INFRARED THEORY

1
Pharmaceutical analysis
Infra Red Spectroscopy
BCPE03
Author
Co-author
Name Anil kumar Appapurapu College Bapatla
college of pharmacy, Bapatla. Year
M. Pharmacy, 2nd year. Profile link http//www.ph
armainfo.net/anil-kumar-appapurapu
Name Dr. T.E.G.K. Murthy, M
Pharm, Ph.D. CollegeBapatla College of
Pharmacy Profile link http//www.pharmainfo.net/
tegkmurthy
2
Importance of analysis of drugs
Natural ---animal ---- plants
----marine Synthetic ----organic
----in-organic
sources1
Drug1
Chemical / functional Group interaction2
Drug receptor interaction1
Molecular basis2
Signal transduction1
Analysis basis
Therapeutic effects1
The challenging scenario in the aspects of
efficacy, safety, purity, and quality
determination of the drug samples became
optimistic.
1.B Sue Brizuela,Ms, Judith A Hesp, MS, Drug
Information Remington The science and practice
of pharmacy,19th edition,volume.1, Mack
publishing company Easton, Pennsylvania18042,
1995. print. 2. B.K. SHARMA," fundamental
principles of spectroscopy ,spectroscopy ,20th
edition, Goel publications, Delhi, 2007. print.
3
Classification of analytical techniques3
Ana
lysis
Structure.
breakdown
3

ANALYSIS
1.Separation techniques 2.Spectrophotometric
3. Electro analytical 4. Titrimetric
analysis chromatography
Potential
conductometry Titrations
Spectroscopy
1.uv-visible 2.Infra red 3.Mass 4.Neclear
magnetic resonance
3. Douglas A.Skoog, F.James Holler, Timothy
A.Nieman, ,introduction to instrumental methods
of analysis", principles of instrumental
analysis, 5th edition, saunders Golden sunburst
series. Forth worth, Philadelohia, Chicago,
Sydney, Toronto. Reprint. 2005. Print.
4
Principle of spectroscopy2,4,5
Spectroscopy2,4,5
study of interaction of electromagnetic radiation
with matter
SPECTROPHOTOGRAPH
ANALYTE
EMR
Conc. should be lower
1.UV-Visible radiations---excitatio
n of electrons----uv-visiblespectrum
2.IR-radiationsvibration changes in
electrons---IR spectrum
3.Microwave radiations---spin resonance----E.S.R
spectrum
4.Radio frequency---spin rotational
changes---N.M.R spectrum
2. B.K. SHARMA," fundamental principles of
spectroscopy ,spectroscopy ,20th edition, page
noS-11, Goel publications, Delhi, 2007. print.

• www.answers.com. Web. 25 feb 2010.
  http//www.answers.com/topic/spectroscopy
• 5. www. en.wikipedia.org. Web. 25 feb 2010 lt
  http//en.wikipedia.org/wiki/Infrared_spectroscopy
  gt.

5
THE ELECTROMAGNETIC SPECTRUM
2,5
nm
Characteristics of radiations
Violet
370
Energy Kcal/mol
Type of spectroscopy
? 0A
Frequency (Hz)
indigo
430
Absorbing radiations
Blue
450
Gamma rays
9.4 x 107
1
1021
Emission
Green
490
X rays
9.4 x103
1017
Both E Abs
15 0
UV
Yellow
550
9.4 x101
1015
Absorption
3 8 0 0
EMR
Visible
9.4 x 10-1
7 6 0 0
1013
Absorption
Orange
590
Drug substance
Infra-Red
9.4 x 10-3
6 x 106
1011
Absorption
Micro waves
9.4 x 10-5
3 x 109
1009
Absorption
Red
650
Radio waves
9.4 x 10-7
3 x 1013
1007
NMR Abs
nm
Resulting spectrum
5. www. en.wikipedia.org. Web. 25 feb 2010 lt
http//en.wikipedia.org/wiki/Infraredspectroscopygt
.
2. B.K. SHARMA," fundamental principles of
spectroscopy Spectroscopy 20th edition, page
no.S-11- S-20, goel publications, Delhi,
2007.print.
6
Multidisciplinary of IR spectroscopy2,3,6
pharmacy BIO-technology Genetic engineering
Applications2,3,6 uses
Engineering6
IR -SPECTROSCOPY 2
Physics3
Instrumentation working
Theory origin of spectra
Chemistry2

