About a week or so ago, I posted an H-NMR problem that we had been assigned on our last homework. The solution to that spectrum was beta-hydroxybutryric acid:
The basic idea, it appears, is that the spectrum was taken of a salt of some sort, so the acidic group is actually deprotonated which explains why it doesn’t show up in the NMR spectrum. Anyway, I wound up with 50/50 on the assignment, even though I wasn’t able to solve the unsolvable problem. I had been able to deduce the presence of a carboxylic acid, but I think that it was more or less a lucky guess on my part. The most difficult part of this problem was the wrong information given about the solvent. If the spectrum was taken in D2O, one would not expect to see the signal due to the alcohol, which, as it turns out, is actually present in the spectrum shown.
For some reason, our professor seemed to think that giving us a poorly-defined problem was a good thing or a good teaching tool. Pretty sure he was wrong on that.