Animated Solution for Chemistry - Organic Chemistry: The correct IUPAC name of the following compound is

Imagine you are a molecular architect, and your canvas is a pristine, hexagonal benzene ring. This ring is not just any structure; it is a highly stable, delocalized cloud of pi-electrons that forms the backbone of countless organic compounds.

In our specific problem, this benzene ring has been decorated with three distinct functional groups. At the top, we have a nitro group (${\text{NO}}_2$). On the bottom right, a chloro group ($\text{Cl}$). And at the very bottom, a methyl group (${\text{CH}}_3$).

Our mission is to give this molecule a universally recognized IUPAC name. To do this, we must follow a strict set of rules, starting with the most critical one: numbering the ring.

When a benzene ring has multiple substituents, we cannot just number the carbon atoms randomly. We must apply the Lowest Locant Rule.

This rule dictates that we must number the ring in a way that gives the substituents the lowest possible set of position numbers (locants). Let's test a few paths to see which one wins.

Path A: Starting from Chloro Suppose we assign position 1 to the carbon bearing the chloro group. To keep the numbers low, we move towards the closest neighbor, the methyl group, giving it position 2. Continuing around the ring, the nitro group lands at position 5.

Our locant set for Path A is $\{1,2,5\}$.

Path B: Starting from Methyl Now, let's try starting from the methyl group at position 1. Moving towards the chloro group gives it position 2. Continuing the sequence, the nitro group falls at position 4.

Our locant set for Path B is $\{1,2,4\}$.

To determine the correct numbering, we compare the locant sets point by point. Comparing $\{1,2,4\}$ with $\{1,2,5\}$, the first point of difference occurs at the third number. Since 4 is less than 5, Path B is the undisputed winner.

We now have our locked-in positions: 1-methyl, 2-chloro, and 4-nitro.

With the positions secured, we face one final challenge: assembling the name. IUPAC rules require that substituents be listed in strict alphabetical order, regardless of their position numbers.

Let's look at the first letters of our substituents: - Chloro - Methyl - Nitro

Alphabetically, 'C' comes first, followed by 'M', and finally 'N'.

Therefore, we write the chloro group first, then the methyl group, and lastly the nitro group. Combining this with our locked-in positions, we construct the final masterpiece:

This perfectly matches option (c), completing our architectural naming process with absolute precision!