Textbook Question
For the hydrogen(s) screened in blue, draw the signal you would expect to see in a ¹H NMR spectrum. At which chemical shift would the signal appear?
(c)
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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 61e
Mullins 1st EditionCh. 15 - Structural Identification II: Nuclear Magnetic Resonance SpectroscopyProblem 61eChapter 14, Problem 61e
Draw the signal for the following multiplicities. What is the ratio of peaks within each signal?
(e) sextet
Verified step by step guidance1
Understand the concept of multiplicity in NMR spectroscopy: Multiplicity refers to the splitting pattern of a signal in an NMR spectrum, which is determined by the number of neighboring hydrogen atoms (n) according to the n+1 rule.
Identify the number of neighboring hydrogens: For a sextet, the multiplicity indicates that there are 5 neighboring hydrogens (n = 5), since a sextet is n+1 = 6.
Determine the ratio of peaks: The ratio of peaks in a multiplet is determined by Pascal's triangle. For a sextet, the ratio of peaks is 1:5:10:10:5:1.
Draw the signal: A sextet will have six peaks with the intensity ratio of 1:5:10:10:5:1. This means the outermost peaks are the smallest, and the middle peaks are the largest.
Visualize the signal: When drawing the sextet, ensure that the spacing between the peaks is consistent, and the height of each peak corresponds to the ratio determined in the previous step.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
NMR Multiplicity
NMR multiplicity refers to the splitting of NMR signals into multiple peaks due to spin-spin coupling between non-equivalent hydrogen atoms. The number of peaks in a signal is determined by the n+1 rule, where n is the number of neighboring hydrogen atoms. Understanding multiplicity is crucial for interpreting NMR spectra and identifying molecular structures.
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General NMR Features
Sextet in NMR
A sextet in NMR spectroscopy is a signal split into six peaks. This occurs when a hydrogen atom is coupled with five equivalent neighboring hydrogen atoms (n=5), resulting in a 6-peak pattern. The intensity ratio of these peaks typically follows Pascal's triangle, specifically 1:5:10:10:5:1 for a sextet, reflecting the statistical distribution of spin states.
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Pascal's Triangle in NMR
Pascal's Triangle is used in NMR to predict the relative intensities of peaks in a multiplet. Each row of the triangle corresponds to the coefficients of the binomial expansion, which represent the intensity ratios of the peaks. For example, a sextet's intensity ratio is derived from the sixth row, providing a clear pattern for interpreting complex splitting in NMR spectra.
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Related Practice
Textbook Question
Draw the signal for the following multiplicities. What is the ratio of peaks within each signal?
(d) quintet
1
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Textbook Question
Draw the signal for the following multiplicities. What is the ratio of peaks within each signal?
(c) quartet
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Textbook Question
Draw the signal for the following multiplicities. What is the ratio of peaks within each signal?
(b) triplet
1
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Textbook Question
Draw the signal for the following multiplicities. What is the ratio of peaks within each signal?
(f) septet
1
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Textbook Question
For the hydrogen(s) screened in blue, draw the signal you would expect to see in a ¹H NMR spectrum. At which chemical shift would the signal appear?
(e)