Which of the following explain why propene undergo electrophilic addition with HBr, but not with HCN?

Options

A. `Br^(-)` is better nucleophile than `CN^(-)`
B. HBr being better source of proton as it is stronger acid than HCN
C. HCN attacks preferentially via lone pair of nitrogen
D. The C-Br bond being stronger is formed easily as compared to C-CN bond

Answer

B

Explanation

HBr is a better source of proton. It gives `H^(+) and Br^(-)` ions. `HBr rarr H^(+)+Br^(-)`
Thus, `H^(+)` attacks the `pi`-bond of propene to form carbonium ion as
`CH_(3)-undersetunderset(CH_(3))(|)overset(+)(CH)+Br^(-)rarrunderset(("major product"))(CH_(3)-underset(CH_(3))underset(|)(CH)-Br)`