Question

The IUPAC name of the following molecule is: 

 

• A. 2-Methyl-5-nitro-1-chlorobenzene
• B. 3-Chloro-4-methyl-1-nitrobenzene
• C. 2-Chloro-1-methyl-4-nitrobenzene
• D. 2-Chloro-4-nitro-1-methylbenzene

Hint:

In benzene derivatives, numbering starts from the highest priority group to ensure the lowest numbering sequence.

Answer 1

The Correct Option is C

Step 1: Understanding IUPAC Nomenclature Rules 
The longest chain in the benzene ring is chosen as the parent chain. The substituents are assigned numbers based on priority groups to ensure the lowest possible sum. 
Step 2: Numbering the Benzene Ring 
Methyl (\(-CH_3\)) is given the highest priority and assigned position 1. Chlorine (\(-Cl\)) is then assigned position 2, and nitro (\(-NO_2\)) is assigned position 4. 
Step 3: Naming the Compound 
The correct name following IUPAC rules is 2-Chloro-1-methyl-4-nitrobenzene. Thus, the correct answer is (C).

Answer 2

To determine the IUPAC name of the compound, we follow the standard nomenclature rules: 
1. Identify the parent hydrocarbon: The structure is based on a benzene ring, so the base name is "benzene". 
2. Identify substituents: There are three substituents on the benzene ring: - One chloro group (Cl) - One methyl group (CH₃) - One nitro group (NO₂) 
3. Number the ring: We must assign locants (numbers) to the substituents such that the sum of the numbers is minimized and alphabetical priority is considered: 
- Start numbering from the substituent that comes first alphabetically. 
- Chloro (Cl), Methyl (CH₃), and Nitro (NO₂): 
Alphabetically, "Chloro" comes first. So we begin numbering from the carbon attached to Cl as carbon 1. 
Then: 
- The methyl group is at position 2 (next to Cl), 
- The nitro group is at position 4 (para to Cl). 
Thus, the correct name becomes: 2-Chloro-1-methyl-4-nitrobenzene This order follows IUPAC rules and gives correct locants to all substituents. 
Final Answer: 2-Chloro-1-methyl-4-nitrobenzene