Question

I need help with interpreting these spectroscopy graphs. Hopefully the picture of these graphs uploads ok. The first (IR) I think tells me that there's a carbonyl and ester (peaks at 1700 and 1100). I'm not sure what to make of the peaks at 3000 but they seem weak. The second (mass spec) I think tells me that the molecular weight is 162 (tallest peak on the right) but there's a short peak at 163 and I'm not sure if that should be my molecular weight instead. The 3rd graph (H proton nmr) i think tells me there's 5 unique hydrogenated, an aldehyde, amide, and/or aromatic. The 4th (carbon nmr) te

Answer 1

Interpreting spec is really hard so any help/feedback at all is greatly appreciated!

Answer 2

Can you 'attach file' the pictures as a comment?

Answer 3

(and also complete the analysis you're thinking of, since you got cut off by question character count)

Answer 4

Oops! I was thinking that the fourth graph tells me that there's 8 unique carbon environments and it tells me the same things as the H NMR- there could be an aldehyde or aromatic- or maybe a ketone

Answer 5

The graphs I'm talking about in the attachment are combo #9 by the way

Answer 6

Okay. I'll take a little to read these. Do you have your own idea of what the pieces are?

Answer 7

Something with a carbonyl- maybe an ester or aldehyde. Maybe an aromatic in there? This is from the NMRs and I'm not sure but the IR might suggest that as well. The table I have of IR frequenceis says that peaks at 3000-3100 are suggestive of an Ar-H group but it doesn't specify the strength of the peak and the peak on the IR seems to be weak. Still, from the mass spec, everything in the molecular formula of the structure should add up to either 162 or 163 (I'm unsure of what to make of the smallest peak)

Answer 8

I'm still here! Just writing and trying different things XD. I think the two IR peaks before and after the 2800 suggests aldehyde. I'll keep you updated, and please let me know if you figure anything more!

Answer 9

I'm not sure if the peaks are strong enough to be considered aldehyde? The picture is very misleading haha. I think the box with the arrow is the zoomed-in version of the graph and if you look at the picture whole graph, the structure seems to have weak peaks at those points. But maybe I'm interpreting this wrong because the NMRs do suggest aldehydes!

Answer 10

Ah, I have to say I may not be able to crack this one tonight. I think there's an aldehyde, and aromatic seems feasible considering how big it is and the NMR. The H NMR suggests some interesting arrangement around the ring? I've been trying various things but either can't get 162/163 or the wrong NMR behavior. I'll keep working for another 10 minutes.

Answer 11

Hmm that's helpful. Do you know anything about the meaning of the small 163 peak in the NMR?

Answer 12

(guessing you mean in the MS) I think 162 is more likely since there's no evidence of amine or halogen presence in the IR. I've seen MSs where there's a higher peak from some contamination, and while it's true that M+ is not always the highest, I've been just trying to ballpark to 162/163 with different structures.

Answer 13

Hmm that's helpful. Do you know anything about the meaning of the small 163 peak in the NMR?

Answer 14

So I've found the following (but it /is/ 2 hrs past when I normally sleep...) which I'm not completely confident with but figured I should show you.

I've a friend who loves spec analysis and I'll show them this tomorrow morning when they're free. Is that okay? Sorry I couldn't help you more - I thought myself decent at spec analysis but there may be a better/correct answer coming tomorrow.

Answer 15

^ should have added that this is 164, not 162. I'll come back to this tomorrow, after some sleep.

Answer 16

That's very kind of you! I really appreciate the help. The solution to this is due in ~9 hours but I'd still love to know the answer if you figure something out! Thanks for all the help.

Answer 17

I'll be awake at the latest 7.5 hrs from now (and free, then) and my spec-loving friend will definitely be awake and hopefully be free. We'll let you know!

Answer 18

Awake! And showing the specs to friend and with some sleep. we'll try to get back to you soon.

Answer 19

Sorry, we've been looking at this for a whole but neither I nor my friend can get any further than the structure from last night (which we both think is not the correct answer). He suggests there may be a hetereoatom. Sorry we couldn't be more help, we're both basically stumped.

Answer 20

Ahh well. Thanks for trying!

Answer 21

If you are able it'd be nice to find out what the right answer is later on. No problem if its a bother, but we'd both like to know XD

Answer 22

Will do!