[Valuum]

Hey all, first ever post. I've sifted through the boards here in the past and its always been of great help. Figure I'd ask directly this time!

Alright, so basically I've been given some spec data as well as a sample of the compound to analyze in lab, and I'm very, very stuck (I've attempted to attach a couple of images, we'll see if it works).

My thoughts on the data are all over the place, as I cant seem to connect them together:

IR:
-an OH group around 3400 (maybe NH)
-POSSIBLY a C-O at 1100

C NMR:
-the two separate peaks from 150-160ppm represent C=C connected to something electronegative (-OH?)
-the two separate peaks at roughly 120ppm represent another C=C
-the peak at 60ppm is a methyl, although its WAY out of its typical range. I had thought it could be bonded to an O which would account for the deshielding, but this is very scarcely supported in the IR

H NMR:
-at roughly 7ppm, 4 H's with no neighbors. This to me looks like they would exist on the ends of alkene groups, but they would have to be in very, very similar positions to show up as a singlet
-at about 4.5ppm, h bonded to an O (or N?)
-at about 4ppm, a methyl group. Again, looking like its bonded to an O but I just cant see it in the IR.

On top of that, I've tested the compound's solubility:
-water (insol)
-5% HCl (insol)
-5% Na2CO3 (insol)
-5% NaOH (soluble)

The lab manual I've been provided with suggests that based on solubility, I likely have a carboxylic acid or a phenol. As there's no C=O in the IR, I had originally gone with phenol. However, there is no way I can arrange an aromatic structure that fits the spectra provided. So I tried a conjugated dienol, thinking that the resonance energy could account for the phenol-like solubility, and I landed on 3-methylbuta-1,3-dien-2-ol. Considering that the illusive ether group might actually be present, I arrived at 3-methoxybuta-1,3-dien-2-ol.

I must have tried a hundred structures before arriving on these two as possibilities, and I still have no idea if they are right! Any help would be fantastic.

[dunno260]

Not easy without a formula.  I don't think your proposed structure fits because you should see geminal coupling, and also I am not sure you have enough of a driving force of conjugation to have it so vastly prefer the enol tautemer.  However, my answer should see some coupling that you don't see in the NMR.

I am fairly sure the structure is p-methoxyphenol.  Yes, you should see coupling between the aromatic protons, but I have observed in my experience that the coupling sometimes isn't present in electron rich aromatics.  The 13C NMR and proton NMR absent the proton coupling certainly are consistent with that.  The IR seems to suggest a p-substituted aromatic ring due to the overtone signatures from 2000-1600 cm-1. 

[cundi]

My proposal
p-metoxyphenol

[Valuum]

Hey guys thanks for the replies,

One of my first thoughts was actually that it was a para substituted ring but I quickly wrote it off (probably too soon) because I couldn't see an aromatic doublet at 7ppm on the H NMR. By coupling are you referring to said doublet? And I guess a follow up question would be, do electron donating groups typically have this sort of effect on benzene rings?

[nox]

It's probably just a case where the chemical shifts are similar enough to overlap and collapse into an apparent singlet. Especially so in this case because the substituents are very similar. I've observed p-methyl styryl derivatives give apparent singlets in the aromatic region, so it's completely possible.