CARBON NMR

[lok900]

Hi guys, topic really confusing??

- The data book has the different chemical shifts and it corresponds to the different linkages/groups .. whatever.

Anyways, say you have a peak at 20, how would you know which "type of carbon" to use?

as three types could correspond to a ppm of 20..?

these are:
R-CH3
R-CH2-R
R-CH2-X


--

Also, what is the difference between X and R? as shown above?

--

Finally, if we are interpreting nmr and we need to find what the molecule is, will we ever get the question with only the C-NMR or will you get both H-NMR and C-NMR?


thanks for help

[jgoudie]

R-CH3 or R-CH2-R are pretty much the same, just a plain carbon in a chain.  CH3 is just at the end of a chain.

R-CH2-X, the X is a halogen (Cl,Br,F) the data booklet does say anywhere between 15 and 80, however from my experience you will see them up the far end more often than not.

Really to know the difference is how they appear in relation to the other peaks and the molecular formula to see that it all fits together.

Thats my 2cents.

Hi guys, topic really confusing??

- The data book has the different chemical shifts and it corresponds to the different linkages/groups .. whatever.

Anyways, say you have a peak at 20, how would you know which "type of carbon" to use?

as three types could correspond to a ppm of 20..?

these are:
R-CH3
R-CH2-R
R-CH2-X


--

Also, what is the difference between X and R? as shown above?

--

Finally, if we are interpreting nmr and we need to find what the molecule is, will we ever get the question with only the C-NMR or will you get both H-NMR and C-NMR?


thanks for help