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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

5 • Additional Problems

5 • Additional Problems

Visualizing Chemistry

Problem 5-26

Which of the following structures are identical? (Green = Cl.)

(a)The ball-and-stick model shows a 3-carbon chain. C1 is a carboxylic acid group on the right. A chlorine atom is bonded to C2  above and a methyl group below C2. (b)The ball-and-stick model shows a 3-carbon  chain. C1 is a carboxylic acid group  on the left. C2 is bonded to a chlorine atom at the top behind the C2 hydrogen. (c)The ball-and-stick model shows a 3-carbon  chain. C1 is a carboxylic acid group on the left. C2 is bonded to a chlorine atom on the right the methyl group above.
(d)The ball-and-stick model shows a 3-carbon  chain. C1 is a carboxylic acid group on the left. C2 is bonded to a chlorine atom in front of the C2 hydrogen

Problem 5-27
Assign R or S configurations to the chirality centers in the following molecules (blue = N):
(a)
The ball-and-stick model of serine. Gray, black, blue, and red spheres represent hydrogen, carbon, nitrogen, and oxygen, respectively.
(b)
The ball-and-stick model of adrenaline. Gray, black, blue, and red spheres represent hydrogen, carbon, nitrogen, and oxygen, respectively.
Problem 5-28
Which, if any, of the following structures represent meso compounds? (Blue = N, green = Cl.)
(a)
The ball-and-stick model has a cyclopentane ring. C1 and C3 are each bonded to cis hydroxyl groups where red spheres represent oxygen atoms.
(b)
The ball-and-stick model has a 5-carbon chain. C2 and C4 are each bonded to an amino group where blue spheres represent nitrogen atoms.
(c)
The ball-and-stick model has a 4-carbon chain. C2 and C3 are each bonded to a chlorine atom where green spheres represent chlorine atoms.
Problem 5-29

Assign R or S configuration to each chirality center in pseudoephedrine, an over-the-counter decongestant found in cold remedies (blue = N).

The ball-and-stick model of pseudoephedrine. Gray, black, blue, and red spheres represent hydrogen, carbon, nitrogen, and oxygen, respectively.
Problem 5-30
Orient each of the following drawings so that the lowest-ranked group is toward the rear, and then assign R or S configuration:
(a)
A carbon is single-bonded to substituents 1 (top) and 3(right), wedge bonded to 2 (front), and dash bonded to 4 (left).
(b)
A carbon is single-bonded to substituents 3 (top) and 4 (right), wedge bonded to 1 (front), and dash bonded to 2 (left).
(c)
A carbon is single-bonded to substituents 4 (top) and 2 (right), wedge bonded to 3 (front), and dash bonded to 1 (left).

Chirality and Optical Activity

Problem 5-31

Which of the following objects are chiral?

(a) A basketball (b) A fork (c) A wine glass (d) A golf club (e) A spiral staircase 
(f) A snowflake

Problem 5-32
Which of the following compounds are chiral? Draw them, and label the chirality centers.
(a)
2,4-Dimethylheptane
(b)
5-Ethyl-3,3-dimethylheptane
(c)
cis-1,4-Dichlorocyclohexane
Problem 5-33
Draw chiral molecules that meet the following descriptions:
(a)
A chloroalkane, C5H11Cl
(b)
An alcohol, C6H14O
(c)
An alkene, C6H12
(d)
An alkane, C8H18
Problem 5-34
Eight alcohols have the formula C5H12O. Draw them. Which are chiral?
Problem 5-35
Draw compounds that fit the following descriptions:
(a)
A chiral alcohol with four carbons
(b)
A chiral carboxylic acid with the formula C5H10O2
(c)
A compound with two chirality centers
(d)
A chiral aldehyde with the formula C3H5BrO
Problem 5-36

Erythronolide B is the biological precursor of erythromycin, a broad-spectrum antibiotic. How many chirality centers does erythronolide B have? Identify them.

The wedge-dash structure of erythronolide B.

