1. Tutorial on Nuclear magnetic resonance Spectroscopy (NMR).
Prepared by
Lawrence Kok

2. Analytical Techniques Spectroscopy analysis
Study on Identification, Structural Determination,
Quantification and Separation
Classical method
Qualitative analysis
Quatitative analysis
Separation analysis
Flame test
Chemical test
Melting/boiling
point
Gravimetric
Titration
Distillation
Precipitation
Chemical test
Involve Qualitative and Quantitative analysis
Quantitative – Amt present in sample/mix
Qualitative – Identity species present in impure sample
Structural – Determination of structure of molecule
Separation of mix – Chromatographic Techniques
Identification of functional gps
Purity of substances
Qualitative analysis
Flame test
Classical
method
Gravimetric
Quatitative analysis
Titration
Analytical
Techniques
InfraRed /UV Spectroscopy
Mass Spectroscopy
Spectroscopy analysis
Nuclear Magnetic Resonance Spectroscopy
Instrumental
method
Atomic Absorption/Emission Spectroscopy
High Performance Liquid Chromatography
Separation analysis
Gas Liquid Chromatography
Paper/Thin Layer/Column Chromatography

3. E = hf Spectroscopy Gamma/X ray UV or visible InfraRed Microwave
Spectroscopy measures interaction of molecules with electromagnetic radiation
Particles (molecule, ion, atom) can interact/absorb a quantum of light
Electromagnetic
Radiation
High Energy Radiation
Low Energy Radiation
Velocity of light (c ) = frequency (f) x wavelength (λ) - c = f λ
All electromagnetic waves travel at speed of light (3.00 x 108ms-1)
Radiation with high ↑ frequency – short ↓ wavelength
Electromagnetic radiation/photon carry a quantum of energy given by
h = plank constant = x Js
f = frequency
λ = wavelength
E = hf
Click here notes spectroscopy
Gamma/X ray
UV or visible
InfraRed
Microwave
Radiowaves
Transition of
inner electrons
Transition of outer most
valence electrons
Molecular vibration
Molecular rotation
Nuclear spin
Ultra Violet
Spectroscopy
Atomic Absorption
Spectroscopy
Infra Red Spectroscopy
Nuclear Magnetic Resonance
Spectroscopy

4. Electromagnetic Radiation and Spectroscopy
Electromagnetic Radiation Interact with Matter (Atoms, Molecules) = Spectroscopy
Electromagnetic Radiation
Radiowaves
Infrared
UV or visible
Nuclear spin
Molecular vibration
Transition of outer valence electron
Nuclear Magnetic Resonance
Spectroscopy
Infrared Spectroscopy
UV Spectroscopy
Atomic A Spectroscopy
Organic structure determination
MRI and body scanning
Organic structure determination
Functional gp determination
Measure bond strength
Measure degree unsaturation in fat
Measure level of alcohol in breath
Quantification of metal ions
Detection of metal in various samples

5. Nuclear Magnetic Resonance Spectroscopy (NMR)
Involve nucleus (proton + neutron) NOT electron
Proton + neutrons = Nucleons
Nucleons like electrons have spin and magnetic moment (acts like tiny magnet)
Nuclei with even number of nucleon (12C and 16O)
Even number of proton and neutron – NO net spin
Nucleon spin cancel out each other –Nucleus have NO overall magnetic moment – NOT absorb radiowave
Nuclei with odd number of nucleon (1H, 13C, 19F, 31P)
Nucleon have net spin – Nucleus have NET magnetic moment – Absorb radiowave
Nuclei with net spin – magnetic moment will interact with radiowaves
Nuclei have a “spin” associated with them (i.e., they act as if they were spinning about an axis) due to the spin
associated with their protons and neutrons.
Nuclei are positively charged, their spin induces a magnetic field
NMR spectroscopy does not work for nuclei with even number of protons and neutrons - nuclei have no net spin.
Spin cancel each other
Net spin

