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1H NMR Identifying Structures HELP

Hey guys,

Doing homework on 1H NMR spectra and have to identify the structure of the compound from the spectrum. I've identified each of the peaks but have no idea what the structure of the compound is:

-Formula: C9H16O2
-Strong IR peak at 1705 cm-1 -- indicates C=O bond
-No reaction with Tollen's reagent or sodium hydrogencarbonate -- indicates not an aldehyde or carboxylic acid
-4 peaks -- 4 unique environments
-Intensities (ratio of H in environment) == 2:2:9:3
-Triplet at 1ppm suggests RCH3. Triplet means adjacent carbon has 2 hydrogens.
-Singlet at 1.2ppm suggests R2CH2. Adjacent carbon has no hydrogen atoms or is identical environment.
-Quartet at 2.5ppm suggests RCOCH. Adjacent carbon has 3 H atoms.
-Singlet at 3.6ppm suggests ROCH. Singlet means adjacent carbon has no hydrogen atoms or is an identical environment.

(This is for AQA A-Level Chemistry)

Any help with how the heck I'm supposed to know the structure of this compound would be greatly appreciated! :smile:

(edited 2 years ago)

Reply 1

ApplePiePanda

I believe this is the right structure, if you could confirm this I can go through it

Reply 2

username5432344

Original post by ApplePiePanda

I believe this is the right structure, if you could confirm this I can go through it

Hi, I'm not sure as it seems to only have 3 environments and one of the oxygens needs to be in a single bond...I'm going to ask my Chemistry teacher next time I have a lesson but thanks for your help though!

Reply 3

ApplePiePanda

I could be wrong, could you send over the full question? I'll let you know if I get something different

Reply 4

Kyri

I agree with the structure drawn out already. I did think about having a C-O-C linkage in there but that would result in having an additional peak in the NMR. The two ketone groups seems to be the only way to have this suggested formula with only 4 proton environments, with that ratio of peak intensities.

Reply 5

username5432344

Original post by Kyri

Had the answer today in my Chemistry lesson today - @ApplePiePanda I'm so sorry, you did have the right answer! I was getting mixed up with some of my environments. Thank you so much for your help!

Reply 6

ApplePiePanda

Want me to go over it? And it's fine! NMR tends to be a bit difficult sometimes especially with trying to identify all the environments. I'll see if I can find the sheet with my workings out