1. Nuclear magnetic resonance spectroscopy uses radio waves and strong magnetic fields to analyze organic molecules. It can identify carbon-hydrogen frameworks and determine the number and type of hydrogen and carbon atoms in a molecule.
2. When nuclei with an odd number of protons and/or neutrons are placed in a strong magnetic field, their spins can be either aligned with or against the field. This creates two energy states that radio waves can excite between.
3. The frequency at which excitation occurs depends on the magnetic field strength and the local electronic environment of the nucleus. This frequency corresponds to absorption peaks in the NMR spectrum and provides information about the structure of the molecule.
Nmr nuclear magnetic resonance spectroscopyJoel Cornelio
Basics of NMR. Suitable for UG and PG courses.
Includes principle, instrumentation, solvents. chemical shift and factors affecting it. Some problems. resolving agents, coupling constant and much more
Nmr nuclear magnetic resonance spectroscopyJoel Cornelio
Basics of NMR. Suitable for UG and PG courses.
Includes principle, instrumentation, solvents. chemical shift and factors affecting it. Some problems. resolving agents, coupling constant and much more
It would be use full to All Needy People. It involve information about NMR Spectroscopy ( a spectroscopic techniques), factors influencing , proton NMR and their applications of NMR as well as Nuclear magnetic imaging.
CHEMICAL SHIFT AND ITS FACTOR EFFECTS, COUPLING CONSTANT, FIRST ORDER TO NON FIRST ORDER, SPIN SYSTEMS, CHEMICAL EQUIVALENCE AND NON EQUIVALENCE, TIRUMALA SANTHOSHKUMAR S
Theory of NMR, nuclear magnetic resonance, instrumentation, solvents, chemical shift, photon NMR, spin coupling, coupling constant and applications.
https://www.linkedin.com/in/preeti-choudhary-266414182/
https://www.instagram.com/chaudharypreeti1997/
https://www.facebook.com/profile.php?id=100013419194533
https://twitter.com/preetic27018281
Please like, share, comment and follow.
stay connected
If any query then contact:
chaudharypreeti1997@gmail.com
Thanking-You
Preeti Choudhary
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.
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.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
Follow us on: Pinterest
Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
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
2. Spin of Nuclei
• Fermions : Odd mass nuclei with an odd number of nucleons have
• fractional spins.
• I = 1/2 ( 1H, 13C, 19F, 31P ), I = 3/2 ( 11B, 33S ) & I = 5/2 ( 17O ).
• Bosons : Even mass nuclei with odd numbers of protons and
• neutrons have integral spins.
•
• I = 1 ( 2H, 14N )
• Even mass nuclei composed of even numbers of protons
• and neutrons have zero spin
• I = 0 (12C, and 16O, 32S)
2
3. 3
• Nuclear magnetic resonance spectroscopy is a powerful
analytical technique used to characterize organic
molecules by identifying carbon-hydrogen frameworks
within molecules.
• Two common types of NMR spectroscopy are used to
characterize organic structure: 1H NMR is used to
determine the type and number of H atoms in a
molecule; 13C NMR is used to determine the type of
carbon atoms in the molecule.
• The source of energy in NMR is radio waves which
have long wavelengths, and thus low energy and
frequency.
• When low-energy radio waves interact with a molecule,
they can change the nuclear spins of some elements,
including 1H and 13C.
Introduction to NMR Spectroscopy
4. 4
• When a charged particle such as a proton spins on its axis, it
creates a magnetic field. Thus, the nucleus can be considered
to be a tiny bar magnet.
• Normally, these tiny bar magnets are randomly oriented in
space. However, in the presence of a magnetic field B0, they
are oriented with or against this applied field. More nuclei are
oriented with the applied field because this arrangement is
lower in energy.
• The energy difference between these two states is very small
(<0.1 cal).
Introduction to NMR Spectroscopy
5. 5
Nuclear Magnetic Resonance Spectroscopy
• In a magnetic field, there are now two energy states
for a proton: a lower energy state with the nucleus
aligned in the same direction as B0, and a higher
energy state in which the nucleus aligned against B0.
• When an external energy source (hn) that matches the
energy difference (DE) between these two states is
applied, energy is absorbed, causing the nucleus to
“spin flip” from one orientation to another.
