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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

22 • Additional Problems

22 • Additional Problems

Visualizing Chemistry

Problem 22-17
Show the steps in preparing each of the following substances using either a malonic ester synthesis or an acetoacetic ester synthesis:
(a)
Ball-stick model of a compound comprising a seven-carbon chain with C 2 being a carbonyl group, a double bond between C 5 and C 6, and a methyl group on C 6. Black, gray, and red spheres represent carbon, hydrogen, and oxygen, respectively.
(b)
A ball-stick model of a compound comprising a benzene ring and a C 3 chain, C1 of which is a carboxylic acid group, and C 2 bearing a methyl group. Black, gray, and red spheres represent carbon, hydrogen, and oxygen, respectively.
Problem 22-18

Unlike most β-diketones, the following β-diketone has no detectable enol content and is about as acidic as acetone. Explain.

A ball-stick model of a compound comprising a six membered ring with carbonyl groups at C 1 and C 3 and with a C H 2 bridge between C 2 and C 5. Black, gray, and red spheres represent carbon, hydrogen, and oxygen, respectively.
Problem 22-19

For a given α hydrogen atom to be acidic, the C–H bond must be parallel to the p orbitals of the C = O double bond (that is, perpendicular to the plane of the adjacent carbonyl group). Identify the most acidic hydrogen atom in the conformation shown for the following structure. Is it axial or equatorial?

A ball-stick model of a compound comprising a chair conformation of cyclohexanone with two methyl groups alpha on C 2. Black, gray, and red spheres represent carbon, hydrogen, and oxygen, respectively.

Mechanism Problems

Problem 22-20
Draw the corresponding keto or enol tautomer for each of the following molecules.
(a)
An enol tautomer of 2-butanone is treated with acid to give an unknown product, represented by a question mark.
(b)
3,3-Dimethyl-2-butanone is treated with base to give an unknown product, represented by a question mark.
Problem 22-21
Predict the product(s) and show the mechanism for each of the following reactions:
(a)
Butyraldehyde reacts with bromine in acetic acid to yield an unknown product, represented by a question mark.
(b)
3,3-Dimethyl-2-butanone reacts with bromine in acetic acid to yield an unknown product, represented by a question mark.
Problem 22-22
Predict the product(s) and show the mechanism for each of the following reactions:
(a)
Methyl propionate reacts with L D A followed by bromoethane to yield an unknown product, represented by a question mark.
(b)
3-pentanone reacts with L D A followed by P h C H 2 B r to yield an unknown product, represented by a question mark.
Problem 22-23
The following two optically active β-keto acids were decarboxylated under the conditions typically used for the acetoacetic ester synthesis. Will the ketone products be optically active? Explain.
(a)
2-ethyl-2-methyl-3-oxobutanoic acid is heated in the presence of acidt to yield an unknown product, represented by a question mark.
(b)
4-methyl-3-oxohexanoic acid is heated in the presence of acid to yield an unknown product, represented by a question mark.
Problem 22-24

In the Hell–Volhard–Zelinskii reaction, only a catalytic amount of PBr3 is necessary because of the following equilibrium. Propose a mechanism for formation of the equilibrium.

An alpha brominated acid bromide reacts reversibly with a carboxylic acid to give an alpha brominated carboxylic acid and an acid bromide.
Problem 22-25
When a ketone is treated with a halogen under acidic conditions, the α-monohalogenated product can be obtained in high yield. Under basic conditions however it is difficult to isolate the monohalogenated product. Explain.
Problem 22-26

Nonconjugated β,γ-unsaturated ketones, such as 3-cyclohexenone, are in an acid-catalyzed equilibrium with their conjugated α,β-unsaturated isomers. Propose a mechanism for the isomerization.

3-cyclohexenone with alpha, beta, and gamma carbons indicated and a double-bond between the beta and gamma carbons reacts with acid to form 2-cyclohexenone with a double-bond between the alpha and beta carbons.
Problem 22-27

2-substituted 2-cyclopentenones can be interconverted with 5-substituted 2-cyclopentenones under basic conditions. Propose a mechanism for this isomerization.

2-methyl-2-cyclopenten-1-one reacts with a base to yield 5-methyl-2-cyclopenten-1-one.
Problem 22-28

Using curved arrows, propose a mechanism for the following reaction, one of the steps in the metabolism of the amino acid alanine.

An analog of alanine reacts with base to form a product with a double bond between the alpha carbon and the nitrogen of the amino acid chain.
Problem 22-29

Using curved arrows, propose a mechanism for the following reaction, one of the steps in the biosynthesis of the amino acid tyrosine.

A reactant comprising a cyclohexadiene ring with substituents attached para to the carbonyl groupundergoes a chemical reaction to yield tyrosine and carbon dioxide.
Problem 22-30

One of the later steps in glucose biosynthesis is the isomerization of fructose 6-phosphate to glucose 6-phosphate. Propose a mechanism, using acid or base catalysis as needed.

