Textbook Question
Predict the product(s) of the reactions shown.
(b)
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Ch. 25 - Amines: Structure, Reactions, and Synthesis
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471
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Table of contents
- Ch. 2 - General Chemistry Translated: Finding the Electrons114
- Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis109
- Ch. 4 - Acids and Bases: Electron Flow144
- Ch. 5 - Chemical Reaction Analysis: Thermodynamics and Kinetics118
- Ch. 6 - Stereoisomerism: Arrangement of Atoms in Space112
- Ch. 7 - Principles of Green (Organic) Chemistry3
- Ch. 8 - Alkenes I: Properties and Electrophilic Additions158
- Ch. 9 - Alkenes II: Oxidation and Reduction150
- Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions101
- Ch. 11 - Properties and Synthesis of Alkyl Halides: Radical Reactions108
- Ch. 12 - Substitution and Elimination: Reactions of Haloalkanes172
- Ch. 13 - Alcohols, Ethers and Related Compounds: Substitution and Elimination239
- Ch. 14 - Structural Identification I: Infrared Spectroscopy and Mass Spectrometry54
- Ch. 15 - Structural Identification II: Nuclear Magnetic Resonance Spectroscopy93
- Ch. 16 - Metals in Organic Chemistry48
- Ch. 17 - Carbonyl Addition Reactions: Aldehydes and Ketones45
- Ch. 18 - Nucleophilic Acyl Substitution I: Carboxylic Acids18
- Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives39
- Ch. 20 - Enolates: Carbonyl Addition and Substitution13
- Ch. 21 - Conjugated Systems I: Stability and Addition Reactions56
- Ch. 22 - Conjugated Systems II: Pericyclic Reactions54
- Ch. 23 - Benzene I: Aromatic Stability and Substitution Reactions64
- Ch. 24 - Benzene II: Reactions Influenced by the Aromatic Ring62
- Ch. 25 - Amines: Structure, Reactions, and Synthesis27
- Ch. 26 - Amino Acids, Proteins, and Peptide Synthesis9
- Ch. 27 - Carbohydrates, Nucleic Acids, and Lipids54
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 24, Problem 46c
Given the pKb, calculate the pKa of the conjugate acid.
(c) 
Verified step by step guidance1
Step 1: Recall the relationship between pKa and pKb for a conjugate acid-base pair. The equation is: \( pKa + pKb = 14 \). This equation is derived from the ionization constant of water \( K_w \), where \( K_w = 10^{-14} \) at 25°C.
Step 2: Identify the given value in the problem. The pKb of morpholine is provided as \( 5.6 \). This corresponds to the basicity of morpholine.
Step 3: Rearrange the equation \( pKa + pKb = 14 \) to solve for pKa. The rearranged equation is: \( pKa = 14 - pKb \).
Step 4: Substitute the given pKb value into the rearranged equation. Replace \( pKb \) with \( 5.6 \) in the equation \( pKa = 14 - pKb \).
Step 5: Perform the subtraction to calculate the pKa value. The result will represent the acidity of the conjugate acid of morpholine.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pKa and pKb Relationship
The pKa and pKb values are related through the equation pKa + pKb = 14 at 25°C. The pKa represents the acidity of a compound, while pKb indicates its basicity. For a conjugate acid-base pair, knowing one value allows the calculation of the other, which is essential for understanding the strength of acids and bases.
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Identifying pKa values
Conjugate Acids and Bases
A conjugate acid is formed when a base accepts a proton (H+), while a conjugate base is what remains after an acid donates a proton. In this context, morpholine acts as a base, and its conjugate acid is formed when it accepts a proton. Understanding this relationship is crucial for calculating pKa from pKb.
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Morpholine Structure and Properties
Morpholine is a cyclic amine with a nitrogen atom in its structure, which contributes to its basic properties. The presence of the nitrogen atom allows morpholine to accept protons, making it a base. Its pKb value of 5.6 indicates its strength as a base, which is important for determining the pKa of its conjugate acid.
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Related Practice
Textbook Question
The nitro group directs electrophilic aromatic substitution to the meta position. After reduction by hydrogenation, to which carbon(s) does it direct?
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Textbook Question
Despite the amino group being an ortho/para director, nitration of aniline gives the meta isomer predominantly. Explain this result.
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Textbook Question
Calculate the equilibrium constant for each of the acid–base reactions shown.
b.
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Textbook Question
Given the pKb, calculate the pKa of the conjugate acid.
(b)
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Textbook Question
Following a LiAlH₄ reduction, an IR spectrum suggested that the product was a mixture of the starting amide and the desired amine.
(b) Once separated, how could you distinguish between the amide and the amine using IR spectroscopy?
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