• Principle
• observed changes

2. B.K. SHARMA," Infrared spectroscopy
Spectroscopy 20th edition, page no.S-220, goel
publications, Delhi, 2007.print. 3. Douglas
A.Skoog, F.James Holler, Timothy A.Nieman,
,Infrared spectroscopy", principles of
instrumental analysis, 5th edition, saunders
Golden sunburst series. Forth worth,
Philadelohia, Chicago, Sydney, Toronto. Page no.
406. Print. 6. Hobart H. Willard, Lynne L.
Merritt. Jr., John A. Dean, Frank A. Settle, Jr.
Infrared spectroscopy, instrumental methods of
analysis,7thedition page288,289,292,293, content
no. 11.1 . CBS publications, Toronto. 2005. print.
7
IR-REGION 12,800 - 10 cm-1
3,6
REGION WAVE LENGTH ? (µm) WAVE NUMBER ? (cm-1) FREQUENCY RANGE Hz
NEAR 0.78 - 2.5 12800 - 4000 3.8x1014-1.2x1014
MIDDLE 2.5 - 50 4000 - 200 1.2x1014 - 6x112
FAR 50 - 1000 200 -10 6x1012- 30x1011
MOST USED 2.5 - 15 4000 - 670 1.2x1014-2x1013
1.Near IR----carbohydrates and proteins 2.Middle
IR-----organic moleculesfunctional groups 3.Far
IRin-organic co-ordination bonds quaternary
ammonium compounds
3. Douglas A.Skoog, F.James Holler,
Timothy A.Nieman, ,Infrared spectroscopy,
introduction to instrumental methods of
analysis", principles of instrumental analysis,
5th edition, saunders Golden sunburst series.
Forth worth, Philadelohia, Chicago, Sydney,
Toronto. Page no. 406. Print. 6. Hobart
H. Willard, Lynne L. Merritt. Jr., John A. Dean,
Frank A. Settle, Jr. Infrared spectroscopy,
instrumental methods of analysis,7thedition
page288,289,292,293, content no. 11.1 . CBS
publications, Toronto. 2005. print.
8
INSTRUMENTAL AND APPLICATIONS OF VARIOUS IR
REGIONS7,8
REGION Detectors Source of radiation Optical system Type of samples
NEAR Photo conductance Tungsten filament lamp Prism grating Solid / liquid
MIDDLE Thermal type Nernst glowers/ Nichrome wire Diffraction grating Liquid / gas
FAR Golay, pyroelectric High pressure mercury lamp Double beam grating Gas
MOST USED Thermal type Nernst glowers/ Nichrome wire Diffraction grating Liquid / gas
Type of analysis measurement
Qualitative Quantitative Diffusive reflectance Absorption
Qualitative Quantitative Chromatographic Diffusive reflectance Absorption Adsorption
Quantitative emission
Qualitative Quantitative Chromatographic Diffusive reflectance Absorption Adsorption
7. www. orgchem.colorado.edu. web,.25.2010. lt
http//orgchem.colorado.edu/hndbksupport/irtutor/t
utorial.html gt 8.Donald L.Pavia, Gary M.Lampman,
George S. Kriz.infrared spectroscopy
"introduction to spectroscopy,3rd edition,
CBSPublications Thomas books Australia,
U.S.print ,Canada, Mexico, 2007. print..
9
ORIGIN OF IR SPECTRUM 2,3

• Due to 4 changes in energies of the molecules
• Electronic transitions -----E t
• Electronic rotations -------E r
• Electronic vibrations-------E v
• Electronic energy-----------E e
• total energy of the
  molecule E e E v E r E t
• energies required in the order ----- E
  e gt E vgt E r gt E t
• Various types IR spectra
• 1. Rotational spectra
• 2. Vibrational- rotational spectra
• 3. Electronic band spectra

