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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

13 • Additional Problems

13 • Additional Problems

Visualizing Chemistry

Problem 13-24
Into how many peaks would you expect the 1H NMR signals of the indicated protons to be split? (Green = Cl.)
(a)
The ball-and-stick model has a 4-carbon chain. C 1 is bonded to chlorine atom. C 2 is double bonded to oxygen atom. C 3 is bonded to methyl group.
(b)
The ball-and-stick model has a benzene ring. C 1 is bonded to a 2-carbon chain, in which C 1 is an aldehyde group. C 4 is bonded to methyl.
Problem 13-25

How many absorptions would you expect the following compound to have in its 1H and 13C NMR spectra?

The ball-and-stick model of 3-methyl-2-cyclohexen-1-one.
Problem 13-26

Sketch what you might expect the 1H and 13C NMR spectra of the following compound to look like (green = Cl):

The ball-and-stick model of ethyl 2-chloropropionate.
Problem 13-27

How many electronically nonequivalent kinds of protons and how many kinds of carbons are present in the following compound? Don’t forget that cyclohexane rings can ring-flip.

The ball-and-stick model of a cyclohexane ring in chair form. C 1 is bonded to equatorial methyl and C 2 is bonded to axial methyl.
Problem 13-28
Identify the indicated protons in the following molecules as unrelated, homotopic, enantiotopic, or diastereotopic.
(a)
The ball-and-stick model of cysteine. The gray, black, blue, yellow, and red spheres represent hydrogen, carbon, nitrogen, sulfur, and oxygen atoms, respectively. Arrows point toward hydrogens at C 3.
(b)
Ball-and-stick model of cyclopentanol. Gray, black, and red spheres represent hydrogen, carbon, and oxygen atoms, respectively. Arrows point toward hydrogens trans to the hydroxy group on C 3 and 4.

Chemical Shifts and NMR Spectroscopy

Problem 13-29
The following 1H NMR absorptions were obtained on a spectrometer operating at 200 MHz and are given in hertz downfield from the TMS standard. Convert the absorptions to δ units.
(a)
436 Hz
(b)
956 Hz
(c)
1504 Hz
Problem 13-30
The following 1H NMR absorptions were obtained on a spectrometer operating at 300 MHz. Convert the chemical shifts from δ units to hertz downfield from TMS.
(a)
2.1 δ
(b)
3.45 δ
(c)
6.30 δ
(d)
7.70 δ
Problem 13-31
When measured on a spectrometer operating at 200 MHz, chloroform (CHCl3) shows a single sharp absorption at 7.3 δ.
(a)
How many parts per million downfield from TMS does chloroform absorb?
(b)
How many hertz downfield from TMS would chloroform absorb if the measurement were carried out on a spectrometer operating at 360 MHz?
(c)
What would be the position of the chloroform absorption in δ units when measured on a 360 MHz spectrometer?
Problem 13-32
Why do you suppose accidental overlap of signals is much more common in 1H NMR than in 13C NMR?
Problem 13-33
Is a nucleus that absorbs at 6.50 δ more shielded or less shielded than a nucleus that absorbs at 3.20 δ? Does the nucleus that absorbs at 6.50 δ require a stronger applied field or a weaker applied field to come into resonance than the one that absorbs at 3.20 δ?

1H NMR Spectroscopy

Problem 13-34
How many types of nonequivalent protons are present in each of the following molecules?
(a)
A chemical structure of 1,1-dimethylcyclohexane.
(b)
The condensed structural formula reads, C H 3 C H 2 C H 2 O C H 3.
(c)
Naphthalene has a benzene ring fused to a cyclohexadiene ring with alternating double bonds.
(d)
A chemical structure of styrene (vinyl benzene).
(e)
Ethyl acrylate has a carbon atom double bonded to another carbon. C 1 is bonded to C O 2 C H 2 C H 3.
Problem 13-35

The following compounds all show a single line in their 1H NMR spectra. List them in order of expected increasing chemical shift:

