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Basics of Organic Chemistry question

2007 · Shift 0 · Q13
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Basics of Organic Chemistry question

2007 · Shift 0 · Q13

JEE MainChemistryBasics of Organic ChemistryMCQ+4 / −1
AIEEE 2007 Chemistry - Basics of Organic Chemistry Question 225 English
  1. A
    333- enthyl -444-444 - dimethylheptane
  2. B
    1,11,11,1- diethyl -2,22,22,2 - dimethylpentane
  3. C
    4,44, 44,4 - dimethyl -5,55,55,5 - diethylpentane
  4. D
    5,55,55,5- diethyl -4,44,44,4 - dimethylpentane.
View written solutionFree

Correct answer: A

The question as provided is incomplete: it lists only four IUPAC names as options, but no structure/formula is given to identify which name is correct.

So, strictly speaking, the answer cannot be uniquely determined from the visible data alone.

However, we can still analyze the options using IUPAC naming rules and check which names are valid/preferred.


1. Check each option for IUPAC consistency

Option A: 333-ethyl-4,44,44,4-dimethylheptane

  • Parent chain: heptane
  • Substituents: one ethyl at C-3 and two methyls at C-4
  • This is a valid IUPAC name.
  • Numbering gives locants 3,4,43,4,43,4,4, which is reasonable for a heptane parent chain.

Option B: 1,11,11,1-diethyl-2,22,22,2-dimethylpentane

  • Parent chain chosen as pentane.
  • But if there are ethyl groups at C-1, the longest continuous chain would likely become longer than pentane.
  • Hence this violates the longest-chain rule and is generally not preferred/correct.

Option C: 4,44,44,4-dimethyl-5,55,55,5-diethylpentane

  • Parent chain: pentane.
  • Substituents at C-5 on a pentane chain are suspicious because C-5 is a terminal carbon; attaching two ethyl groups there indicates the chain was not chosen longest.
  • Also numbering should be minimized from the nearer end.
  • So this is not a correct IUPAC name.

Option D: 5,55,55,5-diethyl-4,44,44,4-dimethylpentane

  • Same structural issue as option C.
  • Also numbering is not lowest possible.
  • Hence incorrect.

2. Most plausible correct option

Among the given choices, Option A is the only properly acceptable IUPAC name:

3-ethyl-4,4-dimethylheptane\boxed{3\text{-ethyl-}4,4\text{-dimethylheptane}}3-ethyl-4,4-dimethylheptane​


3. Comparison with stored answer

Stored correct answer: A

My derived answer: A

So they agree.

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