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CHEM205: Spectroscopy

Unit 4: Nuclear Magnetic Resonance Spectroscopy   Nuclear magnetic resonance spectroscopy (NMR spectroscopy) is a technique that exploits the magnetic properties of certain nuclei.  Elements containing an odd number of protons and/or neutrons within their nucleus have an intrinsic magnetic moment; in other words, their spin is not zero. Nuclei with even numbers of protons and/or neutrons have a spin of zero.  In principle, NMR is applicable to any nucleus possessing spin.  Quite a bit of information can be obtained from an NMR spectrum, including the number and types of functional groups in a molecule.  The most important applications for the organic chemist are proton (1H) NMR and carbon-13 (13C) NMR spectroscopy.   

NMR spectroscopy has had a huge impact on the natural sciences.  The most popular application of NMR is known by the name of Magnetic Resonance Imaging (MRI).  An MRI is principally used for medical diagnostics, but it can also be used to elucidate the structure of analytes, illustrate how temperature affects chemical reactions, and determine reaction mechanisms.  It is an invaluable tool for those seeking to understand protein and nucleic acid structure and function.

This unit begins with a discussion of the theory and instrumentation of NMR spectrometers and how they manipulate magnetic fields to obtain structural information of compounds.  Chemical shifts, spin-spin interactions (coupling), and isomer effects will be discussed.  The unit continues with a section specifically devoted to proton (1H)  NMR, followed by a section on carbon-13 (13C) NMR.  Advanced NMR techniques are also covered.  The unit concludes with several opportunities to enhance your spectroscopic proficiency, combining all spectra from all spectroscopic methods covered in this course.   

Unit 4 Time Advisory
This unit will take approximately 40 hours to complete.

☐    Subunit 4.1: 9.5 hours

☐    Lecture: 4.0 hours

☐    Reading: 5.0 hours

☐    Web Media: 0.5 hours

☐    Subunit 4.2: 3.0 hours

☐    Subunit 4.3: 6.0 hours

☐    Subunit 4.4: 21.5 hours

☐    Reading: 4.0 hours

☐    Web Media: 2.0 hours

☐    Assignments: 9.5 hours

☐    Assessments: 6.0 hours

Unit4 Learning Outcomes
Upon successful completion of this unit, the student will be able to:

  • Identify the components of a nuclear magnetic resonance spectrometer
  • Describe the basic theory of NMR spectroscopy in terms of magnetic field interactions
  • Predict the location of NMR bands based on molecular structure and explain how shielding and de-shielding influence the chemical shifts
  • Explain the spin-spin interactions of atoms within a molecule and  predict coupling patterns based on molecular structure
  • Obtain structural information from 1H NMR and 13C NMR spectra and interpret data from two dimensional NMR techniques
  • Discuss advanced NMR techniques such as DEPT, COSY, and NOE

4.1 Introduction to Nuclear Magnetic Resonance (NMR) Spectroscopy   - Reading: William Reusch’s “Virtual Text of Organic Chemistry: Nuclear Magnetic Resonance Spectroscopy” Link: William Reusch’s “Virtual Text of Organic Chemistry: Nuclear Magnetic Resonance Spectroscopy” (HTML)
 
Instructions: Please read the entire webpage. Spend some time working the example problems and be sure to follow the links for supplemental information required for successful completion of this course.  This material covers all of Unit 4. 
 
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  • Reading: Connexions: Ty Hanna and Andrew R. Barron’s “Introduction to Nuclear Magnetic Resonance Spectroscopy” Link: Connexions: Ty Hanna and Andrew R. Barron’s “Introduction to Nuclear Magnetic Resonance Spectroscopy” (HTML or PDF)
     
    Instructions: Please read the entire webpage. You can also see this material in PDF form by clicking “Download” on the top right corner of the page. This material presents the general theory of NMR spectroscopy, including its instrumentation, interpretation, and limitations.       
     
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  • Lecture: Scribd: Dilip D. Dhavale’s “Nuclear Magnetic Resonance Spectroscopy: Basic Principles” Link: Scribd: Dilip D. Dhavale’s “Nuclear Magnetic Resonance Spectroscopy: Basic Principles” (PowerPoint)
     
    Instructions: Please spend a sufficient amount of time comprehending the material contained in the PowerPoint lecture.  This slideshow (79 slides) contains a thorough description of the theory and application of NMR spectroscopy.  This material also includes information pertaining to MRI, a medical application of NMR spectroscopy.
     
