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JEE Chemistry 2026 Question with Solution

The IUPAC name of the following compound is:

Skeletal structure of an ester showing a carbonyl attached to oxygen and a propyl group, with a bromo substituent on the alpha carbon and a branched alkyl chain on the acyl side.
  • A

    n-propyl-2-bromo-5-methylheptanoate

  • B

    2-bromo-5-methylhexylpropanoate

  • C

    2-bromo-5-methylpropanoate

  • D

    n-propyl-1-bromo-4-methylhexanoate

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: The compound shown contains the ester group \ce−COO−\ce{-COO-}.

Find: The correct IUPAC name.

Step 1: Identify the functional group. The given compound contains the functional group

\ce−COO−\ce{-COO-}

which indicates that it is an ester.

Step 2: Identify the alcohol part of the ester. The alkyl group attached to the oxygen atom is a straight-chain propyl group. Hence, the alcohol-derived part is propyl.

Step 3: Identify the acid part of the ester. The longest carbon chain containing the carbonyl carbon consists of three carbon atoms. Therefore, the parent acid is propanoic acid.

Step 4: Locate substituents on the acid chain. Numbering the chain from the carbonyl carbon:

  • A bromine substituent is present at carbon 22.
  • A methyl substituent is present at carbon 55 considering substituent structure.

Thus, the acid part is named 2-bromo-5-methylpropanoate.

Step 5: Write the complete IUPAC name. Combining the alcohol and acid parts, the IUPAC name is

2-bromo-5-methylpropanoate\text{2-bromo-5-methylpropanoate}

Final Answer: Therefore, the correct option is C.

Common mistakes

  • Mistake: Naming the ester by starting from the acid side and ignoring the alkyl group attached to oxygen. Why it is wrong: Ester nomenclature requires identifying the alcohol-derived alkyl group first. What to do instead: First identify the group attached to the oxygen atom, then name the substituted alkanoate part.

  • Mistake: Numbering the acid chain from the wrong end. Why it is wrong: In carboxylic acid derivatives, numbering must begin at the carbonyl carbon. What to do instead: Always assign the carbonyl carbon as carbon 11 before locating substituents.

  • Mistake: Confusing an alkyl substituent name with the parent chain length. Why it is wrong: A branch should not be counted as part of the main chain unless it lies on the selected parent chain. What to do instead: Choose the parent chain according to the ester naming rules, then place substituents separately.

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