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Organic Chemistry

Additional Problems

Organic ChemistryAdditional Problems

Table of contents
  1. Dedication and Preface
  2. 1 Structure and Bonding
    1. Why This Chapter?
    2. 1.1 Atomic Structure: The Nucleus
    3. 1.2 Atomic Structure: Orbitals
    4. 1.3 Atomic Structure: Electron Configurations
    5. 1.4 Development of Chemical Bonding Theory
    6. 1.5 Describing Chemical Bonds: Valence Bond Theory
    7. 1.6 sp3 Hybrid Orbitals and the Structure of Methane
    8. 1.7 sp3 Hybrid Orbitals and the Structure of Ethane
    9. 1.8 sp2 Hybrid Orbitals and the Structure of Ethylene
    10. 1.9 sp Hybrid Orbitals and the Structure of Acetylene
    11. 1.10 Hybridization of Nitrogen, Oxygen, Phosphorus, and Sulfur
    12. 1.11 Describing Chemical Bonds: Molecular Orbital Theory
    13. 1.12 Drawing Chemical Structures
    14. Chemistry Matters—Organic Foods: Risk versus Benefit
    15. Key Terms
    16. Summary
    17. Additional Problems
  3. 2 Polar Covalent Bonds; Acids and Bases
    1. Why This Chapter?
    2. 2.1 Polar Covalent Bonds and Electronegativity
    3. 2.2 Polar Covalent Bonds and Dipole Moments
    4. 2.3 Formal Charges
    5. 2.4 Resonance
    6. 2.5 Rules for Resonance Forms
    7. 2.6 Drawing Resonance Forms
    8. 2.7 Acids and Bases: The Brønsted–Lowry Definition
    9. 2.8 Acid and Base Strength
    10. 2.9 Predicting Acid–Base Reactions from pKa Values
    11. 2.10 Organic Acids and Organic Bases
    12. 2.11 Acids and Bases: The Lewis Definition
    13. 2.12 Noncovalent Interactions between Molecules
    14. Chemistry Matters—Alkaloids: From Cocaine to Dental Anesthetics
    15. Key Terms
    16. Summary
    17. Additional Problems
  4. 3 Organic Compounds: Alkanes and Their Stereochemistry
    1. Why This Chapter?
    2. 3.1 Functional Groups
    3. 3.2 Alkanes and Alkane Isomers
    4. 3.3 Alkyl Groups
    5. 3.4 Naming Alkanes
    6. 3.5 Properties of Alkanes
    7. 3.6 Conformations of Ethane
    8. 3.7 Conformations of Other Alkanes
    9. Chemistry Matters—Gasoline
    10. Key Terms
    11. Summary
    12. Additional Problems
  5. 4 Organic Compounds: Cycloalkanes and Their Stereochemistry
    1. Why This Chapter?
    2. 4.1 Naming Cycloalkanes
    3. 4.2 Cis–Trans Isomerism in Cycloalkanes
    4. 4.3 Stability of Cycloalkanes: Ring Strain
    5. 4.4 Conformations of Cycloalkanes
    6. 4.5 Conformations of Cyclohexane
    7. 4.6 Axial and Equatorial Bonds in Cyclohexane
    8. 4.7 Conformations of Monosubstituted Cyclohexanes
    9. 4.8 Conformations of Disubstituted Cyclohexanes
    10. 4.9 Conformations of Polycyclic Molecules
    11. Chemistry Matters—Molecular Mechanics
    12. Key Terms
    13. Summary
    14. Additional Problems
  6. 5 Stereochemistry at Tetrahedral Centers
    1. Why This Chapter?
    2. 5.1 Enantiomers and the Tetrahedral Carbon
    3. 5.2 The Reason for Handedness in Molecules: Chirality
    4. 5.3 Optical Activity
    5. 5.4 Pasteur’s Discovery of Enantiomers
    6. 5.5 Sequence Rules for Specifying Configuration
    7. 5.6 Diastereomers
    8. 5.7 Meso Compounds
    9. 5.8 Racemic Mixtures and the Resolution of Enantiomers
    10. 5.9 A Review of Isomerism
    11. 5.10 Chirality at Nitrogen, Phosphorus, and Sulfur
    12. 5.11 Prochirality
    13. 5.12 Chirality in Nature and Chiral Environments
    14. Chemistry Matters—Chiral Drugs
    15. Key Terms
    16. Summary
    17. Additional Problems
  7. 6 An Overview of Organic Reactions
    1. Why This Chapter?
    2. 6.1 Kinds of Organic Reactions
    3. 6.2 How Organic Reactions Occur: Mechanisms
    4. 6.3 Polar Reactions
    5. 6.4 An Example of a Polar Reaction: Addition of HBr to Ethylene
    6. 6.5 Using Curved Arrows in Polar Reaction Mechanisms
    7. 6.6 Radical Reactions
    8. 6.7 Describing a Reaction: Equilibria, Rates, and Energy Changes
    9. 6.8 Describing a Reaction: Bond Dissociation Energies
    10. 6.9 Describing a Reaction: Energy Diagrams and Transition States
    11. 6.10 Describing a Reaction: Intermediates
    12. 6.11 A Comparison Between Biological Reactions and Laboratory Reactions
    13. Chemistry Matters—Where Do Drugs Come From?
    14. Key Terms
    15. Summary
    16. Additional Problems
  8. 7 Alkenes: Structure and Reactivity
    1. Why This Chapter?
    2. 7.1 Industrial Preparation and Use of Alkenes
    3. 7.2 Calculating the Degree of Unsaturation
    4. 7.3 Naming Alkenes
    5. 7.4 Cis–Trans Isomerism in Alkenes
    6. 7.5 Alkene Stereochemistry and the E,Z Designation
    7. 7.6 Stability of Alkenes
    8. 7.7 Electrophilic Addition Reactions of Alkenes
    9. 7.8 Orientation of Electrophilic Additions: Markovnikov’s Rule
    10. 7.9 Carbocation Structure and Stability
    11. 7.10 The Hammond Postulate
    12. 7.11 Evidence for the Mechanism of Electrophilic Additions: Carbocation Rearrangements
    13. Chemistry Matters—Bioprospecting: Hunting for Natural Products
    14. Key Terms
    15. Summary
    16. Additional Problems
  9. 8 Alkenes: Reactions and Synthesis
    1. Why This Chapter?
    2. 8.1 Preparing Alkenes: A Preview of Elimination Reactions
    3. 8.2 Halogenation of Alkenes: Addition of X2
    4. 8.3 Halohydrins from Alkenes: Addition of HO-X
    5. 8.4 Hydration of Alkenes: Addition of H2O by Oxymercuration
    6. 8.5 Hydration of Alkenes: Addition of H2O by Hydroboration
    7. 8.6 Reduction of Alkenes: Hydrogenation
    8. 8.7 Oxidation of Alkenes: Epoxidation and Hydroxylation
    9. 8.8 Oxidation of Alkenes: Cleavage to Carbonyl Compounds