Assigning Configuration to Chirality Centers

Problem 5-37
Which of the following pairs of structures represent the same enantiomer, and which represent different enantiomers?
(a)
A carbon is single-bonded to bromine (top), cyano (right), wedge bonded to hydrogen (front), and dash bonded to methyl (left). The second structure, the positions of substituents are different.
(b)
A carbon is single-bonded to carboxylic acid (top), bromo (right), wedge bonded to cyano (front), and dash bonded to hydrogen (left). The second structure, the positions of substituents are different.
(c)
A carbon is single-bonded to methyl (top),hydroxyl (right), wedge bonded to ethyl (front), and dash bonded to hydrogen (left). The second structure, the positions of substituents are different.
(d)
A carbon is single-bonded to methyl (top), carboxylic acid (right), wedge bonded to amine (front), and dash bonded to hydrogen (left). The second structure, the positions of substituents are different.
Problem 5-38
What is the relationship between the specific rotations of (2R,3R)-dichloropentane and (2S,3S)-dichloropentane? Between (2R,3S)-dichloropentane and (2R,3R)-dichloropentane?
Problem 5-39
What is the stereochemical configuration of the enantiomer of (2S,4R)-2,4-octanediol?
Problem 5-40
What are the stereochemical configurations of the two diastereomers of (2S,4R)-2,4-octanediol? (A diol is a compound with two – OH groups.)
Problem 5-41
Orient each of the following drawings so that the lowest-ranked group is toward the rear, and then assign R or S configuration:
(a)
A carbon is single-bonded to substituents 4 (top) and 3 (right), wedge bonded to 2 (front), and dash bonded to 1 (left).
(b)
A carbon is single-bonded to substituents 3 (top) and 1 (right), wedge bonded to 2 (front), and dash bonded to 4 (left).
(c)
A carbon is single-bonded to substituents 4 (top) and 2 (right), wedge bonded to 1 (front), and dash bonded to 2 (left).
Problem 5-42
Assign Cahn–Ingold–Prelog rankings to the following sets of substituents:
(a)
C H double bonded to C H 2, C H (C H 3) 2, C (C H 3) 3, and C H 2 C H 3 with open single bonds.
(b)
C triple bonded to C H, C H double bonded to C H 2, C (C H 3) 3, and benzene each with an open single bond.
(c)
C O 2 C H 3, C O C H 3, C H 2 O C H 3, and C H 2 C H 3, with open single bonds.
(d)
Four substituents are C triple bonded to N, C H 2 Br, C H 2 C H 2 Br, and Br each with an open single bond.
Problem 5-43
Assign R or S configurations to each chirality center in the following molecules:
(a)
A carbon is single-bonded to wedge hydrogen (front),  dash bonded to hydroxyl (behind ), ethyl (right), and methyl (left).
(b)
A carbon is single-bonded to wedge chlorine atom (front),  dash bonded to hydrogen atom (behind ), methyl (right), and phenyl (left).
(c)
A carbon is single-bonded to wedge hyrdrogen atom (front),  dash bonded to methoxy group (behind ), carboxylic acid  (right), and hydroxymethyl group (left).
Problem 5-44
Assign R or S configuration to each chirality center in the following molecules:
(a)
In a cyclohexane ring, C1 is dash bonded to the hydroxyl group and wedge bonded to hydrogen. C2 is wedge bonded to chlorine and dash bonded to hydrogen.
(b)
In a cyclohexane ring, C1 is wedge bonded to hydrogen and dash bonded to the ethyl group. C2 is dash bonded to hydrogen and wedge bonded to methyl group.
(c)
In a cyclopentane ring, C1 and C3 are each wedge bonded to a hydroxyl group and dash bonded to a methyl group.
Problem 5-45
Assign R or S configuration to each chirality center in the following biological molecules:
(a)
The wedge-dash structure of biotin.
(b)
The wedge-dash structure of prostaglandin E 1.
Problem 5-46
Draw tetrahedral representations of the following molecules:
(a)
(S)-2-Chlorobutane
(b)
(R)-3-Chloro-1-pentene [H2C = CHCH(Cl)CH2CH3]
Problem 5-47
Assign R or S configuration to each chirality center in the following molecules:
(a)
In a 4-carbon chain, C2 and C3 are each wedge bonded to a bromine atom and dash bonded to a hydrogen atom.
(b)
A 4-carbon chain at C1 is a carboxylic acid group (right). C2 is wedge bonded to amino. C3 is wedge bonded to hydroxyl and C4 is bonded to benzene.
Problem 5-48

Assign R or S configurations to the chirality centers in ascorbic acid (vitamin C).

The wedge-dash structure of ascorbic acid.
Problem 5-49
Assign R or S stereochemistry to the chirality centers in the following Newman projections:
(a)
Newman projection of a 4-carbon chain with front carbon chlorine, hydrogen, and methyl substituents (clockwise). The back carbon has hydrogen, methyl, and hydrogen substituents (clockwise).
(b)
Newman projection of a 4-carbon chain with front carbon hydrogen, methyl, and methyl substituents (clockwise). The back carbon has hydroxyl, hydrogen, and methyl  substituents (clockwise).
Problem 5-50

Xylose is a common sugar found in many types of wood, including maple and cherry. Because it is much less prone to cause tooth decay than sucrose, xylose has been used in candy and chewing gum. Assign R or S configurations to the chirality centers in xylose.

