Which one of the following is likely to give a precipitate with $\mathrm{AgNO}_{3}$ solution?

(C) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}$

(A) $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{Cl}$

JEE Main · 2019 · 12 Apr 2019 · Shift 2 · Haloalkanes and Haloarenes

Which one of the following is likely to give a precipitate with

AgNO_{3}

solution?

Answer: (C)

A precipitate of

AgCl

forms only if the

C - Cl

bond can ionise to release

Cl X^{-}

, which means an

S_{N} 1

reaction. Tertiary tert-butyl chloride,

(CH X_{3}) X_{3} CCl

, ionises readily through a stable tertiary carbocation. Vinyl chloride holds a strong

s p^{2}

C - Cl

bond with double-bond character, while

CHCl X_{3}

and

CCl X_{4}

bind their chlorines too tightly, so only

(CH X_{3}) X_{3} CCl

gives the precipitate.

JEE Main · 2019 · 12 Apr 2019 · Shift 2 · Single correct option