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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

7 • Additional Problems

7 • Additional Problems

Visualizing Chemistry

Problem 7-22
Name the following alkenes, and convert each drawing into a skeletal structure:
(a)
The ball-and-stick model has a 6-carbon chain. C2 is double bonded to C3. C2, C4, and C5 are each bonded to a methyl group.
(b)
The ball-and-stick model has a cyclohexene ring. C1 is bonded to an ethyl group. C3 is bonded to two methyl groups.
Problem 7-23
Assign E or Z stereochemistry to the double bonds in each of the following alkenes, and convert each drawing into a skeletal structure (red = O, green = Cl):
(a)
The ball-and-stick model has a 2-carbon chain with double bond. C1 is bonded to chlorine and methyl. C2 is bonded to an aldehyde and an isopropyl group.
(b)
The ball-and-stick model has 5-carbon chain with alternate double bonds. C2 and C3 are each bonded to methyl. C4 is bonded to methoxy. C5 is carboxylic acid.
Problem 7-24

The following carbocation is an intermediate in the electrophilic addition reaction of HCl with two different alkenes. Identify both, and tell which C−H bonds in the carbocation are aligned for hyperconjugation with the vacant p orbital on the positively charged carbon.

The ball-and-stick model has a cyclopentane ring. C1 is bonded to an ethyl group. The gray and white spheres represent carbon and hydrogen atoms, respectively.
Problem 7-25

The following alkyl bromide can be made by HBr addition to three different alkenes. Show their structures.

The ball-and-stick model has a cyclohexane ring. C1 is bonded to bromine and ethyl group. C3 is bonded to a methyl group.

Mechanism Problems

Problem 7-26
Predict the major product and show the complete mechanism for each of the following electrophilic addition reactions.
(a)
An incomplete reaction shows vinylcyclohexane reacting with hydrogen chloride to form unknown product(s) indicated by a question mark.
(b)
An incomplete reaction shows 4-methyl-1-pentene reacting with hydrogen bromide to form unknown product(s) indicated by a question mark.
(c)
An incomplete reaction shows 1-methylcyclopentene reacting with K I and phosphoric acid to form unknown product(s) indicated by a question mark.
Problem 7-27
Each of the following electrophilic addition reactions involves a carbocation rearrangement. Predict the product and draw the complete mechanism of each using curved arrows.
(a)
An incomplete reaction shows 3-methyl-1-pentene reacting with hydrogen chloride to form unknown product(s) indicated by a question mark.
(b)
An incomplete reaction shows 3,6-dimethylcyclohexene reacting with hydrogen bromide to form unknown product(s) indicated by a question mark.
(c)
An incomplete reaction shows vinylcyclobutane reacting with K I and phosphoric acid to form unknown product(s) indicated by a question mark. Text says two different rearrangement products.
Problem 7-28

When 1,3-butadiene reacts with 1 mol of HBr, two isolable products result. Propose mechanisms for both.

A reaction shows 1,3-butadiene reacting with hydrogen bromide to form 3-bromo-1-butene and trans-1-bromo-2-butene.
Problem 7-29

When methyl vinyl ether reacts with a strong acid, H+ adds to C2 instead of C1 or the oxygen atom. Explain.

The structure of methyl vinyl ether shows C1 bonded to a methoxy group and a hydrogen atom. C2 is bonded to two hydrogen atoms.
Problem 7-30

Addition of HCl to 1-isopropylcyclohexene yields a rearranged product. Propose a mechanism, showing the structures of the intermediates and using curved arrows to indicate electron flow in each step.

Cyclohexene with an isopropyl group at C1 reacts with hydrogen chloride to form a product that has a central carbon bonded to two methyl groups, chlorine, and cyclohexane.
Problem 7-31

Addition of HCl to 1-isopropenyl-1-methylcyclopentane yields 1-chloro-1,2,2-trimethylcyclohexane. Propose a mechanism, showing the structures of the intermediates and using curved arrows to indicate electron flow in each step.