2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. 3. Douglas A.Skoog, F.James
Holler, Timothy A.Nieman,Infrared spectroscopy,
introduction to instrumental methods of
analysis", principles of instrumental analysis,
5th edition, saunders Golden sunburst series.
Forth worth, Philadelohia, Chicago, Sydney,
Toronto. Page no. 406. Print.
10
Differences between various types of IR
spectra2,(a,b,c)
Character Electronic band spectra a Vibration- rotational spectra b Rotational spectra c
1. IR region Near IR Middle IR Far IR
2.Energy required Higher less very less
3.Dipole moment less induced Definite dipole Intense dipole
4.Sample state Solids Liquids / gases Only gases
5.Thoery supporting Frank codon principle Harmonic oscillator principle Rigid rotor principle
6.Changes observed Excitation, vibration Vibration , rotation Only rotation
7.Highly feasible for single bonds double bonds Triple bonds

2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. a.S-234 to s-249 b.
s-220 to s- 234 c. s-201 to s-220.
11
INFRARED THEORY 9,10
Matching of Frequency
Dipole moment

• 1. Selection rules9
• 2. Types of vibrations9
• 3. Number of possible vibrational modes10
• 4. Vibrational frequency9,10
• 5. Factors influencing vibrational modes9,10

Vibrational Quantum Number
Translational motion
Rotational motion
Vibrational motion

1. Phase and solvents used
2. Coupled interactions
3. Hydrogen bonding
4. Fermi resonance
5. Electronic effects

9. Robert M.Silverstien Francis X.Webster
,infrared spectroscopy, spectroscopic
identification of organic compounds, 6thedition,
John Wiley, Chichester, Singapore, Toronto,
Brisbane page no. 3.5, 2005. Print. 10. Jag Mohan
,infrared spectroscopy, Organic Spectroscopy,
Principles And Applications, 2ndedition,Narosa,New
delhi, Chennai 2005. Print.
12
For stretching vibration N -1 For bending
vibration (3N - 6)-(N -1)2N -5 for
non-linear (3N - 5)-(N -1) 2N 4
for linear N is the number of atoms in the bond.
Types of vibrations 5,11
Stretching vibrations
Bending vibrations
In-plane
Out -plane
In-plane
Scissoring (s)
Asymmetric (nu)
Symmetric (nu)
Rocking (? )
Wagging (?)
Twisting (tau)
2925 2850
1465 1350
1150 720 cm-1
Vibrational energy depends on - 1. masses
of the atoms 2. strength of bonds 3.
arrangement of atoms within the molecule
5. www. en.wikipedia.org. web.25 feb 2010. lt
http//en.wikipedia.org/wiki/Infrared_spectroscopy
gt. 11. Dudles H,Williams,Ian Fleming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, 2004. Print.
13
Vibrational frequency2

• Ball and spring representation of 2 atom of
  molecule vibrating in the direction of bond

M1 Force constant, k M2

• Factors influencing absorption frequency2
• Masses of attached atoms. As masses increase,
  wave number decreases.

• Strength of chemical bond. As bond strength
  increases, wave number increases.

• Hybridization. Bonds are stronger in the order
• sp gt sp2 gt sp3.

• Resonance. Conjugation lowers the energy
• to vibrate bond.

2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print.
14
Factors influencing vibrational modes 2,10,12
A. Phase and
solvents usedPhase and solvents may bring the
changes in IR in the aspects of1.Band frequency
shifts 2. Band splitting e.g.-
the effect of phase and solvents in Acetone.
gtco in acetone
----------1742 cm-1 in vapor state

-----------1718 cm-1 in liquid state
Acetone interactions with some solvents

-----------1726 cm-1 in
a solution of Hexane
-------------1713 cm-1 in chloroform

--------------1709 cm-1 in ethanol

Dipole-dipole lowers wave number
B. Coupled interactions
Extent of coupling influenced
by 1.stretching vibrations with two
vibrations have common atom 2. bending
vibrations with a common bond b/t vibrating
groups. 3. coupled groups of identical
energies. 4. groups separated by two/more
bonds, little or no interaction occur. 6.
vibrations of symmetrical species.
2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. 10. Jag Mohan ,infrared
spectroscopy, Organic Spectroscopy, Principles
And Applications, 2ndedition,Narosa,Newdelhi,
Chennai 2005. Print. 12.Y.R.Sharma,infrared
spectroscopy, Elementary organic spectroscopy
principles and chemical applications, first
edition 1980, reprint 2007. print.
15
Factors influencing vibrational modes2,10,12
C.. Hydrogen bonding
Strength of H-bond effected by 1. ring
strain 2. molecular geometry
3. relative acidity and basicity of proton donor
and acceptor
Types of hydrogen bonding - 1. intermolecular
hydrogen bonding extent of
bonding

