Q57 / 180 · NEET 2019 (Odisha) · Chemistry

The most stable carbocation, among the following is

  • A
    $\left(\mathrm{CH}_3\right)_3 \mathrm{C}-\stackrel{\oplus}{\mathrm{C}} \mathrm{H}-\mathrm{CH}_3$
  • B
    $\mathrm{CH}_3-\mathrm{CH}_2-\stackrel{\oplus}{\mathrm{C}} \mathrm{H}-\mathrm{CH}_2-\mathrm{CH}_3$
  • Correct answer
    C
    $\mathrm{CH}_3-\stackrel{\oplus}{\mathrm{C}} \mathrm{H}-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{CH}_3$
  • D
    $\mathrm{CH}_3-\mathrm{CH}_2-\stackrel{\oplus}{\mathrm{C}} \mathrm{H}_2$

Solution

$\mathrm{CH}_3 \stackrel{+}{\mathrm{C}} \mathrm{H} \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_3$ is the most stable carbocation among the given carbocations. It is because the number of $\alpha$ - $\mathrm{H}$ atom attached to carbocation is maximum in $\mathrm{CH}_3 \stackrel{+}{\mathrm{C}} \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{CH}_3$. Thus, it has maximum number of hyperconjugating structure hence, it is most stable.

Hence, the correct answer is option: 'C'.

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