The document discusses techniques for interpreting organic compounds using infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry. It elaborates on attenuated total reflectance (ATR) as a method for analyzing samples in various states without preparation and highlights various applications in the pharmaceutical and chemical industries. Additionally, it outlines the noesy technique in NMR for determining the proximity of protons and explains the ring rule for calculating unsaturation in organic compounds.

1. • Interpretation of Organic Compound by IR, NMR and Mass
Spectrometry
• ATR-IR
• NOESY Technique
• Mass Fragmentation & Its Rule
• Fragmentation of –COOH group
• Ring Rule
Mangal Kamble
M pharm Sem-II Pharma’chemistry
Dr. D. Y. Patil College of Pharmacy Akurdi, Pune.
ADVANCED SPECTRALANALYSIS

2. INFRARED SPECTROSCOPY
Wat is ATR-IR?
• Attenuated total reflectance (ATR) spectroscopy is a
versatile and powerful technique for infrared
spectroscopy which enables samples to be examined
directly in the solid or liquid state without further
preparation.

3. Evanescent Waves
The infrared radiation interacts wit the sample
through a series of standing waves, called
evanescent waves.

4. Difference between FTIR & ATR

5. Crystal used in ATR cells are made from materials that
have low solubility in water & a very high refractive
index.
Crystals are typically made of:
• Zinc Selenide (ZnSe)
• Germanium (Ge)
• Diamond
• Zinc Sulfide (ZnS)
• Silicon (Si)
Crystal Composition

6. Sample analysis
• Analysing liquids
• Analysing Solids
• Analysing Powders
• ATR can be used to analyse non-aqueous solutions such
as oils, lubricants, paints, glues, solvents, inks, dyes, gels
and pastes.

7. • Biological industries
• Pharmaceutical industries
• Medicinal industries
• Chemical industries includes measurement of drugs during
manufactured by fermentation of methods, following the
kinetics of metabolism of dietary constituents, investigation of
detergents and cosmetics, or identification of contaminants in
waste water, etc.
• Using ATR combined wit spectral summation the infrared
spectra of solutes, Very dilute aqueous solutions can be
measured.
Application

8. Indometacin
Molecular formula- C19H16ClNO4
Molecular weigt- 357.8g/mol

9. 400-2500 Aromatic C-H stretch Carboxylic acid
O-H stretch
1715,1695 C=O stretch
1600 Aromatic C=C stretch
1450 O-C3 deformation
1230 (C-O) stretch plus O-H deformation
925 Carboxylic O-H out of plane deformation
900-600 Various C-H out of plane deformation for
substituted aromatic
750 C-Cl
Wavelength (Cm-1)
Infrared Spectra

11. 2D NMR
In general , 2D’s can be divided into two types,
Homonuclear
Heteronuclear
Types of 2D NMR include correlation spectroscopy (COSY), J-
spectroscopy, exchange spectroscopy (EXSY), and nuclear Overhauser
effect spectroscopy (NOESY).
Homonuclear Heteronuclear
COSY HSQC
ECOSY HMBC
TOCSY
Through space correlation
NOESY
ROSEY

12. NOESY Technique
• NOESY is Nuclear Overhauser Effect is a useful for determining
which signal arise from protons tat are close to each other in
space even if they are not bonded.
• Nuclear overhauser effect is a phenomenon in which the signal
of a 1 is affected if the another 1 close in space is irradiated or
inverted.
CH3-CH2-CH2-Cl
irradiation wit RF

13. • The two hydrogen can also interact through space means
not through bond because they are close in space and this
is called dipole-dipole interaction.
• there is dipole movement associated with one hydrogen
and dipole movement associated with second hydrogen ,
so these two dipole can interact with each other the
mechanism known as dipolar coupling.

14. Q. How much is the closeness to interact?
5-6 Å
H
H
• The effect is arises due to dipolar interaction between two
spins close in space (through space effect).
• This method used to determine the proximity between two
spins.

20. Nuclear Magnetic Resonance
Ethyl ethanoate
Chemical sift ppm
CH3(s)
CH2(q)
CH3(t)
2.0
4.1
1.3

22. Mass Spectra of 4-Methyl-3-pentene-2-one

24. Fragmentation of Carboxylic Acids

26. If molecular formula of a compound is known the number of
unsaturation can ne calculated by ring rule .
The no. of unsaturated sites R , is equal to the no. of rings in the
molecule + the no. of double bond + 2x no. of triple bond.
The ring rule for molecule CwHxNyOz may be stated as follows
R = w+1+(y-x)/2
R= no. of rings
w= no. of carbon
x= no. of Hydrogen
y= no. of nitrogen
z= no. of oxygen
Ring rule

27. The ring rule for diethyl ether C2H5OC2H5.
R = 4+1+ (0-10)/2
= 4+1-5
= 0
e.g. C6H6
R= w+1+(y-x)/2
R= 6+1+(0-6)/2
=7-3
= 4
Benzene contain 1 ring and 3 double bond