• The energy difference between these two nuclear spin
states corresponds to the low frequency RF region of
the electromagnetic spectrum.
Introduction to NMR Spectroscopy
7. 7
• Thus, two variables characterize NMR: an applied
magnetic field B0, the strength of which is measured
in tesla (T), and the frequency n of radiation used for
resonance, measured in hertz (Hz), or megahertz
(MHz)—(1 MHz = 106 Hz).
Introduction to NMR Spectroscopy
8. 8
Nuclear Magnetic Resonance Spectroscopy
• The frequency needed for resonance and the applied
magnetic field strength are proportionally related:
• NMR spectrometers are referred to as 300 MHz
instruments, 500 MHz instruments, and so forth,
depending on the frequency of the RF radiation used
for resonance.
• These spectrometers use very powerful magnets to
create a small but measurable energy difference
between two possible spin states.
Introduction to NMR Spectroscopy
11. 11
Nuclear Magnetic Resonance Spectroscopy
• Protons in different environments absorb at slightly
different frequencies, so they are distinguishable by
NMR.
• The frequency at which a particular proton absorbs is
determined by its electronic environment.
• The size of the magnetic field generated by the
electrons around a proton determines where it absorbs.
• Modern NMR spectrometers use a constant magnetic
field strength B0, and then a narrow range of
frequencies is applied to achieve the resonance of all
protons.
• Only nuclei that contain odd mass numbers (such as 1H,
13C, 19F and 31P) or odd atomic numbers (such as 2H and
14N) give rise to NMR signals.
Introduction to NMR Spectroscopy
12. 12
Nuclear Magnetic Resonance Spectroscopy
• An NMR spectrum is a plot of the intensity of a peak against its
chemical shift, measured in parts per million (ppm).
1H NMR—The Spectrum
13. 13
Nuclear Magnetic Resonance Spectroscopy
• NMR absorptions generally appear as sharp peaks.
• Increasing chemical shift is plotted from left to right.
• Most protons absorb between 0-10 ppm.
• The terms “upfield” and “downfield” describe the
relative location of peaks. Upfield means to the right.
Downfield means to the left.
• NMR absorptions are measured relative to the position
of a reference peak at 0 ppm on the d scale due to
tetramethylsilane (TMS). TMS is a volatile inert
compound that gives a single peak upfield from typical
NMR absorptions.
1H NMR—The Spectrum
14. 14
Nuclear Magnetic Resonance Spectroscopy
• The chemical shift of the x axis gives the position of an NMR
signal, measured in ppm, according to the following equation:
1H NMR—The Spectrum
• By reporting the NMR absorption as a fraction of the NMR
operating frequency, we get units, ppm, that are
independent of the spectrometer.
• Four different features of a 1H NMR spectrum provide
information about a compound’s structure:
a. Number of signals
b. Position of signals
c. Intensity of signals.
d. Spin-spin splitting of signals.
15. 15
Nuclear Magnetic Resonance Spectroscopy
• The number of NMR signals equals the number of different
types of protons in a compound.
• Protons in different environments give different NMR signals.
• Equivalent protons give the same NMR signal.
1H NMR—Number of Signals
• To determine equivalent protons in cycloalkanes and alkenes,
always draw all bonds to hydrogen.
17. 17
Nuclear Magnetic Resonance Spectroscopy
• In comparing two H atoms on a ring or double bond, two
protons are equivalent only if they are cis (or trans) to
the same groups.
1H NMR—Number of Signals
18. 18
Nuclear Magnetic Resonance Spectroscopy
• Proton equivalency in cycloalkanes can be determined
similarly.
1H NMR—Number of Signals
19. 19
Nuclear Magnetic Resonance Spectroscopy
• In the vicinity of the nucleus, the magnetic field generated by
the circulating electron decreases the external magnetic field
that the proton “feels”.
• Since the electron experiences a lower magnetic field
strength, it needs a lower frequency to achieve resonance.
Lower frequency is to the right in an NMR spectrum, toward a
lower chemical shift, so shielding shifts the absorption upfield.
1H NMR—Position of Signals
20. 20
Nuclear Magnetic Resonance Spectroscopy
• The less shielded the nucleus becomes, the more of
the applied magnetic field (B0) it feels.
• This deshielded nucleus experiences a higher magnetic
field strength, to it needs a higher frequency to
achieve resonance.