    10. 8.9 Addition of Carbenes to Alkenes: Cyclopropane Synthesis
    11. 8.10 Radical Additions to Alkenes: Chain-Growth Polymers
    12. 8.11 Biological Additions of Radicals to Alkenes
    13. 8.12 Reaction Stereochemistry: Addition of H2O to an Achiral Alkene
    14. 8.13 Reaction Stereochemistry: Addition of H2O to a Chiral Alkene
    15. Chemistry Matters—Terpenes: Naturally Occurring Alkenes
    16. Key Terms
    17. Summary
    18. Summary of Reactions
    19. Additional Problems
  10. 9 Alkynes: An Introduction to Organic Synthesis
    1. Why This Chapter?
    2. 9.1 Naming Alkynes
    3. 9.2 Preparation of Alkynes: Elimination Reactions of Dihalides
    4. 9.3 Reactions of Alkynes: Addition of HX and X2
    5. 9.4 Hydration of Alkynes
    6. 9.5 Reduction of Alkynes
    7. 9.6 Oxidative Cleavage of Alkynes
    8. 9.7 Alkyne Acidity: Formation of Acetylide Anions
    9. 9.8 Alkylation of Acetylide Anions
    10. 9.9 An Introduction to Organic Synthesis
    11. Chemistry Matters—The Art of Organic Synthesis
    12. Key Terms
    13. Summary
    14. Summary of Reactions
    15. Additional Problems
  11. 10 Organohalides
    1. Why This Chapter?
    2. 10.1 Names and Structures of Alkyl Halides
    3. 10.2 Preparing Alkyl Halides from Alkanes: Radical Halogenation
    4. 10.3 Preparing Alkyl Halides from Alkenes: Allylic Bromination
    5. 10.4 Stability of the Allyl Radical: Resonance Revisited
    6. 10.5 Preparing Alkyl Halides from Alcohols
    7. 10.6 Reactions of Alkyl Halides: Grignard Reagents
    8. 10.7 Organometallic Coupling Reactions
    9. 10.8 Oxidation and Reduction in Organic Chemistry
    10. Chemistry Matters—Naturally Occurring Organohalides
    11. Key Terms
    12. Summary
    13. Summary of Reactions
    14. Additional Problems
  12. 11 Reactions of Alkyl Halides: Nucleophilic Substitutions and Eliminations
    1. Why This Chapter?
    2. 11.1 The Discovery of Nucleophilic Substitution Reactions
    3. 11.2 The SN2 Reaction
    4. 11.3 Characteristics of the SN2 Reaction
    5. 11.4 The SN1 Reaction
    6. 11.5 Characteristics of the SN1 Reaction
    7. 11.6 Biological Substitution Reactions
    8. 11.7 Elimination Reactions: Zaitsev’s Rule
    9. 11.8 The E2 Reaction and the Deuterium Isotope Effect
    10. 11.9 The E2 Reaction and Cyclohexane Conformation
    11. 11.10 The E1 and E1cB Reactions
    12. 11.11 Biological Elimination Reactions
    13. 11.12 A Summary of Reactivity: SN1, SN2, E1, E1cB, and E2
    14. Chemistry Matters—Green Chemistry
    15. Key Terms
    16. Summary
    17. Summary of Reactions
    18. Additional Problems
  13. 12 Structure Determination: Mass Spectrometry and Infrared Spectroscopy
    1. Why This Chapter?
    2. 12.1 Mass Spectrometry of Small Molecules: Magnetic-Sector Instruments
    3. 12.2 Interpreting Mass Spectra
    4. 12.3 Mass Spectrometry of Some Common Functional Groups
    5. 12.4 Mass Spectrometry in Biological Chemistry: Time-of-Flight (TOF) Instruments
    6. 12.5 Spectroscopy and the Electromagnetic Spectrum
    7. 12.6 Infrared Spectroscopy
    8. 12.7 Interpreting Infrared Spectra
    9. 12.8 Infrared Spectra of Some Common Functional Groups
    10. Chemistry Matters—X-Ray Crystallography
    11. Key Terms
    12. Summary
    13. Additional Problems
  14. 13 Structure Determination: Nuclear Magnetic Resonance Spectroscopy
    1. Why This Chapter?
    2. 13.1 Nuclear Magnetic Resonance Spectroscopy
    3. 13.2 The Nature of NMR Absorptions
    4. 13.3 Chemical Shifts
    5. 13.4 Chemical Shifts in 1H NMR Spectroscopy
    6. 13.5 Integration of 1H NMR Absorptions: Proton Counting
    7. 13.6 Spin–Spin Splitting in 1H NMR Spectra
    8. 13.7 1H NMR Spectroscopy and Proton Equivalence
    9. 13.8 More Complex Spin–Spin Splitting Patterns
    10. 13.9 Uses of 1H NMR Spectroscopy
    11. 13.10 13C NMR Spectroscopy: Signal Averaging and FT–NMR
    12. 13.11 Characteristics of 13C NMR Spectroscopy
    13. 13.12 DEPT 13C NMR Spectroscopy
    14. 13.13 Uses of 13C NMR Spectroscopy
    15. Chemistry Matters—Magnetic Resonance Imaging (MRI)
    16. Key Terms
    17. Summary
    18. Additional Problems
  15. 14 Conjugated Compounds and Ultraviolet Spectroscopy
    1. Why This Chapter?
    2. 14.1 Stability of Conjugated Dienes: Molecular Orbital Theory
    3. 14.2 Electrophilic Additions to Conjugated Dienes: Allylic Carbocations
    4. 14.3 Kinetic versus Thermodynamic Control of Reactions
    5. 14.4 The Diels–Alder Cycloaddition Reaction
    6. 14.5 Characteristics of the Diels–Alder Reaction
    7. 14.6 Diene Polymers: Natural and Synthetic Rubbers
    8. 14.7 Ultraviolet Spectroscopy
    9. 14.8 Interpreting Ultraviolet Spectra: The Effect of Conjugation
    10. 14.9 Conjugation, Color, and the Chemistry of Vision
    11. Chemistry Matters—Photolithography
    12. Key Terms
    13. Summary
    14. Summary of Reactions
    15. Additional Problems
  16. 15 Benzene and Aromaticity
    1. Why This Chapter?
    2. 15.1 Naming Aromatic Compounds
    3. 15.2 Structure and Stability of Benzene
    4. 15.3 Aromaticity and the Hückel 4n + 2 Rule
    5. 15.4 Aromatic Ions
    6. 15.5 Aromatic Heterocycles: Pyridine and Pyrrole
    7. 15.6 Polycyclic Aromatic Compounds
    8. 15.7 Spectroscopy of Aromatic Compounds
    9. Chemistry Matters—Aspirin, NSAIDs, and COX-2 Inhibitors
    10. Key Terms
    11. Summary
    12. Additional Problems
  17. 16 Chemistry of Benzene: Electrophilic Aromatic Substitution
    1. Why This Chapter?
    2. 16.1 Electrophilic Aromatic Substitution Reactions: Bromination
