Mass spectrometry is a technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio. It can be used to determine molecular masses and elucidate molecular structures of organic compounds. There are several types of ions produced including molecular ions, fragment ions, and isotope ions. Compounds undergo various fragmentation modes like homolytic cleavage, heterolytic cleavage, retro-Diels-Alder reactions, hydrogen transfers and McLafferty rearrangements. Mass spectrometry has applications in fields like drug development, environmental analysis, and clinical diagnosis.
MASS SPECTROSCOPY ( Molecular ion, Base peak, Isotopic abundance, Metastable ...Sachin Kale
CONTENT:
Molecular Ion Peak
Significance of Molecular ion & Graphically Method
Base Peak
Isotopic Abundance
Metastable Ion
Significance of Metastable ion
Nitrogen Rule & graphs
Formulation of Rule
MASS SPECTROSCOPY ( Molecular ion, Base peak, Isotopic abundance, Metastable ...Sachin Kale
CONTENT:
Molecular Ion Peak
Significance of Molecular ion & Graphically Method
Base Peak
Isotopic Abundance
Metastable Ion
Significance of Metastable ion
Nitrogen Rule & graphs
Formulation of Rule
Introduction
working principle
fragmentation process
general rules for fragmentation
general modes of fragmentation
metastable ions
isotopic peaks
applications
Introduction & Definition, Theory, instrumentation, Continuous – wave (CW) instrument, The pulsed Fourier Transform [FT] instrument, Solvents, Chemical shift
i. Shielding and de-shielding
ii. Factors affecting chemical shift
Two dimensional Nuclear Magnetic Resonance (2D NMR) refers to a set of multi pulse techniques which were introduced to overcome the complex spectra obtained with NMR.
It is a set of NMR methods which give data plotted in a space defined by two frequency axes rather than one.
Content:
Basic concepts
Fragmentation Process
McLafferty Rearrangement
Mass spectrum
Metastable ion
Isotopic peak
Nitrogen Rule
Basic Concept:
Mass spectrometry uses high energy electrons to break a molecule into fragmentation.
A beam of high-energy electrons breaks the molecule apart.
The masses of the fragments and their relative abundance reveal information about the structure of the molecule.
Separation and analysis of the fragments provides information about:
– Molecular weight
– Structure
Fragmentation Process
Bombardment of molecules by an electron beam with energy between 10-15ev usually results in the ionization of molecules by removal of one electron (Molecular ion formation)
When the energy of electron beam is increased between 50-70ev, these molecular ions acquire a high excitation resulting in their break down into various fragments. This process is called "Fragmentation process".
McLafferty Rearrangement:
Fragmentation due to rearrangement of Molecular or Parent ion:
The cleavage of bonds in Molecular ion is due to the intramolecular atomic rearrangement. This leads to fragmentation whose origin cannot be described by simple cleavage of bonds.
When fragments are accompanied by bond formation as well as bond for breaking, a rearrangement process is said to have occurred.
Such rearrangement involves the transfer of hydrogen from one part of the molecular ion to another via, preferably, a six-membered cyclic transition state.
This process is favoured energetically because as many bonds are formed as are broken.
Compounds containing hydrogen atom at position gamma to carbonyl group have been found to a relative intense peak.
This is probably due to rearrangement and fragmentation is accompanied by the loss of neutral molecule. This rearrangement is known as Mc Lafferty rearrangement.
Thus , the molecular formula of the unknown compound can be determined from the various fragment ions and also the parent ion of the mass spectrum .
More example of McLafferty reaarangements are :
A double McLafferty rearrangement is also reported in ketones .
The second hydrogen atom originates exclusively from the γ – position .
A secondary hydrogen is preffered to a primary hydrogen atom in this process . The mechanism involves.
Ketonisation of the intermediate enol ion by the hydrogen transfer .
Hydrogen transfer to enolic oxygen . Consider the McLafferty rearrangement in 4- Heptanone.
Mass Spectrum :
It is a record of the masses and the relative abundances of the molecular ion and the positively charged fragments formed from it by the electron bombardment.
The molecular ion or Parent ion :
The electron bombardment with energy 10-15 eV usually removes one electron from the molecule of the organic compoound in the vapour phase it results in the formation of molecular ion
The mass of the parent ion gives the molecular mass of the sample. .
