Textbook Question
For each of these ions, draw the important resonance forms and predict which resonance form is likely to be the major contributor.
(c)
650
views
Ch.1 - Structure and Bonding
Wade9th EditionOrganic ChemistryISBN: 9780135213728
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 1, Problem 44b
For each of these ions, draw the important resonance forms and predict which resonance form is likely to be the major contributor.
(b) 
Verified step by step guidance1
Identify the ion in the structure: The given structure is a benzyl anion, where the negative charge is located on the CH2 group attached to the benzene ring.
Draw the first resonance structure: Move the lone pair of electrons from the negatively charged carbon to form a double bond with the adjacent carbon atom in the benzene ring. This will push the electrons in the adjacent double bond towards the next carbon atom, creating a new resonance structure.
Draw the second resonance structure: Continue the electron movement by pushing the electrons from the newly formed double bond to the next carbon-carbon double bond in the benzene ring, creating another resonance structure with the negative charge now on a different carbon atom in the ring.
Draw the third resonance structure: Repeat the electron movement process to push the electrons from the current double bond to the next carbon-carbon double bond, resulting in a resonance structure with the negative charge on yet another carbon atom in the benzene ring.
Predict the major contributor: Evaluate the resonance structures based on stability. The major contributor is typically the one where the negative charge is on the most electronegative atom or the one that maintains aromaticity. In this case, the structure that maintains the aromaticity of the benzene ring and has the negative charge on the CH2 group is likely the major contributor.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
6mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Resonance Structures
Resonance structures are different Lewis structures for a molecule that depict the same arrangement of atoms but differ in the distribution of electrons. They are used to represent delocalized electrons within certain molecules where the bonding cannot be expressed by a single Lewis structure. The true structure is a hybrid of all possible resonance forms, contributing to the molecule's stability.
Recommended video:
Guided course
03:04
Drawing Resonance Structures
Major Resonance Contributor
The major resonance contributor is the resonance structure that most accurately represents the molecule's electron distribution. It typically has the lowest energy, which is achieved by minimizing formal charges, maximizing covalent bonds, and placing negative charges on more electronegative atoms. This structure contributes most to the resonance hybrid, influencing the molecule's properties.
Recommended video:
Guided course
03:04Drawing Resonance Structures
Electronegativity and Charge Distribution
Electronegativity is the tendency of an atom to attract electrons towards itself. In resonance structures, the distribution of charges is influenced by electronegativity, with negative charges preferably residing on more electronegative atoms like oxygen. This affects the stability of resonance forms, as structures with charges on appropriate atoms are more stable and likely to be major contributors.
Recommended video:
Guided course
1:47Electronegativity
Related Practice
Textbook Question
Draw the important resonance forms to show the delocalization of charges in the following ions. In each case, indicate the major resonance form(s).
(j)
(k)
2139
views
Textbook Question
Use resonance structures to identify the areas of high and low electron density in the following compounds:
(a)
(b)
(c)
2291
views
Textbook Question
In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing important resonance forms.
(d)
(e)
1393
views
Textbook Question
For each pair of ions, determine which ion is more stable. Use resonance forms to explain your answers.
(e)
(f)
1571
views
Textbook Question
For each of these ions, draw the important resonance forms and predict which resonance form is likely to be the major contributor.
(a)
695
views