• Higher frequency is to the left in an NMR spectrum,
toward higher chemical shift—so deshielding shifts an
absorption downfield.
• Protons near electronegative atoms are deshielded, so
they absorb downfield.
1H NMR—Position of Signals
24. 24
Nuclear Magnetic Resonance Spectroscopy
• Protons in a given environment absorb in a predictable region in
an NMR spectrum.
1H NMR—Chemical Shift Values
25. 25
Nuclear Magnetic Resonance Spectroscopy
• The chemical shift of a C—H bond increases with
increasing alkyl substitution.
1H NMR—Chemical Shift Values
26. 26
Nuclear Magnetic Resonance Spectroscopy
• The chemical shift of a C—H can be calculated with a
high degree of precision if a chemical shift additivity table is
used.
• The additivity tables starts with a base chemical shift value
depending on the structural type of hydrogen under consideration:
Calculating 1H NMR—Chemical Shift Values
CH3 C
H2
C
H
Methylene Methine
0.87 ppm 1.20 ppm 1.20 ppm
Base Chemical Shift
27. 27
Nuclear Magnetic Resonance Spectroscopy
• The presence of nearby atoms or groups will effect the base
chemical shift by a specific amount:
• The carbon atom bonded to the hydrogen(s) under consideration
are described as alpha () carbons.
• Atoms or groups bonded to the same carbon as the hydrogen(s)
under consideration are described as alpha () substituents.
• Atoms or groups on carbons one bond removed from the a carbon
are called beta () carbons.
• Atoms or groups bonded to the carbon are described as alpha
() substituents.
Calculating 1H NMR—Chemical Shift Values
(Hydrogen under consideration)
C C H
28. 28
Nuclear Magnetic Resonance Spectroscopy
Calculating 1H NMR—Chemical Shift Values
(Hydrogen under consideration)
C C H
H
H
H
H
Cl
Base Chemical Shift = 0.87 ppm
no substituents = 0.00
one -Cl (CH3) = 0.63
TOTAL = 1.50 ppm
(Hydrogen under consideration)
C C H
H
H
H
H
Cl
Base Chemical Shift = 1.20 ppm
one -Cl (CH2) = 2.30
no substituents = 0.00
TOTAL = 3.50 ppm
29. 29
Nuclear Magnetic Resonance Spectroscopy
• In a magnetic field, the six electrons in benzene circulate
around the ring creating a ring current.
• The magnetic field induced by these moving electrons reinforces
the applied magnetic field in the vicinity of the protons.
• The protons thus feel a stronger magnetic field and a higher
frequency is needed for resonance. Thus they are deshielded
and absorb downfield.
1H NMR—Chemical Shift Values
30. 30
Nuclear Magnetic Resonance Spectroscopy
• In a magnetic field, the loosely held electrons of the
double bond create a magnetic field that reinforces the
applied field in the vicinity of the protons.
• The protons now feel a stronger magnetic field, and
require a higher frequency for resonance. Thus the
protons are deshielded and the absorption is downfield.
1H NMR—Chemical Shift Values
31. 31
Nuclear Magnetic Resonance Spectroscopy
• In a magnetic field, the electrons of a carbon-carbon triple
bond are induced to circulate, but in this case the induced
magnetic field opposes the applied magnetic field (B0).
• Thus, the proton feels a weaker magnetic field, so a lower
frequency is needed for resonance. The nucleus is shielded and
the absorption is upfield.
1H NMR—Chemical Shift Values
34. 1H NMR of Methyl Acetate
C
O
R O
H3C C O
Base Chemical Shift = 0.87 ppm
one = 2.88 ppm
TOTAL = 3.75 ppm
O
CH3
C
O
R
Base Chemical Shift = 0.87 ppm
one = 1.23 ppm
TOTAL = 2.10 ppm
36. 36
Nuclear Magnetic Resonance Spectroscopy
• The area under an NMR signal is proportional to the
number of absorbing protons.
• An NMR spectrometer automatically integrates the area
under the peaks, and prints out a stepped curve
(integral) on the spectrum.
• The height of each step is proportional to the area under
the peak, which in turn is proportional to the number of
absorbing protons.
• Modern NMR spectrometers automatically calculate and
plot the value of each integral in arbitrary units.