Cyclopentane bonded to a methyl group and C2 of propene reacts with hydrogen chloride to form 1-chloro-1,2,2-trimethylcyclohexane.
Problem 7-32

Limonene, a fragrant hydrocarbon found in lemons and oranges, is biosynthesized from geranyl diphosphate by the following pathway. Add curved arrows to show the mechanism of each step. Which step involves an alkene electrophilic addition? (The ion OP2O64− is the diphosphate ion, and “Base” is an unspecified base in the enzyme that catalyzes the reaction.)

A 3-step biosynthesis reaction shows the formation of limonene from geranyl diphosphate.
Problem 7-33

epi-Aristolochene, a hydrocarbon found in both pepper and tobacco, is biosynthesized by the following pathway. Add curved arrows to show the mechanism of each step. Which steps involve alkene electrophilic addition(s), and which involve carbocation rearrangement(s)? (The abbreviation H—A stands for an unspecified acid, and “Base” is an unspecified base in the enzyme.)

A 5-step reaction shows the formation of epi-Aristolochene. H-A (acid) is used in first step and base in the last step.

Calculating a Degree of Unsaturation

Problem 7-34
Calculate the degree of unsaturation in the following formulas, and draw five possible structures for each:
(a)
C10H16
(b)
C8H8O
(c)
C7H10Cl2
(d)
C10H16O2
(e)
C5H9NO2
(f)
C8H10ClNO
Problem 7-35
How many hydrogens does each of the following compounds have?
(a)
C8H?O2, has two rings and one double bond
(b)
C7H?N, has two double bonds
(c)
C9H?NO, has one ring and three double bonds
Problem 7-36

Loratadine, marketed as an antiallergy medication under the brand name Claritin, has four rings, eight double bonds, and the formula C22H?ClN2O2. How many hydrogens does loratadine have? (Calculate your answer; don’t count hydrogens in the structure.)

The structure of Loratadine.

Naming Alkenes

Problem 7-37
Name the following alkenes:
(a)
A double bond with hydrogen (up) and methyl (down) substituents on the left and s-butyl (up) and hydrogen (down) substituents on the right.
(b)
A double bond with 2-methylheptane connected by C 5 (up) and methyl (down) substituents on the left and methyl (up) and hydrogen (down) substituents on the right.
(c)
A double bond withtwo hydrogen substituents on the left and two ethyl substituents on the right.
(d)
A double bond with H (up) and 3-methyl-1-pentene connected by C 4 (down) substituents on the left and methyl (up) and hydrogen (down) substituents on the right.
(e)
An 8-carbon chain with double bonds between C2-C3 and C4-C5. C4 and C5 are each bonded to a methyl group (opposite sides).
(f)
The structure has a methylene group double bonded to carbon, which is double bonded to C H C H 3.
Problem 7-38
Draw structures corresponding to the following systematic names:
(a)
(4E)-2,4-Dimethyl-1,4-hexadiene
(b)
cis-3,3-Dimethyl-4-propyl-1,5-octadiene
(c)
4-Methyl-1,2-pentadiene
(d)
(3E,5Z)-2,6-Dimethyl-1,3,5,7-octatetraene
(e)
3-Butyl-2-heptene
(f)
trans-2,2,5,5-Tetramethyl-3-hexene
Problem 7-39
Name the following cycloalkenes:
(a)
A six-membered ring with one double bond. There is a methyl group one carbon from the double bond.
(b)
A five-membered ring with one double bond. There are methyl groups on a double-bonded carbon and on the single-bonded carbon next to it.
(c)
A four-membered ring with two double bonds. There is one ethyl substituent.
(d)
A six-membered ring with two double bonds opposite one another on the ring. There are methyl groups at each end of one double bond.
(e)
A six-membered ring with two double bonds separated by one single bond. There is one methyl group one carbon away from the end of one double bond.
(f)
An eight-membered ring with two double bonds opposite one another on the ring.
Problem 7-40

Ocimene is a triene found in the essential oils of many plants. What is its IUPAC name, including stereochemistry?

An eight-carbon chain with bonds (from left) as: single, double, single, single, double, single, double. There are methyl groups at the second and sixth carbons from the left.
Problem 7-41

α-Farnesene is a constituent of the natural wax found on apples. What is its IUPAC name, including stereochemistry?