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  • Web Media: OCHeM.com: Thomas Poon’s “Theory of NMR” Link: Web Media: OCHeM.com: Thomas Poon’s “Theory of NMR” (Adobe Shockwave)
     
    Instructions: Scroll down the list of Shockwave Animations to find a link entitled “Theory of NMR.”  Click on the link; it will launch an Adobe Shockwave application in a new window.  This material provides a basic visual demonstration of how NMR spectroscopy utilizes the magnetic field to obtain spectra.
     
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4.1.1 Chemical Shift   - Reading: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Chemical Shift” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Chemical Shift” (HTML)
 
Instructions: Click on the “NMR” button on the left-hand side of the webpage, then click on the link “Chemical Shift” (Section I, B).  This material explains the origin of chemical shifts in NMR spectroscopy.
 
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4.1.2 Spin-Spin Interactions (Coupling)   - Reading: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Origin of Spin-Spin Splitting” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Origin of Spin-Spin Splitting” (HTML)
 
Instructions: Click on the “NMR” button on the left-hand side of the webpage, then click on the link “Why Does Splitting Occur?” (Section I, E.5.a).  This material explains the origin of spin-spin interaction coupling in NMR spectroscopy.
 
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4.1.3 Structural Elucidation of Isomers   - Reading: Connexions: Sequoyah King and Andrew R. Barron’s “NMR Spectroscopy of Stereoisomers” Link: Connexions: Sequoyah King and Andrew R. Barron’s “NMR Spectroscopy of Stereoisomers” (HTML or PDF)
 
Instructions: Please read the entire webpage.  This material explains how isomerism affects NMR spectra as well as how isomer information can be obtained from experimental results.  You can access the PDF version under the download tab in the top right corner.     
 
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4.2 Proton (1H) NMR Spectroscopy   - Lecture: OCHeM.com: Thomas Poon’s “Spectroscopy, Part 4 of 4” Link: OCHem.com: Thomas Poon’s “Spectroscopy, Part 4 of 4” (QuickTime)
 
Instructions: Scroll down the list of “PreLectures” to find a link entitled “Spectroscopy, Part 4 of 4.”  Click on the link; it will launch a QuickTime application in a new window.  Watch the video (runtime = 22:40 minutes).  This material gives a detailed review of 1H-NMR and demonstrates its use as a tool for structure elucidation.  Please remember 1H-NMR is the most important spectroscopic tool for structure elucidation.  It can be a very selective technique, differentiating between many hydrogen atoms within a molecule or within a collection of similar molecules that differ only in terms of their local chemical environment. 
 
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  • Web Media: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: 1H Correlation Chart” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: 1H Correlation Chart” (HTML)
     
    Instructions: Click on the “NMR” button on the left-hand side of the webpage, then click on the link “1H Correlation Chart” (Section I, E.4).  This is a quick reference chart for proton NMR chemical shifts.  All organic molecules referenced in peer-reviewed scientific journals must contain all of the molecule’s 1H-NMR shifts.
     
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  • Interactive Lab: Jean-Claude Bradley and Andrew Lang’s “Spectral Game” Link: Jean-Claude Bradley and Andrew Lang’s “Spectral Game” (HTML)
     
    Instructions: Please enter a username in the required field.  Note: You do not need to register and this does not need to be your actual name (i.e., student1).  Choose the format you prefer for your viewer and select H NMR from the “Type” drop-down box.  A general video tutorial from the creators of the game can be found here.  Please spend an ample amount of time using this game as a learning tool to increase your spectral analysis proficiency.
     
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4.3 Carbon-13 NMR Spectroscopy   - Lecture: OCHeM.com: Thomas Poon’s “Spectroscopy, Part 3 of 4” Link: OCHem.com: Thomas Poon’s “Spectroscopy, Part 3 of 4” (QuickTime)
 
Instructions: Scroll down the list of “PreLectures” to find a link entitled “Spectroscopy, Part 3 of 4.”  Click on the link; it will launch a QuickTime application in a new window.  Watch the video (runtime = 18:47 minutes).  This material gives a detailed review of 13C-NMR and demonstrates its use as a tool for structure elucidation.  Please remember 13C-NMR is used to determine the types of carbons present in a molecule.
 
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  • Web Media: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: 13C Correlation Chart” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: 13C Correlation Chart” (HTML)
     
    Instructions: Click on the “NMR”button on the left-hand side of the webpage, then click on the link “13C Correlation Chart” (Section II, B).  This is a quick reference chart for carbon-13 NMR chemical shifts.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Interactive Lab: Jean-Claude Bradley and Andrew Lang’s “Spectral Game” Link: Jean-Claude Bradley and Andrew Lang’s “Spectral Game” (HTML)
     
    Instructions: Please enter a username in the required field.  Note: You do not need to register and this does not need to be your actual name (i.e., student1).  Choose the format you prefer for your viewer and select C NMR from the “Type” drop-down box.  A general video tutorial from the creators of the game can be found here.  Please spend an ample amount of time using this game as a learning tool to increase your spectral analysis proficiency.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.   

