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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

29 • Additional Problems

29 • Additional Problems

Visualizing Chemistry

Problem 29-17
Identify the amino acid that is a catabolic precursor of each of the following α-keto acids:
(a)
A ball-and-stick model of a four-carbon chain with carboxylate anion at C 1, a carbonyl group at C 2 , and a methyl group at C 3.
(b)
A ball-and-stick model of a five-carbon chain with a carboxylate anion at C 1, carbonyl at C 2, sulfur at C4, and a methyl group attached to S5.
Problem 29-18

Identify the following intermediate in the citric acid cycle, and tell whether it has R or S stereochemistry:

A ball-and-stick model of a four-carbon chain with two  carboxylate anions at C1 and C4, and a hydroxyl group at C2
Problem 29-19

The following compound is an intermediate in the biosynthesis of one of the 20 common α-amino acids. Which one is it likely to be, and what kind of chemical change must take place to complete the biosynthesis?

A ball-and-stick model of a seven-carbon chain, with two carboxylate anions at C 1 and C 7, and two amine groups C 2 and C 6.
Problem 29-20

The following compound is an intermediate in the pentose phosphate pathway, an alternative route for glucose metabolism. Identify the sugar it is derived from.

A ball-and-stick model of four-carbon chain with C 1 having an aldehyde group and  oxygen linked to phosphate group at C4.

Mechanism Problems

Problem 29-21

In the pentose phosphate pathway for degrading sugars, ribulose 5-phosphate is converted to ribose 5-phosphate. Propose a mechanism for the isomerization.

Ribulose-5-phosphate reacts to form ribose-5-phosphate. Both structures are presented in Fischer projection.
Problem 29-22

Another step in the pentose phosphate pathway for degrading sugars (see Problem 29-21) is the conversion of ribose 5-phosphate to glyceraldehyde 3-phosphate. What kind of organic process is occurring? Propose a mechanism for the conversion.

Ribose-5-phosphate reacts to form glyceraldehyde-3-phosphate and an aldehyde connected to a methylene linked to a phosphate group. Both structures are presented in Fischer projection.
Problem 29-23

One of the steps in the pentose phosphate pathway for glucose catabolism is the reaction of sedoheptulose 7-phosphate with glyceraldehyde 3-phosphate in the presence of a transaldolase to yield erythrose 4-phosphate and fructose 6-phosphate.

Sedoheptulose-7-phosphate reacts with glyceraldehyde-3-phosphate to form erythrose-4-phosphate and fructose-6-phosphate. All the structures are presented in Fischer projection.
(a)
The first part of the reaction is the formation of a protonated Schiff base of sedoheptulose 7-phosphate with a lysine residue in the enzyme followed by a retro-aldol cleavage to give an enamine plus erythrose 4-phosphate. Show the structure of the enamine and the mechanism by which it is formed.
(b)
The second part of the reaction is a nucleophilic addition of the enamine to glyceraldehyde 3-phosphate followed by hydrolysis of the Schiff base to give fructose 6-phosphate. Show the mechanism.
Problem 29-24

One of the steps in the pentose phosphate pathway for glucose catabolism is the reaction of xylulose 5-phosphate with ribose 5-phosphate in the presence of a transketolase to give glyceraldehyde 3-phosphate and sedoheptulose 7-phosphate.

Xylulose-5-phosphate reacts with ribose-5-phosphate to form glyceraldehyde-3-phosphate and sedoheptulose-7-phosphate. Both structures are presented in Fischer projection.
(a)
The first part of the reaction is nucleophilic addition of thiamin diphosphate (TPP) ylide to xylulose 5-phosphate, followed by a retro-aldol cleavage to give glyceraldehyde 3-phosphate and a TPP-containing enamine. Show the structure of the enamine and the mechanism by which it is formed.
(b)
The second part of the reaction is addition of the enamine to ribose 5-phosphate followed by loss of TPP ylide to give sedoheptulose 7-phosphate. Show the mechanism.
Problem 29-25

The amino acid tyrosine is biologically degraded by a series of steps that include the following transformations:

Tyrosine is degraded to maleoylacetoacetate and then to fumaroylacetoacetate, and acetoacetate and fumarate with acetoacetate forming coenzyme A.

The double-bond isomerization of maleoylacetoacetate to fumaroylacetoacetate is catalyzed by practically any nucleophile, :Nu. Propose a mechanism.

