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Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy
Bruice - Organic Chemistry 8th Edition
Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook
All textbooksBruice 8th EditionCh. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis SpectroscopyProblem 59
Chapter 14, Problem 59

Which one of the following five compounds produced the IR spectrum shown below?

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Verified step by step guidance
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Analyze the IR spectrum provided and identify the key absorption peaks. Look for characteristic wavenumbers (in cm⁻¹) that correspond to specific functional groups. For example, a broad peak around 3200-3600 cm⁻¹ indicates an O-H stretch (alcohol or carboxylic acid), while a sharp peak near 1700 cm⁻¹ suggests a C=O stretch (carbonyl group).
Compare the identified functional groups from the IR spectrum with the functional groups present in each of the five compounds provided. Match the observed peaks to the possible functional groups in the compounds.
Pay attention to any unique or distinguishing peaks in the IR spectrum that can help differentiate between the compounds. For instance, a peak near 2200 cm⁻¹ could indicate a C≡C or C≡N triple bond, while peaks near 1500-1600 cm⁻¹ might suggest aromatic C=C stretches.
Eliminate compounds that do not have functional groups corresponding to the observed peaks in the IR spectrum. Narrow down the options by systematically ruling out mismatches.
Once you have identified the compound that matches all the key peaks in the IR spectrum, verify your choice by ensuring that no other compound fits the spectrum as well. This will confirm the correct answer.

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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 frequencies of IR radiation, resulting in a spectrum that can be analyzed to determine the presence of specific functional groups, such as alcohols, carbonyls, and amines.
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General Features of IR Spect

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Understanding common functional groups, such as hydroxyl (-OH), carbonyl (C=O), and carboxyl (-COOH), is essential for interpreting IR spectra, as each group has distinct absorption peaks.
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Spectrum Interpretation

Interpreting an IR spectrum involves analyzing the peaks and their corresponding wavenumbers to deduce the molecular structure of a compound. Peaks indicate the presence of specific functional groups, and their intensity and position can provide insights into molecular interactions and the environment of the functional groups.
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Related Practice
Textbook Question

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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Textbook Question

Rank the following compounds from highest wavenumber to lowest wavenumber for their C-O absorption band:

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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

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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