Which of the following compounds would be hydrolysed most easily?

Which of the following compounds would be hydrolysed most easily?
  1. $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Br}$
  2. $\mathrm{CH}_{3}\mathrm{Br}$
  3. $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{Br}$
  4. $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2} \mathrm{Br}$

Solution

In case of given compounde, Jdydralypio involves the breaking of $C$ - Br bond. leading to the formation of Corbocation. $C^{(t)}$
If the formed carbocation is move stable, then rate of hydrolysis will be more.
$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Br} \longrightarrow \mathrm{C}_{2} \mathrm{H}_{\mathrm{S}}^{\Theta}$
Methylcarbocation
$\mathrm{CH}_{3} \mathrm{Br} \longrightarrow \mathrm{CH}_{3} \oplus$
$1^{\circ}$ - carbocation
$\mathrm{CH}_{2}=\mathrm{CH}-B r ightarrow \mathrm{CH}_{2}=\mathrm{CH}^{\oplus}$
$\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2} \mathrm{Br} ightarrow \mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}^{\oplus}$
resonance stabilized carbocation.
The most stable carbocation is :
$\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}^{\oplus}$
Hence, $\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}$ br will be hydrolised most easily. /

Asked in: JEE-TOPICTESTS-CHEMISTRY

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