[CopperSmurf]

I'm stuck on trying to solve this proton NMR problem. Usually they aren't a problem for me unless it involves a lot of J coupling stuff. I'm told that this compound is water insoluble and is a clear colourless liquid that was dissolved in CDCl₃ to analyze it in the proton NMR.

The bad part is that there are two broad blobs (peaks) at ~3.8 and ~1.4 ppm. I'm pretty sure that peak at ~3.8 is -OH of an alcohol. The peak at 0.88 ppm is a triplet and the peak at 1.19 is a doublet. The stuff in between 2 and 2.5 ppm I feel are not important and are probably there to mess me up (super low integration). Whoever ran this probably had some leftovers in there. I got a "zoomed in" version posted too.

Then I tried to come up with the best integration ratios (left to right): 1:4:7:3:3 or 1:4:8:3:3. I know for sure there isn't any aromatic rings or phenol in there since there are no chemical shifts above 4 ppm. Now I'm stuck on putting it all together. I also uploaded a .gif file with the original integrations I was given on the bottom and labelled chemical shifts on the top in the proton NMR. I got snacks to give if anyone's willing to help.

[James Newby]

Stupid question but do you have any information on what the compound may be?  Mass specs, composition, starting materials etc

[CopperSmurf]

sadly, I have no mass spec or composition given to me and this was not a synthesis problem, otherwise I wouldn't be struggling for so long. All I have is this horribly messy proton NMR and some bits of info given to me: water insoluble alcohol, clear colourless liquid, dissolved in CDCl₃ and soluble in diethyl ether, and it was implied in this problem that there's no sulphur, no nitrogen, no halogens. It's complete focus on this proton NMR.

*edit* We've been working on neutral compounds and this would be classified as one of them. I don't know if that helps any to solve this, but I guess getting as much info as possible could lead into something.

[James Newby]

From the integrations i think:

3-4 protons at 0.9
6 protons at 1.12
3 protons at 1.14
1 proton at 1.4

3-4 protons at 0.9 ia likely to be a terminal methyl group
6 protons at 1.12 are probably CH2 units
3 protons at 1.14 may be methyl group near the OH
1 proton at 1.4 i think is attached to the carbon with the OH on it

so thats 14 protons in your molecule, and 5 environments, very tricky!

[CopperSmurf]

Hm... sounds possible. Maybe an alkene with one alcohol group?

I was thinking along the lines of octanol or heptanol, depending on how many hydrogens there actually is...

[James Newby]

i was thinking hexanol, such as hexan-2-ol. There are many other possiblilities such as cyclopentanol with a methyl group attached.  I dont think its an alkene as the signals appear slightly further up the spectra

[CopperSmurf]

hm, hexanol could work too. Anyways, thank you James for helping me out with this. At least I narrowed it down a bit more.

P.S. I looked up a spectra database for 2-hexanol, 2-heptanol, 2-octanol, 2-nonanol, cyclopentanol and they all look really dead similar to each other, and to this.

[alphahydroxy]

Yeah, I think it must be 2-octanol, for the numbers to work.

alcohol proton = 1H  (although you should never rely on hydroxyl protons even appearing in a spectrum, much less base any integration measurements on them...)

methyl next to hydroxyl = d, 3H

other methyl = t, 3H

remaining protons = gak left over between 1-2 - 1.5 ppm, 11H

[frenchy]

your group at 0.90ppm and the other one at 1.25ppm make me think of pentane or hexane.

[CopperSmurf]

thank you all so much for your input. I finally decided upon 2-octanol as my answer for now.  again, thanks sooooo much!