depends on Temp. 2. intramolecular hydrogen
bonding
D. Fermi resonance
Factors leads to Fermi resonance a)
vibrational levels are same for symmetrical
compounds. b) interacting groups located in the
molecule for an appreciable mechanical coupling
to occur. e.g.- 1. co2 actual absorption
frequencies at 1286,1388 cm-1 the splitting
caused by coupling b/t fundamental co stre. near
1340 cm-1 and 667 cm-1 -----1344 cm-1 1st
overtone 2. lactones, lactims, lactums,
aldehydes.
2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. 10. Jag Mohan ,infrared
spectroscopy, Organic Spectroscopy, Principles
And Applications, 2ndedition,Narosa,Newdelhi,
Chennai 2005. Print. 12.Y.R.Sharma,infrared
spectroscopy, Elementary organic spectroscopy
principles and chemical applications, first
edition 1980, reprint 2007. print.
16
Factors influencing vibrational modes 2,10,12
E. Electronic effects
1.Inductive effectintroduction of alkyl group
length 2.Mesomeric effect
bond
strength 3.Field effect.
force constant




vibrational frequency


HCHO----1750 cm-1 CH3CHO---1745
cm-1 CH3COCH3---1715 cm-1
? Lone pair of electrons ? conjugation lowers
absorption ? Mesomeric effect dominate inductive
effect for some time and vice versa
Bond strength
Introduction of electronegative atoms
Force constant
CH3COCH3---1715 cm-1 ClCH2COCH3---1725
cm-1 Cl2CHCOCH3----1740 cm-1
Vibrational frequency
2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. 10. Jag Mohan ,infrared
spectroscopy, Organic Spectroscopy, Principles
And Applications, 2ndedition,Narosa,Newdelhi,
Chennai 2005. Print. 12.Y.R.Sharma,infrared
spectroscopy, Elementary organic spectroscopy
principles and chemical applications, first
edition 1980, reprint 2007. print.
17
INSTRUMENTATION 2,6
1.Radiation source 2. Monochromatic
light. 3.Sample handling. 4.Detectros
5.Amplifiers .
2.Sampling of substances solids
liquids gases .
1.solids run in solution form 2.solid
films 3.mull technique 4.pressured pellet
technique.
2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. 6. Hobart H. Willard, Lynne
L. Merritt. Jr., John A. Dean, Frank A. Settle,
Jr. Infrared spectroscopy, instrumental methods
of analysis,7thedition content no. 6.18. CBS
publications, Toronto. 2005. print.
18
INFRARED SOURCES 3,6
S.NO Character Nernst glower Globar Incandescent Mercury arc Tungsten lamp Co2 laser
1. Composition Rare earth oxides Silicone carbide Nichrome wire High (Hg) pressure Tungsten Halogen Tunable Co2 laser.
2. Operating temp. 1200 2200K 1300 ---1500 K 1100K 1000K 3500K -------
3. Radiations produced O.P 12,800-4000cm-1 5200 cm-1 10,800--8000cm-1 lt 665 cm-1 10,1004000 cm-1 1100-900cm-1
4. IR region used Near / visible Middle Near Far Middle Middle /near
5. Intensity of radiation More intense As equal to Nernst Less but longer life. Greater Mild More effective
6. Out put significant (?) gt2µm gt5µm 2-4µm 10µm 2-4µm 5 µm
7. Used for Carbohydrate , protein Simple Functional groups complex organic molecules. In- organic complexes. Most organic functional groups NH3 C6H6, C2H5OH
3.Douglas A.Skoog, F.James Holler, Timothy
A.Nieman, ,Infrared spectroscopy", principles of
instrumental analysis, 5th edition, saunders
Golden sunburst series. Forth worth,
Philadelohia, Chicago, Sydney, Toronto. Page no.
406. Print. 6. Hobart H. Willard, Lynne L.
Merritt. Jr., John A. Dean, Frank A. Settle, Jr.
Infrared spectroscopy, instrumental methods of
analysis,7thedition page288,289,292,293, content
no. 11.1 . CBS publications, Toronto. 2005.
print.
19
DETECTORS or TRANSDUCERS3,6
S.No Character Thermocouple or Thermopile Thermister or Bolometer Pyroelectric Golay or Pneumatic
1. Principle Pelletier effect Whetstone bridge Electric polarization Expanction of gases
2. Materials used Bismuth Antimony, coated by metal oxides Sintered oxides of Mn, co, Ni TGS, DTGS, LiTGO3 , LiTubO3 generally CO2
3. Material should be Thermally active Thermally sensitive resistors Non-center symmetric crystal Inert nature
4. Description Half -junction- hot Alternate -junction -cold -------------- ------------ Metal cylinder closed in b/t metal plate Ag
5. Conversion unit Radiant to Electric signal ---measured Change in resistance - Q Thermal alteration to E.polarization Expanction of gas to pressure to e.signal
6. Used Photocuastic spectroscopy Diffusive reflectance FTIR Non dispersive IR
7. Response time 30 sec 4 sec multiple scanning 0.01sec
3.Douglas A.Skoog, F.James Holler, Timothy
A.Nieman, Infrared spectroscopy, introduction
to instrumental methods of analysis, principles
of instrumental analysis, 5th edition, saunders
Golden sunburst series. Forth worth,
Philadelohia, Chicago, Sydney, Toronto. Page no.
408-410. 2006 Print. 6. Hobart H. Willard, Lynne
L. Merritt. Jr., John A. Dean, Frank A. Settle,
Jr. Infrared spectroscopy, instrumental methods
of analysis,7thedition page288,289,292,293,
content no. 11.1 . CBS publications, Toronto.
2005. print.
20
? 36003000cm-1