    3. 16.2 Other Aromatic Substitutions
    4. 16.3 Alkylation and Acylation of Aromatic Rings: The Friedel–Crafts Reaction
    5. 16.4 Substituent Effects in Electrophilic Substitutions
    6. 16.5 Trisubstituted Benzenes: Additivity of Effects
    7. 16.6 Nucleophilic Aromatic Substitution
    8. 16.7 Benzyne
    9. 16.8 Oxidation of Aromatic Compounds
    10. 16.9 Reduction of Aromatic Compounds
    11. 16.10 Synthesis of Polysubstituted Benzenes
    12. Chemistry Matters—Combinatorial Chemistry
    13. Key Terms
    14. Summary
    15. Summary of Reactions
    16. Additional Problems
  18. 17 Alcohols and Phenols
    1. Why This Chapter?
    2. 17.1 Naming Alcohols and Phenols
    3. 17.2 Properties of Alcohols and Phenols
    4. 17.3 Preparation of Alcohols: A Review
    5. 17.4 Alcohols from Carbonyl Compounds: Reduction
    6. 17.5 Alcohols from Carbonyl Compounds: Grignard Reaction
    7. 17.6 Reactions of Alcohols
    8. 17.7 Oxidation of Alcohols
    9. 17.8 Protection of Alcohols
    10. 17.9 Phenols and Their Uses
    11. 17.10 Reactions of Phenols
    12. 17.11 Spectroscopy of Alcohols and Phenols
    13. Chemistry Matters—Ethanol: Chemical, Drug, and Poison
    14. Key Terms
    15. Summary
    16. Summary of Reactions
    17. Additional Problems
  19. 18 Ethers and Epoxides; Thiols and Sulfides
    1. Why This Chapter?
    2. 18.1 Names and Properties of Ethers
    3. 18.2 Preparing Ethers
    4. 18.3 Reactions of Ethers: Acidic Cleavage
    5. 18.4 Cyclic Ethers: Epoxides
    6. 18.5 Reactions of Epoxides: Ring-Opening
    7. 18.6 Crown Ethers
    8. 18.7 Thiols and Sulfides
    9. 18.8 Spectroscopy of Ethers
    10. Chemistry Matters—Epoxy Resins and Adhesives
    11. Key Terms
    12. Summary
    13. Summary of Reactions
    14. Additional Problems
    15. Preview of Carbonyl Chemistry
  20. 19 Aldehydes and Ketones: Nucleophilic Addition Reactions
    1. Why This Chapter?
    2. 19.1 Naming Aldehydes and Ketones
    3. 19.2 Preparing Aldehydes and Ketones
    4. 19.3 Oxidation of Aldehydes and Ketones
    5. 19.4 Nucleophilic Addition Reactions of Aldehydes and Ketones
    6. 19.5 Nucleophilic Addition of H2O: Hydration
    7. 19.6 Nucleophilic Addition of HCN: Cyanohydrin Formation
    8. 19.7 Nucleophilic Addition of Hydride and Grignard Reagents: Alcohol Formation
    9. 19.8 Nucleophilic Addition of Amines: Imine and Enamine Formation
    10. 19.9 Nucleophilic Addition of Hydrazine: The Wolff–Kishner Reaction
    11. 19.10 Nucleophilic Addition of Alcohols: Acetal Formation
    12. 19.11 Nucleophilic Addition of Phosphorus Ylides: The Wittig Reaction
    13. 19.12 Biological Reductions
    14. 19.13 Conjugate Nucleophilic Addition to α,β‑Unsaturated Aldehydes and Ketones
    15. 19.14 Spectroscopy of Aldehydes and Ketones
    16. Chemistry Matters—Enantioselective Synthesis
    17. Key Terms
    18. Summary
    19. Summary of Reactions
    20. Additional Problems
  21. 20 Carboxylic Acids and Nitriles
    1. Why This Chapter?
    2. 20.1 Naming Carboxylic Acids and Nitriles
    3. 20.2 Structure and Properties of Carboxylic Acids
    4. 20.3 Biological Acids and the Henderson–Hasselbalch Equation
    5. 20.4 Substituent Effects on Acidity
    6. 20.5 Preparing Carboxylic Acids
    7. 20.6 Reactions of Carboxylic Acids: An Overview
    8. 20.7 Chemistry of Nitriles
    9. 20.8 Spectroscopy of Carboxylic Acids and Nitriles
    10. Chemistry Matters—Vitamin C
    11. Key Terms
    12. Summary
    13. Summary of Reactions
    14. Additional Problems
  22. 21 Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution Reactions
    1. Why This Chapter?
    2. 21.1 Naming Carboxylic Acid Derivatives
    3. 21.2 Nucleophilic Acyl Substitution Reactions
    4. 21.3 Reactions of Carboxylic Acids
    5. 21.4 Chemistry of Acid Halides
    6. 21.5 Chemistry of Acid Anhydrides
    7. 21.6 Chemistry of Esters
    8. 21.7 Chemistry of Amides
    9. 21.8 Chemistry of Thioesters and Acyl Phosphates: Biological Carboxylic Acid Derivatives
    10. 21.9 Polyamides and Polyesters: Step-Growth Polymers
    11. 21.10 Spectroscopy of Carboxylic Acid Derivatives
    12. Chemistry Matters—β-Lactam Antibiotics
    13. Key Terms
    14. Summary
    15. Summary of Reactions
    16. Additional Problems
  23. 22 Carbonyl Alpha-Substitution Reactions
    1. Why This Chapter?
    2. 22.1 Keto–Enol Tautomerism
    3. 22.2 Reactivity of Enols: α-Substitution Reactions
    4. 22.3 Alpha Halogenation of Aldehydes and Ketones
    5. 22.4 Alpha Bromination of Carboxylic Acids
    6. 22.5 Acidity of Alpha Hydrogen Atoms: Enolate Ion Formation
    7. 22.6 Reactivity of Enolate Ions
    8. 22.7 Alkylation of Enolate Ions
    9. Chemistry Matters—Barbiturates
    10. Key Terms
    11. Summary
    12. Summary of Reactions
    13. Additional Problems
  24. 23 Carbonyl Condensation Reactions
    1. Why This Chapter?
    2. 23.1 Carbonyl Condensations: The Aldol Reaction
    3. 23.2 Carbonyl Condensations versus Alpha Substitutions
    4. 23.3 Dehydration of Aldol Products: Synthesis of Enones
    5. 23.4 Using Aldol Reactions in Synthesis
    6. 23.5 Mixed Aldol Reactions
    7. 23.6 Intramolecular Aldol Reactions
    8. 23.7 The Claisen Condensation Reaction
    9. 23.8 Mixed Claisen Condensations
    10. 23.9 Intramolecular Claisen Condensations: The Dieckmann Cyclization
    11. 23.10 Conjugate Carbonyl Additions: The Michael Reaction
    12. 23.11 Carbonyl Condensations with Enamines: The Stork Enamine Reaction
    13. 23.12 The Robinson Annulation Reaction