  • Assessment: William Reusch’s “Virtual Text of Organic Chemistry: Nuclear Magnetic Resonance Spectroscopy: Practice Problems” Link: William Reusch’s “Virtual Text of Organic Chemistry: Nuclear Magnetic Resonance Spectroscopy: Practice Problems” (HTML)
     
    Instructions: Please scroll to the bottom of the page and work through the practice problems (Questions 1–10) found there.  This site is designed to require you to attempt the problems prior to obtaining the solutions from its answer key. 
     
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  • Assessment: OCHeM.com: Thomas Poon’s “NMR Spectroscopy Problems” Link: OCHeM.com: Thomas Poon’s “NMR Spectroscopy Problems” (HTML or PDF)
     
    Instructions: Please work through these problems dealing primarily with NMR.  Then, click here for the answer key.
     
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4.4 Advanced NMR Techniques   4.4.1 Double Resonance   - Reading: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Double Resonance” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Double Resonance” (HTML)
 
Instructions: Click on the “NMR”button on the left-hand side of the webpage, then click on the link “Double Resonance” (Section V, A).  This material explains how spin decoupling can be used to simplify complex NMR spectra.
 
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4.4.2 DEPT   - Reading: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: DEPT (Distortionless Enhancement by Polarization Transfer) Experiment” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: DEPT (Distortionless Enhancement by Polarization Transfer) Experiment” (HTML)
 
Instructions: Click on the “NMR” button on the left-hand side of the webpage, then click on the link “DEPT (Distortionless Enhancement by Polarization Transfer) Experiment” (Section V, B).  This material explains how the hybridization (sp, sp2, sp3) at the carbon can be used to simplify complex NMR spectra.
 
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4.4.3 Nuclear Overhauser Enhancement (NOE)   - Reading: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Nuclear Overhauser Enhancement” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: Nuclear Overhauser Enhancement” (HTML)
 
Instructions: Click on the “NMR”button on the left-hand side of the webpage, then click on the link “Nuclear Overhauser Enhancement” (Section II, F.1).  This material explains how simultaneous irradiation of two different nuclei can be used to simplify complex NMR spectra.
 
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4.4.4 Two-Dimensional NMR   - Reading: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: COSY (Correlation Spectroscopy) Experiment” Link: Central Connecticut State University: Dr. Neil Glagovich’s “NMR Spectroscopy: COSY (Correlation Spectroscopy) Experiment” (HTML)
 
Instructions: Click on the “NMR”button on the left-hand side of the webpage, then click on the link “COSY (Correlation Spectroscopy) Experiment” (Section V, C.1).  This material provides an overview of 2-D techniques and demonstrates how correlation spectroscopy is applied to simplify analysis of complex NMR spectra.
 
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  • Web Media: Antony Williams and Andrew Lang’s “2D Spectral Game” Link: Antony Williams and Andrew Lang’s “2D Spectral Game” (HTML)
     
    Instructions: Please enter a username in the required field.  Note: You do not need to register and this does not need to be your actual name (i.e., student1).  A general video tutorial from the creators of the game can be found here.  Please spend an ample amount of time using this game as a learning tool to increase your spectral analysis proficiency.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.   

  • Assessment: University of Calgary: Dr. Ian Hunt’s “Interactive Spectroscopy Problems” Link: University of Calgary: Dr. Ian Hunt’s “Interactive Spectroscopy Problems” (HTML and Java)
     
    Instructions: Please read through the instructions on the webpage, then work through the 27 problems provided.  These problems include the spectroscopic methods from the entire course.
     
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  • Assessment: MIT OpenCourseWare: Prof. Tim Jamison’s “Organic Structure Determination: Study Materials” Link: MIT OpenCourseWare: Prof. Tim Jamison’s “Organic Structure Determination: Study Materials” (PDF)
     
    Instructions: Please click on the link to the PDF for “Problem Session Examples” to access the file.  Printing the problem set is highly recommended.  Work through the problems, then click on the PDF link entitled “Problem Session Solutions” for the answer key.
     
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  • Assessment: MIT OpenCourseWare: Prof. Tim Jamison’s “Organic Structure Determination: Exams” Link: MIT OpenCourseWare: Prof. Tim Jamison’s “Organic Structure Determination: Exams” (PDF)
     
    Instructions: Please use the links on the webpage to complete both Exam 1 and Exam 2, following the instructions provided on the exams, disregarding the time limit.  The exams primarily cover the different NMR spectroscopy techniques; however, some problems also include MS and IR.  Use the answer keys to check your work and as a study aide for what you may have missed. 
     
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