Fructose-6-phosphate undergoes a chemical reaction to yield glucose-6-phosphate as a product. Both the structures are represented in Fischer projection.
Problem 22-31

The Favorskii reaction involves treatment of an α-bromo ketone with base to yield a ring-contracted product. For example, reaction of 2-bromocyclohexanone with aqueous NaOH yields cyclopentanecarboxylic acid. Propose a mechanism.

When treated first with base and then with acid, 2-bromocyclohexanone is converted to cyclopentanecarboxylic acid.
Problem 22-32

Treatment of a cyclic ketone with diazomethane is a method for accomplishing a ring-expansion reaction. For example, treatment of cyclohexanone with diazomethane yields cycloheptanone. Propose a mechanism.

Cyclohexanone reacts with diazomethane in ether to yield cycloheptanone and molecular nitrogen as the products.
Problem 22-33

The final step in an attempted synthesis of laurene, a hydrocarbon isolated from the marine alga Laurencia glandulifera, involved the Wittig reaction shown. The product obtained, however, was not laurene but an isomer. Propose a mechanism to account for the unexpected results.

A substituted cyclopentanone reacts with the Wittig reagent P P h 3- C H 2 in T H F to yield a product, but the expected product Laurene is not formed.
Problem 22-34

Amino acids can be prepared by reaction of alkyl halides with diethyl acetamidomalonate, followed by heating the initial alkylation product with aqueous HCl. Show how you would prepare alanine, CH3CH(NH2)CO2H, one of the twenty amino acids found in proteins, and propose a mechanism for acid-catalyzed conversion of the initial alkylation product to the amino acid.

The structure of diethyl acetamidomalonate where diethyl malonate is substituted with an acetamide group.
Problem 22-35
Amino acids can also be prepared by a two-step sequence that involves Hell–Volhard–Zelinskii reaction of a carboxylic acid followed by treatment with ammonia. Show how you would prepare leucine, (CH3)2CHCH2CH(NH2)CO2H, and identify the mechanism of the second step.
Problem 22-36

Heating carvone with aqueous sulfuric acid converts it into carvacrol. Propose a mechanism for the isomerization.

When heated, carvone reacts with aqueous sulfuric acid to yield carvacrol.

Acidity of Carbonyl Compounds

Problem 22-37
Identify all the acidic hydrogens (pKa < 25) in the following molecules:
(a)
The structure of 3-methyl-2 pentanone comprises of a five carbon chain in which C 2 is a carbonyl group and a methyl group is on C 3.
(b)
The structure of 1, 3-cyclopentanedione where two carbonyl groups constitute the C 1 and C 3 positions of the cyclopentane ring.
(c)
Structure comprising a six-carbon chain in which C 2 is bonded to C 3 by a triple bond and a hydroxyl group is on C 6
(d)
A substituted benzene ring in which C O 2 C H 3 group is ortho to a C H 2 C triple bond N group
(e)
The structure of cyclopentanecarbonyl chloride in which C O C l is attached to a cyclopntane ring.
(f)
The structure of 2-methyl-1-penten-3-one which comprises of a five carbon chain with a double bond between C 1 and C 2, C 3 is a carbonyl group, and a methyl group is bonded to C 2
Problem 22-38

Rank the following compounds in order of increasing acidity:

(a)The structure of propanoic acid.(b)The structure of ethanol(c)The structure of diethyl amine where the N H group is bonded to two ethyl groups.(d)The structure of acetone where a central carbonyl group is bonded to two methyl groups.(e)The structure of pentane-2,4-dione, carbonyl groups being at C 2 and C 4 of a five carbon chain.(f)The structure of trichloroacetic acid where a trichloromethyl group is attached to a carboxylic acid group.

Problem 22-39
Write resonance structures for the following anions:
(a)
The structure of pentane-2,4-dione with a negative charge and a lone pair of electrons on C 3
(b)
The structure of 2-hexenone with a negative charge and a lone pair of electrons on C 3
(c)
The structure of a compound comprising of an isocyanide group joined to a carbon bearing a lone pair of electrons and a negative charge which in turn is attached to a methyl ester group.
(d)
A structure of phenylacetone with a negative charge and a lone pair of electrons on the carbon between the benzene ring and the carbonyl group.
(e)
A structure comprising a benzene ring that is bonded to cyclopentane-1,3-dione. C 2 of the cyclopentane ring is attached to a methyl ester group and also has a lone pair of electrons and a negative charge on it.
Problem 22-40

Base treatment of the following α,β-unsaturated carbonyl compound yields an anion by removal of H+ from the γ carbon. Why are hydrogens on the γ carbon atom acidic?