    14. 23.13 Some Biological Carbonyl Condensation Reactions
    15. Chemistry Matters—A Prologue to Metabolism
    16. Key Terms
    17. Summary
    18. Summary of Reactions
    19. Additional Problems
  25. 24 Amines and Heterocycles
    1. Why This Chapter?
    2. 24.1 Naming Amines
    3. 24.2 Structure and Properties of Amines
    4. 24.3 Basicity of Amines
    5. 24.4 Basicity of Arylamines
    6. 24.5 Biological Amines and the Henderson–Hasselbalch Equation
    7. 24.6 Synthesis of Amines
    8. 24.7 Reactions of Amines
    9. 24.8 Reactions of Arylamines
    10. 24.9 Heterocyclic Amines
    11. 24.10 Spectroscopy of Amines
    12. Chemistry Matters—Green Chemistry II: Ionic Liquids
    13. Key Terms
    14. Summary
    15. Summary of Reactions
    16. Additional Problems
  26. 25 Biomolecules: Carbohydrates
    1. Why This Chapter?
    2. 25.1 Classification of Carbohydrates
    3. 25.2 Representing Carbohydrate Stereochemistry: Fischer Projections
    4. 25.3 D,L Sugars
    5. 25.4 Configurations of the Aldoses
    6. 25.5 Cyclic Structures of Monosaccharides: Anomers
    7. 25.6 Reactions of Monosaccharides
    8. 25.7 The Eight Essential Monosaccharides
    9. 25.8 Disaccharides
    10. 25.9 Polysaccharides and Their Synthesis
    11. 25.10 Some Other Important Carbohydrates
    12. Chemistry Matters—Sweetness
    13. Key Terms
    14. Summary
    15. Summary of Reactions
    16. Additional Problems
  27. 26 Biomolecules: Amino Acids, Peptides, and Proteins
    1. Why This Chapter?
    2. 26.1 Structures of Amino Acids
    3. 26.2 Amino Acids and the Henderson–Hasselbalch Equation: Isoelectric Points
    4. 26.3 Synthesis of Amino Acids
    5. 26.4 Peptides and Proteins
    6. 26.5 Amino Acid Analysis of Peptides
    7. 26.6 Peptide Sequencing: The Edman Degradation
    8. 26.7 Peptide Synthesis
    9. 26.8 Automated Peptide Synthesis: The Merrifield Solid-Phase Method
    10. 26.9 Protein Structure
    11. 26.10 Enzymes and Coenzymes
    12. 26.11 How Do Enzymes Work? Citrate Synthase
    13. Chemistry Matters—The Protein Data Bank
    14. Key Terms
    15. Summary
    16. Summary of Reactions
    17. Additional Problems
  28. 27 Biomolecules: Lipids
    1. Why This Chapter?
    2. 27.1 Waxes, Fats, and Oils
    3. 27.2 Soap
    4. 27.3 Phospholipids
    5. 27.4 Prostaglandins and Other Eicosanoids
    6. 27.5 Terpenoids
    7. 27.6 Steroids
    8. 27.7 Biosynthesis of Steroids
    9. Chemistry Matters—Saturated Fats, Cholesterol, and Heart Disease
    10. Key Terms
    11. Summary
    12. Additional Problems
  29. 28 Biomolecules: Nucleic Acids
    1. Why This Chapter?
    2. 28.1 Nucleotides and Nucleic Acids
    3. 28.2 Base Pairing in DNA
    4. 28.3 Replication of DNA
    5. 28.4 Transcription of DNA
    6. 28.5 Translation of RNA: Protein Biosynthesis
    7. 28.6 DNA Sequencing
    8. 28.7 DNA Synthesis
    9. 28.8 The Polymerase Chain Reaction
    10. Chemistry Matters—DNA Fingerprinting
    11. Key Terms
    12. Summary
    13. Additional Problems
  30. 29 The Organic Chemistry of Metabolic Pathways
    1. Why This Chapter?
    2. 29.1 An Overview of Metabolism and Biochemical Energy
    3. 29.2 Catabolism of Triacylglycerols: The Fate of Glycerol
    4. 29.3 Catabolism of Triacylglycerols: β-Oxidation
    5. 29.4 Biosynthesis of Fatty Acids
    6. 29.5 Catabolism of Carbohydrates: Glycolysis
    7. 29.6 Conversion of Pyruvate to Acetyl CoA
    8. 29.7 The Citric Acid Cycle
    9. 29.8 Carbohydrate Biosynthesis: Gluconeogenesis
    10. 29.9 Catabolism of Proteins: Deamination
    11. 29.10 Some Conclusions about Biological Chemistry
    12. Chemistry Matters—Statin Drugs
    13. Key Terms
    14. Summary
    15. Additional Problems
  31. 30 Orbitals and Organic Chemistry: Pericyclic Reactions
    1. Why This Chapter?
    2. 30.1 Molecular Orbitals of Conjugated Pi Systems
    3. 30.2 Electrocyclic Reactions
    4. 30.3 Stereochemistry of Thermal Electrocyclic Reactions
    5. 30.4 Photochemical Electrocyclic Reactions
    6. 30.5 Cycloaddition Reactions
    7. 30.6 Stereochemistry of Cycloadditions
    8. 30.7 Sigmatropic Rearrangements
    9. 30.8 Some Examples of Sigmatropic Rearrangements
    10. 30.9 A Summary of Rules for Pericyclic Reactions
    11. Chemistry Matters—Vitamin D, the Sunshine Vitamin
    12. Key Terms
    13. Summary
    14. Additional Problems
  32. 31 Synthetic Polymers
    1. Why This Chapter?
    2. 31.1 Chain-Growth Polymers
    3. 31.2 Stereochemistry of Polymerization: Ziegler–Natta Catalysts
    4. 31.3 Copolymers
    5. 31.4 Step-Growth Polymers
    6. 31.5 Olefin Metathesis Polymerization
    7. 31.6 Intramolecular Olefin Metathesis
    8. 31.7 Polymer Structure and Physical Properties
    9. Chemistry Matters—Degradable Polymers
    10. Key Terms
    11. Summary
    12. Additional Problems
  33. A | Nomenclature of Polyfunctional Organic Compounds
  34. B | Acidity Constants for Some Organic Compounds
  35. C | Glossary
  36. D | Periodic Table
  37. Answer Key
    1. Chapter 1
    2. Chapter 2
    3. Chapter 3
    4. Chapter 4
    5. Chapter 5
    6. Chapter 6
    7. Chapter 7
    8. Chapter 8
    9. Chapter 9
    10. Chapter 10
    11. Chapter 11
    12. Chapter 12
    13. Chapter 13
    14. Chapter 14
    15. Chapter 15
    16. Chapter 16
    17. Chapter 17
    18. Chapter 18
    19. Chapter 19
    20. Chapter 20
    21. Chapter 21
    22. Chapter 22
    23. Chapter 23
    24. Chapter 24
    25. Chapter 25
    26. Chapter 26
    27. Chapter 27
    28. Chapter 28
    29. Chapter 29
    30. Chapter 30
    31. Chapter 31
  38. Index

