Textbook Question
The following 1H NMR spectra are for four compounds, each with molecular formula of C6H12O2. Identify the compounds.
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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 76
Identify the compound with molecular formula C6H10O that gives the following DEPT 13C NMR spectrum:
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Verified step by step guidance1
Analyze the molecular formula C6H10O. This indicates the compound contains six carbons, ten hydrogens, and one oxygen. The degree of unsaturation can be calculated using the formula: (2C + 2 - H)/2. For C6H10O, the degree of unsaturation is (2(6) + 2 - 10)/2 = 2, suggesting two double bonds, rings, or a combination thereof.
Interpret the DEPT 13C NMR spectrum. The 'all' spectrum shows four distinct peaks, indicating four unique carbon environments. The CH3 spectrum shows one peak, the CH2 spectrum shows one peak, and the CH spectrum shows one peak. This suggests the presence of one methyl group (CH3), one methylene group (CH2), and one methine group (CH). The remaining carbon is likely a quaternary carbon (not bonded to hydrogen).
Examine the chemical shift values. The peak near 200 ppm in the 'all' spectrum is characteristic of a carbonyl group (C=O). The peak near 140 ppm suggests a carbon in a double bond (likely part of an alkene). Peaks near 40-20 ppm correspond to sp3 hybridized carbons, such as CH3 and CH2 groups.
Combine the structural information. The presence of a carbonyl group (C=O) and an alkene (C=C) suggests the compound may be an α,β-unsaturated ketone. The sp3 carbons (CH3 and CH2) likely form part of the alkyl chain attached to the unsaturated system.
Propose a structure consistent with the data. Based on the molecular formula, degree of unsaturation, and DEPT NMR data, the compound is likely 3-hexen-2-one, which contains a ketone group, an alkene, and the appropriate number of CH3, CH2, and CH groups.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molecular Formula Interpretation
The molecular formula C6H10O indicates a compound containing six carbon atoms, ten hydrogen atoms, and one oxygen atom. Understanding the molecular formula is crucial for predicting the structure and reactivity of the compound. It provides insights into the degree of unsaturation, which can suggest the presence of double bonds or rings in the structure.
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How to interpret condensed structures.
DEPT NMR Spectroscopy
DEPT (Distortionless Enhancement by Polarization Transfer) NMR is a technique used to differentiate between carbon types in a molecule. It provides information about the number of hydrogen atoms attached to each carbon atom, allowing for the identification of CH3, CH2, and CH groups. This information is essential for deducing the structure of the compound based on the observed signals in the spectrum.
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Chemical Shift in NMR
Chemical shift refers to the resonant frequency of a nucleus relative to a standard in a magnetic field, measured in parts per million (ppm). In carbon NMR, different types of carbon atoms resonate at different chemical shifts based on their electronic environment. Analyzing the chemical shifts in the DEPT spectrum helps in identifying the types of carbon present in the compound and aids in constructing its molecular structure.
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Related Practice
Textbook Question
How many signals are produced by each of the following compounds in its
a. 1H NMR spectrum?
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Textbook Question
When compound A (C5H12O) is treated with HBr, it forms compound B (C5H11Br). The 1H NMR spectrum of compound A has a 1H singlet, a 3H doublet, a 6H doublet, and two 1H multiplets. The 1H NMR spectrum of compound B has a 6H singlet, a 3H triplet, and a 2H quartet. Identify compounds A and B.
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Textbook Question
The following 1H NMR spectra are for four compounds, each with molecular formula of C6H12O2. Identify the compounds.
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Textbook Question
Identify each of the following compounds from its molecular formula and its IR and 1H NMR spectra:
b.C6H14O
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Textbook Question
How many signals are produced by each of the following compounds in its
b. 13C NMR spectrum?
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