon that has fewer hydrogens.
Example:
Propene (CH₃–CH=CH₂) + HBr → ?
- The middle carbon (CH) has one H.
- The end carbon (CH₂) has two H.
According to Markovnikov’s rule:
- H goes to the carbon with more H’s (CH₂).
- Br goes to the carbon with fewer H’s (CH).
Result: 2-bromopropane (major product).
In short:
“The rich get richer” → the carbon already rich in hydrogens gets the new hydrogen.