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Determing number of ion/C-13 spectrum peaks

Hello :biggrin:

Cannot find a straightforward explanation for this.
Will anyone kindly offer some help?


Thank you.
Reply 1
Avatar for Basmaa
Basmaa
What exactly don't you understand? How the number of environments is known or...?


Posted from TSR Mobile
Reply 2
Avatar for Joyful_soul
Joyful_soul
OP
16
Original post by Basmaa
What exactly don't you understand? How the number of environments is known or...?


Posted from TSR Mobile


Thanks for responding

For example, how do I determine the no of C-13/H-1 peaks in DPE (taken Jun 11 paper)

chemquest.png19.4KB
Reply 3
Avatar for Basmaa
Basmaa
A C-13 peak on an NMR spectra represents a carbon environment.

So you'll just have to count the different carbon environments in the structure.. Doesn't matter how much an environment is repeated, it'll produce one peak (with a different area)


Posted from TSR Mobile
13C NMR has the nice feature that there is a peak for every different type of carbon atom present in the molecule. So if there are 5 different carbon environments, then there will be 5 peaks. Does that help?
Reply 5
Avatar for Joyful_soul
Joyful_soul
OP
16
Original post by EierVonSatan
13C NMR has the nice feature that there is a peak for every different type of carbon atom present in the molecule. So if there are 5 different carbon environments, then there will be 5 peaks. Does that help?


Hi,

I knew that much already. I am just confused on how I determine the no of environments.



I count 4... would you kindly list each environment.
Only having real issues with this in the papers so far.

Thanks
Original post by Joyful_soul
Hi,

I knew that much already. I am just confused on how I determine the no of environments.



I count 4... would you kindly list each environment.
Only having real issues with this in the papers so far.

Thanks


There are five different carbon environments in this one. The CH3 group then four of the carbons in the aromatic ring. This is due to the line of symmetry straight down the molecule.
Original post by Joyful_soul
Hi,

I knew that much already. I am just confused on how I determine the no of environments.



I count 4... would you kindly list each environment.
Only having real issues with this in the papers so far.

Thanks


The trick is to imagine that you are starting a (microscopic) journey on a bus from one carbon atom to another. If you 'see' exactly the same carbon atoms (in terms of what they have attached) at each 'station' (carbon atom) then the carbons are in the same environment...

.. ok I'll put it out now ...

...
Reply 8
Avatar for Basmaa
Basmaa
Original post by EierVonSatan
There are five different carbon environments in this one. The CH3 group then four of the carbons in the aromatic ring. This is due to the line of symmetry straight down the molecule.


What are the four environments in the aromatic ring? :s I can only count 3; the one bonded with the CH3, the 3 bonded with the NO2 and the 2 bonded with other carbons.
Original post by Basmaa
What are the four environments in the aromatic ring? :s I can only count 3; the one bonded with the CH3, the 3 bonded with the NO2 and the 2 bonded with other carbons.


The three carbons directly bonded to the NO2 groups are not all in the same environment. Two of them have a CH3 attached to the carbon next to it (one environment) the reamining carbon hasn't (the other environment).
Reply 10
Avatar for Basmaa
Basmaa
Original post by EierVonSatan
The three carbons directly bonded to the NO2 groups are not all in the same environment. Two of them have a CH3 attached to the carbon next to it (one environment) the reamining carbon hasn't (the other environment).


So the carbon environment involves the environment of the neighbouring carbons? Similar to proton nmr?
Reply 11
Avatar for Basmaa
Basmaa
Original post by EierVonSatan
The three carbons directly bonded to the NO2 groups are not all in the same environment. Two of them have a CH3 attached to the carbon next to it (one environment) the reamining carbon hasn't (the other environment).


Thanks for you help btw!!
Original post by Basmaa
So the carbon environment involves the environment of the neighbouring carbons? Similar to proton nmr?


Just like proton NMR, the atom needs to be an identical environment to have the same signal so you can't just look at what it's directly attached to :yy:
Original post by charco
The trick is to imagine that you are starting a (microscopic) journey on a bus from one carbon atom to another. If you 'see' exactly the same carbon atoms (in terms of what they have attached) at each 'station' (carbon atom) then the carbons are in the same environment...

.. ok I'll put it out now ...

...


so would there be 5 peaks so the
CH3 - 1 peak
C attached to CH3, C- NO2, C- N2O - 2nd peak
C- NO2 and C - N2O - 3rd peak
C - H and C -H - 4th peak
C - NO2 attached to both C - H as the 5th peak.

Would that be correct
Original post by haseebi82
so would there be 5 peaks so the
CH3 - 1 peak
C attached to CH3, C- NO2, C- N2O - 2nd peak
C- NO2 and C - N2O - 3rd peak
C - H and C -H - 4th peak
C - NO2 attached to both C - H as the 5th peak.

Would that be correct


Doesn't seem to be ...

CH3 - 1 peak
C attached to CH3, second peak
C- NO2, C- N2O - 3rd peak
C - H and C -H - 4th peak
C - NO2 attached to both C - H as the 5th peak.

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