Which of the compounds is the least reactive toward the addition of hydrogen halides?

Options

A. `(CH_(3))_(2)C=CH_(2)`
B. `CH_(3)CH=CHCH_(3)`
C. `CH_(2)=CH-Cl`
D. `CH_(2)=CH_(2)`

Answer

C

Explanation

During the addition of acids such as `HX`, the rate controlling step is the formation of carbocation. Therefore, the more stable the carbonation, the faster is the reaction. As substituents, halogens tend to attract electrons. Just as electron release by alkyl groups disperses the positive charge and stabilizes a carbonation, electron withdrawal by halgoen intensifies the positive charge and destabilizes the carbonation.