Question

Complete an analysis by utilizing all four spectral data (see IR, Mass Spectroscopy, H-NMR and C-NMR on next post). What is the molecular formula, structure and index of hydrogen deficiency? Logically and thoroughly explain by referencing the data to confirm the molecule's identity.

Answer 1

Below are the graphs of the unknown molecule.

Answer 2

The IR graph reads 4000 -- 3000 -- 2000 - 1500 - 1000 - 500 on the x axis and 0 - 50 - 100 on the y axis.

Answer 3

did they give you the formula?

Answer 4

The molecular formula or...? No, it's completely unknown. You have figure out the structure, formula and index of hydrogen deficiency and explain in detail and I don't even know where to start.

Answer 5

From the mass spec data you have the atomic mass at the top. Since atoms can only connect in certain ways, this limits you down quite a ways.

Then look at your proton NMR data and you'll be able to interpret each signal (a signal is a cluster of peaks; a triplet is one signal with three peaks.) and that should tell you something about how it looks.

I mean, I could go more into this, but I really hesitate to help people with these things since this does take an involved effort and you really haven't shown any attempt, so take a good guess and I'll help you along the way. Make sure you explain why you have narrowed it down to certain structures or what maybe, or ask a specific question and I can help you out from there. :)

Answer 6

I guess then they're assuming that this is a purely "organic" molecule?

You should start by figuring it out the formula. From the NMRs you can find the number of hydrogens and carbons, add those up and compare the molecular weight given from the mass spec. If it doesn't add up then you probably have other atoms like nitrogen or oxygen. After you figure out the formula, you can look at the IR to find the functional groups present, then, go back to the NMRs to figure out the structure.

Answer 7

What I got so far from looking at the Mass Spec:
Mass spectrometry measures the molecular weight of the compound. The molecular weight is the same as the mass of the molecular ion, which is 112 (M). Except for the isotope peaks at M+1 and M+2, the molecular ion has the highest mass in a mass spectrum. The base peak is the tallest peak in a mass spectrum, which is at 55. A compound with an odd number of N atoms gives an odd molecular ion. This compound has either an even number of N atoms or none at all because it is at 112. There are no monochlorides or monobromides since there is not a 3:1 or 1:1 ratio peak.

I don't really understand the fragmentation of radical cations formed or how to see functional groups in the mass spec, but I'm guessing you have to compare it to the other spectral data?

And yes, this is an organic molecule.

Answer 8

What I got so far for IR:
Infrared Spectroscopy identifies functional groups. The functional group region from 4000-1500 cm-1 is the most useful region of an IR spectrum. C-H, O-H, and N-H bonds absorb at high frequencies greater than or equal to 2500 cm-1, meaning there is a possibility of being found in this compound. The O-H group can ruled out because there is not a strong peak between 3600-3200 cm-1 and there is no N-H group due to no medium peak at 3500-3200 cm-1. However, there is a strong peak at ~3150, indicating a C-H group. More specifically, it is a Csp3 – H.
There is no reading between 2500-2000 cm-1, meaning there are no C triple bonds with another C or N. There is a reading between 2000-1500 cm-1, meaning there could be a C=C, C=O or C=N bond. The strong peak at ~1700 cm-1 suggests there is a carbonyl group.
The fingerprint region is between 1500-400 cm-1, indicating C-C, C-O, C-N and C-X bonds, which is found in the spectral data.

Answer 9

1H-NMR
• 1 H multiplet just over ~7 ppm, weak signal
• 1 H doublet just under ~6 ppm, weak signal
• 3 H singlet just under ~2 ppm, strong signal
• 2 H multiplet just under ~ 2ppm, weak signal
• 2 H multiplet at 1.5 ppm, weak signal
• 3 H triplet at 1 ppm, medium signal

13C-NMR
• 200 ppm, medium signal
• 150 ppm, strong signal
• ~130 ppm, strong signal
• ~35 ppm, strong signal
• ~28 ppm, strong signal
• ~22 ppm, strong signal
• ~14 ppm, strong signal

Answer 10

This is my best guess.
12 H's, 7 C's
Benzene with a carbonyl functional group attached

MW does equal 112...

Is that just called carbonylcyclohexene? cyclohexenecarbonyl?
I know you don't add the 1 since it's the only one.

Answer 11

I need to incorporate the ketone, so I switched it around.

Answer 12

Adding ion charge