1. WIDIASTUTI AGUSTINA ES, S.Si., M.Si.
NUCLEAR
MAGNETIC
RESONANCE
(NMR)
WIDIASTUTI AGUSTINA ES, S.Si., M.Si.

2. Nuclear Magnetic Resonance Spectroscopy (NMR) :
Spectroscopic technique that provide information about amount and type of atomic molecule
Hydrogen atoms H NMR
Carbon atoms C NMR
Phosphor atoms P NMR

3. NUCLEAR SPIN ATOM
Electron have quantum number ½ with a value of +1/2 and -1/2
- Spin Charge generates magnetic field so that electron act as a tiny magnet called a magnetic moment
This effect also valid for another atom. An atomic nucleus has an odd number and atomic number of the odd or both will have to have spin and produced magnetic moment
Nuclear Spin Rate depends on the quantum spin number , l, of nuclei

4. NUCLEAR SPIN NUMBER Number of spin state = 2 l +1
l = nuclear spin quantum number

5. Without magnetic field, both spin state have the same energy
Nuclear atomic spin with + charge, generating a magnetic moment vector m + + m
Without magnetic field, both spin state have the same energy
+ 1/2
- 1/2

6. IN MAGNETIC FIELD (BO)

7. RESONANCE
In NMR spectroscopy, resonance is the energy absorption by the core-precision results in a change of spin nuclei from lower energy level to a higher energy level
The precision results in a magnetic field oscillations and produce a "signal"

8. DE = hn quantized -1/2 -1/2 DE
In a strong magnetic field, a rotating nuclei absorbs radio frequency (resonance phenomena)
+1/2
+1/2 Bo
Magnetic Field

9. LARMOR EQUATION n = Bo 2p g
= frequency of the radiation that comes, which will cause
the transition
= giromagnetic ratio
different for each atom (H, C, N)
B0 = magnetic field

10. Magnetic Field
In organic compounds, hydrogen atoms are surrounded by electrons moving in the presence of a magnetic field.
The movement of electrons around the nuclei of hydrogen atoms in the magnetic field result in Diamagnetic Current
The area around the atomic nucleus that is formed by electrons are called Diamagnetic Shielding
B Induced
(opposed Bo)
Bo Applied

12. MEASUREMENT Liquid Sample Sample volume  0,5 mL Solvent
1H NMR = deuterated solvent
CDCl3, CDOH3, Acetone-d6, Benzene-d6
Piridin-d5, DMSO-d6, D2O
13C NMR = CHCl3, CHOH3, Acetone, Benzene
Piridin, DMSO, H2O
Sampel Amount = ≤ 50 mg

13. 1H NMR

14. INFORMATION FROM 1H NMR
1. Chemical Shift (, ppm), expressed as ppm (per million)  functional group 2. Integration  number of proton 3. Multiplicity (s, d, t, q, qi, sext., hept.)  proton relationship 4. Coupling Constant (J, Hz)  type of proton relationship  stereochemistry or position of proton 5. Proton Signal: 0-15 ppm

15. integration
multiplicity
Coupling constante
ppm
standart TMS
Chemical shift
H group = amount & type of proton

16. HYDROGEN EQUIVALENT
Hydrogen Equivalent : Hydrogen that have a same chemical environtment
Compounds that have one hydrogen equivalent, producing one peak of proton NMR

17. - Compounds that have two/three hydrogen equivalent, producing two/three peak of proton NMR

18. How many proton signal??

19. CHEMICAL SHIFT
NMR signal is not measured by resonance position, but based on
how far to shift from TMS, called CHEMICAL SHIFT
Has a highly protected proton and carbon
(appears on upfield region)

20. PROTON CHEMICAL SHIFT
Proton chemical shift depends on the frequency of tool used (shear difference for protons appear the same but measured in different tools)
TMS
shift in Hz
downfield n
shift in Hz
chemical
shift
= d =
= ppm
spectrometer frequency in MHz
Any specific protons in a molecule will always appear at the same chemical shift (constant value)

21. PROTON CHEMICAL SHIFT

22. PROTON CHEMICAL SHIFT

23. PROTON CHEMICAL SHIFT Factors affecting proton chemical shift :
Electronegatifity of the neighbour atoms
Hibridisation from the adjacent atoms
Diamagnetic Effect from the adjacent phi bond

24. Cl C H ELECTRONEGATIFITY d- d+ d- d+
Chlorine pull electron density away from carbon , caused electron density around the proton.
Chlorine caused proton to be “deshields” Cl C H d- d+
electronegative
NMR CHART
Deshielding protons, appears at low field
Shielding protons, appears at high field
more deshielding

25. ELECTRONEGATIFITY Chemical Shift of X on CH3X CH3X
CH3F CH3OH CH3Cl CH3Br CH3I CH4 (CH3)4Si X
F O Cl Br I H Si
Electronegativity of X
Geseran Kimia d
TMS
Most deshielded

26. ELECTRONEGATIFITY
"deshielding" effect increased with increasing number of electronegative atoms
most
deshielded
CHCl3 CH2Cl2 CH3Cl
ppm
“deshielding” effect decrease with increasing proton distance of electronegative atoms
most
deshielded
-CH2-Br CH2-CH2Br -CH2-CH2CH2Br
ppm

27. HIBRIDISATION

28. DIAMAGNETIC
Magnetic Induction on phi bond causes the formation of pi bonds
The presence of phi bond (double bond) or phi system will affect the chemical shift of nearby proton
Accured on alkyne, alkene and benzene ring

29. - ALKYNE

30. - ALKENE

31. - BENZENE RING

32. SPLITTING SIGNAL
On NMR spectrum, proton signals often do not appear as a single peak (singlet), but appear as doublet, triplet, quartet, and so on
Spin-spin splitting on ​​the H atom is due to the interaction (coupling) with the neighboring H atom
Spin-spin splitting followed the (n +1) RULES, if an Atom H has n non-equivalent H atoms which are neighbors, then the NMR spectrum of H atom signal will experience a breakdown as a (n +1) peaks

33. (n+1) RULES n = 1, the signal will be splitted as (1+1) peaks, doublet
peaks, quartet

34. EXCEPTIONAL FOR (n+1) RULES
Equivalent protons due to symmetry effects are usually not mutually spliting each other
no splitting if x=y
no splitting if x=y 2)
Protons in the same group (tied to the same C) are usually not mutually splitting each other or

35. EXEPTIONAL FOR (n+1) RULES3)
N +1 rule applied to the protons in the aliphatic chain (saturated) or cyclic saturated. or
YES
YES
But it is not applied to the protons of the double bond or benzene compounds NO NO

36. PASCAL TRIANGLE
Splitting pattern similar with PASCAL TRIANGLE rule

37. SPLITTING PATTERN
( x = y )
( x = y )

38. SPLITTING