Textbook Question
Identify each of the following compounds from its molecular formula and its IR and 1H NMR spectra.
d. C4H8O2
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Ch. 14 - NMR Spectroscopy
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
Chapter 15, Problem 69a
Sketch the following spectra that would be obtained for 2-chloroethanol:
a. The 1H NMR spectrum for an anhydrous sample of the alcohol.
Verified step by step guidance1
Identify the structure of 2-chloroethanol (ClCH2CH2OH) and determine the number of unique hydrogen environments. There are three distinct environments: (1) the hydrogens on the CH2 group attached to the chlorine, (2) the hydrogens on the CH2 group attached to the hydroxyl group, and (3) the hydroxyl (OH) hydrogen.
Predict the chemical shifts for each hydrogen environment: (1) The CH2 group attached to the electronegative chlorine will appear downfield (higher ppm) due to deshielding, (2) the CH2 group attached to the hydroxyl group will also be deshielded but less so than the first group, and (3) the OH hydrogen will appear as a broad singlet, typically in the range of 1-5 ppm, depending on hydrogen bonding.
Determine the splitting patterns for each group based on the n+1 rule: (1) The CH2 group attached to chlorine will be split into a triplet by the adjacent CH2 group (n=2), (2) the CH2 group attached to the hydroxyl group will be split into a quartet by the adjacent CH2 group (n=3), and (3) the OH hydrogen will typically appear as a singlet because it does not couple strongly with neighboring hydrogens.
Estimate the relative integration of the peaks: (1) The CH2 group attached to chlorine will integrate to 2 hydrogens, (2) the CH2 group attached to the hydroxyl group will also integrate to 2 hydrogens, and (3) the OH hydrogen will integrate to 1 hydrogen.
Sketch the spectrum: Place the peaks at their approximate chemical shifts, with the appropriate splitting patterns and relative integrations. Ensure the triplet for the CH2 group attached to chlorine, the quartet for the CH2 group attached to the hydroxyl group, and the broad singlet for the OH hydrogen are clearly represented.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nuclear Magnetic Resonance (NMR) Spectroscopy
NMR spectroscopy is a powerful analytical technique used to determine the structure of organic compounds. It relies on the magnetic properties of certain nuclei, primarily hydrogen (1H), to provide information about the number of hydrogen atoms, their environment, and connectivity in a molecule. The resulting spectrum displays peaks corresponding to different hydrogen environments, allowing chemists to infer structural details.
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General NMR Features
Chemical Shifts
Chemical shifts in NMR spectroscopy refer to the variation in resonance frequency of nuclei due to their electronic environment. Measured in parts per million (ppm), these shifts help identify the type of hydrogen atoms present in a molecule. For 2-chloroethanol, the chemical shifts will indicate the presence of hydrogen atoms on the carbon adjacent to the hydroxyl group and those on the carbon bonded to chlorine, reflecting their differing electronic environments.
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Integration and Splitting Patterns
Integration in NMR refers to the area under the peaks, which correlates to the number of hydrogen atoms contributing to that signal. Splitting patterns arise from the interaction of neighboring hydrogen atoms, described by the n+1 rule, where n is the number of adjacent hydrogens. In the case of 2-chloroethanol, the integration and splitting will reveal the number of hydrogen atoms on each carbon and their relationships, providing insight into the molecule's structure.
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Related Practice
Textbook Question
Sketch the following spectra that would be obtained for 2-chloroethanol:
d. The proton-coupled 13C NMR spectrum.
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Textbook Question
Sketch the following spectra that would be obtained for 2-chloroethanol:
c. The 13C NMR spectrum.
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Textbook Question
Sketch the following spectra that would be obtained for 2-chloroethanol:
b. The 1H NMR spectrum for a sample of the alcohol that contains a trace amount of acid.
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Textbook Question
The 1H NMR spectrum of 2-propen-1-ol is shown here. Indicate the protons in the molecule that are responsible for each of the signals in the spectrum.
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Textbook Question
Draw a splitting diagram for the Hb proton if Jbc = 10 and Jba = 5.
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