# Organic Chemistry - 1H and 13C NMR Problem. HELP!

1. Sep 8, 2012

### Zipzap

1. The problem statement, all variables and given/known data
Determine the structure of the compound given the information below

2. Relevant equations
Molecular Formula:
C8H6O4

1H NMR:
1.57 (d, J=8.66 Hz, 1 H) 1.77 (d, J=8.66 Hz, 1 H) 3.51 (d, J=3.00 Hz, 1 H) 3.51 (d, J=3.00 Hz, 1 H) 3.60 (sc,J=7.56, 3.00 Hz, 1 H) 3.60 (sc, J=7.56, 3.00 Hz, 1 H) 6.31 (s, 2 H)

13C NMR:
46.10 (s, 1 C) 46.10 (s, 1 C) 47.20 (s, 1 C) 47.20 (s, 1 C) 52.80 (s, 1 C) 135.60 (s, 1 C) 135.60 (s, 1 C) 171.50 (s, 1 C) 171.50 (s, 1 C)

3. The attempt at a solution
So, here's what I've been able to figure out thus far:

I decided to first find the degree of unsaturation in this molecule, which comes out as 6.

From that, my first thought was that I could get 4 degrees from a benzene ring, and 2 degrees from 2 carbonyls (somehow) attached to the ring.

Based on the highest signal of the carbon NMR, I know that one of the carbons is going to be some sort of R(CO)X derivative, and thus I won't have any hydroxyls within my final structure.

Given the highest signal on my proton NMR, I figured that there were only going to be 2 symmetrical hydrogen atoms (somewhere) on my ring. Either that, or the remote possibility of putting a CH2 right between two esters. There's also the possibility of having a double end, with one end being attached directly to two esters.

My biggest problem comes from the fact that I have two proton signals in the 1.57-1.77 range, and the 3.51-3.60 range. This tells me that I have some carbons NOT involved in the ring, but at the same time I have carbons that are adjacent to either side of the ester groups.

I've tried designing a few structures, but they always keep falling short of either the molecular formula, the integration of each shift, or the group I tried adding doesn't match with the observed deshielding.

What are your thoughts, guys? All feedback is greatly appreciated!

Last edited: Sep 8, 2012