Textbook Question
How many distinct signals would you expect to see in the ¹H NMR spectrum of the following molecules? [Ignore diastereotopic hydrogens for the sake of this assessment.]
(c)
1078
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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 57a
Mullins 1st EditionCh. 15 - Structural Identification II: Nuclear Magnetic Resonance SpectroscopyProblem 57aChapter 14, Problem 57a
How many distinct signals would you expect to see in the ¹H NMR spectrum of the following molecules? [Ignore diastereotopic hydrogens for the sake of this assessment.]
(a) 
Verified step by step guidance1
Identify the unique hydrogen environments in the molecule. Each unique environment will correspond to a distinct signal in the ¹H NMR spectrum.
Consider the symmetry of the molecule. Symmetrical molecules often have fewer unique hydrogen environments because equivalent hydrogens will produce the same signal.
Look for different types of hydrogens such as those attached to sp3 hybridized carbons, sp2 hybridized carbons, and any hydrogens involved in functional groups like alcohols or amines.
Count the number of unique hydrogen environments. This will give you the number of distinct signals expected in the ¹H NMR spectrum.
Remember to ignore diastereotopic hydrogens as per the problem's instructions, focusing only on the unique environments that are not diastereotopic.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
¹H NMR Spectroscopy
¹H NMR spectroscopy is a technique used to determine the structure of organic compounds by analyzing the magnetic environment of hydrogen atoms. Each distinct hydrogen environment in a molecule produces a separate signal in the NMR spectrum, allowing chemists to infer the number and type of hydrogen atoms present.
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General NMR Features
Chemical Equivalence
Chemical equivalence refers to hydrogen atoms in a molecule that are in identical environments and thus produce the same NMR signal. Identifying chemically equivalent hydrogens is crucial for predicting the number of distinct signals in an NMR spectrum, as equivalent hydrogens contribute to a single peak.
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Symmetry in Molecules
Symmetry in molecules can lead to chemical equivalence among hydrogen atoms, reducing the number of distinct NMR signals. Recognizing symmetry elements, such as mirror planes or rotational axes, helps determine which hydrogens are equivalent and simplifies the analysis of the NMR spectrum.
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Related Practice
Textbook Question
How many distinct signals would you expect to see in the ¹H NMR spectrum of the following molecules? [Ignore diastereotopic hydrogens for the sake of this assessment.]
(f)
1053
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Textbook Question
Draw the expected results of a DEPT sequence for the molecules shown.
(b)
949
views
Textbook Question
How many distinct signals would you expect to see in the ¹H NMR spectrum of the following molecules? [Ignore diastereotopic hydrogens for the sake of this assessment.]
(b)
1095
views
Textbook Question
Draw the expected results of a DEPT sequence for the molecules shown.
(a)
930
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Textbook Question
With information from the ¹H NMR and the ¹³C DEPT spectra, structure elucidation becomes even easier. Provide the structure that corresponds to the following data. [The identity of the carbons comes from the DEPT experiment.]
C₆H₁₁BrO₂
IR: 1745 cm ⁻¹
¹H NMR: δ 1.25 (t, 3H), 2.18 (quint, 2H), 2.58 (t, 2H), 3.46 (t, 2H), 4.15 (q, 2H)
¹³C NMR: δ 14.2 (CH₃) , 27.8 (CH₂) , 32.5 (CH₂) , 32.6 (CH₂) , 60.5 (CH₂) , 172.4 (C)
793
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