Organic Structure Determination Using 2-D NMR Spectroscopy

Organic Structure Determination Using 2-D NMR Spectroscopy

A Problem-Based Approach

1st Edition - July 10, 2008

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  • Authors: Jeffrey Simpson, Jeffrey Simpson
  • eBook ISBN: 9780080916637

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Description

Organic Structure Determination Using 2-D NMR Spectroscopy is a primary text for a course in NMR techniques, with the goal to learn to identify organic molecular structure. It presents strategies for assigning resonances to known structures and for deducing structures of unknown organic molecules based on their NMR spectra. It contains 20 known and 20 unknown structure determination problems and features a supporting website from which instructors can download the structures of the unknowns in selected chapters, digital versions of all figures, and raw data sets for processing. Many other books describe the methods used, but none offer a large number of problems. Instructors at universities and colleges are forced to cobble together problems from a wide range of sources. The fragmentary approach to assembling course materials has a negative impact on course continuity and thus adversely impacts student retention. This book will stand as a single source to which instructors and students can go to obtain a comprehensive compendium of NMR problems of varying difficulty.

Key Features

• Presents strategies for assigning resonances to known structures and for deducing structures of unknown organic molecules based on their NMR spectra
• Contains 20 known and 20 unknown structure determination problems

Readership

This is a primary text for a course in NMR techniques, with the goal to learn to identify organic molecular structure.

Table of Contents

  • PART I: Background and Methods

    Chapter 1: Introduction
    What is NMR?
    Consequences of Nuclear Spin
    Application of a Magnetic Field to a Single Nuclear Spin
    Application of a Magnetic Field to an Ensemble of Nuclear Spins
    Tipping the Net Magnetization Vector from Equilibrium
    Signal Detection
    The Chemical Shift
    The 1-D NMR Spectrum
    The 2-D NMR Spectrum
    Information Content Available Using NMR

    Chapter 2: Instrumental Considerations
    Sample Preparation
    Locking
    Shimming
    Temperature Regulation
    Modern NMR Instrument Architecture
    Pulse Calibration
    Sample Excitation and the Rotating Frame of Reference
    Pulse Rolloff
    Probe Variations
    Analog Signal Detection
    Signal Digitization

    Chapter 3: Data Collection, Processing, and Plotting
    Setting the Spectral Window
    Determining the Optimal Wait Between Scans
    Setting the Acquisition Time
    How Many Points to Acquire in a 1-D Spectrum
    Zero Filling and Digital Resolution
    Setting the Number of Points to Acquire in a 2-D Spectrum
    Truncation Error and Apodization
    The Relationship Between T2* and Observed Line Width
    Resolution Enhancement
    Forward Linear Prediction
    Pulse Ringdown and Backward Linear Prediction
    Phase Correction
    Baseline Correction
    Integration
    Measurement of Chemical Shifts and J-Couplings
    Data Representation

    Chapter 4: 1H and 13C Chemical Shifts
    The Nature of the Chemical Shift
    Aliphatic Hydrocarbons
    Saturated, Cyclic Hydrocarbons
    Olefinic Hydrocarbons
    Acetylenic Hydrocarbons
    Aromatic Hydrocarbons
    Heteroatom Effects

    Chapter 5: Symmetry and Topicity
    Homotopicity
    Enantiotopicity
    Diastereotopicity
    Chemical Equivalence
    Magnetic Equivalence

    Chapter 6: Through-Bond Effects: Spin-Spin (J) Coupling
    Origin of J-Coupling
    Skewing of the Intensity of Multiplets
    Prediction of First-Order Multiplets
    The Karplus Relationship for Spins Separated by Three Bonds
    The Karplus Relationship for Spins Separated by Two Bonds
    Long Range J-Coupling
    Decoupling Methods
    One-Dimensional Experiments Utilizing J-Couplings
    Two-Dimensional Experiments Utilizing J-Couplings

    Chapter 7: Through-Space Effects: the Nuclear Overhauser Effect (NOE)
    The Dipolar Relaxation Pathway
    The Energetics of an Isolated Heteronuclear Two-Spin System
    The Spectral Density Function
    Decoupling One of the Spins in a Heteronuclear Two-Spin System
    Rapid Relaxation via the Double Quantum Pathway
    A One-Dimensional Experiment Utilizing the NOE
    Two-Dimensional Experiments Utilizing the NOE

    Chapter 8: Molecular Dynamics
    Relaxation
    Rapid Chemical Exchange
    Slow Chemical Exchange
    Intermediate Chemical Exchange
    Two-Dimensional Experiments that Show Exchange

    Chapter 9: Strategies for Assigning Molecules
    Prediction of Chemical Shifts
    Prediction of Integrals and Intensities
    Prediction of 1H Multiplets
    Good Bookkeeping Practices
    Assigning 1H Resonances on the Basis of Chemical Shifts
    Assigning 1H Resonances on the Basis of Multiplicities
    Assigning 1H Resonances on the Basis of the gCOSY Spectrum
    The Best Way to Read a 2-D gCOSY Spectrum
    Assigning 13C Resonances on the Basis of Chemical Shifts
    Pairing 1H and 13C Shifts By Using the HSQC/HMQC Spectrum
    Assignment of Non-Protonated 13C’s on the Basis of the HMBC Spectrum

    Chapter 10: Strategies for Elucidating Unknown Molecular Structures
    Initial Inspection of the One-Dimensional Spectra
    Good Accounting Practices
    Identification of Entry Points
    Completion of Assignments

    PART II: Problems

    Chapter 11 Simple Assignment Problems

    Chapter 12: Complex Assignment Problems

    Chapter 13: Simple Unknown Problems

    Chapter 14: Complex Unknown Problems

Product details

  • No. of pages: 384
  • Language: English
  • Copyright: © Academic Press 2008
  • Published: July 10, 2008
  • Imprint: Academic Press
  • eBook ISBN: 9780080916637

About the Authors

Jeffrey Simpson

Jeffrey H Simpson, PhD, was Director of the Instrumentation Facility in the Department of Chemistry at M.I.T. from 2006 to 2017. Dr. Simpson’s career in NMR/instrumentation research and instruction spans 20 years, and he has authored an introductory text on the subject of NMR as well as publishing a number of peer-reviewed articles. He is one of the Founding Members of the New England NMR Society and served as VP from its inception to 2017. He currently is a faculty member in the Department of Chemistry at the University of Richmond.

Affiliations and Expertise

Department of Chemistry, University of Richmond, USA

Jeffrey Simpson

Affiliations and Expertise

Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA

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