Chemistry Aldehydes & Ketones MDCAT 2017
PMDC Verified Question 69 of 94
Which one of the following compounds will give iodoform test on treatment with aqueous iodine?
A
3-pentanone
B
Propanal
C
Propanone
D
Butanal
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Propanone
Concept:

The iodoform test is highly specific for the methyl ketone structural motif: a carbonyl carbon bonded directly to a terminal methyl group (\( CH_3-CO- \)).

Solution:

  • Let's examine the structure of Propanone (acetone): \( CH_3-CO-CH_3 \).


  • Propanone possesses two methyl groups attached to the carbonyl group. Therefore, it contains the necessary \( CH_3-CO- \) unit.


  • When treated with iodine and base, it rapidly undergoes halogenation and cleavage to form the yellow precipitate of iodoform (\( CHI_3 \)).


Why other options are incorrect:

3-pentanone (\( CH_3CH_2-CO-CH_2CH_3 \)) lacks a terminal methyl attached to the carbonyl. Propanal and Butanal are aldehydes that lack the \( CH_3-CO- \) group (only acetaldehyde has it).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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