6. NMR spectrum CH3CH2Br Chemical Shift
Nuclear Magnetic Resonance Spectroscopy (NMR)
Main features of HNMR Spectra
1. Number of diff absorption peaks
– Number of diff proton/chemical environment
2. Area under peaks
- Number of hydrogen in a particular proton/chemical environment (Integration trace)
- Ratio of number of hydrogen in each environment
3. Chemical shift
- Chemical environment where proton is in
- Spinning electrons create own magnetic field, creating a shielding effect
- Proton which are shielded appear upfield. (Lower frequency for resonance to occur)
- Proton which are deshielded appear downfield. (Higher frequency for resonance to occur)
- Measured in ppm (δ)
4. Splitting pattern
- Due to spin-spin coupling
- Number of peak split is equal to number of hydrogen on neighbouring carbon +1 (n+1) peak
Click here khan NMR videos.
NMR spectrum CH3CH2Br
Chemical Shift
Number of peaks
Splitting pattern
Area under peaks
Chemical shift

7. Nuclear Magnetic Resonance Spectroscopy (NMR)
Absence of External magnetic Field (EMF)
TWO nuclear spin have same energy level.
Presence of External Magnetic Field (EMF)
TWO nuclear spin split to TWO diff energy level
Presence of External Magnetic Field (EMF)
External MF applied to atomic nuclei, MF of nuclei align themselves either with or against MF
Nuclei have a slight preference for parallel alignment with the applied field as it has a slightly lower energy
Nuclei can absorb energy to move/flip to higher energy level by absorbing energy in radio freq region
High spin nuclei align against magnetic field
Presence of EMF
Two spins in diff energy level
Lower spin nuclei absorb radio freq equivalent to ∆E
Move to higher energy level ∆E
Absence of EMF
Two spins in same energy level
Lower spin nuclei align with magnetic field

8. Chemical Shift (Shielding Effect) Without SHIELDING EFFECT
Proton in nucleus – have spin – generate its magnetic field (MF)
Electron around nucleus – have spin- also generate its MF
Proton shielded by MF produced by electron - appear UPFIELD
Proton deshielded by electron withdrawing gp - appear DOWNFIELD
Downfield
Upfield
Presence of EMF
Two spins in diff energy level
Lower spin nuclei absorb radio freq equivalent to ∆E
Move to higher energy level S H ׀
H – C – H
Without SHIELDING EFFECT
Energy of ∆E absorb by H to move
to higher energy level ∆E MF
H nucleus
proton N
Absence of EMF
Two spins in same energy level
Presence of EMF
Two spins at diff energy level S
SHIELDING EFFECT
Electron around H produce MF and shield the H
H in CH3 will experience less EMF (SHIELDED)
Absorb at lower radiofreq to move to higher level
∆E absorb by H to move to higher energy level is less
Appear upfield. H ׀
H – C MF
∆E is smaller
- H
proton
H nucleus
shield by electron MF N
Absence of EMF
Two spins in same energy level
Presence of EMF
Two spins at diff energy level

9. Chemical Shift (Deshielding Effect) Without SHIELDING EFFECT
Proton in nucleus – have spin – generate its magnetic field (MF)
Electron around nucleus – have spin- also generate its MF
Proton shielded by MF produced by electron - appear UPFIELD
Proton deshielded by electron withdrawing gp - appear DOWNFIELD
Downfield
Upfield
Presence of EMF
Two spins in diff energy level
Lower spin nuclei absorb radio freq equivalent to ∆E
Move to higher energy level S H ׀
H – C – H ∆E
Without SHIELDING EFFECT
Energy of ∆E absorb by H to move
to higher energy level MF
proton
H nucleus N
Absence of EMF
Two spins in same energy level
Presence of EMF
Two spins at diff energy level S
DESHIELDING EFFECT
Electron withdrawn by C=O gp
Carbonyl gp has electron withdrawing effect
Less electron around H in CH3
H in CH3 deshielded, experience greater EMF
∆E absorb by H, to move to high energy is higher
Absorb at higher radiofreq, to move to high level
Appear downfield MF
∆E is higher
H nucleus
deshield by elec MF
proton N
Absence of EMF
Two spins in same energy level
Presence of EMF
Two spins at diff energy level

