Question

An organic compound having molecular formula $C_9H_{10}O_2$ exhibits the following spectral characteristics:
$'H NMR: \delta 9.72 (t, 1H), 7.1 (d, 2H), 6.7 (d, 2H), 3.8 (s, 3H), 3.6 (d, 2H)$
$IR: ~1720 cm^{-1}$
The most probable structure of the compound is

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is C

To determine the structure of the organic compound with the molecular formula \( C_9H_{10}O_2 \), we need to analyze the given spectral characteristics and correlate them with the structural features shown in the options.

Step-by-Step Analysis:

1. Identify key spectral features:
   • H NMR: \( \delta 9.72 \, (t, 1H), 7.1 \, (d, 2H), 6.7 \, (d, 2H), 3.8 \, (s, 3H), 3.6 \, (d, 2H) \)
   • IR: \(\sim 1720 \, \text{cm}^{-1} \)
2. Analyze each spectral feature:
   • The IR peak at \(\sim 1720 \, \text{cm}^{-1} \) suggests the presence of a carbonyl group, typical of aldehydes or esters.
   • In the H NMR:
     • \(\delta 9.72 \, (t, 1H) \) indicates a hydrogen on a carbon adjacent to a carbonyl group (aldehydic proton).
     • \(\delta 7.1 \, (d, 2H) \) and \(\delta 6.7 \, (d, 2H) \) suggest aromatic protons, likely parasubstituted, as there are two sets of doublets.
     • \(\delta 3.8 \, (s, 3H) \) suggests a methoxy group (—OCH₃).
     • \(\delta 3.6 \, (d, 2H) \) indicates a methylene group (—CH₂—) possibly next to an electronegative atom (like an oxygen in an ether, or part of an ester).
3. Determine the most probable structure based on the above analysis:
   • Considering all the features, the compound is likely an aromatic ester with a methoxy group and a para-substitution pattern. The aldehyde proton at \(\delta 9.72 \, (t, 1H) \) and the aromatic protons suggest a para-methoxy benzaldehyde structure.
4. Matching this analysis with the options provided, the structure in the corresponding option is consistent with the discussed features.

Conclusion:

The structure that matches all observed spectral data is identified in the option depicted by the following image: