Organic ReactionsMedium
Markovnikov rule
Addition of HBr to 2-methylpropene CH₂=C(CH₃)₂. On which carbon does the Br bond?
Given data
Asymmetric alkene + HBr- The addition goes through a carbocation, and the more stable one always forms. So the H bonds to the carbon that is already more hydrogenated: this way the positive charge ends up on the more substituted carbon, stabilized by hyperconjugation and the inductive effect. This is Markovnikov's rule.
Full worked solution
- The addition goes through a carbocation, and the more stable one always forms. So the H bonds to the carbon that is already more hydrogenated: this way the positive charge ends up on the more substituted carbon, stabilized by hyperconjugation and the inductive effect. This is Markovnikov's rule.The Br bonds to the central (tertiary) carbon. The H adds to the CH₂, generating a 3° carbocation (more stable). Product: 2-bromo-2-methylpropane.
Result:Br on the tertiary C (Markovnikov)