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Unformatted text preview: N O B N O NOT a valid resonance structure! Bridghead double bond! Here, there is NO donation from the nitrogen to the carbonyl AT ALL. B may technically be an amide, but in a very real sense it is NOT an amide, in that there is no resonance interaction between the N lone pair and the carbonyl pi system. Build a model to convince yourself of the fact that the N lone pair cannot achieve the proper orientation for resonance in this case. Thus, B is really best thought of as a ketone that happens to be attached to a nitrogen atom, and we would expect it to have a ketone-like C=O stretch, and therefore that it would have the highest frequency. C B A lowest frequency highest frequency...
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- Spring '08
- Organic chemistry, Amide, Carbonyl, Bridghead