This document discusses proton nuclear magnetic resonance (1H NMR) spectroscopy. It provides information on the magnetic properties of nuclei, factors that influence chemical shifts, coupling patterns between protons, and typical chemical shift ranges for different types of protons. The principles of NMR spectroscopy are explained, including precession, resonance, magnetic shielding and deshielding, spin-spin coupling, and factors that affect chemical shifts such as electronegativity and anisotropic effects. Examples of 1H NMR spectra of various compounds are also shown.

1. Dr. Prabhakar Chavan
Assistant Professor
Department of Studies and Research in Chemistry
Sahyadri Science College, Kuvempu University, Shivamogga-577203
Karnataka. INDIA
prabhakarchavan7@gmail.com

7. Magnetic properties of nucleus
 The spin no.I can be determined from the mass no. & atomic
no. as shown
Mass no. Atomic no. Spin quantum no.
odd Odd or even ½,3/2,5/2……
even even 0
even odd 1,2,3………

9. PRECESSIONAL MOTION

11. Proton Magnetic Resonance Spectroscopy
H
-C-H,-C C-H -C C-H
1. Nature of Proton attached to
2. Chemical environment refers to H-attached to electronegative atom i.e. O-H, N-
H, C-H, and S-H.
3. Chemical non equivalency of protons
4. Geometrical relationship of proton (cis or trans isomers)
Depending on the nature of nucleus NMR is divided into
1
H 13
C 19
F
31
P 15
N 11
B

13. Nucleus has to generate magnetic field
Resonance:
If we take particle x and y
1H 1 Proton+ Zero Neutron (Nucleus going to produce magnetic field around it)
2H 1 Proton+ 1 Neutron (Nucleus is not going to produce magnetic field around it)

14. Magnetic Shielding
 If all protons absorbed the same amount of energy in
a given magnetic field, not much information could
be obtained.
 But protons are surrounded by electrons that shield
them from the external field.
 Circulating electrons create an induced magnetic field
that opposes the external magnetic field.
=>
14

15. Shielded Protons
Magnetic field strength must be increased for a
shielded proton to flip at the same frequency.
15
=>

16. Protons in a Molecule
Depending on their chemical environment, protons
in a molecule are shielded by different amounts.

17. NMR Signals
 The number of signals shows how many different kinds
of protons are present.
 The location of the signals shows how shielded or
deshielded the proton is.
 The intensity of the signal shows the number of
protons of that type.
 Signal splitting shows the number of protons on
adjacent atoms. =>

18. The NMR Spectrometer

19. SOLVENTS USED IN TAKING 1HNMR SPECTRUM
1. Carbon tetrachloride (CCl4)
2. Carbondisulfide (CS2)
3. Deuterated dimethylsulphoxide (DMSO)
4. Deuterated chloroform (CDCl3)
5. Dueterated benzene
6. Deuterated acetone

20. The NMR Graph
=>

21. Tetramethylsilane
 TMS is added to the sample as reference Std.
 Since silicon is less electronegative than carbon and there
is back bonding of filled P orbitals of carbon with empty
d orbitals of Silicon . Hence C—Si bond is stronger,
therefore TMS protons are highly shielded and Signal
is defined as zero.
 TMS is inert to Organic solvents and compounds.
 TMS has low boiling point (20oc)
 Most organic protons absorb downfield (to the left) of the
TMS signal.

22.  Limitations of TMS
 For recording 1HNMR of few samples water is
used as the solvent.
 Ex; carbohydrates, Nucleic acid and polymers.
 Whenever water is used as solvent TMS is not a
good reference because it is insoluble in water.
Alternate reference for this is 3-trimethylsilyl-
propane salfonic acid or its salt.

23. Chemical Shift
 Measured in parts per million (ppm).
 Ratio of shift downfield from TMS (Hz) to total
spectrometer frequency (Hz).
 Same value for 60, 100, 300, 400 or 500 MHz machines.
 It is written in delta scale.
=>

24.  NMR Standard Internal Reference
 1H-NMR TMS/DSS
(Sodium trimethyl silyl propanesulfonate)
 13C-NMR TMS
 19F-NMR
 31P-NMR H3PO4
 15N-NMR NH3, NH4NO3
 11B-NMR H3BO3
C C
F
Cl
F
F
Cl
Cl

25. Delta Scale
Chapter 13 25
=>

27. Chemical non-equivalency and equivalency of protons
1.Chemical connectivity.
2. Substitution.
3. Symmetry criteria.
4. Stereochemical relationship.