10. Chemical Shift (Shielding and Deshielding Effect)
Absence of EMF
Two spins in same energy level
Presence of EMF
Two spins at diff energy level
Deshielding Effect S
DESHIELDING EFFECT
Electron withdrawn by C=O gp
Carbonyl gp has electron withdrawing effect
Less electron around H in CH3
H in CH3 deshielded, experience greater EMF
∆E absorb by H, to move to high energy is higher
Absorb at higher radiofreq, to move to high level
Appear downfield MF
∆E is higher
H nucleus
deshield by elec MF
proton N
No shielding S H ׀
H – C – H MF
Without any SHIELDING EFFECT
Energy of ∆E absorb by H to move
to higher energy level ∆E
H nucleus
proton N
Shielding Effect S
SHIELDING EFFECT
Electron around H produce MF and shield H
H in CH3 experience less EMF (SHIELDED)
∆E absorb by H to move to higher energy level is less
Appear upfield. MF
∆E is smaller
proton N
H nucleus
shield by elec MF

11. Downfield Upfield Chemical Shift (Shielding and Deshielding Effect)
Shielding/Deshielding:
Electron circulate nucleus, create MF opposing external MF.
Each nucleus experience a slightly diff magnetic field
(Sum external field and field from electron cloud).
Energy a nucleus achieve resonance depend on its surrounding.
Freq absorption depend on electron density around nucleus
Chemical shift of various electron withdrawing gp
Downfield
Upfield 12
9.7
- Electron withdrawn from CH3 by C=O
Deshield H in CH3
Absorb at slightly higher freq
Upfield ≈ 2.1
Electron withdrawn from CH2 by COO
Stronger electron withdrawing effect
Higher ↑ Deshielding effect on H in CH2
Absorb at Higher ↑ freq
Slightly Downfield ≈ 4.1
Electron withdrawn from H by CHO
Very strong electron withdrawing effect
Higher ↑ Deshielding effect on H in CHO
Absorb at Very High ↑ freq
Very Very Downfield ≈ 9.7
Electron withdrawn by benzene
Stronger electron withdrawing effect
Higher ↑ deshielding effect on H
Absorb at Very high ↑ freq
Very Downfield ≈
Electron withdrawn by COOH
Very strong electron withdrawing effect
Highest deshielding effect on H
Absorb at Very High ↑ freq
Very Very Very Downfield ≈ 12

12. HO-CH2-CH3 1 2 3 12 TMS Nuclear Magnetic Resonance Spectroscopy (HNMR)OH
chemical shift ≈ 4.8
integration = 1 H
No split (Singlet)
CH2
chemical shift ≈ 3.8
integration = 2 H
split into 4
CH3
chemical shift ≈ 1
integration = 3 H
split into 3 1 2 3 12
Downfield
Upfield
3 diff proton environment
Ratio of 3:2:1
TMS
CH3 ׀
H3C – Si – CH3
Tetramethyl Silane (TMS) as STD
Strong peak upfield (shielded)
Silicon has lower EN value < carbon
Electron shift to carbon
H in CH3 more shielded
Experience lower EMF, absorb ↓ freq
UPFIELD ≈ 0
Advantages using TMS
Volatile and can be removed from sample
All 12 hydrogen in same proton environment
Single strong peak, upfield, wont interfere with other peak
All chemical shift, in ppm (δ) are relative to this STD, ( zero)
Click here Spectra database (Ohio State)
Click here Spectra database (NIST)
Click here for more complicated proton chemical shift