CH4, CH2Cl2, cyclohexane, CH3COCH3, H2C  =  CH2, benzene

Problem 13-36
How many signals would you expect each of the following molecules to have in its 1H and 13C spectra?
(a)
The structure has two carbon atoms with a double bond in-between. C 1 and C 2 are each bonded to two methyl groups.
(b)
The structure has a cyclohexane ring. C 1 is a carbonyl group. C 4 is bonded to two methyl groups.
(c)
A condensed structure of acetone.
(d)
A chemical structure of methyl 2,2-dimethyl propionate.
(e)
The structure has a benzene ring. C 1 and C 4 are each bonded to a methyl group.
(f)
A chemical structure of 1,1-dimethylcyclopropane.
Problem 13-37
Propose structures for compounds with the following formulas that show only one peak in their 1H NMR spectra:
(a)
C5H12
(b)
C5H10
(c)
C4H8O2
Problem 13-38
Predict the splitting pattern for each kind of hydrogen in the following molecules:
(a)
(CH3)3CH
(b)
CH3CH2CO2CH3
(c)
trans-2-Butene
Problem 13-39
Predict the splitting pattern for each kind of hydrogen in isopropyl propanoate, CH3CH2CO2CH(CH3)2.
Problem 13-40
Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic:
(a)
A chemical structure of 3-pentanone. Arrows point to highlighted hydrogens on C 2.
(b)
A chemical structure of 3-pentanol. Arrows point to highlighted hydrogens on C 2.
(c)
A chemical structure of 3-chloropentane, with chlorine on a wedge bond. Arrows point to highlighted wedge hydrogen on C 2 and dash hydrogen on C 4.
Problem 13-41
Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic:
(a)
A cyclohexane ring is fused to another cyclohexane ring. The top and bottom fusion sites are wedge bonded to hydrogen (highlighted) and dash bonded to another hydrogen (highlighted), respectively.
(b)
A cyclohexane ring is fused to a cyclopentane ring. The top and bottom fusion sites are wedge bonded to hydrogen (highlighted) and dash bonded to another hydrogen (highlighted), respectively.
(c)
A structure of bicyclo[3.1.1.]heptane. C 2 has a methylene substituent. C 6 has two methyl substituents with highlighted hydrogens.
Problem 13-42

The acid-catalyzed dehydration of 1-methylcyclohexanol yields a mixture of two alkenes. How could you use 1H NMR to help you decide which was which?

A cyclohexane ring with methyl and hydroxyl at C 1 reacts with hydronium ion to form cyclohexane double bonded to methylene and cyclohexene with methyl at C 1.
Problem 13-43
How could you use 1H NMR to distinguish between the following pairs of isomers?
(a)
Condensed structures of 2-pentene and ethylcyclopropane.
(b)
Condensed structures of diethyl ether and methyl propyl ether.
(c)
Condensed structures of diethyl ether and methyl propyl ether.
(d)
Condensed structures of ethyl acetate and 2-butanone.
Problem 13-44
Propose structures for compounds that fit the following 1H NMR data:
(a)
  • C5H10O
  • 0.95 δ (6 H, doublet, J = 7 Hz)
  • 2.10 δ (3 H, singlet)
  • 2.43 δ (1 H, multiplet)
(b)
  • C3H5Br
  • 2.32 δ (3 H, singlet)
  • 2.32 δ (3 H, singlet)
  • 2.32 δ (3 H, singlet)
Problem 13-45
Propose structures for the two compounds whose 1H NMR spectra are shown.
(a)

C4H9Br

The 1 H N M R spectrum of C 4 H 9 B r shows peaks at 0 (T M S), 1 (doublet), 2 (septet), and 3.3 (doublet).
(b)

C4H8Cl2

1 H N M R spectrum of C 4 H 8 C l 2 shows peaks at 0 (T M S), 1.5 (doublet), 2.1 (quartet), 3.7 (multiplet), and 4.2 (multiplet).

13C NMR Spectroscopy

Problem 13-46
How many 13C NMR absorptions would you expect for cis-1,3-dimethylcyclohexane? For trans-1,3-dimethylcyclohexane? Explain.
Problem 13-47
How many absorptions would you expect to observe in the 13C NMR spectra of the following compounds?
(a)
1,1-Dimethylcyclohexane
(b)
CH3CH2OCH3
(c)
tert-Butylcyclohexane
(d)
3-Methyl-1-pentyne
(e)
cis-1,2-Dimethylcyclohexane
(f)
Cyclohexanone
Problem 13-48
Suppose you ran a DEPT-135 spectrum for each substance in Problem 13.47. Which carbon atoms in each molecule would show positive peaks, and which would show negative peaks?
Problem 13-49

How could you use 1H and 13C NMR to help distinguish the following isomeric compounds of the formula C4H8?

Condensed structures of cyclobutane, 1-butene, 2-butene, and 2-methyl-1-propene.
Problem 13-50

How could you use 1H NMR, 13C NMR, and IR spectroscopy to help you distinguish between the following structures?

An illustration shows the structures of 3-Methyl-2-cyclohexenone and 3-Cyclopentenyl methyl ketone. 3-Methyl-2-cyclohexenone shows a cyclohexenone bonded to a methyl group. 3-Cyclopentenyl methyl ketone shows a cyclopentene bonded to a carbonyl group bonded to a methyl group.
Problem 13-51

Assign as many resonances as you can to specific carbon atoms in the 13C NMR spectrum of ethyl benzoate.

The 13 C N M R spectrum of ethyl benzoate shows peaks at 0 (T M S), 15 (sharp), 61 (sharp), between 126 and 132 (variable heights), and 165 (tiny).

