Textbook Question
Draw the 13C NMR spectrum you would expect to see for each of the molecules shown.
(b)
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Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
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Mullins 1st EditionCh. 15 - Structural Identification II: Nuclear Magnetic Resonance SpectroscopyProblem 67c
Mullins 1st EditionCh. 15 - Structural Identification II: Nuclear Magnetic Resonance SpectroscopyProblem 67cChapter 14, Problem 67c
Draw the 13C NMR spectrum you would expect to see for each of the molecules shown.
(c) 
Verified step by step guidance1
Identify the unique carbon environments in the molecule. Each unique carbon environment will correspond to a distinct signal in the ¹³C NMR spectrum.
Consider the symmetry of the molecule. Symmetrical molecules may have fewer unique carbon environments due to equivalent positions.
Analyze the chemical shifts for each carbon. Carbons bonded to electronegative atoms or within functional groups will have characteristic chemical shifts.
Determine the splitting pattern, if any. In ¹³C NMR, splitting is less common due to the low natural abundance of ¹³C, but coupling with nearby protons can occur.
Sketch the spectrum, placing each signal at the appropriate chemical shift on the x-axis, and indicate the relative intensity of each signal based on the number of equivalent carbons.
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Key Concepts
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13C NMR Spectroscopy
13C NMR spectroscopy is a technique used to determine the structure of organic compounds by analyzing the magnetic environment of carbon atoms. Each unique carbon environment in a molecule produces a distinct signal in the spectrum, allowing chemists to infer the number and types of carbon atoms present. The chemical shift, measured in parts per million (ppm), provides information about the electronic environment surrounding each carbon.
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13C NMR General Features
Chemical Shift
Chemical shift in NMR spectroscopy refers to the resonant frequency of a nucleus relative to a standard in a magnetic field. In 13C NMR, the chemical shift indicates the electronic environment of carbon atoms, influenced by factors such as electronegativity of neighboring atoms and hybridization. Typical chemical shift ranges for carbon atoms vary, with sp3 hybridized carbons appearing upfield (0-50 ppm) and sp2 hybridized carbons downfield (100-150 ppm).
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Symmetry and Equivalent Carbons
In 13C NMR, symmetry in a molecule can lead to equivalent carbon atoms, which produce a single signal in the spectrum. Identifying symmetry elements, such as planes or axes, helps determine which carbons are equivalent. Equivalent carbons experience the same electronic environment, simplifying the spectrum by reducing the number of distinct signals, which is crucial for interpreting complex molecules.
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Related Practice
Textbook Question
Draw the ¹³C NMR spectrum you would expect to see for each of the molecules shown.
(a)
1417
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Textbook Question
A graduate student ran a reaction that produced a mixture of the following two compounds. After painstaking purification, she is able to separate the two compounds. Using ¹H NMR, how can she determine which diastereomer is in which separated sample?
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Textbook Question
Assign the peaks in the ¹H NMR spectrum for the molecule shown.
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Textbook Question
For the compound shown, produce a table of the shift, integration, and multiplicity of each peak you would expect to see in a ¹H NMR spectrum.
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Textbook Question
For the molecules in Assessment 15.58, give an approximate chemical shift for each indicated carbon. [The range of correct answers is large here.].
(c)
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