Textbook Question
Two resonance structures are shown for each molecule. Use the arrow-pushing formalism to represent the electron flow from the structure on the left to the one on the right.
(d)
1. A Review of General Chemistry
Resonance Structures
4:59 minutesProblem 45c,d
Textbook Question
Draw the important resonance forms of the following free radicals.
(c) 
(d) 
Verified step by step guidance1
Identify the free radical in the given structure. For CH3COO⋅, the radical is on the oxygen atom. For the cyclohexene radical, the radical is on the carbon atom adjacent to the double bond.
For CH3COO⋅, consider the resonance between the radical on the oxygen and the carbonyl group. The lone electron on the oxygen can form a double bond with the carbon, while the π bond of the carbonyl group can shift to the oxygen, creating a new radical site.
Draw the resonance structure for CH3COO⋅: Move the lone electron from the oxygen to form a double bond with the carbon, and move the π bond electrons of the carbonyl group to the oxygen, resulting in a structure with a radical on the carbonyl oxygen.
For the cyclohexene radical, consider the resonance involving the π bond. The radical electron can pair with one of the π electrons, forming a new π bond, while the other π electron moves to the adjacent carbon, creating a new radical site.
Draw the resonance structure for the cyclohexene radical: Shift the radical electron to form a double bond with the adjacent carbon, and move one of the π electrons to the next carbon, resulting in a new radical site on the carbon adjacent to the original double bond.
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4mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Resonance Structures
Resonance structures are different ways of drawing the same molecule that illustrate the delocalization of electrons. They help in understanding the stability and reactivity of molecules, particularly in cases where a single Lewis structure cannot adequately represent the electron distribution. In free radicals, resonance can stabilize the unpaired electron by allowing it to be shared across multiple atoms.
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Drawing Resonance Structures
Free Radicals
Free radicals are species that contain an unpaired electron, making them highly reactive. They can be formed through various processes, including the breaking of covalent bonds. Understanding the nature of free radicals is crucial for predicting their behavior in chemical reactions, as they often seek to pair their unpaired electron by reacting with other molecules.
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Stability of Radicals
The stability of free radicals is influenced by their structure and the presence of substituents. Generally, radicals are more stable when they are tertiary (attached to three other carbon atoms) compared to secondary or primary radicals. This stability can be explained by hyperconjugation and resonance effects, which help to delocalize the unpaired electron, reducing the overall energy of the radical.
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03:43The radical stability trend.
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