The increasing order of the reactivity of the following with $\mathrm{LiAlH}_{4}$ is : (a) (see structure) (b) (see structure) (c) (see structure) (d) (see structure)

(C) (a) $<$ (b) $<$ (d) $<$ (c)

(A) (b) $<$ (a) $<$ (c) $<$ (d)

(B) (b) $<$ (a) $<$ (d) $<$ (c)

(D) (a) $<$ (b) $<$ (c) $<$ (d)

JEE Main · 2019 · 12 Jan 2019 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

The increasing order of the reactivity of the following with

LiAlH_{4}

is :
(a)
(see structure)
(b)
(see structure)
(c)
(see structure)
(d)
(see structure)

(A)(b) $<$ (a) $<$ (c) $<$ (d)
(B)(b) $<$ (a) $<$ (d) $<$ (c)
(C)(a) $<$ (b) $<$ (d) $<$ (c)✓ Correct
(D)(a) $<$ (b) $<$ (c) $<$ (d)

Answer: (C)

Solution

Reactivity of acyl compounds toward hydride follows the ease of expelling the leaving group: acid chloride

>

anhydride

>

ester

>

amide. Reading the four structures as the amide, the ester, the acid chloride and the anhydride, the increasing order of reactivity runs amide

<

ester

<

anhydride

<

acid chloride.

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

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