Q19 / 100 · BITSAT 2024 (Memory Based Paper 3) · Chemistry

Which of the following compounds will undergo self aldol condensation in the presence of cold dilute alkali?

  • A
    $\mathrm{CH}_2=\mathrm{CH}-\mathrm{CHO}$
  • B
    $\mathrm{CH} \equiv \mathrm{C}-\mathrm{CHO}$
  • C
    $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CHO}$
  • Correct answer
    D
    $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO}$

Solution

Aldehydes which contain $\alpha$-hydrogen on a saturated carbon, i.e. $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO}$ will undergo aldol condensation. Although $\mathrm{CH}_2=\stackrel{\alpha}{\mathrm{C}} \mathrm{H}-\mathrm{CHO}$ also contain a $\alpha$-hydrogen atom but cannot be easily abstracted by a base to form a carbanion and hence does not undergo aldol condensation.

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

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