20 • Additional Problems

20 • Additional Problems

Visualizing Chemistry

Problem 20-17
Give IUPAC names for the following carboxylic acids (reddish brown = Br):
(a)
A ball-and-stick model of a benzene ring with a carboxyl group, a bromine meta to the carboxyl, and a methoxy group para to the carboxyl.
(b)
A ball-and-stick model of a four-carbon chain with a carboxyl end. There is a double bond on C 2 and a methyl on C 3.
(c)
The ball-and-stick model represents a cyclopentadiene ring with a carboxylic acid group attached to C 1. The double bonds are located on the first and third carbon atoms.
(d)
A ball-and-stick model of a three-carbon chain with a carboxyl end. There is a methyl on C 2 and a cyclopentane on C 3.
Problem 20-18
Would you expect the following carboxylic acids to be more acidic or less acidic than benzoic acid? Explain. (Reddish brown = Br.)
(a)
A ball-and-stick model of a benzene ring with a carboxyl group and a bromine para to the carboxyl.
(b)
A ball-and-stick model of a benzene ring with a carboxyl group and a dimethylamine group para to the carboxyl.
Problem 20-19

The following carboxylic acid can’t be prepared from an alkyl halide by either the nitrile hydrolysis route or the Grignard carboxylation route. Explain.

A ball-and-stick model of a four-carbon chain with a carboxyl end. There are two methyl groups on C 2 and a hydroxy group on C 4.
Problem 20-20

Electrostatic potential maps of anisole and thioanisole are shown. Which do you think is the stronger acid, p-methoxybenzoic acid or p-(methylthio)benzoic acid? Explain.

The ball-and-stick model with electrostatic potential maps of anisole (methoxybenzene) and thioanisole ([methylsulfanyl]benzene).