Introduction
working principle
fragmentation process
general rules for fragmentation
general modes of fragmentation
metastable ions
isotopic peaks
applications
Introduction & Definition, Theory, instrumentation, Continuous – wave (CW) instrument, The pulsed Fourier Transform [FT] instrument, Solvents, Chemical shift
i. Shielding and de-shielding
ii. Factors affecting chemical shift
Two dimensional Nuclear Magnetic Resonance (2D NMR) refers to a set of multi pulse techniques which were introduced to overcome the complex spectra obtained with NMR.
It is a set of NMR methods which give data plotted in a space defined by two frequency axes rather than one.
Content:
Basic concepts
Fragmentation Process
McLafferty Rearrangement
Mass spectrum
Metastable ion
Isotopic peak
Nitrogen Rule
Basic Concept:
Mass spectrometry uses high energy electrons to break a molecule into fragmentation.
A beam of high-energy electrons breaks the molecule apart.
The masses of the fragments and their relative abundance reveal information about the structure of the molecule.
Separation and analysis of the fragments provides information about:
– Molecular weight
– Structure
Fragmentation Process
Bombardment of molecules by an electron beam with energy between 10-15ev usually results in the ionization of molecules by removal of one electron (Molecular ion formation)
When the energy of electron beam is increased between 50-70ev, these molecular ions acquire a high excitation resulting in their break down into various fragments. This process is called "Fragmentation process".
McLafferty Rearrangement:
Fragmentation due to rearrangement of Molecular or Parent ion:
The cleavage of bonds in Molecular ion is due to the intramolecular atomic rearrangement. This leads to fragmentation whose origin cannot be described by simple cleavage of bonds.
When fragments are accompanied by bond formation as well as bond for breaking, a rearrangement process is said to have occurred.
Such rearrangement involves the transfer of hydrogen from one part of the molecular ion to another via, preferably, a six-membered cyclic transition state.
This process is favoured energetically because as many bonds are formed as are broken.
Compounds containing hydrogen atom at position gamma to carbonyl group have been found to a relative intense peak.
This is probably due to rearrangement and fragmentation is accompanied by the loss of neutral molecule. This rearrangement is known as Mc Lafferty rearrangement.
Thus , the molecular formula of the unknown compound can be determined from the various fragment ions and also the parent ion of the mass spectrum .
More example of McLafferty reaarangements are :
A double McLafferty rearrangement is also reported in ketones .
The second hydrogen atom originates exclusively from the γ – position .
A secondary hydrogen is preffered to a primary hydrogen atom in this process . The mechanism involves.
Ketonisation of the intermediate enol ion by the hydrogen transfer .
Hydrogen transfer to enolic oxygen . Consider the McLafferty rearrangement in 4- Heptanone.
Mass Spectrum :
It is a record of the masses and the relative abundances of the molecular ion and the positively charged fragments formed from it by the electron bombardment.
The molecular ion or Parent ion :
The electron bombardment with energy 10-15 eV usually removes one electron from the molecule of the organic compoound in the vapour phase it results in the formation of molecular ion
The mass of the parent ion gives the molecular mass of the sample. .
In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules in the ionization chamber of a mass spectrometer. The fragments of a molecule cause a unique pattern in the mass spectrum.
MS Fragmentation Process and Application of MS.pdfDr. Dinesh Mehta
Bombardment of molecules by an electron beam with energy
between 10-15ev usually results in the ionization of molecules by
removal of one electron (Molecular ion formation).
MS Fragmentation Process and Application of MS.pdfDr. Dinesh Mehta
Fragmentation process:
Bombardment of molecules by an electron beam with energy between 10-15ev usually results in the ionization of molecules by removal of one electron (Molecular ion formation).
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
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- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
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Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Ocular injury ppt Upendra pal optometrist upums saifai etawah
Mass Spectroscopy
1. Presented By :- RAHUL KRISHNAN.P.R
M.Pharm 1st Year
Dept.Of Pharmaceutics
Mass Spectrometry
11
2. Contents
Introduction of Mass spectrum.
Types of Ions
Fragmentation modes
Fragment characteristics
Applications
References
2
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3. Introduction of MS
The impact of a stream of high energy electrons causes the
molecule to lose an electron forming a radical cation.
A species with a positive charge and one unpaired electron
+ e-
H
H C H
H
H
H C H
H
+ 2 e-
3
Molecular ion (M+)
m/z = 16
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4. Introduction of MS
Only cations are detected.
- Radicals are “invisible” in MS
The amount of deflection observed depends on the mass to
charge ratio (m/z).
-Most cations formed have a charge of +1 so the amount of
deflection observed is usually dependent on the mass of
the ion.
.
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5. Mass Spectrum
The resulting mass spectrum is a graph of the mass of each
cation vs. its relative abundance.
