Textbook Question
Which is a better nucleophile?
c. CH3O− or CH3OH in H2O
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Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 11
Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 11Chapter 10, Problem 11
a. Which is a stronger base: RO− or RS−?
b. Which is a better nucleophile in an aqueous solution?
c. Which is a better nucleophile in DMSO?
Verified step by step guidance1
Step 1: To determine which is a stronger base (RO⁻ or RS⁻), consider the periodic trends in electronegativity and the stability of the conjugate acid. Oxygen (O) is more electronegative than sulfur (S), meaning RO⁻ holds onto its negative charge more tightly, making it less stable and a stronger base. RS⁻, on the other hand, is more stable due to the larger size of sulfur, which can better delocalize the negative charge.
Step 2: To determine which is a better nucleophile in an aqueous solution, consider the solvation effects. In water, the smaller RO⁻ ion is more strongly solvated due to hydrogen bonding, which reduces its nucleophilicity. RS⁻, being larger and less solvated, is a better nucleophile in aqueous solution.
Step 3: To determine which is a better nucleophile in DMSO (a polar aprotic solvent), consider the lack of hydrogen bonding in such solvents. In DMSO, solvation effects are minimal, so the intrinsic nucleophilicity of the species dominates. RS⁻, being larger and more polarizable, is a better nucleophile than RO⁻ in DMSO.
Step 4: Summarize the periodic trends and solvent effects. The strength of a base is influenced by electronegativity and charge delocalization, while nucleophilicity depends on solvation and polarizability. RO⁻ is a stronger base, but RS⁻ is a better nucleophile in both aqueous and DMSO solvents.
Step 5: Conclude by emphasizing the importance of understanding the interplay between periodic trends, solvent effects, and the specific properties of the nucleophile or base in question. This knowledge is crucial for predicting reactivity in organic chemistry.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Basicity
Basicity refers to the ability of a species to accept protons (H+). In organic chemistry, the strength of a base is often influenced by the stability of its conjugate acid. For alkoxide ions (RO−) and thiolate ions (RS−), the presence of electronegative atoms and resonance can affect their basicity, with RO− generally being a stronger base due to the higher electronegativity of oxygen compared to sulfur.
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Understanding the difference between basicity and nucleophilicity.
Nucleophilicity
Nucleophilicity is the measure of a species' ability to donate an electron pair to an electrophile during a chemical reaction. Factors influencing nucleophilicity include charge, electronegativity, and solvent effects. In aqueous solutions, nucleophiles are often more hindered by solvation, while in polar aprotic solvents like DMSO, nucleophilicity can be enhanced due to reduced solvation of the nucleophile.
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Solvent Effects
Solvent effects play a crucial role in determining the reactivity of nucleophiles and bases. In polar protic solvents, such as water, nucleophiles are stabilized by hydrogen bonding, which can hinder their reactivity. Conversely, in polar aprotic solvents like DMSO, nucleophiles are less solvated, allowing for greater reactivity and making them better nucleophiles in such environments.
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Related Practice
Textbook Question
Indicate whether each of the following solvents is protic or aprotic:
a. chloroform (CHCl3)
b. diethyl ether
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Textbook Question
Indicate whether each of the following solvents is protic or aprotic:
c. acetic acid
d. hexane
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Textbook Question
Which is a better nucleophile?
e. HO− or -NH2 in NH3
f. HO− or -NH2 in DMSO
1924
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Textbook Question
Which is a better nucleophile?
d. CH3O− or CH3OH in DMSO
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Textbook Question
Which alkyl halide is more reactive in an SN2 reaction with a given nucleophile?
c.
d.
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