Q42 / 150 · MHT CET 2025 (21 Apr Shift 1) · Chemistry

What is the number of chiral carbon atoms present in 3,4-Dibromohexane?

  • A
    $5$
  • B
    $4$
  • C
    $3$
  • Correct answer
    D
    $2$

Solution

3,4-Dibromohexane has the molecular structure $\mathrm{CH_3-CH_2-CHBr-CHBr-CH_2-CH_3}$.

A chiral carbon center requires four distinct substituents. Carbon atoms 1, 2, 5, and 6 are attached to multiple identical hydrogen atoms and cannot be chiral.

Carbon 3 is bonded to $\mathrm{H}$, $\mathrm{Br}$, $\mathrm{CH_2 CH_3}$, and $\mathrm{CHBrCH_2 CH_3}$. Carbon 4 is bonded to $\mathrm{H}$, $\mathrm{Br}$, $\mathrm{CH_3 CH_2}$, and $\mathrm{CHBrCH_3}$.

Both carbons 3 and 4 have four distinct substituents and are therefore chiral centers.

$\boxed{2}$

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

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