Textbook Question
Give approximate wavenumbers for the major characteristic IR absorption bands that would be given by each of the following compounds:
e.
f.
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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 67a,b
Bruice 8th EditionCh. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis SpectroscopyProblem 67a,bChapter 14, Problem 67a,b
Give approximate wavenumbers for the major characteristic IR absorption bands that would be given by each of the following compounds:
a. 
b. 
Verified step by step guidance1
Step 1: Analyze the structure of compound I. It contains a benzene ring and a ketone functional group. The benzene ring will exhibit characteristic IR absorption bands due to C-H stretching (around 3000-3100 cm⁻¹) and C=C stretching (around 1500-1600 cm⁻¹). The ketone group will show a strong C=O stretching band near 1700 cm⁻¹.
Step 2: Analyze the structure of compound II. It contains an alkene group, an ester functional group, and an ether group. The alkene will exhibit C-H stretching (around 3000-3100 cm⁻¹) and C=C stretching (around 1600-1680 cm⁻¹). The ester group will show a strong C=O stretching band near 1735-1750 cm⁻¹ and C-O stretching bands near 1000-1300 cm⁻¹.
Step 3: For compound I, note that the benzene ring may also exhibit overtone bands in the region of 1800-2000 cm⁻¹, which are weaker but characteristic of aromatic compounds.
Step 4: For compound II, the ether group will exhibit C-O stretching bands near 1000-1300 cm⁻¹, which overlap with the ester C-O stretching bands. This region is typically broad and complex due to multiple overlapping vibrations.
Step 5: Summarize the major IR absorption bands for each compound based on their functional groups and structural features. Compound I will primarily show bands for aromatic and ketone groups, while compound II will show bands for alkene, ester, and ether groups.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Infrared (IR) Spectroscopy
Infrared spectroscopy is a technique used to identify functional groups in organic compounds by measuring the absorption of infrared light at specific wavelengths. Each functional group has characteristic absorption bands, which correspond to the vibrations of chemical bonds. Understanding these bands allows chemists to deduce the presence of specific functional groups in a molecule.
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General Features of IR Spect
Wavenumber
Wavenumber is a unit of measurement used in spectroscopy, defined as the number of wave cycles per unit distance, typically expressed in cm⁻¹. It is inversely related to wavelength and directly proportional to energy; higher wavenumbers correspond to higher energy transitions. In IR spectroscopy, wavenumbers are used to specify the frequencies at which molecular vibrations occur, aiding in the identification of functional groups.
Characteristic Absorption Bands
Characteristic absorption bands are specific ranges of wavenumbers where certain functional groups absorb infrared radiation. For example, carbonyl groups (C=O) typically absorb around 1700 cm⁻¹, while hydroxyl groups (O-H) absorb around 3200-3600 cm⁻¹. Recognizing these bands is crucial for interpreting IR spectra and determining the structure of organic compounds.
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Related Practice
Textbook Question
Each of the IR spectra shown below is the spectrum of one of the following compounds. Identify the compound that produced each spectrum.
a. <IMAGE>
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
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
Phenolphthalein is an acid–base indicator. In solutions of pH < 8.5, it is colorless; in solutions of pH > 8.5, it is deep red-purple. Account for the change in color.
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