Twelve-carbon chain with bonds (from left) as: single, double, single, single, single, double, single, single, double, single, double. Methyl groups at the second, sixth, and tenth carbons from the left.
Problem 7-42
Menthene, a hydrocarbon found in mint plants, has the systematic name 1-isopropyl-4-methylcyclohexene. Draw its structure.
Problem 7-43
Draw and name the six alkene isomers, C5H10, including E,Z isomers.
Problem 7-44
Draw and name the 17 alkene isomers, C6H12, including E,Z isomers.

Alkene Isomers and Their Stability

Problem 7-45
Rank the following sets of substituents according to the Cahn–Ingold–Prelog sequence rules:
(a)
The figure shows four sets of substituents. Methyl, bromine, hydrogen, and iodine each with an open single bond.
(b)
The figure shows four sets of substituents. A hydroxyl group, methoxy group, hydrogen atom, and carboxylic acid group each with an open single bond.
(c)
The figure shows four sets of substituents. Carboxyl, methyl ester, hydroxymethyl, and methyl each with an open single bond.
(d)
The figure shows three sets of substituents. Methyl, ethyl, C H 2 C H 2 O H, and acetyl group bonded to methyl each with an open single bond.
(e)
The figure shows four sets of substituents. Vinyl, cyano, C H 2 N H 2, and bromomethyl each with an open single bond.
(f)
The figure shows four sets of substituents. Vinyl, ethyl, C H 2 O C H 3, and hydroxymethyl with open single bonds.
Problem 7-46
Assign E or Z configuration to each of the following compounds:
(a)
A double bond with hydroxymethyl (up) and methyl (down) substituents on the left and methyl (up) and hydrogen (down) substituents on the right.
(b)
A double bond with carbonyl (up) and chlorine (down) substituents on the left and hydrogen (up) and methoxy (down) substituents on the right.
(c)
A double bond with nitrile (up) and ethyl (down) substituents on the left and methyl (up) and hydroxymethyl (down) substituents on the right.
(d)
A double bond with methyl ester (up) and carboxyl (down) substituents on the left and vinyl (up) and ethyl (down) substituents on the right.
Problem 7-47
Which of the following E,Z designations are correct, and which are incorrect?
(a)
The structure labeled Z shows C1 of a cyclohexane ring double bonded to carbon, which is bonded to a carboxylic acid group (up). C3 (up) is bonded to a methyl group.
(b)
The structure labeled E has a double bond with hydrogen (up) and methyl (down) substituents on the left and allyl (up) and s-butyl (down) substituents on the right.
(c)
Structure labeled Z has double bond. C1 has bromine (up). C2 has C H 2 N H 2 (up) and C H 2 N H C H 3.
(d)
Structure labeled E has double bond. C1 has nitrile (up) and C H 2 N (C H 3) 2. C2 has methyl (up) and ethyl.
(e)
The structure labeled Z shows C1 of cyclopentane double bonded to carbon, which is single bonded to bromine and hydrogen atom.
(f)
Structure labeled E has double bond. C1 has hydroxymethyl (up) and C H 2 O C H 3. C2 has carboxyl (up) and acetyl.
Problem 7-48
Rank the double bonds according to their increasing stability.
(a)
Dimethylcyclopentane with double bond between C1-C6, dimethylcyclopentane with a double bond between C1-C2, and cyclopentane with double bonded methylene at C1 and methyl at C2.
(b)
Cyclohexane fused to cyclohexene with the double bond opposite the fusion, two cyclohexanes with a shared double bond, and cyclohexane fused to cyclohexene with the double bond adjacent to fusion.
(c)
Pent-2-ene with methyl at C3, a pentane with double-bonded methylene at C3, and 1-pentene with a methyl group at C3.
Problem 7-49
trans-2-Butene is more stable than cis-2-butene by only 4 kJ/mol, but trans-2,2,5,5-tetramethyl-3-hexene is more stable than its cis isomer by 39 kJ/mol. Explain.
Problem 7-50
Cyclodecene can exist in both cis and trans forms, but cyclohexene cannot. Explain.
Problem 7-51
Normally, a trans alkene is more stable than its cis isomer. trans-Cyclooctene, however, is less stable than cis-cyclooctene by 38.5 kJ/mol. Explain.
Problem 7-52
trans-Cyclooctene is less stable than cis-cyclooctene by 38.5 kJ/mol, but trans-cyclononene is less stable than cis-cyclononene by only 12.2 kJ/mol. Explain.
Problem 7-53