---OH, --NH2 , gtNH, ?C-H.
? 32003000cm-1
?C-H, Ar
C-H. ?30002500 cm-1

--CH of methyl/methelene

asymmetric stre. --CH, --COOH
?23002100 cm-1
Alkynes
2210---2100
Cyanides 22602200
Isocyanides
22802250
?19001650 cm-1
strong bands---
gtco---17251760
anhydrides -----
1850---1740
Imides ------ two broad band at 1700
General guidelines for IR
11,13
Interpretation
Functional 11,13 group region
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print. 13.Harold F.Walton,Jorge Reyes,
"infrared spectroscopy", Modern Chemical Analysis
And Instrumentation,IMBD, Mumbai, Reprint
2001page no 201-203. Print.
21
General guidelines for IR interpretation 11,13

• ?
  1650--1000cm-1
• 
  confirms ---
• 
  esters, alcohol, ethers. Nitro
• ?
  1000800 cm-1
• 
  C Cl, C-Br
• ?
  800710cm-1
• 
  meta substituted benzene
• ?
  770730cm-1
• 
  strong mono substituted benzene.
• ?
  710665cm-1
• 
  ortho, Para, benzene.

Finger print region11,13
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print. 13.Harold F.Walton,Jorge Reyes,
"infrared spectroscopy", Modern Chemical Analysis
And Instrumentation,IMBD, Mumbai, Reprint
2001page no 201-203. Print.
22

• OH
• NH
• CH
• CC
• HO-CO
• 
  C_N
• 
  CO CN CC CS NO SO CN CO
• 
  
  benzene
• 
  
  

Graphical interpretation of functional groups in
IR 2,10
esters, alcohol, ethers, Nitro groups
T
?C-H, Ar C-H
OH, --NH2 , gtNH, ?C-H
CH, --COOH
2. B.K. SHARMA," Infrared spectroscopy
,spectroscopy ,20th edition, Goel publications,
Delhi, 2007. print. 10. Jag Mohan ,infrared
spectroscopy, Organic Spectroscopy, Principles
And Applications, 2ndedition,Narosa,Newdelhi,
Chennai 2005. Print.
23
General guidelines for IR interpretation 10,11

• Alkanes
• CH stretch from 30002850 cm-1
• CH bend or scissoring from 1470-1450 cm-1
• CH rock, methyl from 1370-1350 cm-1
• CH rock, methyl, seen only in long chain
  alkanes, from 725-720 cm-1