Acyclic wedge-dash structure of (plus)-xylose.

Meso Compounds

Problem 5-51
Draw examples of the following:
(a)
A meso compound with the formula C8H18
(b)
A meso compound with the formula C9H20
(c)
A compound with two chirality centers, one R and the other S
Problem 5-52
Draw the meso form of each of the following molecules, and indicate the plane of symmetry in each:
(a)
In a 6-carbon chain, C2 and C5 are each bonded to hydroxyl groups.
(b)
In a cyclohexane ring, C1 and C3 are each bonded to methyl groups.
(c)
In a cyclohexane ring, C1 and C3 are each bonded to methyl groups.
Problem 5-53
Draw the structure of a meso compound that has five carbons and three chirality centers.
Problem 5-54

Ribose, an essential part of ribonucleic acid (RNA), has the following structure:

Acyclic wedge-dash structure of ribose.
(a)
How many chirality centers does ribose have? Identify them.
(b)
How many stereoisomers of ribose are there?
(c)
Draw the structure of the enantiomer of ribose.
(d)
Draw the structure of a diastereomer of ribose.
Problem 5-55

On reaction with hydrogen gas in the presence of a platinum catalyst, ribose (Problem 5-54) is converted into ribitol. Is ribitol optically active or inactive? Explain.

Acyclic wedge-dash structure of ribitol.

Prochirality

Problem 5-56
Identify the indicated hydrogens in the following molecules as pro-R or pro-S:
(a)
Wedge-dash structure of malic acid. Two arrows point toward the pro-S  and pro-R hydrogen atoms bonded at C3.
(b)
Wedge-dash structure of methionine zwitterion. Arrows point toward the pro-S  and pro-R hydrogen atoms bonded at C3 and C4.
(c)
Wedge-dash structure of cysteine zwitterion. Arrows point toward the pro-S and pro-R hydrogen atoms bonded at C3.
Problem 5-57
Identify the indicated faces in the following molecules as Re or Si:
(a)
The structure of pyruvate. Two arrows, one from the top and the other from bottom, point toward the central carbon.
(b)
The structure of crotonate. Two arrows, one from the top and the other from bottom, point toward C3.
Problem 5-58

One of the steps in fat metabolism is the hydration of crotonate to yield 3-hydroxybutyrate. The reaction occurs by addition of  – OH to the Si face at C3, followed by protonation at C2, also from the Si face. Draw the product of the reaction, showing the stereochemistry of each step.

The figure shows a reaction where crotonate converts to 3-hydroxybutyrate. In crotonate, the double bond is between C2 and C3.
Problem 5-59

The dehydration of citrate to yield cis-aconitate, a step in the citric acid cycle, involves the pro-R “arm” of citrate rather than the pro-S arm. Which of the following two products is formed?

The figure shows a reaction where citrate converts to two forms of cis-aconitate structures.
Problem 5-60

The first step in the metabolism of glycerol, formed by digestion of fats, is phosphorylation of the pro-R – CH2OH group by reaction with adenosine triphosphate (ATP) to give the corresponding glycerol phosphate plus adenosine diphosphate (ADP). Show the stereochemistry of the product.

The figure shows a reaction where glycerol on the conversion of A T P to A D P forms glycerol phosphate.
Problem 5-61

One of the steps in fatty-acid biosynthesis is the dehydration of (R)-3-hydroxybutyryl ACP to give trans-crotonyl ACP. Does the reaction remove the pro-R or the pro-S hydrogen from C2?

The dehydration of (R)-3-hydroxybutyryl A C P to form trans-crotonyl A C P.

General Problems

Problem 5-62
Draw all possible stereoisomers of 1,2-cyclobutanedicarboxylic acid, and indicate the interrelationships. Which, if any, are optically active? Do the same for 1,3-cyclobutanedicarboxylic acid.
Problem 5-63
Draw tetrahedral representations of the two enantiomers of the amino acid cysteine, HSCH2CH(NH2)CO2H, and identify each as R or S.
Problem 5-64

The naturally occurring form of the amino acid cysteine (Problem 5-63) has the R configuration at its chirality center. On treatment with a mild oxidizing agent, two cysteines join to give cystine, a disulfide. Assuming that the chirality center is not affected by the reaction, is cystine optically active? Explain.