13. O HO-C-CH2-CH3 12 O ‖ CH3-C-O-CH2-CH3 B A C 2 3 3 ‖ A B C 1 2 3
1H NMR Spectrum O ‖
CH3-C-O-CH2-CH3 B A C 2 3 3
3 diff proton environment, Ratio H - 3:2:3
Peak A – split to 3 (2H on neighbour C)
Peak B - No split
Peak C – split to 4 (3H on neighbour C) O ‖
HO-C-CH2-CH3 A B C 1 2 3 12
3 diff proton environment, Ratio H - 3:2:1
Peak A – split to 3 (2H on neighbour C)
Peak B – split to 4 (3H on neighbour C)
Peak C – No split

14. HO-CH2-CH3 A B C 1 2 3 O ‖ CH3-C-CH2-CH2-CH3 A C D B 2 3 2 3
1H NMR Spectrum
HO-CH2-CH3 A B C 1 2 3
3 diff proton environment, Ratio H - 3:2:1
Peak A – split to 3 (2H on neighbour C)
Peak B – split to 4 (3H on neighbour C)
Peak C – No split O ‖
CH3-C-CH2-CH2-CH3 A C D B 2 3 2 3
4 diff proton environment, Ratio H - 3:2:2:3
Peak A – split to 3 (2H on neighbour C)
Peak B – split to 6 (5H on neighbour C)
Peak C – No split
Peak D – split to 3 (2H on neighbour C)

15. 2 diff proton environment, Ratio H - 3:1
1H NMR Spectrum O ‖
CH3-C-O-CH2-CH2-CH3 A D C B 2 3 2 3
4 diff proton environment, Ratio H – 3:2:2:3
Peak A – split to 3 (2H on neighbour C)
Peak B – split to 6 (5H on neighbour C)
Peak C – No split
Peak D – split to 3 (2H on neighbour C) O ‖
H-C-CH3 A B 3 1
9.8
2 diff proton environment, Ratio H - 3:1
Peak A – split to 2 (1H on neighbour C)
Peak B – split to 4 (3H on neighbour C)

16. Molecule with plane of symmetry Molecule with plane of symmetry
1H NMR Spectrum
CH3 ׀
H-C-OH
Molecule with plane of symmetry C A B 1 1 6
3 diff proton environment, Ratio H - 6:1:1
Peak A – split to 2 (1H on neighbour C)
Peak B – No split
Peak C – split to 7 (6H on neighbour C)
O CH3
‖ ׀
CH3-C-O-C-H ׀
CH3
Molecule with plane of symmetry A B C 3 6 1
3 diff proton environment, Ratio H - 6:3:1
Peak A – split to 2 (1H on neighbour C)
Peak B – No split
Peak C – split to 7 (6H on neighbour C)

17. Molecule with plane of symmetry Molecule with plane of symmetry
1H NMR Spectrum O ‖
CH3-CH2-C-CH2-CH3
Molecule with plane of symmetry A B 4 6
2 diff proton environment, Ratio H – 6:4
Peak A – split to 3 (2H on neighbour C)
Peak B – split to 4 (3H on neighbour C)
O CH3
‖ ׀
H-C-C-CH3 ׀
CH3
Molecule with plane of symmetry A B 1 9
2 diff proton environment, Ratio H – 9:1
Peak A – No split
Peak B – No split

18. Molecule with plane of symmetry Molecule with plane of symmetry
1H NMR Spectrum
CH3 ׀
HO-CH2-CH
Molecule with plane of symmetry A B D C 2 1 1 6
4 diff proton environment, Ratio H- 6:1:1:2
Peak A – split to 2 (1H on neighbour C)
Peak B – split to 7 (6H on neighbour C)
Peak C – No split
Peak D – split to 2 (1H on neighbour C)
Molecule with plane of symmetry
CH3-CH-CH3 ׀ CI A B 1 6
2 diff proton environment, Ratio H – 6:1
Peak A – split to 2 (1H on neighbour C)
Peak B – split to 7 (6H on neighbour C)

19. Acknowledgements
Thanks to source of pictures and video used in this presentation
Thanks to Creative Commons for excellent contribution on licenses
Prepared by Lawrence Kok
Check out more video tutorials from my site and hope you enjoy this tutorial