Question

The correct IUPAC name of the compound

is:

• A. 4-ethyl-1-fluoro-2-nitrobenzene
• B. 4-ethyl-1-fluoro-6-nitrobenzene
• C. 3-ethyl-6-fluoro-1-nitrobenzene
• D. 1-ethyl-4-fluoro-3-nitrobenzene

Answer 1

The Correct Option is A

To determine the correct IUPAC name for the given compound, let's analyze the structure based on IUPAC naming conventions:

• The base structure is a benzene ring. 
• There are three substituents: a fluoro group (F), a nitro group (NO₂), and an ethyl group (C₂H₅).
• According to IUPAC rules, the substituents should be numbered to give the lowest possible numbers. The priority order is based on alphabetical order:
  • Ethyl (C₂H₅)
  • Fluoro (F)
  • Nitro (NO₂)
• Start numbering the benzene ring from the fluorine, as it appears first alphabetically.
• Assign positions as follows:
  • Position 1: Fluoro group (F)
  • Position 2: Nitro group (NO₂)
  • Position 4: Ethyl group (C₂H₅)

Based on the numbering, the correct IUPAC name is: 4-ethyl-1-fluoro-2-nitrobenzene.

Let's briefly evaluate the other options to confirm:

• 4-ethyl-1-fluoro-6-nitrobenzene: Incorrect as the nitro group is at position 2, not 6.
• 3-ethyl-6-fluoro-1-nitrobenzene: Incorrect numbering and position for the substituents.
• 1-ethyl-4-fluoro-3-nitrobenzene: Incorrect positions assigned.

Therefore, the correct answer is 4-ethyl-1-fluoro-2-nitrobenzene.