The figure shows a reaction where two molecules of cysteine convert to cystine.
Problem 5-65
Draw tetrahedral representations of the following molecules:
(a)
The 2S,3R enantiomer of 2,3-dibromopentane
(b)
The meso form of 3,5-heptanediol
Problem 5-66

Assign R or S configurations to the chiral centers in cephalexin, trade-named Keflex, the most widely prescribed antibiotic in the United States.

The wedge-dash structure of cephalexin.
Problem 5-67

Chloramphenicol, a powerful antibiotic isolated in 1947 from the Streptomyces venezuelae bacterium, is active against a broad spectrum of bacterial infections and is particularly valuable against typhoid fever. Assign R or S configurations to the chirality centers in chloramphenicol.

The wedge-dash structure of chloramphenicol.
Problem 5-68

Allenes are compounds with adjacent carbon–carbon double bonds. Many allenes are chiral, even though they don’t contain chirality centers. Mycomycin, for example, a naturally occurring antibiotic isolated from the bacterium Nocardia acidophilus, is chiral and has [α]D = −130. Explain why mycomycin is chiral.

The condensed structural formula of mycomycin.
Problem 5-69

Long before chiral allenes were known (Problem 5-68), the resolution of 4-methylcyclohexylideneacetic acid into two enantiomers had been carried out. Why is it chiral? What geometric similarity does it have to allenes?

The wedge-dash structure of 4-methylcyclohexylideneacetic acid.
Problem 5-70
(S)-1-Chloro-2-methylbutane undergoes light-induced reaction with Cl2 to yield a mixture of products, among which are 1,4-dichloro-2-methylbutane and 1,2-dichloro-2-methylbutane.
(a)
Write the reaction, showing the correct stereochemistry of the reactant.
(b)
One of the two products is optically active, but the other is optically inactive. Which is which?
Problem 5-71
How many stereoisomers of 2,4-dibromo-3-chloropentane are there? Draw them, and indicate which are optically active.
Problem 5-72
Draw both cis- and trans-1,4-dimethylcyclohexane in their more stable chair conformations.
(a)
How many stereoisomers are there of cis-1,4-dimethylcyclohexane, and how many of trans-1,4-dimethylcyclohexane?
(b)
Are any of the structures chiral?
(c)
What are the stereochemical relationships among the various stereoisomers of 1,4-dimethylcyclohexane?
Problem 5-73
Draw both cis- and trans-1,3-dimethylcyclohexane in their more stable chair conformations.
(a)
How many stereoisomers are there of cis-1,3-dimethylcyclohexane, and how many of trans-1,3-dimethylcyclohexane?
(b)
Are any of the structures chiral?
(c)
What are the stereochemical relationships among the various stereoisomers of 1,3-dimethylcyclohexane?
Problem 5-74
cis-1,2-Dimethylcyclohexane is optically inactive even though it has two chirality centers. Explain.
Problem 5-75

We’ll see in Chapter 11 that alkyl halides react with hydrosulfide ion (HS) to give a product whose stereochemistry is inverted from that of the reactant.

Draw the reaction of (S)-2-bromobutane with HS ion to yield 2-butanethiol, CH3CH2CH(SH)CH3. Is the stereochemistry of the product R or S?

The figure shows a reaction where an alkyl bromide reacts with H S anion  to form a thiol compound and a bromide ion.
Problem 5-76

Ketones react with sodium acetylide (the sodium salt of acetylene, Na+– : C CH) to give alcohols. For example, the reaction of sodium acetylide with 2-butanone yields 3-methyl-1-pentyn-3-ol:

In a reaction, 2-butanone reacts with Na superscript plus C superscript minus triple bonded to C H in first step and hydronium ion in the second step to form 3-methyl-1-pentyn-3-ol.
(a)
Is the product chiral?
(b)
Assuming that the reaction takes place with equal likelihood from both Re and Si faces of the carbonyl group, is the product optically active? Explain.
Problem 5-77

Imagine that a reaction similar to that in Problem 5-76 is carried out between sodium acetylide and (R)-2-phenylpropanal to yield 4-phenyl-1-pentyn-3-ol:

In a reaction, (R)-2-phenylpropanal reacts with Na superscript plus C superscript minus triple bonded to C H in first step and hydronium ion in the second step to form 4-phenyl-1-pentyn-3-ol.
(a)
Is the product chiral?
(b)
Draw both major and minor reaction products, assuming that the reaction takes place preferentially from the Re face of the carbonyl group. Is the product mixture optically active? Explain.
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