Tamoxifen, a drug used in the treatment of breast cancer, and clomiphene, a drug used in fertility treatment, have similar structures but very different effects. Assign E or Z configuration to the double bonds in both compounds.

The structures of Tamoxifen (anticancer) and Clomiphene (fertility treatment).

Carbocations and Electrophilic Addition Reactions

Problem 7-54
Rank the following carbocations according to their increasing stability.
(a)
Isopropyl with a positive charge at central carbon, a 4-carbon chain with a positive charge at C1, and another 4-carbon chain with a positive charge at C2.
(b)
Cyclopentane bonded to methyl with positive charge on it, cyclopentane with a positive charge at C1 bonded to methyl, and cyclopentane bonded to methyl group.
(c)
Three structures show cyclohexane fused to cyclopentane with shared methyl. Carbocation at carbon opposite fusion in cyclopentane, on methyl, and at a fusion site in first, second, and third structure.
Problem 7-55
Use the Hammond Postulate to determine which alkene in each pair would be expected to form a carbocation faster in an electrophilic addition reaction.
(a)
Structures of 3-methyl-1-pentene and E-3-methyl-2-pentene.
(b)
Structures of methylenecyclopentane and 4-methylcyclopentene.
(c)
Structures of 3-methyl-1-butene and 3-methyl-2-butene
Problem 7-56
The following carbocations can be stabilized by resonance. Draw all the resonance forms that would stabilize each carbocation.
(a)
2-methyl-1,4-pentadiene with carbocation on C 3 in resonance with an unknown compound indicated by question mark.
(b)
A cyclohexadiene ring with a positive charge at C 6 and a nitro group at C 5 in resonance with an unknown compound indicated by question mark.
(c)
3-methoxy-1-butene with carbocation on C 3 in resonance with an unknown compound indicated by question mark.
Problem 7-57
Predict the major product in each of the following reactions:
(a)
An incomplete reaction shows 3-methyl-3-hexene reacting with water and sulfuric acid to form unknown product(s) indicated by a question mark. Text says addition of H 2 O occurs.
(b)
An incomplete reaction shows 1-ethylcyclopentene reacting with H Br to form unknown product(s) indicated by a question mark.
(c)
An incomplete reaction shows 3-methylcyclohexene reacting with H Br to form unknown product(s) indicated by a question mark.
(d)
An incomplete reaction shows 1,6-heptadiene reacting with 2 equivalents of H Cl to form unknown product(s) indicated by a question mark.
Problem 7-58
Predict the major product from addition of HBr to each of the following alkenes:
(a)
A cyclohexane ring is double bonded to a methylene group.
(b)
A cyclohexane ring is fused to C1 and C6 of cyclohexene.
(c)
The condensed structure has a 5-carbon chain. C2 is double bonded to C3. C4 is bonded to a methyl group.
Problem 7-59
Alkenes can be converted into alcohols by acid-catalyzed addition of water. Assuming that Markovnikov’s rule is valid, predict the major alcohol product from each of the following alkenes.
(a)
The condensed structure has a 5-carbon chain. C2 is double bonded to C3. C3 is bonded to a methyl group.
(b)
A cyclohexane ring is double-bonded to a methylene group.
(c)
The condensed structure has a 5-carbon chain. C1 is double bonded to C2. C4 is bonded to a methyl group.
Problem 7-60
Each of the following carbocations can rearrange to a more stable ion. Propose structures for the likely rearrangement products.
(a)
A 4-carbon chain with a positive charge at C1.
(b)
A 4-carbon chain with a positive charge at C2 and a methyl group at C3.
(c)
A cyclobutane ring. C1 is bonded to a methyl group and a methylene group with a positive charge.

