Spectroscopy Flashcards
1
Q
what are the headings for hydrogen NMR?
A
- chemical shift
- integration value
- environment
- splitting
- number of Hs on adjacent carbon(s)
- possible fragments
2
Q
what does the integration value show?
A
the number of hydrogens in the environment
3
Q
what are the splitting names from 1 to 5?
A
- singlet = 1
- doublet = 2
- triplet = 3
- quartet = 4
- multiplet(5) = 5
4
Q
how do we find the number of hydrogens on the adjacent carbons?
A
- splitting pattern - 1
5
Q
what is used as a standard for chemical shift measurements?
A
TMS (tetramethylsilane)
6
Q
why is TMS used?
A
- inert
- does not interfere
- TMS gives a chemical shift of 0ppm so is used as a standard reference chemical
7
Q
why are deuterated solvents used?
A
- CDCl3 used as a solvent
- D2O (heavy water) added to sample as it is used to identify OH or NH protons
- deuterium does not produce signals in 1H NMR as it causes the signals corresponding to OH and NH to disappear
8
Q
what happens when D2O is added to the sample solution?
A
deuterium in D2O exchanges and replaces the OH and NH protons in the sample with deuterium atoms
- causing the OH or NH peak to disappear
9
Q
why is deuterium a good atom?
A
- does not absorb in this chemical shift range
