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Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
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All textbooksMullins 1st EditionCh. 15 - Structural Identification II: Nuclear Magnetic Resonance SpectroscopyProblem 6
Chapter 14, Problem 6

The spectrum shown here is for a molecule with a molecular formula of C₄H₉Cl. Suggest a structure for this molecule.
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Identify the degree of unsaturation for the molecule using the formula: \( \text{Degree of Unsaturation} = rac{2C + 2 + N - X - H}{2} \), where \( C \) is the number of carbons, \( N \) is the number of nitrogens, \( X \) is the number of halogens, and \( H \) is the number of hydrogens. For \( C_4H_9Cl \), calculate the degree of unsaturation.
Since the degree of unsaturation is zero, the molecule is saturated, meaning it contains no double bonds, triple bonds, or rings.
Consider the possible structures for a saturated alkyl chloride with four carbon atoms. These structures are based on the possible arrangements of the carbon skeleton: straight chain or branched.
Draw the possible isomers of \( C_4H_9Cl \). These include 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, and 2-chloro-2-methylpropane.
Analyze the given spectrum data (e.g., NMR, IR, or mass spectrometry) to determine which of the possible isomers matches the spectral characteristics. Look for key signals or peaks that indicate the presence of specific functional groups or structural features.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molecular Formula Interpretation

Understanding the molecular formula C₄H₉Cl involves recognizing that it represents a compound with four carbon atoms, nine hydrogen atoms, and one chlorine atom. This formula suggests a saturated hydrocarbon backbone with a single chlorine substituent, indicating potential structures such as chlorinated alkanes.
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Spectroscopy Analysis

Spectroscopy is a technique used to determine the structure of molecules by analyzing the interaction of light with matter. In this context, interpreting the spectrum involves identifying peaks that correspond to specific functional groups or structural features, such as the presence of chlorine and the arrangement of carbon and hydrogen atoms.
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Isomerism in Organic Chemistry

Isomerism refers to the existence of compounds with the same molecular formula but different structural arrangements. For C₄H₉Cl, several isomers are possible, including different positions for the chlorine atom on the carbon chain. Understanding isomerism is crucial for proposing a plausible structure based on the given spectrum.
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Related Practice
Textbook Question

Radical chlorination, a reaction studied in Chapters 5 and 11, replaces a hydrogen with a chlorine. Assuming there is no regioselectivity (all hydrogens can react equally), how many different chloroalkanes are possible upon reaction of each alkane with one equivalent of Cl₂

(a)

(b)

(c)

(d)

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Textbook Question

How many sets of equivalent hydrogens are in each molecule shown?

(a)

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Textbook Question

(a) Rank the following bonds in terms of the strength of their bond dipole (1 = weakest, 6 = strongest).

(b) Which carbon has the largest δ⁺ ?

C―F, C―Br, C―I, C―H, C―C, C―Cl

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Textbook Question

Draw the peak that would correspond to the hydrogens at C₃ in the molecule shown. Be sure to indicate the integration and place it at an appropriate chemical shift.

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Textbook Question

Every number in Pascal’s triangle is the sum of the two numbers above it. Given this, fill in the missing numbers.

4
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Textbook Question

Calculate the index of hydrogen deficiency for curacin A, which has a molecular formula of C23H35NOS .

6
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