90
Octane spectrum
1383
C-H rock
728
1470
2963
Long chain CH2 stretch
2971
C-H scissoring
C-H stretch
0
4000 2000
1000 500
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
24
General guidelines for IR interpretation1011

• Alkenes -
• CC stretch from 1680-1640 cm-1
• CH stretch from 3100-3000 cm-1
• CH bend from 1000-650 cm-1

1- Octene spectrum

1. 3083- C-H stretch
2. 2966- C-H stretch
3. 2863 C-H stretch
4. 1644- CC str
5. 1455 C-H sis
6. 1378 C-H rock
7. 1004 C-H bond

90
transmittance
1
4
5
6
2
3
7
4000 2000 1000
500
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
25
General guidelines for IR interpretation 10,11

• Alkynes -
• CC stretch from 2260-2100 cm-1
• CCH CH stretch from 3330-3270 cm-1
• CCH CH bend from 700-610 cm-1

1- hexyne spectrum
90
1383
2126
C-H rock
C?C-
transmittance
1470
636
3324
C-H scissoring
2679
C?C- H
2971
C-H scissoring
C-H stretch
0
4000 2000
1000 500
Wavelength cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
26
General guidelines for IR interpretation 10,11

• Alkyl halides -
• CH wag (-CH2X) from 1300-1150 cm-1
• CX stretches (general) from 850-515 cm-1
• C Cl stretch 850-550 cm-1
• CBr stretch 690-515 cm-1

1- bromo propane spectrum
90
1291
C-H wag
651
1470
2940
Long chain, C-Br stretch
2976
C-H scissoring
C-H stretch
0
4000 2000
1000 500
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
27
General guidelines for IR interpretation 10,11

• Aromatics-
• CH stretch from 3100-3000 cm-1
• overtones, weak, from 2000-1665 cm-1
• CC stretch (in-ring) from 1600-1585 cm-1
• CC stretch (in-ring) from 1500-1400 cm-1
• CH "loop" from 900-675 cm-1

• Aromatic C-H stretches are left to 3000, and
  aliphatic C-H stretches are right to 3000

90
overtones
1465
3099
1614
transmittance
2925
1086
C-H stretch alkyl
3068
1035
1505
Spectrum of Toluene
3032
C- H stretch In aromatic ring
738
C-H stretch aromatics
In-plane C-H bending
0
Wavelength cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
28
General guidelines for IR interpretation10,11

• Alcohol-
• OH stretch, hydrogen bonded 3500-3200 cm-1
• CO stretch 1260-1050 cm-1 (s)
• The spectrum of ethanol is shown below. Note the
  very broad, strong band of the OH stretch (3391)
  and the CO stretches (1102, 1055).

90
Spectrum of Ethanol
transmittance
1102
2961
3391
C-O stretch
C-H stretch
1105
O-H stretch
0
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
29
General guidelines for IR interpretation 10,11

• ketones
• CO stretch
• aliphatic ketones 1715 cm-1
• a, ß-unsaturated ketones 1685-1666 cm-1
• The spectrum of 2-butanone is shown below. This
  is a saturated ketone, and the CO band appears
  at 1715. Note the CH stretches (around 2991) of
  alkyl groups.

90
transmittance
2991
2-butanone spectrum
C-H stretch
CO stretch
1715
0
4000 3000 2000 1500 1000
500
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
30
General guidelines for IR interpretation 10,11

• Aldehydes
• HCO stretch 2830-2695 cm-1
• CO stretch
• aliphatic Aldehydes 1740-1720 cm-1
• alpha, beta-unsaturated aldehydes 1710-1685 cm-1
• The spectra of benzaldehyde and butyraldehyde are
  shown below. Note that the OC stretch of the
  alpha, beta-unsaturated compound -- benzaldehyde
  -- is at a lower wave number than that of the
  saturated butyraldehyde.

