Nmr Spec Flashcards
What is nmr used for
Used to determine the structures of unknown organic substances
Why is nmr so good
Easy to obtain a sample
Only small amount of sample needed
It is non destructive
Why is c13 used
Has spin and is significant enough to obtain a spectrum
Things you need to be able to interpret from a c13 spectrum
Number of peaks tells you number of carbon environments
Location of peaks tells you about the type of carbon environments
What does symmetry show
Same environments
Tms
Tetra methyl silane
Used as a reference standard for chemical shifts
Why is tms used as a standard
Generates 1 sharp peak (as all c are equivalent)
Unreactive so won’t affect sample being dissolved
What u need to be able to infer from h nmr spectrum
Number of peaks tells u number of environments
Location of peaks shows u type of proton environment
Area under each peak tells u number of protons in each environment
Splitting shows number of protons in neighbouring carbon
Spin rule
N+1
N is number of hydrogens on neighbouring carbon
What does o- h always split to
Singlet
Solvents
Has to be hydrogen free environment so doesn’t produce any peaks
So solvents using deuterium are used
For polar samples
Deuterated trichloromethane - CDCl3
Non polar samples
Deuterated benzene
C6D6