Textbook Question
Each of these compounds can react as a nucleophile. In each case, use curved arrows to show how the nucleophile would react with the strong electrophile BF3.
(e) CH3CH2OH
552
views
Ch. 2 - Acids and Bases; Functional Groups
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 2, Problem 54c
The pKa of ascorbic acid (vitamin C, page 55) is 4.17, showing that it is slightly more acidic than acetic acid (CH3COOH, pKa 4.74).
c. Compare the most stable conjugate base of ascorbic acid with the conjugate base of acetic acid, and suggest why these two compounds have similar acidities, even though ascorbic acid lacks the carboxylic acid (COOH) group.
Verified step by step guidance1
Identify the functional groups in ascorbic acid and acetic acid. Ascorbic acid contains multiple hydroxyl groups and a lactone ring, while acetic acid contains a carboxylic acid group.
Determine the conjugate base of each acid. For ascorbic acid, deprotonation occurs at one of the hydroxyl groups, leading to a resonance-stabilized anion. For acetic acid, deprotonation occurs at the carboxylic acid group, forming an acetate ion.
Analyze the resonance stabilization of the conjugate bases. Ascorbic acid's conjugate base is stabilized by resonance within the lactone ring and adjacent hydroxyl groups, while acetic acid's conjugate base is stabilized by resonance between the oxygen atoms in the carboxylate group.
Consider the electronegativity and inductive effects. The electronegative oxygen atoms in ascorbic acid contribute to its acidity, similar to the electronegative oxygen in acetic acid's carboxyl group.
Conclude why the acidities are similar. Despite lacking a carboxylic acid group, ascorbic acid's structure allows for effective resonance stabilization and electronegative influence, making its acidity comparable to acetic acid.
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.
Acidity and pKa
Acidity is a measure of a substance's ability to donate protons (H+ ions) in solution. The pKa value quantifies this acidity, with lower pKa values indicating stronger acids. Ascorbic acid has a pKa of 4.17, making it a stronger acid than acetic acid, which has a pKa of 4.74. Understanding these values helps compare the relative strengths of different acids.
Recommended video:
Guided course
07:45
Identifying pKa values
Conjugate Bases
When an acid donates a proton, it forms its conjugate base. The stability of the conjugate base significantly influences the acidity of the original acid. In the case of ascorbic acid, its conjugate base is stabilized by resonance and intramolecular hydrogen bonding, which can explain its comparable acidity to acetic acid, despite the absence of a carboxylic acid group.
Recommended video:
Guided course
03:27Conjugated states
Resonance Stabilization
Resonance stabilization occurs when a molecule can be represented by multiple valid Lewis structures, allowing for the delocalization of electrons. This delocalization can enhance the stability of a conjugate base. In ascorbic acid, the presence of hydroxyl groups and the structure of the molecule allow for effective resonance stabilization, contributing to its acidity despite lacking a traditional carboxylic acid group.
Recommended video:
Guided course
03:43The radical stability trend.
Related Practice
Textbook Question
The pKa of ascorbic acid (vitamin C, page 55) is 4.17, showing that it is slightly more acidic than acetic acid (CH3COOH, pKa 4.74).
a. Show the four different conjugate bases that would be formed by deprotonation of the four different OH groups in ascorbic acid.
b. Compare the stabilities of these four conjugate bases, and predict which OH group of ascorbic acid is the most acidic.
1076
views
Textbook Question
Each of these compounds can react as a nucleophile. In each case, use curved arrows to show how the nucleophile would react with the strong electrophile BF3.
(f) (CH3)2S
609
views
Textbook Question
Many naturally occurring compounds contain more than one functional group. Identify the functional groups in the following compounds:
a. Penicillin G is a naturally occurring antibiotic.
b. Dopamine is the neurotransmitter that is deficient in Parkinson’s disease.
1003
views
Textbook Question
Many naturally occurring compounds contain more than one functional group. Identify the functional groups in the following compounds:
d. Thyroxine is the principal thyroid hormone.
785
views