Question

13C NMR INDEX FREQUENCY PPM 16654.3 220.80B 5842.6 77.462 5810.2 77.033 5777.B 76.604 2892.5 38.350 1750.4 23.208 HEIGHT 10.4 61.8 73.8 62.5 104.4 43.2 signarfrom Solvent from solent 38.350 77.462 - 77.033 76.604 -220.00 and heal 8 thiest 220 200 180 160 140 120 100 80 60 40 20 0 ppm

Can anybody help me decipher the compound that produced this carbon NMR and proton NMR? From the qualitative tests done in lab, I know that the molecule is a ketone. I think the compound has 3,6,or 9 distinct carbons. Note that the cluster of three signals on the carbon NMR is due to the solvent used (this was mentioned in my lab notebook and was told that it was not due to my compound.

Answer 1

Your analysis about ketone is right and for 3,6 carbon type too

First lets take a look at 13C NMR.

1. three signals suggest three type of carbon

2. signal at 220 ppm suggests it may be a ketone

3. two signals in aliphatic region (23, 38 ppm) suggests of aliphatic ketone.

1HNMR analysis

1. signals around 2.00 ppm also suggests aliphatic nature of proton.

2. ratio of peaks is 4:4 or simply 1:1 suggests that equal number of aliphatic protons

so this indicates compound is most likely cyclic ketone.

CYCLOPENTANONE fits the analysis.