CL 29- spectroscopy Flashcards
1
Q
what do the number of peaks tell you in C-13 NMR?
A
the no. of C environments
2
Q
what do the number of peaks tell you in H-1 NMR?
A
the no. of H environments
3
Q
what information do you get from the integration traces or peak area ratios?
A
the relative numbers of each type of proton
4
Q
what information do you get from splitting patterns?
A
how many H’s are attached to the neighbouring C using n+1 rule
5
Q
what is tetramethylsilane, TMS, used for?
A
- reference peak, defined to have a chemical shift of 0
- suitable as it is unreactive
- gives a single strong peak to the right of all the other peaks
- easily removed from the sample as volatile
6
Q
what solvent are samples dissolved in for NMR?
A
- CDCl₃
- D atoms do not give a peak in the same frequency ranges of C or H NMR
- in C-13 NMR it appears as 3 short lines at 77ppm
7
Q
how do you use D₂O in NMR?
A
allows us to identify -OH and -NH protons
1. run a normal NMR
2. shake the sample with D₂O- the H atoms are replaced with D
3. run NMR again
4. the signals due to -OH or -NH would disappear, as D does not give signals at the same frequency of H-1 NMR