28. 1. Chemical connectivity
Carbon containing similar protons known as equivalent .
In methane all protons are chemically equivalent.
In ethane all protons are chemically equivalent .
C C
AH
AH
AH
HB
HB
C
HA
HA
HA In propane chemically non-equivalent sets of protons.
HA
HA
HA
HA
AH
AH
In benzene all protons are chemically equivalent.
C
HA
HA
AH
HA
C C
HA
HA
HA
AH
AH
AH

29. Cl
HD
HD
EH
HE HC
HC
HB
HB
HA
HA
HE
In 1-Chloro pentane five non-equivalent sets of
protons are present.
In cyclohexane chemically equivalent set of protons

30. 2. Substitution
C
H4
H2
H3
H1
C
H4
H2
H3
Cl
C
H4
Cl
H3
H1
C
H4
H2
Cl
H1
C
Cl
H2
H3
H1
ReplaceH1 by Cl
ReplaceH2 by Cl
ReplaceH3 by Cl
ReplaceH4 by Cl
All above compounds are chloromethane
C C
H3
H1
H2
H4
H6
H5 In ethane all protons are chemically equivalent

31. C C
H6
H8
H7
H4
H5
C
H1
H3
H2
C C
H6
H8
H7
H4
H5
C
Br
H3
H2
C C
H6
H8
H7
H4
H5
C
H1
H3
Br
C C
H6
H8
H7
H4
H5
C
H1
Br
H2
C C
H6
H8
H7
Br
H5
C
H1
H3
H2
C C
H6
H8
H7
H4
Br
C
H1
H3
H2
C C
Br
H8
H7
H4
H5
C
H1
H3
H2
C C
H6
H8
Br
H4
H5
C
H1
H3
H2
Replace H1by Br
Replace H2by Br
Replace H3by Br
Replace H8 by Br
Replace H4by Br
Replace H5by Br
Replace H6by Br
Replace H7by Br
C C
H6
Br
H7
H4
H5
C
H1
H3
H2
1-Bromo
propane
2-Bromo
propane
1-Bromo
propane

32. N
H1
H2
H3
H4
H5
H6
H7
In cyclohexane all protons are chemically equivalent.
Cl
H1
H2
H3
H4
H5
In 1-chlorobenzene all protons are chemically non-
equivalent.
In indole all protons are chemically non-equivalent.

33. 3. Symmetry Criteria
AH3C CH3A
O
HE
HC
HD
AH
HA
HD
HB
CH
EH
BH
In a molecule reference protons if exchanged with Cn
symmetry element or related to each other with Cn
symmetry element the protons are chemically
equivalent.
1800
One chemically equivalent set of protons
Five chemically non-equivalent sets of protons

34. 4. Stereochemical relationship
HB
HB
AH
X
HC
HB
AH
X
HE
DH
HC
HB
HA
COOH
Cl
H
H
H
H
H
H
Three sets of protons
Five non-equivalent sets of protons
Five non-equivalent sets of protons
In cubane all protons are chemically equivalent.

35. Nature of
nucleus
Magnetically active nucleus
Nucleus is positively charged entity
composed of positively charged
protons and neutrons. Some of the
nuclei are spinning around its own
axis.
Induced magnetic field

36. I
0
Integer
1,2,3….
Non integer ½, 3/2, 5/2….

37. δ=  sample proton-  reference proton
 instrument (MHz)
Chemical Shift
Factor influencing δ Chemical Shift
1 Electro negativity of groups
2 Anisotropic effect
3 Hydrogen bonding at the proton

38. 1. Electronegativity of groups
H F
H Cl
H Br
H I
E.N. decreases from top to bottom
therefore electron cloud arround
hydrogen increases
From top to bottom delta
chemical shift of proton
decreases
H3C I
H3C Br
H3C Cl
H3C F
E.N. increases from top to
bottom
therefore electron cloud arround
hydrogen decreases
From top to bottom delta
chemical shift of protons
increases