Problem 29-26
Propose a mechanism for the conversion of fumaroylacetoacetate to fumarate plus acetoacetate (see Problem 29-25).
Problem 29-27
Propose a mechanism for the conversion of acetoacetate to acetyl CoA (see Problem 29-25).
Problem 29-28

Design your own degradative pathway. You know the rules (organic mechanisms), and you’ve seen the kinds of reactions that occur in the biological degradation of fats and carbohydrates into acetyl CoA. If you were Mother Nature, what series of steps would you use to degrade the amino acid serine into acetyl CoA?

Serine reacts in the presence of unknown reagents, represented as a question mark, to form acetyl Co A.
Problem 29-29

The amino acid serine is biosynthesized by a route that involves reaction of 3-phosphohydroxypyruvate with glutamate to give 3-phosphoserine. Propose a mechanism.

3-Phosphohydroxypyruvate is converted to 3-phosphoserine via the deamination of glutamate   to alpha-ketoglutarate.
Problem 29-30

The amino acid leucine is biosynthesized from α-ketoisocaproate, which is itself prepared from α-ketoisovalerate by a multistep route that involves (1) reaction with acetyl CoA, (2) hydrolysis, (3) dehydration, (4) hydration, (5) oxidation, and (6) decarboxylation. Show the steps in the transformation, and propose a mechanism for each.

Alpha-ketoisovalerate reacts to form alpha-ketoisocaproate via the conversion acetyl CoA, and  nicotinamide adenine dinucleotide cation  to H S CoA, carbon dioxide and nicotinamide adenine dinucleotide phosphate hydride.
Problem 29-31

The amino acid cysteine, C3H7NO2S, is biosynthesized from a substance called cystathionine by a multistep pathway.

Cystathionine reacts to form ammonium ion, an unknown product represented as a question mark and cysteine.
(a)
The first step is a transamination. What is the product?
(b)
The second step is an E1cB reaction. Show the products and the mechanism of the reaction.
(c)
The final step is a double-bond reduction. What organic cofactor is required for this reaction, and what is the product represented by the question mark in the equation?

Enzymes and Coenzymes

Problem 29-32
What chemical events occur during the digestion of food?
Problem 29-33
What is the difference between digestion and metabolism?
Problem 29-34
What is the difference between anabolism and catabolism?
Problem 29-35
Draw the structure of adenosine 5′-monophosphate (AMP), an intermediate in some biochemical pathways.
Problem 29-36
Cyclic adenosine monophosphate (cyclic AMP), a modulator of hormone action, is related to AMP (Problem 29-35) but has its phosphate group linked to two hydroxyl groups at C3′ and C5′ of the sugar. Draw the structure of cyclic AMP.
Problem 29-37
What general kind of reaction does ATP carry out?
Problem 29-38
What general kind of reaction does NAD+ carry out?
Problem 29-39
What general kind of reaction does FAD carry out?
Problem 29-40
What enzyme cofactor is associated with each of the following kinds of reactions?
(a)
Transamination
(b)
Carboxylation of a ketone
(c)
Decarboxylation of an α-keto acid
Problem 29-41

Lactate, a product of glucose catabolism in oxygen-starved muscles, can be converted into pyruvate by oxidation. What coenzyme do you think is needed? Write the equation in the normal biochemical format using a curved arrow.

The structure of lactate anion, having a four-carbon chain with a carboxylate anion at C1 and a hydroxyl group at C2.

Metabolism

Problem 29-42
Write the equation for the final step in the β-oxidation pathway of any fatty acid with an even number of carbon atoms.
Problem 29-43

Show the products of each of the following reactions:

