Chemistry Fundamental Principles of Organic Chemistry MDCAT 2017
PMDC Verified Question 71 of 83
Which one of the followings is the best name according to IUPAC system for the formula given below?

$$ \text{CH}_3\text{--CH}(\text{Cl})\text{--CH}(\text{CH}_3)\text{--CH}_2\text{--CH}_2\text{--CH}_3 $$
A
4-methyl-6-chloro heptane
B
2-chloro-3-methyl hexane
C
2-chloro-4n propyl hexane
D
2-chloro-4-n propyl pentane
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 2-chloro-3-methyl hexane
Concept:

According to IUPAC rules, find the longest continuous carbon chain, number it to give the lowest locants to the substituents, and list substituents alphabetically.

Solution:

  • Longest chain: The main chain has 6 carbon atoms (hexane).


  • Numbering: Numbering from left to right gives substituents at positions 2 and 3. Numbering right to left gives 4 and 5. We choose the lower set (2,3).


  • Substituents: A chlorine atom at C2 (chloro) and a methyl group at C3 (methyl).


  • Alphabetically arranging them gives: 2-chloro-3-methylhexane.


Why other options are incorrect:

Option A has an incorrect parent chain length and numbering. Options C and D misidentify the substituents and parent chain.

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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