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Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
All textbooksMullins 1st EditionCh. 12 - Substitution and Elimination: Reactions of HaloalkanesProblem 56e
Chapter 11, Problem 56e

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.
(e)

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1
Analyze the given reactants: The starting material is a brominated compound with a phenyl group (Ph) and a stereocenter. The reagent is sodium azide (NaN₃) in a solvent containing a cyclic ether (likely polar aprotic). This suggests a nucleophilic substitution reaction.
Determine the reaction mechanism: Sodium azide (NaN₃) is a strong nucleophile, and the polar aprotic solvent favors an SN2 mechanism. In an SN2 reaction, the nucleophile attacks the electrophilic carbon directly, leading to inversion of stereochemistry at the stereocenter.
Identify the leaving group: Bromine (Br) is the leaving group. The azide ion (N₃⁻) will replace the bromine via backside attack, resulting in inversion of the stereochemistry at the carbon where bromine was attached.
Predict the stereochemical outcome: Since the reaction proceeds via an SN2 mechanism, the stereochemistry of the product will be inverted relative to the starting material. The azide group (N₃) will occupy the position opposite to the original bromine.
Write the product structure: The product will be a compound where the azide group (N₃) replaces the bromine, with inverted stereochemistry at the carbon center. The phenyl group (Ph) and the ethyl group will retain their original positions.

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Key Concepts

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

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions involve the replacement of a leaving group in a molecule by a nucleophile. These reactions can occur via two main mechanisms: SN1, which is a two-step process involving carbocation formation, and SN2, which is a one-step process where the nucleophile attacks the substrate simultaneously as the leaving group departs. Understanding the mechanism is crucial for predicting the products and their stereochemistry.
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Elimination Reactions

Elimination reactions involve the removal of a leaving group and a hydrogen atom from adjacent carbon atoms, resulting in the formation of a double bond. The two primary types are E1, which proceeds through a carbocation intermediate, and E2, which is a concerted mechanism. The choice between substitution and elimination often depends on the structure of the substrate and the reaction conditions, influencing the stereochemical outcome.
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Stereochemistry

Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In substitution and elimination reactions, the stereochemical outcome can lead to different isomers, such as cis/trans or R/S configurations. Recognizing the stereochemical implications is essential for accurately predicting the products of reactions, especially in cases where chirality is involved.
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Related Practice
Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(h)

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Textbook Question

Predict the major product(s) of the following elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(f)

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Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(a)

2
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Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(g)

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Textbook Question

Predict the product(s) of the following substitution or elimination reactions, paying close attention to the stereochemical outcome of the reactions.

(d)

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Textbook Question

For each pair, choose the nucleophile that would react most quickly in an SN2 reaction (assume H2O is the solvent).

(a) F- vs Br-

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