Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

3-chloro-1-butene undergo protonation and gives secondary carbocation according Markonikov's addition in the first step. In the second step the lone pair on the chlorine attacks the positively charged carbon to form cyclic intermediate. Now the nucleophile in the reaction i.e., chloride ion attacks cyclic intermediate and forms two structural products as shown below.

2,2-dichlorobutane exit in single isomer only, but 2,3-dichlorobutane exhibits three isomers.