3.15 Nuclear Magnetic Resonance Spectroscopy
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What is nmr?
Nuclear magnetic resonance spectroscopy
What is used in nmr?
Solvent Standard
What kind of solvents are used in nmr?
Free of H atoms (protons) CDCl3 D = deuterium
Why is a standard used?
To calibrate it (zero it) Compounds are measured against a standard molecule TMS - tetramethylsilane Si(CH3)4
Why is TMS used as a standard in nmr?
It’s signal is far away from the others only gives one signal Non-toxic Inert Low boiling point - easy to remove
What is a molecular environment in nmr?
There is one signal for each set of H atoms The ‘groups’ of H atoms have to be discrete - if another group is attached to exactly the same then it could be the same environment
What is the integration value in nmr?
The intensity of each signal being proportional to the number of equivalent H atoms it represents Eg 3:2:1
What is the n+1 rule?
n = number of adjacent non-equivalent protons (In the next molecular environment) Then you + 1
What are all the n+1 names?
1 - singlet 2 - doublet 3 - triplet 4 - quartet 5 - multiplet
What are the splitting patterns?
Using the n+1 rule put those numbers into a ratio