What is the IUPAC name of the following compound?
A. 5-ethyl-3-1-methylethyl)heptane
B. 2-methyl-3-ethyl-5-ethylheptane
C. 3,5-diethyl-2-methylheptane
D. 2-methyl-3,5-diethylheptane
The correct answer and explanation is :
The correct IUPAC name of the compound is:
D. 2-methyl-3,5-diethylheptane
Explanation (Approx. 300 words):
To determine the IUPAC name of an organic compound, particularly an alkane with substituents, we follow a systematic nomenclature procedure as per IUPAC rules:
Step 1: Identify the Longest Continuous Carbon Chain
- The main chain must be the longest unbroken chain of carbon atoms. In this case, it’s a heptane (7 carbon atoms).
Step 2: Number the Carbon Chain
- The carbon atoms in the main chain should be numbered such that the substituents receive the lowest possible numbers.
- Suppose the chain is numbered from left to right: the methyl group is on carbon 2, and ethyl groups are on carbons 3 and 5.
Step 3: Identify and Name the Substituents
- Methyl group (–CH₃) on carbon 2
- Ethyl groups (–CH₂CH₃) on carbons 3 and 5
Step 4: Combine the Substituents with the Base Name
- When multiple identical substituents exist (like two ethyl groups), we use prefixes: di-, tri-, etc.
- Alphabetize the substituents for correct ordering in the name:
- Ethyl (starts with ‘E’) comes before Methyl (starts with ‘M’), even if methyl has the lower number.
Step 5: Assemble the Full IUPAC Name
- Ethyl groups at positions 3 and 5 → 3,5-diethyl
- Methyl group at position 2 → 2-methyl
- Parent chain → heptane
Putting it all together, and ordering substituents alphabetically:
2-methyl-3,5-diethylheptane
Why Not the Other Options?
- A. Contains incorrect and unclear substituent naming.
- B. Lists ethyl three times, which is redundant and not systematic.
- C. Has the correct components but incorrect ordering (methyl should come after ethyl alphabetically, not first).
Thus, Option D follows all IUPAC naming rules correctly. Would you like a structural diagram to visualize it?