An alpha-beta unsaturated carbonyl compound reacts with L D A to yield a carbonyl compound comprising an anion with a set of lone pairs on gamma carbon.
Problem 22-41

Treatment of 1-phenyl-2-propenone with a strong base such as LDA does not yield an anion, even though it contains a hydrogen on the carbon atom next to the carbonyl group. Explain.

A structure of 1-phenyl-2-propenone where a phenyl ring is bonded to the carbonyl group of the propene chain.

α-Substitution Reactions

Problem 22-42
Predict the product(s) of the following reactions:
(a)
When heated, a compound which has two carboxylic acid groups are bonded to the same carbon of a cyclohexane ring reacts to form an unknown product, represented by a question mark.
(b)
1, 3-cyclopentanedione reacts first with sodium ethoxide and then with methyl iodide to yield an unknown product, represented by a question mark.
(c)
Butanoic acid reacts with bromine and phosphorus tribromide, yielding an unknown product which further reacts with water to yield another unknown product. Unknown products are represented by question marks.
(d)
Acetophenone  reacts with sodiium hydroxide, water, and iodine to give an unknown product, represented by a question mark.
Problem 22-43

Which, if any, of the following compounds can be prepared by a malonic ester synthesis? Show the alkyl halide you would use in each case.

(a) Ethyl pentanoate (b) Ethyl 3-methylbutanoate (c) Ethyl 2-methylbutanoate 
(d) Ethyl 2,2-dimethylpropanoate

Problem 22-44

Which, if any, of the following compounds can be prepared by an acetoacetic ester synthesis? Explain.

(a)The structure of 2-(5-bromophenyl) acetone where a bromine atom is bonded to meta to an acetone group on the benzene ring.(b)The structure of cyclohexyl methyl ketone where a methyl group and a cyclohexane group are bonded to a central carbonyl group.(c)The structure of 4,4-dimethyl-2-pentanone where the carbonyl group is located at C 2 and two methyl groups at C 4.

Problem 22-45
How would you prepare the following ketones using an acetoacetic ester synthesis?
(a)
The structure of 3-ethyl-2-hexanone where the carbonyl group is located at C 2 and an ethyl group at C 3.
(b)
The structure of 3-methyl-2-hexanone where the carbonyl group is located at C 2 and a methyl group at C 3.
Problem 22-46
How would you prepare the following compounds using either an acetoacetic ester synthesis or a malonic ester synthesis?
(a)
The structure of diethyl-2,2-dimethylmalonate, a derivative of malonic acid where the H atoms of the acid groups are replaced by ethyl groups and two methyl groups are attached to C 2.
(b)
The structure of cycloheptyl methyl ketone where a methyl group and a cycloheptane group are bonded to a central carbonyl group.
(c)
The structure of cyclobutanoic acid in which a carboxylic acid is bonded to a cyclobutane ring.
(d)
The structure of 5-hexen-2-one in which a carbonyl group is located at C 2 and a double bond is present between C 5 and C 6 of the compound.
Problem 22-47

Which of the following substances would undergo the haloform reaction?

(a) CH3COCH3(b) Acetophenone (c) CH3CH2CHO (d) CH3CO2H (e) CH3C N

Problem 22-48

How might you convert geraniol into either ethyl geranylacetate or geranylacetone?

When using reagents represented by question marks, geraniol undergoes a chemical reaction to form ethyl geranylacetate and geranyl acetone.
Problem 22-49

Aprobarbital, a barbiturate once used in treating insomnia, is synthesized in three steps from diethyl malonate. Show how you would synthesize the necessary dialkylated intermediate, and then propose a mechanism for the reaction of this intermediate with urea to give aprobarbital.

A derivative of ethyl malonate bearing an isopropyl and a vinyl group at the central carbon reacts with urea and sodium ethoxide to yield aprobarbital as a product.

General Problems

Problem 22-50
One way to determine the number of acidic hydrogens in a molecule is to treat the compound with NaOD in D2O, isolate the product, and determine its molecular weight by mass spectrometry. For example, if cyclohexanone is treated with NaOD in D2O, the product has MW = 102. Explain how this method works.
Problem 22-51
When optically active (R)-2-methylcyclohexanone is treated with either aqueous base or acid, racemization occurs. Explain.
Problem 22-52
Would you expect optically active (S)-3-methylcyclohexanone to be racemized on acid or base treatment in the same way as 2-methylcyclohexanone (Problem 22-51)? Explain.
Problem 22-53
When an optically active carboxylic acid such as (R)-2-phenylpropanoic acid is brominated under Hell–Volhard–Zelinskii conditions, is the product optically active or racemic? Explain.
Problem 22-54

Fill in the reagents ac that are missing from the following scheme:

A three-step reaction in which cyclohexanone sequentially reacts with reagents a, b, and c yielding 2, 6-dimethylcyclohexanone via two intermediate products.
Problem 22-55

Although 2-substituted 2-cyclopentenones are in a base-catalyzed equilibrium with their 5-substituted 2-cyclopentenone isomers, the analogous isomerization is not observed for 2-substituted 2-cyclohexenones. Explain.