Mechanism Problems

Problem 20-21
Predict the product(s) and write the mechanism of each of the following reactions:
(a)
Conversion of bromobenzene to unknown products depicted by a question mark by reaction first with magnesium, then with carbon dioxide, and finally with hydronium.
(b)
Conversion of 2-bromobutane to unknown products depicted by a question mark by reaction first with magnesium, then with carbon dioxide, and finally with hydronium.
Problem 20-22
Predict the product(s) and write the mechanism of each of the following reactions:
(a)
Conversion of cyclopentanecarboxamide to unknown products depicted by a question mark by reaction with thionyl chloride.
(b)
Conversion of benzamide to unknown products depicted by a question mark by reaction with thionyl chloride.
Problem 20-23
Predict the product(s) and write the mechanism of each of the following reactions:
(a)
Conversion of 2-methylbutanenitrile to unknown products depicted by a question mark by reaction with sodium hydroxide and water.
(b)
Conversion of 3-methylbenzonitrile to unknown products depicted by a question mark by reaction with sodium hydroxide and water.
Problem 20-24
Predict the product(s) and write the complete mechanism of each of the following reactions:
(a)
2-methoxybenzonitrile reacts with methylmagnesium bromide in the presence of ether followed by acidic hydrolysis to give unknown products depicted by a question mark.
(b)
Cyclopropanecarbonitrile reacts with phenylmagnesium bromide in the presence of ether followed by acidic hydrolysis to give unknown products depicted by a question mark.
Problem 20-25
Acid-catalyzed hydrolysis of a nitrile to give a carboxylic acid occurs by initial protonation of the nitrogen atom, followed by nucleophilic addition of water. Review the mechanism of base-catalyzed nitrile hydrolysis in Section 20.7 and then predict the products for the following reactions. Write the steps involved in the acid-catalyzed reaction, using curved arrows.
(a)
Conversion of 3,3-dimethylbutane nitrile to unknown products depicted by a question mark by reaction with hydrochloric acid and water.
(b)
Conversion of 4-methylbenzonitrile to unknown products depicted by a question mark by reaction with hydrochloric acid and water.
Problem 20-26

Nitriles can be converted directly to esters by the Pinner reaction, which first produces an iminoester salt that is isolated and then treated with water to give the final product. Propose a mechanism for the Pinner reaction using curved arrows to show the flow of electrons at each step.

Conversion of benzonitrile to methyl benzoate. An imine ester intermediate is formed (reacting with hydrochloric acid in methanol) in which carbon is double-bonded to nitrogen, carrying a positive charge.
Problem 20-27
Naturally occurring compounds called cyanogenic glycosides, such as lotaustralin, release hydrogen cyanide, HCN, when treated with aqueous acid. The reaction occurs by hydrolysis of the acetal linkage to form a cyanohydrin, which then expels HCN and gives a carbonyl compound.
(a)

Show the mechanism of the acetal hydrolysis and the structure of the cyanohydrin that results.

(b)

Propose a mechanism for the loss of HCN, and show the structure of the carbonyl compound that forms.

Structure of Lotaustralin comprises a pyran ring in the chair conformation, with attached hydroxyl groups. The carbon connected to side-chain oxygen bonded to carbon carries wedged-methyl and dashed-wedged nitrile groups.
Problem 20-28

2-Bromo-6,6-dimethylcyclohexanone gives 2,2-dimethylcyclopentanecarboxylic acid on treatment with aqueous NaOH followed by acidification, a process called the Favorskii reaction. Propose a mechanism.

Conversion of 6-bromo-2,2-dimethylcyclohexanone to 2,2-dimethylcyclopentanecarboxylic acid on reaction with aqueous sodium hydroxide followed by acid hydrolysis.
Problem 20-29

Naturally occurring compounds called terpenoids, which we’ll discuss in Section 27.5, are biosynthesized by a pathway that involves loss of CO2 from 3-phosphomevalonate 5-diphosphate to yield isopentenyl diphosphate. Use curved arrows to show the mechanism of this reaction.

The reaction of 3-phosphomevalonate 5-diphosphate forms three products: isopentenyl diphosphate, carbon dioxide, and phosphate.
Problem 20-30

In the Ritter reaction, an alkene reacts with a nitrile in the presence of strong aqueous sulfuric acid to yield an amide. Propose a mechanism.

Conversion of 1-methylcyclohex-1-ene to N-(1-methylcyclohexyl)acetamide. The reagents used are aqueous sulfuric acid and acetonitrile.

Naming Carboxylic Acids and Nitriles

Problem 20-31
Give IUPAC names for the following compounds:
(a)
A six-carbon chain with carboxyl groups on carbons 2 and 5.
(b)
A three-carbon chain in which the first carbon is part of a carboxyl group. There are two methyl groups on the adjacent carbon.
(c)
A benzene ring with a carboxyl substituent. Meta to the carboxyl is a cyano substituent.
(d)
A ten-carbon ring with a carboxyl substituent. There is a double bond on the alpha carbon, with trans orientation.
(e)
A three-carbon chain in which the first carbon is part of a nitrile group. There are two methyl groups on the adjacent carbon.
(f)
A six-carbon chain with a substituent on the third carbon. The substituent has the condensed formula C H 2 C O 2 H.
(g)
A five-carbon chain in which the first carbon is part of a carboxyl group. There are bromine groups on the furthest and next-to-furthest carbons from the carboxyl.
(h)
A cyclopentene with a cyano substituent one carbon from the end of the double bond.
Problem 20-32
Draw structures corresponding to the following IUPAC names:
(a)
cis-1,2-Cyclohexanedicarboxylic acid
(b)
Heptanedioic acid
(c)
2-Hexen-4-ynoic acid
(d)
4-Ethyl-2-propyloctanoic acid
(e)
3-Chlorophthalic acid
(f)
Triphenylacetic acid
(g)
2-Cyclobutenecarbonitrile
(h)
m-Benzoylbenzonitrile
Problem 20-33
Draw and name the following compounds:
(a)
The eight carboxylic acids with the formula C6H12O2
(b)
Three nitriles with the formula C5H7N
Problem 20-34
Pregabalin, marketed as Lyrica, is an anticonvulsant drug that is also effective in treating chronic pain. The IUPAC name of pregabalin is (S)-3-(aminomethyl)-5-methylhexanoic acid. (An aminomethyl group is –CH2NH2.) Draw the structure of pregabalin.
Problem 20-35
Isocitric acid, an intermediate in the citric acid cycle of food metabolism, has the systematic name (2R,3S)-3-carboxy-2-hydroxypentanedioic acid. Draw the structure.

