Chemistry - Aromatic Hydrocarbon Question with Solution | TestHub
How many benzenoid isomers are possible for which will give brisk effervesence with ?
Answer:
Solution:
The compound C₈H₈O₂ giving brisk effervescence with NaHCO₃ indicates the presence of a carboxylic acid group (-COOH).
The degree of unsaturation (DBE) for C₈H₈O₂ is .
A benzene ring accounts for 4 DBE. A carboxylic acid group accounts for 1 DBE (C=O) and 1 DBE (ring).
Thus, the remaining structure must be a benzene ring with a -COOH group and a -CH₃ group.
The possible isomers are:
1. Benzoic acid with a methyl group at ortho position (2-methylbenzoic acid).
2. Benzoic acid with a methyl group at meta position (3-methylbenzoic acid).
3. Benzoic acid with a methyl group at para position (4-methylbenzoic acid).
4. Phenylacetic acid (C₆H₅-CH₂-COOH).
Therefore, there are 4 benzenoid isomers.