90
Benzaldehyde spectrum
2725
3073
2827
C-H aldehyde
C-H Stretch alkyl
transmittance
1696
CO stretch
0
4000 3000 2000 1500 1000
500
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
31

• Carboxylic acids -
• OH stretch from 3300-2500 cm--1
• CO stretch from 1760-1690 cm-1
• CO stretch from 1320-1210 cm-1
• OH bend from 1440-1395 and 950-910 cm-1
• The spectrum of hexanoic acid is shown below.
  Note the broad peak due to OH stretch
  superimposed on the sharp band due to CH
  stretch. Note the CO stretch (1721), CO stretch
  (1296), OH bends (1419, 948), and CO stretch
  (1296

General guidelines for IR interpretation 10,11
90
transmittance
948
O-H
2971
1419
O-H stretch and C-H stretch
O-H band
1296
C-O stretch
1721
CO stretch
0
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
32

• Esters -
• CO stretch
• aliphatic from 1750-1735 cm-1
• a, ß-unsaturated from 1730-1715 cm-1
• CO stretch from 1300-1000 cm-1
• The spectra of ethyl acetate and ethyl benzoate
  are shown below. Note that the CO stretch of
  ethyl acetate (1752) is at a higher wavelength
  than that of the a, ß-unsaturated ester ethyl
  benzoate (1726). Also note the CO stretches in
  the region 1300-1000 cm-1 .

General guidelines for IR interpretation10,11

• Ethyl acetate
• 2981- C-H stretch
• 1752- CO ester stretch
• 1250- C-O stretch
• 1055- C-O stretch

90
transmittance
1
2
3
4

• Ethyl benzoate
• 3078- C-H aromatic stretch
• 2966- C-H alkyl stretch
• 1726-CO stretch
• 1266, 1117- C-O stretch

90
1
3
2
4
4000 3000 2000
1000 500
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
33
General guidelines for IR interpretation 10,11

• Amines -
• NH stretch 3400-3250 cm-1
• 1 amine two bands from 3400-3300 and 3330-3250
  cm-1
• 2 amine one band from 3350-3310 cm-1
• 3 amine no bands in this region
• NH bend (primary amines only) from 1650-1580
  cm-1
• CN stretch (aromatic amines) from 1335-1250 cm-1
  
• CN stretch (aliphatic amines) from 12501020
  cm-1
• NH wag (primary and secondary amines only) from
  910-665 cm-1

10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
34
General guidelines for IR interpretation 10,11
10,20,30 amine spectrums
90
Tri ethyl amine 1. 1241- C-N stretching
1
Aniline 1.3442 2. 3360- 3. Shoulder band 4.
1619- N-H primary amine 5.1281- C-N stretch
90
transmittance
1
4
5
3
2
90
Diethyl amine 1. 3288- N-H stretch Secondary
amine 2.1143- C-N stretching 3.733- N-H waging 10
,20.
1
3
2
4000 3000 2000
1000 500
Wave number cm-1
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
35
General guidelines for IR interpretation 10,11

• Nitro groups-
• NO asymmetric stretch from 1550-1475 cm-1
• NO symmetric stretch from 1360-1290 cm-1

90
transmittance
1358
1573
1383
1537
N-O stretch
N-O stretch
N-O stretch
0
Wave number cm-1
Blue spectrum
Meta nitro toluene
Nitro methane
Black spectrum
10. Jag Mohan ,infrared spectroscopy, Organic
Spectroscopy, Principles And Applications,
2ndedition,Narosa,Newdelhi, Chennai 2005. Print.
11.Dudles H,Williams,Ian Flemming ,infrared
spectroscopy, Spectroscopy Methods In Organic
Chemistry, 5thedition,Tata mecGrawHill.Education.
Newyork, Singapore, Sydney, page no. 45-60. 2004
. Print.
36
Example for interpretation of IR for known
structure9,10,14

1. N-H Amide----3360 cm -1 .
2. PhenolicOH -- 3000 cm -1 --3500 cm -1
3. CH Stretching---3000 cm-1 .
4. Aromatic overtone ----1840 cm-1 --1940 cm -1
5. gtCO Amide stretching -----1650 cm -1
6. Aromatic CC stretching--- 1608 cm -1 .
7. N-H Amide bending ----1568 cm -1
8. Aromatic CC stretching ----1510 cm -1 .
9. gtCH bending --------810 cm -1