Relative abundance of an ion means the % of total ion
current.
Mass spectrum is an analytical techniques which can provide
information concerning the molecular structure of organic
comp.
Base peak is the highest peak or the most intense peak in the
spectrum.
5
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6. Types of Ion
Types of ion produced in MS
1.Molecular ions (parent ion)
2.Metastable ions
3.Fragment ions (Dissociation process)
4.Rearrangement ions
5.Multiple charged ions
6.Isotopes ions
7.Negative ions
8.Base peak
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7. Molecular ion
Molecular ion (parent ion):
-The radical cation corresponding to the mass of the
original molecule
The molecular ion is usually the highest mass in
the spectrum
H
H C H
H
H H
H C C H
H H
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8. Molecular ion
•When a sample sub.is bombarded with
electrons of energies of 9 to 15eV, the
molecular ions produced by loss of a single
electron.
•This will give rise to a very simple mass
spectrum with essentially all of the ion appearing
in one peak called parent peak.
M + e = M+ + 2e-
Most important ion.
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9. Molecular ion
•The relative height of parent peak decreases in
the following order
aromatic>conjugated olefins>sulphides>
unbranched>hydrocarbon>ketones>amine>est
er> ethers >carboxylic acid>branched
hydrocarbons.
9
•If a molecule yields the parent peak due to
molecular ion ,the exact molecular weight can be
calculated.
•The peak intensity of the molecular ion differs from
one compound to other.
Grace College Of Pharmacy
11. Isotope Ion
•Many elements have the natural isotopes.
•For example, Chlorine with mass number 37 exists in
addition to Chlorine 35.
•The presence of isotopes readily produces the isotope
ions in the spectrum accompanied by a main molecular
ion peak and fragment peaks.
11Grace College Of Pharmacy
13. Fragment ion
•The molecular ion produced in MS is generally
left with considerable excess energy.
•This energy is rapidly lost by the molecular ion
resulting in one or more cleavages in it with or without
some rearrangement.
•One of the fragment retains the charge where as
the remaining fragment may be stable molecule or
radicals.
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14. Fragment ion
•The energy required to remove one electron from
the neutral parent molecule is usually 10eV.
•But the energy of the bombarding electron will be
around 70eV.
•The additional energy is consumed in fragmenting
the parent ion.
E.g. : Ethyl chloride.
CH3-CH2-Cl + e- = CH3-CH2-Cl + + 2e-
CH3-CH2-Cl + = CH3-CH2
+ + Cl. Or
CH2-CH2
+ + HCl. (Fragment ion)
14Grace College Of Pharmacy
16. Metastable ion
The ions in a mass spectrometer that have sufficient
energy to fragment sometime after leaving the ion
source but before arriving at the detector.
M+
A+ + N
M+ with large amount of internal energy will fragment
in the ionization source, producing “normal” A+ ions.
These A+ ions will be seen as narrow peaks at m/z
values correct for the mass and charge on the ion A+.
M+ having only a small excess of internal energy,
reach detector before decomposition can occur.
Narrow peaks for “normal” M+ appear
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17. Metastable ion
•M+ which posses excesses of internal energy that are
in between the those in above two cases, may
fragment after leaving the ion source and before
reaching the detector. The product ions, A+, are seen
in the mass spectrum as broad peaks, centered at m/z
values that are nor correct for the mass and charge on
the ion A+.
•These broad peaks are called “metastable ion
peaks”.
•The metastable ions are detected differently form
normal ions is due to their different momentum.
17Grace College Of Pharmacy
19. Rearrangement Ion
•These are commonly formed due to the
rearrangement of the fragmented ions.
•In most of the cases, rearrangement takes place with
respect to hydrogen, by a reaction known as
McLafferty Rearrangement.
•It involves the migration of a ϒ hydrogen atom,
followed by cleavage of a β bond.
19Grace College Of Pharmacy
20. Multi-charged Ions
•These ions may exist in 2 or 3 charges instead of a
usual single charge.
•These are known as doubly or triply charged ions and
peaks due to these ions are known as multicharged
ion peak.
M + e- → M++ + 3e-
M + e- → M+++ + 4e-
•common in case of the heteroaromatic compounds
•Fixed gases such as co2, N, O etc have measurable
peaks corresponding to co2+2, N+2, O+2
20Grace College Of Pharmacy
21. Negative ions
.
•In addition to the positive ions, negative ions are also
formed during the electron bombardment of the
sample.
•This results due to the capture of the electrons during
the bombardment.
•These are not observable with the usual mass
spectrophotometer, unless some modifications are
made, and hence are generally ignored during
studies.
