[Lafleche]

Hey everyone!

So I have a question concerning an NMR spec for C4H10O2, I am quite puzzled here.  Unfortunately I can't attach the spec here because I don't have a scanner but I'll try explaining it.  Basicly I have 4 sets of peaks, the first two are a doublet around 1.2 (integrates at 3), a quartet at 1.65(integrates at 2).  Now I don't have many options here so I'm guessing this is an ethyl group.  Where it gets complicated is that I have an overlap at around 3.6.  One signal doesn't look like anything, just a multiplet with weird intensities and there's what looks like a singlet that integrates at 3 right beside.  Now initially I thought I had a singlet and a multiplet so I came up with the structure CH3-C(OH)2-CH2-CH3 (butan-2,2-diol).  Now my issue is that my prof gave is a hint that the singlet was actually a doublet and the other signal was either a quintet or sextet and both were very near in chemical shift.

So now I'm back to square 1.  The info I have is

doublet 1.2ppm integral=3
quartet 1.6ppm integral=2
Doublet 3.5ppm integral=2
quintet or sextet 3.6ppm integral=2

These to me don't make much sense and I can't seem to come up with a structure that is plausible.  Any help would be greatly appreciated. 

I also have 2 more question that I can't seem to figure out but I'll give it a few more hours before I give up on those haha, I'll post them here if ever I'm completely stuck.

(ps.  sorry if my post is confusing in any way, English is my second language)

Thanks a lot to anyone who can help me
Cheers!

[Messi]

Can't you go to your library and scan the spectra?

[Lafleche]

Unfortunately no haha, we're not very advance technology wise, we don't have a program like that

[Messi]

Unfortunately no haha, we're not very advance technology wise, we don't have a program like that

Could you maybe take a pic of it with your webcam from your computer? Or do you have a cell phone that takes high resolution pictures?

[discodermolide]

Your integrals don't match with the formula. Integrals total 9H formula has 10H.

[fledarmus]

First, gem-diols (one carbon with two alcohols), as far as I know, do not exist in a form stable enough to take an NMR. They dehydrate very rapidly to form ketones.

Second, an ethyl group would show a triplet for the -CH3 protons, rather than a doublet. The triplet-quartet pattern for an isolated ethyl group is very clear.

So what do you actually have? You seem to show a methyl group at 1.2ppm (3H), which is adjacent to a carbon with one proton. You have another methyl group at around 3.6ppm (3H), which shows only a slight coupling to one proton and looks very much like a singlet instead of a doublet. (What does a methyl group need to be attached to, for it to move all the way to 3.6?) You have a quartet at 1.65 (are you sure that isn't a doublet of doublets) integrating for 2 protons. And you have a quintet or sextet at around 3.6 (1H). So, a CH adjacent to four or five protons. Let's see, that's a CH3, another CH3, a CH2, a CH, and a missing proton - what are missing protons usually attached to? And you still have those two oxygens - what sort of effects might they have? Can you put together the puzzle?

[Lafleche]

Thanks everyone for the answers!!! I only have a few minutes to check in, but I just wanted to make a correction, I made a typo, the signal at 3.5 actually integrates at 3.  I'm in a hurry but later on I'll try to take a picture of the spec.

fledarmus thanks a lot for the answer, I only had time to go over it quickly but I'll work on it this afternoon before posting again.

Cheers!