JEE PYQ: Haloalkanes And Haloarenes Question 15
Question 15 - 2019 (09 Apr Shift 2)
Increasing order of reactivity of the following compounds for $\text{S}_\text{N}1$ substitution is:
(A) Neopentyl chloride ($(\text{CH}_3)_3\text{CCH}_2\text{Cl}$) (B) Allyl chloride ($\text{H}_3\text{C}-\text{CHCl}$) (C) $p$-Methoxybenzyl chloride (D) $p$-Chlorobenzyl chloride
(1) (B) < (C) < (D) < (A)
(2) (B) < (C) < (A) < (D)
(3) (B) < (A) < (D) < (C)
(4) (A) < (B) < (D) < (C)
Show Answer
Answer: (3)
Solution
In $\text{S}_\text{N}1$ reaction, carbocation acts as an intermediate. Carbocation produced by (C) ($p$-$\text{OCH}_3$ benzyl) is more stable than carbocation produced by (D) ($p$-Cl benzyl) due to +I effect of $-\text{OCH}_3$ group. Further in (A) there is formation of tertiary carbocation after rearrangement while (B) is primary carbocation. So, the correct order is (C) > (D) > (A) > (B).
BETA
