Question

What is the reaction according to Markovnikov's rule?

CH3-C=CH-CH3 + HCl with a methyl group on the "C" or carbon 2

Answer 1

Markovnikoff’s addition rule: In an addition reaction of an unsymmetrical reagent (like H-Cl) across an unsymmetrical double bond, the negative part of the addendum (H-Cl) itself attach to more substituted carbon atom and +ve part goes to less substituted carbon atom.

In the addition of HCl across 2-Methylbut-2-ene, firstly H+ ads onto less substituted C and gives carbocation on more substituted C. Then Cl- attack this carbocation and formation of 2-Chloro-2-methylbutane takes place.

The carbocation stability is the basis for Markovnikoff’s addition rule.