Acidity of Carboxylic Acids

Problem 20-36
Order the compounds in each of the following sets with respect to increasing acidity:
(a)
Acetic acid, oxalic acid, formic acid
(b)
p-Bromobenzoic acid, p-nitrobenzoic acid, 2,4-dinitrobenzoic acid
(c)
Fluoroacetic acid, 3-fluoropropanoic acid, iodoacetic acid
Problem 20-37
Arrange the compounds in each of the following sets in order of increasing basicity:
(a)
Magnesium acetate, magnesium hydroxide, methylmagnesium bromide
(b)
Sodium benzoate, sodium p-nitrobenzoate, sodium acetylide
(c)
Lithium hydroxide, lithium ethoxide, lithium formate
Problem 20-38
Calculate the pKa’s of the following acids:
(a)
Lactic acid, Ka = 8.4 × 10–4
(b)
Acrylic acid, Ka = 5.6 × 10–6
Problem 20-39
Calculate the Ka’s of the following acids:
(a)
Citric acid, pKa = 3.14
(b)
Tartaric acid, pKa = 2.98
Problem 20-40
Thioglycolic acid, HSCH2CO2H, a substance used in depilatory agents (hair removers) has pKa = 3.42. What is the percent dissociation of thioglycolic acid in a buffer solution at pH = 3.0?
Problem 20-41

In humans, the final product of purine degradation from DNA is uric acid, pKa = 5.61, which is excreted in the urine. What is the percent dissociation of uric acid in urine at a typical pH = 6.0? Why do you think uric acid is acidic even though it does not have a CO2H group?

The structure of uric acid from pyrimidine base. The nitrogen atom in the five-membered ring is attached to a highlighted hydrogen. The nitrogen is placed in between two carbonyl groups.
Problem 20-42

Some pKa data for simple dibasic acids is shown. How can you account for the fact that the difference between the first and second ionization constants decreases with increasing distance between the carboxyl groups?

Name Structure pK1 pK2
Oxalic HO2CCO2H 1.2 4.2
Succinic HO2CCH2CH2CO2H 4.2 5.6
Adipic HO2C(CH2)4CO2H 4.4 5.4

Reactions of Carboxylic Acids and Nitriles

Problem 20-43
How could you convert butanoic acid into the following compounds? Write each step showing the reagents needed.
(a)
1-Butanol
(b)
1-Bromobutane
(c)
Pentanoic acid
(d)
1-Butene
(e)
Octane
Problem 20-44
How could you convert each of the following compounds into butanoic acid? Write each step showing all reagents.
(a)
1-Butanol
(b)
1-Bromobutane
(c)
1-Butene
(d)
1-Bromopropane
(e)
4-Octene
Problem 20-45
How could you convert butanenitrile into the following compounds? Write each step showing the reagents needed.
(a)
1-Butanol
(b)
Butylamine
(c)
2-Methyl-3-hexanone
Problem 20-46
How would you prepare the following compounds from benzene? More than one step is needed in each case.
(a)
m-Chlorobenzoic acid
(b)
p-Bromobenzoic acid
(c)
Phenylacetic acid, C6H5CH2CO2H
Problem 20-47
Predict the product of the reaction of p-methylbenzoic acid with each of the following:
(a)
LiAlH4, then H3O+
(b)
N-Bromosuccinimide in CCl4
(c)
CH3MgBr in ether, then H3O+
(d)
KMnO4, H3O+
Problem 20-48
Using 13CO2 as your only source of labeled carbon, along with any other compounds needed, how would you synthesize the following compounds?
(a)
CH3CH213CO2H
(b)
PRODCH313CH2CO2H
Problem 20-49

How would you carry out the following transformations?

The conversion of methylenecyclohexane reacts with one set of unknown reagents to form 2-cyclohexylacetic acid, and with another set of unknown reagents to form 1-methylcyclohexanecarboxylic acid.
Problem 20-50
Which method—Grignard carboxylation or nitrile hydrolysis—would you use for each of the following reactions? Explain.
(a)
2-(bromomethyl)phenol separated from 2-(2-hydroxyphenyl)acetic acid by a reaction arrow.
(b)
2-bromobutane separated from 3-methylbutanoic acid by a reaction arrow.
(c)
5-iodopentan-2-one separated from 5-oxohexanoic acid by a reaction arrow.
(d)
3-bromopropanol separated from 4-hydroxybutanoic acid by a reaction arrow.
Problem 20-51

1,6-Hexanediamine, a starting material needed for making nylon, can be made from 1,3-butadiene. How would you accomplish the synthesis?

The conversion of buta-1,3-diene to hexane-1,6-diamine. The missing reagents are depicted with a question mark.
Problem 20-52
3-Methyl-2-hexenoic acid (mixture of E and Z isomers) has been identified as the substance responsible for the odor of human sweat. Synthesize the compound from starting materials having five or fewer carbons.

Spectroscopy

Problem 20-53
Propose a structure for a compound C6H12O2 that dissolves in dilute NaOH and shows the following 1H NMR spectrum: 1.08 δ (9 H, singlet), 2.2 δ (2 H, singlet), and 11.2 δ (1 H, singlet).
Problem 20-54

What spectroscopic method could you use to distinguish among the following three isomeric acids? Tell what characteristic features you would expect for each acid.

The condensed formulas for pentanoic acid, 3-methylbutanoic acid, and 2,2-dimethylpropanoic acid.
Problem 20-55
How would you use NMR (either 13C or 1H) to distinguish between the following pairs of isomers?
(a)
The structures of benzene-1,3-dicarboxylic acid and benzene-1,4-dicarboxylic acid. Structure 1 carboxyl groups at first and third carbons. Structure 2 carboxyl groups at first and fourth carbons.
(b)
The condensed formulas read H O 2 C C H 2 C H 2 C O 2 H and C H 3 C H (C O 2 H)2
(c)
Formulas read C H 3 C H 2 C H 2 C O 2 H and H O C H 2 C H 2 C H 2 C H O.
(d)
The condensed formula of 4-methylpent-3-enoic acid, and the chemical structure of cyclopentanecarboxylic acid.
Problem 20-56

Compound A, C4H8O3, has infrared absorptions at 1710 and 2500 to 3100 cm–1 and has the 1H NMR spectrum shown. Propose a structure for A.