2-Methyl-2-cyclohexen-1-one reacts with base to form 6-Methyl-2-cyclohexen-1-one
Problem 22-56
How would you synthesize the following compounds from cyclohexanone? More than one step may be required.
(a)
The structure of methylenecyclohexane where a C H 2 group is double-bonded to one carbon of a cyclohexane ring
(b)
The structure of (bromomethyl) cyclohexane where a C H 2 B r group is bonded to a carbon of a cyclohexane ring.
(c)
The structure of 2-benzylcyclohexanone where a carbonyl group is at C1 of a cyclohexane ring, and a benzyl group is attached to C 2 of the ring.
(d)
The structure of 3-cyclohexylpropanoic acid where a cyclohexane ring is bonded to the C 3 of a propanoic acid chain..
(e)
The structure of 1-cyclohexenecarboxylic acid in which a carboxylic acid group is attached to one of the double-bonded carbons in a cyclohexene ring.
(f)
The structure 2-cyclohexen-1-one in which a carbonyl group is located at C 1 of a cyclohexene ring, the double bond being between C 2 and C 3.
Problem 22-57
The two isomers cis- and trans-4-tert-butyl-2-methylcyclohexanone are interconverted by base treatment. Which isomer do you think is more stable, and why?
Problem 22-58
The following synthetic routes are incorrect. What is wrong with each?
(a)
Ethyl pentanoate is treated first with bromine in acetic acid followed by pyridine and heat to produce ethyl 2-pentenoate
(b)
Diethyl 2 methylmalonate is treated first with sodium ethoxide, then with bromobenzene, and finally heated in the presence of acid to produce 2-methyl-2-phenylethanoic acid.
(c)
Ethyl acetoacetate is treated first with sodium ethoxide, then with 3- bromo-1-propene, and finally heated in the presence of acid to produce 4-pentenoic acid
Problem 22-59

Attempted Grignard reaction of cyclohexanone with tert-butylmagnesium bromide yields only about 1% of the expected addition product along with 99% unreacted cyclohexanone. If D3O+ is added to the reaction mixture after a suitable period, however, the “unreacted” cyclohexanone is found to have one deuterium atom incorporated into it. Explain.

Cyclohexanone is treated first with tert-butylmagnesium bromide and then with deuterium plus to form one percent of the expected addition product and 99 percent of alpha-deuterocyclohexanone.
Problem 22-60

Ketones react slowly with benzeneselenenyl chloride in the presence of HCl to yield α-phenylseleno ketones. Propose a mechanism for this acid-catalyzed α-substitution reaction.

A ketone undergoes a chemical reaction with benzeneselenenyl chloride and hydrochloric acid, yielding an alpha-phenylseleno ketone.
Problem 22-61

South American Incas chewed the leaves of the coca bush, Erythroxylon coca, to combat fatigue. Chemical studies of Erythroxylon coca by Friedrich Wöhler in 1862 resulted in the discovery of cocaine, C17H21NO4, as the active component. Basic hydrolysis of cocaine leads to methanol, benzoic acid, and another compound called ecgonine, C9H15NO3. Oxidation of ecgonine with CrO3 yields a keto acid that readily loses CO2 on heating, giving tropinone.

A chair conformation of tropinone in which an N C H 3 group bridges from C3 to C6 of a cycloheptanone ring.
(a)
What is a likely structure for the keto acid?
(b)
What is a likely structure for ecgonine, neglecting stereochemistry?
(c)
What is a likely structure for cocaine, neglecting stereochemistry?
Problem 22-62

The key step in a reported laboratory synthesis of sativene, a hydrocarbon isolated from the mold Helminthosporium sativum, involves the following base treatment of a keto tosylate. What kind of reaction is occurring? How would you complete the synthesis?

A keto tosylate reacts with a base to yield an intermediate which reacts with an unknown reagent, represented by a question mark to yield sativene as a product.
Problem 22-63

Sodium pentothal is a short-acting barbiturate derivative used as a general anesthetic and known in popular culture as a truth serum. It is synthesized like other barbiturates (see the Chemistry Matters at the end of this chapter), using thiourea, (H2N)2C S, in place of urea. How would you synthesize sodium pentothal?

The structure of sodium pentothal comprising of a six-membered ring with carbon atoms at positions 1 and 4, nitrogen atoms at positions 2 and 6, and carbonyl groups at positions 3 and 5. A sulfur anion is bonded to the carbon at position 1 and an alyl chain to the carbon at position 4. The sulfur anion is associated with a soidum cation.
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