[fjfiji]

Provide a structure for the following compound:
C10H13NO2;
IR: 3285, 1659, 1246 cm–1;
1H NMR spectrum, along with my best guess, which was incorrect:



Here are the hints I have been provided:

The resonance at δ 7.6 is a broad singlet.

The IR absorptions indicate the presence of two functional groups, one of which is a carboxylic acid derivative. The coupled quartet and triplet splittings indicate the presence of which common alkyl group? Remember the n+1 rule: n adjacent protons cause the resonance of an observed proton to be split into n+1 lines. The aromatic splitting patterns indicate a para substitution pattern.

The IR data indicate the presence of a secondary amide (i.e., has an N–H bond).

Here is what it said about my attempt: The chemical shifts don't match the proposed structure. For example, nothing in your structure accounts for the magnitude of the chemical shift of the quartet; N-adjacent alkyl group protons resonate below δ 3, and a phenolic OH resonance typically appears at δ 5–6.

I answered the way I did because I thought the coupled quartet and triplet splittings indicated an ethyl substituent, and my book says a phenolic OH resonance is δ 6-8, so I was surprised to see the disagreement. I didn’t know about the N-H bond when I answered. I thought that the 3285 IR frequency might be the OH group, the 1659 frequency a CC double bond and/or CO double bond, and the 1246 frequency an sp3 CO single bond.

I considered replacing the methyl on the nitrogen with a hydrogen and replacing the hydrogen on the OH group with a methyl, but I thought that might make the chemical shift of the singlet currently at ~2.1 increase too much.

Any help is appreciated!

[Babcock_Hall]

What sort of functional groups are consistent with a chemical shift of about 2.1 ppm?  It is possible that the IR stretching frequency of 1659 might help.

[fjfiji]

Okay I was able to figure it out based on that group, H3C-C(=O)-. Thank you!