The increasing order of reactivity of the following compounds towards aromatic electrophilic substitution…

The increasing order of reactivity of the following compounds towards aromatic electrophilic substitution reaction is:

1. $\mathrm{A}<\mathrm{B}<\mathrm{C}<\mathrm{D}$
2. $\mathrm{B}<\mathrm{C}<\mathrm{A}<\mathrm{D}$
3. $\mathrm{D}<\mathrm{B}<\mathrm{A}<\mathrm{C}$
4. $\mathrm{D}<\mathrm{A}<\mathrm{C}<\mathrm{B}$

Solution

Reactivity of ${\mathrm{E}}^{+}$ substitution$\propto$$\mathrm{\pi }{\mathrm{e}}^{-}$ can be present on the aromatic compound.
Electrophilic substitution $\propto +\mathrm{M}\mathrm{ }\propto \frac{1}{-\mathrm{M}}$
$\propto +\mathrm{H}\mathrm{C}\mathrm{ }\propto \frac{1}{-\mathrm{H}\mathrm{C}}$
$\propto +\mathrm{I}\mathrm{ }\propto \frac{1}{-\mathrm{I}}$

(order of ${\mathrm{e}}^{-}$ density $\mathrm{\alpha }$ electrophilic substitution)
Ring ${\mathrm{e}}^{-}$ density is highest.
So $\mathrm{B}>\mathrm{C}>\mathrm{A}>\mathrm{D}$

Asked in: JEE Main 2019 (09 Apr Shift 1)

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