What is IUPAC name of following compound? Choose the correct answer from the options given below.
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Always prioritize the double bond over alkyl or halogen substituents when numbering the carbon chain. Once you establish that the longest chain has 7 carbons and the double bond starts at position 3, "hept-3-ene" isolates option (B) as the only logical choice.
Step 1: Understanding the Question:
The problem asks for the correct IUPAC name of a branched aliphatic alkene that contains a chlorine atom substituent along its carbon chain. Step 2: Key Formula or Approach:
Apply standard IUPAC nomenclature rules for unsaturated hydrocarbons:
1. Identify the longest continuous carbon chain containing the double bond ($\mathrm{C=C}$) to establish the parent alkane name.
2. Number the principal chain from the end that gives the double bond carbon atoms the lowest possible locant numbers.
3. List the substituent groups alphabetically with their respective position numbers before the parent alkene stem name. Step 3: Detailed Explanation:
Let's analyze the structural framework provided in the problem:
Counting the longest straight chain that runs through the double bond reveals a 7-carbon parent chain, which corresponds to the root name heptene. This immediately eliminates options (C) and (D), which suggest a 6-carbon "hexene" chain.
Now, let's determine the correct numbering direction for the 7-carbon chain:
Numbering from left-to-right gives the double bond a locant position of C3. The substituents are located as a chloro group at C3 and a methyl group at C5.
Numbering from right-to-left would give the double bond a locant position of C4.
Since C3 is smaller than C4, the left-to-right numbering direction is chosen to satisfy the lowest locant rule for the principal double bond functional group.
Combining the positions alphabetically ("chloro" comes before "methyl"), we get: 3-chloro-5-methylhept-3-ene. Step 4: Final Answer:
The correct IUPAC name is 3-Chloro-5-methylhept-3-ene, matching option (B).
