OChem - NMR question/brain teaser?

Question

Compound Y has only two singlets in its H NMR spectrum, at 1.42 and 1.96, with relative intensities of 3:1. Its Carbon 13 NMR spectrum has signals at 22.3, 28.1, 79.9, and 170.2. The important bands in the infrated spectrum are at 1738, 1256, and 1173 cm-1. Propose a structure of this compound that can be justified by the given pectral data.

Answer 1

With an IR band at 1740ish, it's probably an ester. That would help explain the lack of different protons on the atom.

Do you have information on the intensities of the C-13 NMR? If they're 1:1:1:1, then its obviously only a 4 carbon molecule.

Don't forget that the ratio 3:1 on the HNMR may also indicate a 9:3 ratio for the protons.

I'm pretty rusty on my spectral analysis, but I think 1 possibility may be t-pentyl methyl ester. That would give you the 4 carbons (in a 3:1:1:1 ratio) and the 2 different protons in a 9:3 ratio (although I think the shift isn't anywhere close to what it would be in an ester)

But with a ratio of 3:1 for protons, a tert- structure is pretty common. That is the best insight I can give you.

Answer 2

it's not that hard. you know from IR that you have a carbonyl, and the molecule is highly symmetrical. it would be a lot easier with molecular weight data because that would narrow down possibilities.