39. 2. Anisotropic effect

40. 2. Anisotropic effect

42. CH3F 4.3 δ, CH3Cl 3.1 δ, CH3Br 2.6 δ, CH3I 2.2 δ
CH3O 3.3 δ, CH3N 2.3 δ, CH3C 0.9 δ

46. H
H
H
H
H
H
-1.89ppm
H
H
H
H
H
H
H
H
H
H
H
H
8-9ppm
10.5ppm
5.25ppm
Ha
He
1.2ppm
1.7ppm
18- Annulene 16-Annulene
In cyclohexane

47. 3. Hydrogen bonding
O
O
H
At higher concentration delta chemical shift
increases and at lower concentration decreases.

49. D2O
R-OH R O
H
R O
D
+ D2O
O
R OD
OH
D2O
+
OD
O
R OH
D2O
+
R SH D2O
+ R SD
R NH D2O
+ R ND
Deuteration in 1H NMR
Replacement of proton on hetero atom or acidic proton with deuterium by
adding D2O Called as Deuteration

53. Note: Fixed frequency, Change(Sweep) magnetic field

54. Note: Fixed frequency, Change(Sweep) magnetic field

55. Note: Shift = resonance frequency-operating frequency

69. Spin-Spin Coupling
C C
Y
HB
Y
X
HA
X
HA
HB
Expected spectrum

70. Principle of Spin-Spin Coupling
C C
Y
HB
Y
X
HA
X
C C
Y
HB
Y
X
HA
X
In a molecule if non-equivalent nuclei closer to
each other . The nuclei are not independent,
spin orientation of nuclei mutually influences
each other.
The splitting of signals due to mutual influence
of spin orientation of magnetic nuclei.
For single proton nucleus the possible spin
orientations only two upward (2I+1), DOWN
WORDS.
spin-spin coupling not a special coupling it is
indirect coupling transmits through the
intervening covalent bonds
(n+1) Rule prediction of multiplicity of signal
N= no. of neighborhood protons for reference

71. Intensity ratio of the lines in NMR signals by Pascal's triangle

72. Coupling types in 1H NMR
Strong coupling Weak coupling
C C
H
H
C
H
H
C C
H
CH2
H
H
H
H
H
H
H
Aromatic coupling
Ortho Meta Para

73. C
H
H
2HC CH2
H H
C C CH2
H H
C C C
H
CH2
H
H H
H
H
Based on type of protons
Geminal
coupling
Vecinal
copupling
Allylic
coupling
Homo Allylic
coupling
Cis Trans
J2 J3 J4
J5
J cis J trans

80. C
H
R CH2
X
CH2
I
CH2
Br
CH2
Cl
CH2
F
1. Alkanes: (10, 20, 30) 0.1to 1.5ppm
and Cyclo alkanes: 0.1-2.0ppm
2. Alkyl halides
2.0-4.5ppm
2.0ppm
2.5ppm
3.0-3.5ppm
4.0-4.5ppm
CHEMICAL SHIFTS RANGES FOR PROTONS

81. CH2
NH2
CH2
OH
CH2
OR
CH2
SH
CH2
SR
3.Aliphatic amines, alcohols, mercapto, ethers attached
methylene protons
3.0-3.5ppm
4.0-4.5ppm
2.5ppm

82. H
H
H
CH2
H2C
W
4. Alkenes, Alkynes, Allylic, Benzylic, Electron
withdrawing group methylene protons
4.0-6.5ppm
1.5-3.0ppm
2.0-2.5ppm

83. R O
H
R N
H
H
Ar O
H
O
H
O
H
H
O
5. Aromatic, Aldehydic and protons on Hetero atoms
6.5-8.5ppm
9.0-10.0ppm
2.0-8.0ppm
1.0-5.0ppm
11.0-12.0ppm
12.0-14.0ppm

84. O
H
C
H
NH
Ar
Aromatic imines, Enolic and protons on Carbocation
8.0-12.00ppm
16.0-18.0ppm
18.0-22.0ppm

85. 0
2
4
6
8
10
PPM
H
N
N
H
N
O
2-(5-methoxy-3-phenyl-1H-indol-2-yl)-1H-benzo[d]imidazole
1H-NMR SPECTRUM OF DIFFERENT COMPOUNDS

