Question:
In the IR spectrum, the absorption band due to the carbonyl group in phenyl acetate appears at:
In the IR spectrum, the absorption band due to the carbonyl group in phenyl acetate appears at:
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Aryl ester oxygen shares its lone pair with the ring, raising the C=O force constant.
Updated On: Jul 3, 2026
- \(1800\ \text{cm}^{-1}\)
- \(1700\ \text{cm}^{-1}\)
- \(1740\ \text{cm}^{-1}\)
- \(1660\ \text{cm}^{-1}\)
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The Correct Option is A
Solution and Explanation
Step 1: A saturated aliphatic ester absorbs near 1740 cm-1 for C=O stretch.
Step 2: Phenyl acetate has its ester oxygen attached to a phenyl ring.
Step 3: The ring competes for the oxygen lone pair, leaving less donation into the carbonyl.
Step 4: Reduced donation means more true double bond character, higher force constant, higher frequency.
Step 5: This shifts the band up to about 1800 cm-1.
\[\boxed{1800\ \text{cm}^{-1}}\]Was this answer helpful?
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