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Proton NMR question help!!

Need help with this question.

Have I counted the proton environments right here? I counted 5, so surely there are 5 carbon peaks but the answer says only 2.

Thanks

Reply 1

username2476735

I think the question's answer is right, if you look region 2 has a carbon connected to it with 3 hydrogens on it, but every other carbon has just 1 hydrogen coming off it, so it might be that you've got one carbon atom with 5 hydrogens attached to the other carbon atoms next to it and the others each have 2 on the adjoining carbon atoms. I think by 2 peaks it means 2 different peaks, i.e. if they've all got the same environment that would count as one peak. Don't trust me fully on that though, I could easily be wrong.

Reply 2

alow

Original post by RallySPORT

Yeah you're wrong.

There are 5 environments. Here is the (simulated) ¹³C NMR of TNT:

Here's a quick simulated NMR I did myself (don't pay too much attention to the shifts, just to the distinct peaks):

However for proton environments, there are two (as only the methyl and 3 carbons have protons attached):

(edited 7 years ago)

Reply 3

coconut64

Original post by RallySPORT

Hey, I realise where I have gone wrong now. Thanks. So does this molecule have 5 carbon environments?

Reply 4

coconut64

Original post by alow

Yeah you're wrong.

There are 5 environments. Here is the (simulated) ¹³C NMR of TNT:

Where can you find this app to check the no of environments?
So No of H environments : 2 No of carbon envirnonment : 5 or 7?

Thanks again

Reply 5

username2476735

Original post by alow

Yeah you're wrong

well rip me

Reply 6

alow

Original post by coconut64

Where can you find this app to check the no of environments?
So No of H environments : 2 No of carbon envirnonment : 5 or 7?

Thanks again

I use ChemDoodle to generate NMRs, but it's not that good at predicting shifts (although they're not too far off), only for showing the number of environments.

I edited my last post to include a simulated ¹H NMR, there are 2 environments.

Reply 7

coconut64

Original post by alow

So there are 7 carbon environments in total? Why isn't the carbon environment the same on the carbon atom attaching to NO2 ?? I don't quite get it... This is very annoying but pls help me!!

THXX

Reply 8

alow

Original post by coconut64

So there are 7 carbon environments in total? Why isn't the carbon environment the same on the carbon atom attaching to NO2 ?? I don't quite get it... This is very annoying but pls help me!!

THXX

There are 5 carbon environments. There are 5 peaks in the NMR.

Reply 9

coconut64

Original post by alow

There are 5 carbon environments. There are 5 peaks in the NMR.

Why does your stimulated image show 7? Is my labelling right here?

Reply 10

alow

Original post by coconut64

Why does your stimulated image show 7? Is my labelling right here?

It doesn't. It shows 5.

Reply 11

coconut64

Original post by alow

It doesn't. It shows 5.

Right, so there are 5 peaks but why is there a 7 labelled next to the molecule?

Also have I labelled my molecules right??

Reply 12

alow

Original post by coconut64

Right, so there are 5 peaks but why is there a 7 labelled next to the molecule?

Also have I labelled my molecules right??

That's just counting the carbons... Look at the spectrum...

Your labelling is fine.

Reply 13

coconut64

Original post by alow

That's just counting the carbons... Look at the spectrum...

Your labelling is fine.

Cool, thats more reassuring. Also I have just downloaded that chemdoodle thing but I am so clueless as to how to use it. So just wondering if you know other apps that can do the same thing?

Thank you so much