General Problems

Problem 7-61
Allene (1,2-propadiene), H2C = C = CH2, has two adjacent double bonds. What kind of hybridization must the central carbon have? Sketch the bonding π orbitals in allene. What shape do you predict for allene?
Problem 7-62
The heat of hydrogenation for allene (Problem 7-61) to yield propane is −295 kJ/mol, and the heat of hydrogenation for a typical monosubstituted alkene, such as propene, is −125 kJ/mol. Is allene more stable or less stable than you might expect for a diene? Explain.
Problem 7-63

Retin A, or retinoic acid, is a medication commonly used to reduce wrinkles and treat severe acne. How many different isomers arising from E,Z double-bond isomerizations are possible?

The structure of retin A (retinoic acid): one double bond in a ring, and four double bonds in a long substituent chain, each with two different substituents at each carbon.
Problem 7-64

Fucoserratene and ectocarpene are sex pheromones produced by marine brown algae. What are their systematic names? (Ectocarpene is difficult; make your best guess, and then check your answer in the Student Solutions Manual.)

The structures of fucoserratene and ectocarpene.
Problem 7-65

tert-Butyl esters [RCO2C(CH3)3] are converted into carboxylic acids (RCO2H) by reaction with trifluoroacetic acid, a reaction useful in protein synthesis (Section 26.7). Assign E,Z designation to the double bonds of both reactant and product in the following scheme, and explain why there is an apparent change in double-bond stereochemistry:

The figure shows tertiary-butyl ester reacts with trifluoroacetic acid to form a carboxylic acid and an alkene.
Problem 7-66

Vinylcyclopropane reacts with HBr to yield a rearranged alkyl bromide. Follow the flow of electrons as represented by the curved arrows, show the structure of the carbocation intermediate in brackets, and show the structure of the final product.

A 2-step reaction shows vinylcyclopropane reacting with hydrogen bromide via abstraction of hydrogen and alkyl shift. The intermediate and products are unknown.
Problem 7-67
Calculate the degree of unsaturation in each of the following formulas:
(a)
Cholesterol, C27H46O
(b)
DDT, C14H9Cl5
(c)
Prostaglandin E1, C20H34O5
(d)
Caffeine, C8H10N4O2
(e)
Cortisone, C21H28O5
(f)
Atropine, C17H23NO3
Problem 7-68

The isobutyl cation spontaneously rearranges to the tert-butyl cation by a hydride shift. Is the rearrangement exergonic or endergonic? Draw what you think the transition state for the hydride shift might look like according to the Hammond postulate.

The figure shows isobutyl cation converts to tertiary-butyl cation.
Problem 7-69
Draw an energy diagram for the addition of HBr to 1-pentene. Let one curve on your diagram show the formation of 1-bromopentane product and another curve on the same diagram show the formation of 2-bromopentane product. Label the positions for all reactants, intermediates, and products. Which curve has the higher-energy carbocation intermediate? Which curve has the higher-energy first transition state?
Problem 7-70
Sketch the transition-state structures involved in the reaction of HBr with 1-pentene (Problem 7-69). Tell whether each structure resembles reactant or product.
Problem 7-71

Aromatic compounds such as benzene react with alkyl chlorides in the presence of AlCl3 catalyst to yield alkylbenzenes. This reaction occurs through a carbocation intermediate, formed by reaction of the alkyl chloride with AlCl3 (R−Cl + AlCl3 ⟶ R+ + AlCl4). How can you explain the observation that reaction of benzene with 1-chloropropane yields isopropylbenzene as the major product?

Benzene reacts with propyl chloride in the presence of aluminum trichloride to form a benzene ring, in which C1 is bonded to an isopropyl group.
Problem 7-72
Reaction of 2,3-dimethyl-1-butene with HBr leads to an alkyl bromide, C6H13Br. On treatment of this alkyl bromide with KOH in methanol, elimination of HBr occurs and a hydrocarbon that is isomeric with the starting alkene is formed. What is the structure of this hydrocarbon, and how do you think it is formed from the alkyl bromide?
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