• The ratio of integrals to one another gives the ratio of
absorbing protons in a spectrum. Note that this gives a
ratio, and not the absolute number, of absorbing
protons.
1H NMR—Intensity of Signals
46. Spin-Spin Splitting in 1H NMR Spectra
• Peaks are often split into multiple peaks due to magnetic
interactions between nonequivalent protons on adjacent carbons,
The process is called spin-spin splitting
• The splitting is into one more peak than the number of H’s on the
adjacent carbon(s), This is the “n+1 rule”
• The relative intensities are in proportion of a binomial distribution
given by Pascal’s Triangle
• The set of peaks is a multiplet (2 = doublet, 3 = triplet, 4 =
quartet, 5=pentet, 6=hextet, 7=heptet…..)
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
singlet
doublet
triplet
quartet
pentet
hextet
heptet
47. Rules for Spin-Spin Splitting
• Equivalent protons do not split each other
• Protons that are farther than two carbon atoms apart do not
split each other
48. 48
1H NMR—Spin-Spin Splitting
Splitting is not generally observed between protons separated by
more than three bonds.
If Ha and Hb are not equivalent, splitting is observed when:
49. 49
• Spin-spin splitting occurs only between nonequivalent protons
on the same carbon or adjacent carbons.
The Origin of 1H NMR—Spin-Spin Splitting
Let us consider how the doublet due to the CH2 group on
BrCH2CHBr2 occurs:
• When placed in an applied field, (B0), the adjacent proton
(CHBr2) can be aligned with () or against () B0. The likelihood
of either case is about 50% (i.e., 1,000,006 vs 1,000,000).
• Thus, the absorbing CH2 protons feel two slightly different
magnetic fields—one slightly larger than B0, and one slightly
smaller than B0.
• Since the absorbing protons feel two different magnetic fields,
they absorb at two different frequencies in the NMR spectrum,
thus splitting a single absorption into a doublet, where the two
peaks of the doublet have equal intensity.
50. 50
The Origin of 1H NMR—Spin-Spin Splitting
The frequency difference, measured in Hz, between two peaks
of the doublet is called the coupling constant, J.
J
51. 51
The Origin of 1H NMR—Spin-Spin Splitting
Let us now consider how a triplet arises:
• When placed in an applied magnetic field (B0), the adjacent
protons Ha and Hb can each be aligned with () or against () B0.
• Thus, the absorbing proton feels three slightly different
magnetic fields—one slightly larger than B0(ab). one slightly
smaller than B0(ab) and one the same strength as B0 (ab).
52. 52
The Origin of 1H NMR—Spin-Spin Splitting
• Because the absorbing proton feels three different magnetic
fields, it absorbs at three different frequencies in the NMR
spectrum, thus splitting a single absorption into a triplet.
• Because there are two different ways to align one proton with B0,
and one proton against B0—that is, ab and ab—the middle peak
of the triplet is twice as intense as the two outer peaks, making
the ratio of the areas under the three peaks 1:2:1.
• Two adjacent protons split an NMR signal into a triplet.
• When two protons split each other, they are said to be coupled.
• The spacing between peaks in a split NMR signal, measured by the
J value, is equal for coupled protons.
56. 56
Nuclear Magnetic Resonance Spectroscopy
1H NMR—Spin-Spin Splitting
Whenever two (or three) different sets of adjacent protons are
equivalent to each other, use the n + 1 rule to determine the
splitting pattern.
57. 57
Nuclear Magnetic Resonance Spectroscopy
1H NMR—Spin-Spin Splitting
Whenever two (or three) different sets of adjacent protons are
equivalent to each other, use the n + 1 rule to determine the
splitting pattern.
58. 58
Nuclear Magnetic Resonance Spectroscopy
1H NMR—Spin-Spin Splitting
Whenever two (or three) different sets of adjacent protons are
not equivalent to each other, use the n + 1 rule to determine the
splitting pattern only if the coupling constants (J) are identical:
a a
b
c
Free rotation around C-C bonds averages
coupling constant to J = 7Hz
Jab = Jbc
59. 59
Nuclear Magnetic Resonance Spectroscopy
1H NMR—Spin-Spin Splitting
Whenever two (or three) different sets of adjacent protons are
not equivalent to each other, use the n + 1 rule to determine the
splitting pattern only if the coupling constants (J) are identical:
a
b
c
c
Jab = Jbc