86. 0
1
2
3
4
5
6
7
8
PPM
OCH3
COOCH2CH3
ethyl 4-methoxybenzoate
0
1
2
3
4
5
6
7
PPM
OCH3
COCH2CH3
1-(4-methoxyphenyl)propan-1-one
0
1
2
3
4
5
6
PPM
OCH3
OCH2CH3
1-ethoxy-4-methoxybenzene

87. 0
1
2
3
4
5
6
7
8
PPM
CH3
COOCH2CH3
ethyl 4-methylbenzoate
0
1
2
3
4
5
6
7
PPM
CH3
COCH2CH3
1-p-tolylpropan-1-one
0
1
2
3
4
5
6
7
CH3
OCH2CH3
1-ethoxy-4-methylbenzene

88. 0
1
2
3
4
5
6
7
PPM
0
1
2
3
4
5
6
7
PPM
0
1
2
3
4
5
6
NH2
COOCH2CH3
ethyl 4-aminobenzoate
NH2
COCH2CH3
1-(4-aminophenyl)propan-1-one
NH2
OCH2CH3
4-ethoxybenzenamine

89. 0
2
4
6
8
10
PPM
0
2
4
6
8
10
PPM
CHO
COOCH2CH3
ethyl 4-formylbenzoate
0
2
4
6
8
10
CHO
COCH2CH3
4-propionylbenzaldehyde
CHO
OCH2CH3
4-ethoxybenzaldehyde

90. 0
1
2
3
4
5
6
7
8
PPM
NO2
COOCH2CH3
ethyl 4-nitrobenzoate
0
1
2
3
4
5
6
7
8
PPM
0
1
2
3
4
5
6
7
8
PPM
NO2
COCH2CH3
1-(4-nitrophenyl)propan-1-one
NO2
OCH2CH3
1-ethoxy-4-nitrobenzene

91. General anesthetics
Lidocaine H
N
N
O
0
1
2
3
4
5
6
7
8
PPM
H
N
N
O
6.85
6.76
6.85
2.35
2.35
8.0 3.30 2.40
2.40
1.00
1.00

92. H
N
O
N
0
1
2
3
4
5
6
7
8
PPM
H
N
O
N
6.85
6.76
6.85
2.35
2.35
8.0
2.68
2.29;2.19
1.51;1.49
1.55;1.45
1.97;1.72
2.36 1.39
1.33
0.96
Bupivacaine

93. Ephedrine
CH3
OH
NH
H3C
OH
NH
7.19
7.19
7.19
7.19
7.19
4.73
3.26
1.10
2.0
2.0
2.47
0
1
2
3
4
5
6
7
PPM

94. Anti-inflammatory
O OH
O
O
Aspirin
O OH
O
O
8.10
7.28
7.57
7.28
11.0
2.08
0
2
4
6
8
10
PPM

95. OH
O
OH
O
7.07
7.07
7.07
7.07
3.82
1.47
11.0
2.51
2.22
1.01
1.01
0
2
4
6
8
10
PPM
Ibuprofen

96. H
N
O
HO
H
N
O
HO
6.71
6.71
7.47
7.47 8.0
2.02
5.0
0
1
2
3
4
5
6
7
8
PPM
Paracetamol

97. Penicillamine
Anti rheumatoid
HS OH
O
NH2
HS OH
O
NH2
1.5
3.79
11.0
1.46
1.46
2.0
0
2
4
6
8
10
PPM

98. N
HN
N
Cl
Chloroquine
N
HN
N
Cl
7.43
8.00
7.61
8.64
6.49
4.0
2.79
1.10
1.48
1.39
2.36
2.40
1.00
2.27
0
1
2
3
4
5
6
7
8
PPM

99. Chlorpheniramine
Antiallergics
N
Cl
N
N
Cl
N
7.50
7.67
7.18
8.61
4.05
7.06
7.22
7.22
7.06
2.01
2.36
2.27
2.27
0
1
2
3
4
5
6
7
8
PPM

100. Epinephrin
OH
HO
H
N
OH
OH
HO
H
N
OH
6.49
6.49
6.58
4.74
5.0
5.0
3.15;2.90
2.0
2.47
2.0
0
1
2
3
4
5
6
PPM

101. Thank You