The proton spectrum of C 4 H 8 O 3 shows peaks at 1.26 (triplet), 3.64 (quartet), 4.14 (singlet), and 11.12 (singlet).

General Problems

Problem 20-57
A chemist in need of 2,2-dimethylpentanoic acid decided to synthesize some by reaction of 2-chloro-2-methylpentane with NaCN, followed by hydrolysis of the product. After the reaction sequence was carried out, however, none of the desired product could be found. What do you suppose went wrong?
Problem 20-58

Show how you might prepare the anti-inflammatory agent ibuprofen starting from isobutylbenzene. More than one step is needed.

Chemical structure of isobutylbenzene with arrows pointing toward ibuprofen (isobutyl benzene with substituent in para position: ethyl group with C O 2 H at ethyl C 1).
Problem 20-59
The following synthetic schemes all have at least one flaw in them. What is wrong with each?
(a)
Conversion of 3-bromopentane to 2-ethylbutanoic acid through reaction first with magnesium, then sodium cyanide, then hydronium.
(b)
Conversion of 2-phenylacetic acid to ethylbenzene through reaction first with lithium aluminum hydride, then hydronium.
(c)
Conversion of 4-chloro-2-methylbutan-2-ol to 4-hydroxy-4-methylpentanoic acid using sodium cyanide followed by acid hydrolysis.
Problem 20-60
p-Aminobenzoic acid (PABA) was once widely used as a sunscreen agent. Propose a synthesis of PABA starting from toluene.
Problem 20-61

Propose a synthesis of the anti-inflammatory drug fenclorac from phenylcyclohexane.

The structure of Fenclorac. A phenylcyclohexane ring is depicted with a chlorine atom bonded to the third carbon of the benzene. 2-chloroacetic acid occupies the first carbon of the benzene.
Problem 20-62

The pKa’s of five p-substituted benzoic acids (YC6H4CO2H) are listed below. Rank the corresponding substituted benzenes (YC6H5) in order of their increasing reactivity toward electrophilic aromatic substitution. If benzoic acid has pKa = 4.19, which of the substituents are activators and which are deactivators?

Substituent Y The structure of benzoic acid with a substituent Y placed para to the carboxylic acid group attached to the benzene ring. To the left, p k a term is mentioned.
–Si(CH3)3 4.27
–CH═CHC≡N 4.03
–HgCH3 4.10
–OSO2CH3 3.84
–PCl2 3.59
Problem 20-63
How would you carry out the following transformations? More than one step is needed in each case.
(a)
Benzene separated from 2-methyl-2-phenylpropanoic acid by a reaction arrow.
(b)
Cyclohexanone separated from 1-phenylcyclohexanecarboxylic acid by a reaction arrow. 1-phenylcyclohexanecarboxylic acid has a cyclohexane ring single bonded to a phenyl group and a carboxyl group at C 1.
Problem 20-64

The following pKa values have been measured. Explain why a hydroxyl group in the para position decreases the acidity while a hydroxyl group in the meta position increases the acidity.

The acid strengths of 4-hydroxybenzoic acid (p K a equals 4.48), benzoic acid (p K a equals 4.19), and 3-hydroxybenzoic acid (p K a equals 4.07) are compared.
Problem 20-65

Identify the missing reagents af in the following scheme:

Reaction of 3-methylbut-1-ene to form 3-methylbutan-1-ol, then 3-methyl-1-bromobutane, then 3-methylpentanoic acid, then 4-methylpentan-1-ol, then 4-methylpentanal, then 4-methyl pentane. Missing reagents in each step indicated using letters a through f.
Problem 20-66

Propose a structure for a compound, C4H7N, that has the following IR and 1H NMR spectra:

An I R spectrum with a strong band below 3000 and around 1750 wavenumbers. A proton spectrum with shifts of 1.06 (triplet), 1.68 (sextet), and 2.31 (triplet).
Problem 20-67
The two 1H NMR spectra shown here belong to crotonic acid (trans-CH3CH = CHCO2H) and methacrylic acid [H2C = C(CH3)CO2H]. Which spectrum corresponds to which acid? Explain.
(a)
The proton spectrum shows peaks at 1.91 (doublet), 5.83 (doublet), 7.10 (multiplet), and 12.21 (singlet).
(b)
The proton spectrum shows peaks at 1.93 (singlet), 5.66 (singlet), 6.25 (singlet), and 12.24 (singlet).
Problem 20-68
The 1H and 13C NMR spectra below belong to a compound with formula C6H10O2. Propose a structure for this compound.
(a)
The proton spectrum shows peaks at 1.05 (triplet), 1.80 (singlet), 2.25 (multiplet), 6.85 (triplet), and 12.5 (singlet).
(b)
The carbon-13 spectra show peaks at 11.79, 12.89, 22.24, 126.62, 146.71, and 174.19.
Problem 20-69
Propose structures for carboxylic acids that show the following peaks in their 13C NMR spectra. Assume that the kinds of carbons (1°, 2°, 3°, or 4°) have been assigned by DEPT-NMR.
(a)
C7H12O2: 25.5 δ (2°), 25.9 δ (2°), 29.0 δ (2°), 43.1 δ (3°), 183.0 δ (4°)
(b)
C8H8O2: 21.4 δ (1°), 128.3 δ (4°), 129.0 δ (3°), 129.7 δ (3°), 143.1 δ (4°), 168.2 δ (4°)
Problem 20-70

Carboxylic acids having a second carbonyl group two atoms away lose CO2 (decarboxylate) through an intermediate enolate ion when treated with base. Write the mechanism of this decarboxylation reaction using curved arrows to show the electron flow in each step.

Conversion of 3-oxobutanoic acid on reaction with aqueous sodium hydroxide to a three-carbon enolate ion and carbon dioxide. Further reaction with water produces propan-2-one.
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