Q.31. - Organic Chemistry

Question

Question: Which compounds are aromatic? For any compound that is not aromatic, state why this is so.

Step-by-Step Solution

Answer

Answer

a.

Not aromatic in nature

b. 

Not an aromatic compound

c. 

Non-aromatic compound

d.

Non-aromatic compound

Step 1: Aromatic compounds

The compounds which fulfil all of the following conditions are aromatic in nature:

• The compounds which are cyclic.
• The compounds which are planar.
• The compounds which are conjugated with $\left(4n+2\right) \mathrm{\pi }$ electrons.

The compound which is aromatic in nature is always more stable than the corresponding acyclic compound with the same number of $\mathbf{\pi }$electrons.

Step 2: The aromatic compounds among the given compounds

a. In the following compound, the marked carbon atoms are not $s{p}^2$ hybridized. They are not completely conjugated. This compound is not aromatic.

Not aromatic in nature

 

b. The circled carbon atom is not $s{p}^2$ hybridized. These are not completely conjugated. This compound is not aromatic in nature.

Not an aromatic compound

 

c. This compound has $12\mathrm{\pi }$ electrons. It does not have $\left(4n+2\right)\mathrm{\pi }$ electrons.   Therefore, this compound is not aromatic in nature.

Non-aromatic compound

 

d. This compound has $12\mathrm{\pi }$ electrons and is not aromatic. It does not have $\left(4n+2\right)\mathrm{\pi }$ electrons.  

Non-aromatic compound