Textbook Question
Which of the following reactions would you expect to be faster/more favorable in each pair? Why?
(b)
16. Conjugated Systems
Stability of Conjugated Intermediates
8:15 minutesProblem 10
Textbook Question
Which has the greater delocalization energy?
Verified step by step guidance1
Step 1: Analyze the structures provided in the image. Both molecules contain conjugated systems with alternating double and single bonds, and an oxygen atom attached to the chain. The conjugation allows for delocalization of π-electrons across the system.
Step 2: Delocalization energy is influenced by the extent of conjugation. A longer conjugated system (more alternating double and single bonds) typically results in greater delocalization energy because the π-electrons can spread over a larger area.
Step 3: Compare the conjugated systems in the two molecules. Count the number of conjugated double bonds in each structure. The molecule with more conjugated double bonds will have greater delocalization energy.
Step 4: Consider the position of the oxygen atom. The oxygen atom can participate in resonance, potentially increasing the delocalization energy. Evaluate how the oxygen atom interacts with the conjugated system in each molecule.
Step 5: Based on the analysis of conjugation length and the role of the oxygen atom, determine which molecule has the greater delocalization energy. The molecule with the longer conjugated system and better resonance interaction with the oxygen atom will have higher delocalization energy.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Delocalization Energy
Delocalization energy refers to the stabilization that occurs when electrons are spread out over multiple atoms rather than localized between two. This phenomenon is particularly significant in conjugated systems, where alternating single and double bonds allow for resonance. The greater the delocalization, the lower the energy of the system, leading to increased stability.
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Conjugation
Conjugation is a structural feature in organic molecules where alternating single and double bonds create a system of overlapping p-orbitals. This arrangement allows for the delocalization of π electrons across the entire molecule, enhancing stability and influencing reactivity. Conjugated systems often exhibit unique optical and electronic properties due to this electron delocalization.
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Resonance Structures
Resonance structures are different Lewis structures that represent the same molecule, illustrating the delocalization of electrons. These structures help visualize how electrons are distributed across a molecule, contributing to its overall stability. The true structure of the molecule is a hybrid of these resonance forms, and the more resonance forms a molecule has, the greater its delocalization energy.
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