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22. Base Peak
.
•The largest peak in the mass spectrum
corresponding to the most abundant ion or the most
intense peak in the spectrum is known as the base
peak.
•Depending on the nature of the compound, it may be
a fragmented ion peak or parent ion peak.
•Sometimes the molecular ion peak may be the base
peak, and in that case, it is easy to find out the
molecular weight of the compound.
•The base peak will be assigned with a value of 100%
•All other peaks are reported as percentages of base
peak.
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24. FRAGMENTATION MODES
•The Relative abundance of fragment ion
formed depends upon
1)The stability of the ion
2)Also the stability of radical lost.
•The radical site is reactive and can form a new bond.
• The formation of a new bond is a powerful driving
force for ion decompositions
•The energy released during bond formation is available
for the cleavage of some bonds in the ion.
.
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25. FRAGMENTATION MODES
1.Simple Clevage
i)Homolytic Clevage
a)Mode1
b)Mode2
c)Mode3
ii)Heterolytic clevage
2.Retro-Diel’s-Alder reaction
3.Hydrogen transfer rearrangements
4.Mc Lafferty Rearrangements
25Grace College Of Pharmacy
26. Fragmentation modes
1) Homolytic cleavage :
odd electron ions have unpaired electron which is
capable of new bond formation.
Bond is formed , energy is released , help offset the
energy required for the cleavage of some other bond in
the ion.
Homolytic cleavage reactions are very common.
It is divided into 3:
a. Mode 1
b. Mode 2
c. Mode 3
26Grace College Of Pharmacy
27. Mode1
•Operates in compounds where hetero atom is singly
bonded to a carbon atom.
•Parent ion is formed by removal of one electron from hetero
atom.
•New bond is formed with adjacent atom through donation of
the unpaired electron and transfer of electron from adjacent
bond.
27
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28. Mode 2
•When hetero atom is attached to the carbon atom by double
bond, α clevage is the preferred fragmentation mode.
•It is shown by ketones, aldehydes, esters, amides etc.
28Grace College Of Pharmacy
29. Mode 3
•Mainly occurs in the aromatic compounds.
•It involves the cleavage of c-c bond, which is β to the
aromatic ring.
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30. Heterolytic Clevage
•It may be noted the cleavage of C-X (X= 0,N,S,Cl) bond is
more difficult than that of C-C bond.
•In such cleavage , the positive charge is carried by the
carbon atom and not by the heteroatom.
•As size of the halogen atom attached to the carbon atom
increases, the c-x bond becomes very weak, and will
undergo easy fragmentation.
R-CH2-Cl.+ = Cl. + RC+H2
30Grace College Of Pharmacy
31. Fragmentation modes
2) Retro –Diels –Alder reaction
•The reaction is an example of multicentre fragmentation
which is characteristic of cyclic olefins.
•It involves the cleavage of two bonds of a cyclic system
which result the formation of 2 stable unsaturated
fragment in which 2 new bonds are formed.
•This process is not accompanied by any hydrogen
transfer rearrangement.
•The charge can be carried by any one of the fragment.
31
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32. Fragmentation modes
2) Hydrogen ion Transfer Rearrangements
•Transfer of the Hydrogen atom from one part of the
molecule to another.
•Generally the fragmentation occurs through a six
membered transition states.
+
C6H5-NH-C=O C6H5NH2
+ + H2C=O
I
H-CH2
32Grace College Of Pharmacy
33. Fragmentation modes
3) Mc Lafferty Rearrangement
• It involves the migration of γ hydrogen atom followed by the
cleavage of β bond.
• To undergo a Mc Lafferty Rearrangement a molecule must
possess
a) An appropriately located heteroatom e.g. O, N
b) A pi electron system ( usually a double bond) &
c) An abstractable hydrogen atom gamma to the C = X system
• Rearrangement leads to the elimination of neutral
molecules from aldehydes, ketones , amines etc.
• Rearrangement proceeds through sterically hindered six
membered transition state. 33
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35. APPLICATIONS
1. Molecular mass determination
2. Isotopic abundance determination.
3. Structural elucidation of organic and biologic
molecules.
4. Detection of impurities.
5. Drug metabolism studies
6. Quantitative analysis of mixtures
7. To detect the distinction between cis and trans isomer
8. Determination of ionization potential
9. Detection of bonding informations.
10.Clinical, toxicological and forensic applications.
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36. References
1. Mass Spectrometry, Second edition by James Barker
2. Elementary organic spectroscopy by Y.R. Sharma
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