Textbook Question
Which one of the following five compounds produced the IR spectrum shown below?
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Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis 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
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Bruice 8th EditionCh. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis SpectroscopyProblem 60
Bruice 8th EditionCh. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis SpectroscopyProblem 60Chapter 14, Problem 60
The IR spectrum of compound A with a molecular formula of C5H12O is shown below. Compound A is oxidized to give compound B, a ketone with a molecular formula of C5H10O. When compound A is heated with H2SO4, compounds C and D are obtained. Considerably more D is obtained than C. Reaction of compound C with O3, followed by treatment with dimethyl sulfide, gives two products: formaldehyde and compound E, with a molecular formula of C4H8O. Reaction of compound D with O3, followed by treatment with dimethyl sulfide, gives two products: compound F, with a molecular formula of C3H6O, and compound G, with a molecular formula of C2H4O. What are the structures of compounds A through G?
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Verified step by step guidance1
Step 1: Analyze the molecular formula of compound A (C5H12O) and its IR spectrum. The presence of an -OH group can be inferred if there is a broad absorption around 3200-3600 cm⁻¹. This suggests that compound A is likely an alcohol.
Step 2: Consider the oxidation of compound A to compound B, which is a ketone (C5H10O). Oxidation of a secondary alcohol typically produces a ketone. This indicates that compound A is likely a secondary alcohol.
Step 3: Examine the dehydration reaction of compound A with H2SO4 to form compounds C and D. Dehydration of alcohols typically leads to alkenes. The fact that more of compound D is formed suggests that it is the more stable alkene, likely due to Zaitsev's rule (the more substituted alkene is favored).
Step 4: Analyze the ozonolysis of compound C. The products are formaldehyde (CH2O) and compound E (C4H8O). This indicates that compound C contains a terminal double bond, as ozonolysis cleaves double bonds to form carbonyl compounds.
Step 5: Analyze the ozonolysis of compound D. The products are compound F (C3H6O) and compound G (C2H4O). This suggests that compound D contains an internal double bond, as ozonolysis cleaves it to form two carbonyl compounds. Use the molecular formulas of the products to deduce the structure of compound D.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Infrared Spectroscopy (IR)
Infrared spectroscopy is a technique used to identify functional groups in organic compounds by measuring the absorption of infrared light. Different bonds absorb characteristic wavelengths of IR radiation, allowing chemists to deduce the presence of specific functional groups, such as alcohols, ketones, and alkenes, based on their unique absorption patterns.
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General Features of IR Spect
Oxidation and Reduction in Organic Chemistry
Oxidation in organic chemistry typically involves the loss of electrons or an increase in oxidation state, often resulting in the formation of carbonyl compounds like ketones or aldehydes. Understanding the oxidation states and the types of reactions that convert alcohols to ketones is crucial for predicting the transformations of compound A to compound B in the given question.
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00:54Distinguishing between Oxidation and Reduction
Ozonolysis
Ozonolysis is a reaction involving the cleavage of alkenes using ozone (O3), which results in the formation of carbonyl compounds. This reaction is significant for determining the structures of compounds C, D, F, and G, as it helps identify the products formed from the oxidative cleavage of double bonds, leading to smaller carbonyl-containing fragments.
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06:30General properties of ozonolysis.
Related Practice
Textbook Question
Five compounds are shown for each of the IR spectra below. Indicate which of the five compounds is responsible for each spectrum.
c.
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Textbook Question
The mass spectrum for a compound with molecular weight of 102 is shown below. Its IR spectrum has a broad, strong absorption at 3600 cm–1 and a medium absorption at 1360 cm–1.
a. Identify the compound.
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Textbook Question
How can IR spectroscopy distinguish between 1-hexyne, 2-hexyne, and 3-hexyne?
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Textbook Question
Each of the IR spectra shown below is accompanied by a set of four compounds. In each case, indicate which of the four compounds is responsible for the spectrum.
a.
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Textbook Question
The mass spectrum for a compound with molecular weight of 102 is shown below. Its IR spectrum has a broad, strong absorption at 3600 cm–1 and a medium absorption at 1360 cm–1.
b. Show the mechanism for formation of the peak at m/z = 84.
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