(a)
Hexyl CoA reacts in the presence of Acyl  CoA dehydrogenase and favin adenine dinucleotide to form an unknown product represented as a question mark.
(b)
Product of (a) reacts with water in the presence of enoyl CoA hydratase to form an unknown product represented as a question mark.
(c)
Product of (b) reacts in the presence of beta-hydroxyacyl CoA dehydrogenase and  nicotinamide adenine dinucleotide cation  to form an unknown product shown as a question mark.
Problem 29-44
Why aren’t the glycolysis and gluconeogenesis pathways the exact reverse of each other?
Problem 29-45
How many moles of acetyl CoA are produced by catabolism of the following substances?
(a)
1.0 mol of glucose
(b)
1.0 mol of palmitic acid
(c)
1.0 mol of maltose
Problem 29-46
How many grams of acetyl CoA (MW = 809.6 amu) are produced by catabolism of the following substances? Which substance is the most efficient precursor of acetyl CoA on a weight basis?
(a)
100.0 g of glucose
(b)
100.0 g of palmitic acid
(c)
100.0 g of maltose
Problem 29-47
What is the structure of the α-keto acid formed by transamination of each of the following amino acids?
(a)
Threonine
(b)
Phenylalanine
(c)
Asparagine
Problem 29-48
The glycolysis pathway shown in Figure 29.8 has a number of intermediates that contain phosphate groups. Why can 3-phosphoglyceryl phosphate and phosphoenolpyruvate transfer a phosphate group to ADP while glucose 6-phosphate cannot?
Problem 29-49
Write a mechanism for the conversion of α-ketoglutarate to succinyl CoA in step 4 of the citric acid cycle (Figure 29.14).
Problem 29-50

In step 2 of the citric acid cycle (Figure 29.14), cis-aconitate reacts with water to give (2R,3S)-isocitrate. Does  –OH add from the Re face of the double bond or from the Si face? What about  –H? Does the addition of water occur with syn or anti geometry?

Cis-aconitate having a three-carbon chain and a double bond reacts with water to form (2 R,3 S)-Isocitrate. The double bond is replaced by single bond in the product.

General Problems

Problem 29-51

In glycerol metabolism, the oxidation of sn-glycerol 3-phosphate to give dihydroxyacetone phosphate is catalyzed by sn-glycerol-3-phosphate dehydrogenase, with NAD+ as cofactor. The reaction is stereospecific, occurring exclusively on the Re face of the nicotinamide ring.

A reaction with nicotinamide adenine dinucleotide cation oxidizes sn-glycerol-3-phosphate to dihydroxyactone phosphate. Nicotinamide adenine dinucleotide cation converts to nicotinamide adenine dinucleotide hydride

Which hydrogen in the NADH product comes from sn-glycerol 3-phosphate? Does it have pro-R or pro-S stereochemistry?

Problem 29-52

The primary fate of acetyl CoA under normal metabolic conditions is degradation in the citric acid cycle to yield CO2. When the body is stressed by prolonged starvation, however, acetyl CoA is converted into compounds called ketone bodies, which can be used by the brain as a temporary fuel. Fill in the missing information indicated by the four question marks in the following biochemical pathway for the synthesis of ketone bodies from acetyl CoA:

Acetyl CoA forms acetoacetyl CoA , which converts water to an unknown reagent and acetoacetate anion,  the acetoacetate anion reacts with unknown reagents to form ketone bodies acetone and 3-hydroxybutyrate.
Problem 29-53
The initial reaction in Problem 29-52, conversion of two molecules of acetyl CoA to one molecule of acetoacetyl CoA, is a Claisen reaction. Assuming that there is a base present, show the mechanism of the reaction.
Problem 29-54

In step 6 of fatty-acid biosynthesis (Figure 29.6), acetoacetyl ACP is reduced stereospecifically by NADPH to yield an alcohol. Does hydride ion add to the Si face or the Re face of acetoacetyl ACP?

Acetoacetyl A C P forms beta-hydroxybutyryl A C P via the reduction of nicotinamide adenine dinucleotide phosphate hydride to nicotinamide adenine dinucleotide phosphate cation.
Problem 29-55

In step 7 of fatty-acid biosynthesis (Figure 29.6), dehydration of a β-hydroxy thioester occurs to give trans-crotonyl ACP. Is the dehydration a syn elimination or an anti elimination?

A beta hydroxy thioester is dehydrated to form trans-crotonyl A C P. The C-C single bond in the reactant converts to a double bond in the product.
Problem 29-56

In step 8 of fatty-acid biosynthesis (Figure 29.6), reduction of trans-crotonyl ACP gives butyryl ACP. A hydride from NADPH adds to C3 of the crotonyl group from the Re face, and protonation on C2 occurs on the Si face. Is the reduction a syn addition or an anti addition?

trans-Crotonyl ACP reacts to form butyryl A C P. The product has a four-carbon chain with carbonyl linked to S A C P.
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