E

A
C
G
D
F
H
I
B
Acetaminophen 14 (4-acetamido-Phenol)
9. Robert M.Silverstien Francis X.Webster
,infrared spectroscopy, spectroscopic
identification of organic compounds, 6thedition,
John Wiley, Chichester, Singapore, Toronto,
Brisbane page no. 3.5, 2005. Print. 10. Jag Mohan
,infrared spectroscopy, Organic Spectroscopy,
Principles And Applications, 2ndedition,Narosa,New
delhi, Chennai 2005. Print. 14.David
watson,infrared spectroscopy, pharmaceutical
Analysis, A test book for pharmacy students
pharmaceutical chemists, 2nd edition, Elsevier
churchil,livingston. Edinburgh,london,newyork,oxfo
rd,sydney, and Toronto. Print
37
Examples for interpretation of IR for known
structure15
15
15
15
15
15.www.cem.msu.edu. Web feb 25 2010. lt
http//www.cem.msu.edu/reusch/VirtualText/Spectrp
y/InfraRed/irspec1.htmir1 gt
38

• Tips for interpretation of IR for unknown
  structure 14
• Always place relines to negative information
  evidence i.e., absence of band at
• 1900 cm-1---1600 cm-1----absence of gtCO,
  gtCHO
• Always starts from higher frequency end of the
  spectrum.
• Absence of band at 880 cm-1650 cm-1 indicates
  absence of aromatic ring.
• For easy identification go for fingerprint and
  functional group region.
• Finger print region range is 1400 cm-1--900 cm-1.
  In this region if absorbance band is present the
  groups esters, alcohols, ethers, nitro are
  Confirmed.
• Functional region range is 4000 cm-1---1400
  cm-1.amines, alcohols, aromatic rings, carboxylic
  acids, alkynes, alkanes, alkenes, anhydrides,
  imides, etc, may be confirmed.
• Stretching vibrations at 4000 cm-1----600 cm-1.
• Bending vibrations at 1500 cm-1-----500 cm-1.

14.David watson,infrared spectroscopy,
pharmaceutical Analysis, A test book for pharmacy
students pharmaceutical chemists, 2nd edition,
Elsevier churchil,livingston. Edinburgh,london,new
york,oxford,sydney, and Toronto. Print
39
Example for interpretation of IR for unknown
structure14,15
Unsatd
90
Aromatic P- Disubst
Satd
transmittance
CH3
CH2
Aromatic P- Disubst
NH2
CC
C0
0
4000 3000 2000 1500 1000
500
Wave number cm-1
Carbonyl Group Carbon Oxygen Group Primary Amine
Group Saturated Alkane Unsaturated Alkene /
Aromatic Methyl Group
14.David watson,infrared spectroscopy,
pharmaceutical Analysis, A test book for pharmacy
students pharmaceutical chemists, 2nd edition,
Elsevier churchil,livingston. Edinburgh,london,new
york,oxford,sydney, and Toronto. Print
15.www.cem.msu.edu. Web feb 25 2010. lt
http//www.cem.msu.edu/reusch/VirtualText/Spectrp
y/InfraRed/irspec1.htmir1 gt
40
Example for interpretation of IR for unknown
structure15
Peak status Reason inference
POSITION REDUCED MASS BOND STRENGTH (STIFFNESS) LIGHT ATOMS HIGH FREQUENCY STRONG BONDS HIGH FREQUENCY
STRENGTH CHANGE IN POLARITY STRONGLY POLAR BONDS GIVE INTENSE BANDS
WIDTH HYDROGEN BONDING STRONG HYDROGEN BONDING GIVES BROAD BANDS
3350 -- OH stetching vibrational frequency2950
-- CH aliphatic asymmetrical stretching
vibrational band. The less intense band at 2860
is the symmetrical stretching vibrational
band.1425 -- CH2 characteristic absorption1065
-- CO absorption
15.www.cem.msu.edu. Web feb 25 2010. lt
http//www.cem.msu.edu/reusch/VirtualText/Spectrp
y/InfraRed/irspec1.htmir1 gt
41
Conclusion
Drug discovery
IR spectroscopy
Drug Quality control
Drug incompatibility
On considering the all above aspects of
INFRA RED SPECTROSCOPY. It is concluded that IR
technique is an unbound spectroscopic technique
for quality optimization from drug discovery to
drug quality control parameters.
41
42
THANK YOU
NOTE This presentation does not include
plagiarized material.