JEE MAIN - Chemistry (2023 - 13th April Evening Shift - No. 10)
Given below are two statements :
Statement I : Tropolone is an aromatic compound and has $$8 \pi$$ electrons.
Statement II : $$\pi$$ electrons of $$ > \mathrm{C}=\mathrm{O}$$ group in tropolone is involved in aromaticity.
In the light of the above statements, choose the correct answer from the options given below:
Explanation
Let's analyze the structure of tropolone to evaluate the given statements.
1. Statement I: "Tropolone is an aromatic compound and has $$8 \pi$$ electrons."
Tropolone is a seven-membered ring compound with an oxygen atom attached to it through a double bond, creating a carbonyl group (C=O). To determine if it is aromatic, we should check if it meets Hückel's rule for aromaticity, which states that a molecule is aromatic if it is cyclic, planar, and has a $$4n + 2$$ $\pi$ electrons (where n is a non-negative integer).
Upon examining the structure of tropolone:
| Electrons | Count |
|---|---|
| Electrons from double bonds in the ring | 6 |
| Electrons from the carbonyl $$\pi$$ bond | 2 |
| Total $$\pi$$ electrons | 8 |
According to the table, tropolone has a total of 8 $$\pi$$ electrons. Since 8 does not satisfy the $$4n + 2$$ rule (where n would be 1 or 2, leading to 6 or 10 $$\pi$$ electrons), tropolone does not qualify as aromatic. Therefore, Statement I is false.
2. Statement II: "$$\pi$$ electrons of $$ > \mathrm{C}=\mathrm{O}$$ group in tropolone is involved in aromaticity."
As established, tropolone does not meet the criteria for aromaticity. Additionally, the $$\pi$$ electrons of the carbonyl group indeed contribute to the total count of $$\pi$$ electrons in the ring system, but since tropolone isn't aromatic, Statement II is false.
Given the analysis, the correct answer is:
Option B: Both Statement I and Statement II are false
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