The alkyl halide that undergoes `S_(N)I` reaction more readily is :

Options

A. ethyl bromide
B. isopropyl bromide
C. vinyl bromine
D. t-butyl bromide

Answer

D

Explanation

Since the reaction follows `S_(N)1` mechanism the alkyl halide giving most stable carbocation will be the most reactive.
`H_(3)C-underset("t-Butyl bromide")underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-BrrarrH_(3)C-underset(3^(@)" carbocation")underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C^(+))+Br^(-)`
Ethyl bromide and n-propyl bromide give primary carbocation, isopropyl bromide gives secondary carbocation, t-butyl bromide gives `3^(@)` carbocation. Order of stability of carbocation is `3^(@)gt2^(@)gt1^(@)`. Hence t-butyl bromide is the most stable.