General Problems

Problem 13-52
Assume that you have a compound with the formula C3H6O.
(a)
How many double bonds and/or rings does your compound contain?
(b)
Propose as many structures as you can that fit the molecular formula.
(c)
If your compound shows an infrared absorption peak at 1715 cm–1, what functional group does it have?
(d)
If your compound shows a single 1H NMR absorption peak at 2.1 δ, what is its structure?
Problem 13-53

The compound whose 1H NMR spectrum is shown has the molecular formula C3H6Br2. Propose a structure.

The 1 H N M R spectrum shows peaks at 0 (T M S), 2.3 (quintet), and 3.6 (triplet).
Problem 13-54

The compound whose 1H NMR spectrum is shown has the molecular formula C4H7O2Cl and has an infrared absorption peak at 1740 cm–1. Propose a structure.

The H N M R spectrum shows peaks at 0 (T M S), 1.3 (triplet), 4.1 (singlet), and 4.3 (quartet).
Problem 13-55
Propose structures for compounds that fit the following 1H NMR data:
(a)
  • C4H6Cl2
  • 2.18 δ (3 H, singlet)
  • 4.16 δ (2 H, doublet, J = 7 Hz)
  • 5.71 δ (1 H, triplet, J = 7 Hz)
(b)
  • C10H14
  • 1.30 δ (9 H, singlet)
  • 7.30 δ (5 H, singlet)
(c)
  • C4H7BrO
  • 2.11 δ (3 H, singlet)
  • 3.52 δ (2 H, triplet, J = 6 Hz)
  • 4.40 δ (2 H, triplet, J = 6 Hz)
(d)
  • C9H11Br
  • 2.15 δ (2 H, quintet, J = 7 Hz)
  • 2.75 δ (2 H, triplet, J = 7 Hz)
  • 3.38 δ (2 H, triplet, J = 7 Hz)
  • 7.22 δ (5 H, singlet)
Problem 13-56

Long-range coupling between protons more than two carbon atoms apart is sometimes observed when π bonds intervene. An example is found in 1-methoxy-1-buten-3-yne. Not only does the acetylenic proton, Ha, couple with the vinylic proton Hb, it also couples with the vinylic proton Hc, four carbon atoms away. The data are:

1-Methoxy-1-buten-3-yne structure with hydrogen shifts of 3.08 (alkyne). 4.52 (on C 2), and 6.35 (on C 1). J values are also mentioned.

Construct tree diagrams that account for the observed splitting patterns of Ha, Hb, and Hc.

Problem 13-57

The 1H and 13C NMR spectra of compound A, C8H9Br, are shown. Propose a structure for A, and assign peaks in the spectra to your structure.

H N M R shifts: 0, 1.2 (triplet), 2.6 (quartet), 7.1 (singlet), and 7.1 and 7.4 (two doublets). C N M R shifts: 17, 30, 120 (short), 130, and 132.
Problem 13-58
Propose structures for the three compounds whose 1H NMR spectra are shown.
(a)

C5H10O

The 1 H N M R spectrum shows peaks at 0 (T M S), 0.9 (triplet), 1.7 (sextet), and 2.4 (triplet).
(b)

C7H7Br

The 1 H N M R spectrum shows peaks at 0 (T M S), 2.3 (singlet), 7 (doublet), and 7.3 (doublet).
(c)

C8H9Br

The 1 H N M R spectrum shows peaks at 0 (T M S), 3.1 (triplet), 3.6 (triplet), and 7.2 (indistinct, messy multiplet).
Problem 13-59

The mass spectrum and 13C NMR spectrum of a hydrocarbon are shown. Propose a structure for this hydrocarbon, and explain the spectral data.

The mass spectrum shows main peaks at 15, 26, 29, 39, 41, 42, 43, 56 (base), 69, and 84. C N M R spectrum shifts at 15, 26, ad 132.
Problem 13-60

Compound A, a hydrocarbon with M+ = 96 in its mass spectrum, has the following 13C spectral data. On reaction with BH3, followed by treatment with basic H2O2, A is converted into B, whose 13C spectral data are also given. Propose structures for A and B.

Compound A

  • Broadband-decoupled 13C NMR: 26.8, 28.7, 35.7, 106.9, 149.7 δ
  • DEPT-90: no peaks
  • DEPT-135: no positive peaks; negative peaks at 26.8, 28.7, 35.7, 106.9 δ

Compound B

  • Broadband-decoupled 13C NMR: 26.1, 26.9, 29.9, 40.5, 68.2 δ
  • DEPT-90: 40.5 δ
  • DEPT-135: positive peak at 40.5 δ; negative peaks at 26.1, 26.9, 29.9, 68.2 δ
Problem 13-61

Propose a structure for compound C, which has M+ = 86 in its mass spectrum, an IR absorption at 3400 cm–1, and the following 13C NMR spectral data:

Compound C

  • Broadband-decoupled 13C NMR: 30.2, 31.9, 61.8, 114.7, 138.4 δ
  • DEPT-90: 138.4 δ
  • DEPT-135: positive peak at 138.4 δ; negative peaks at 30.2, 31.9, 61.8, 114.7 δ
Problem 13-62

Compound D is isomeric with compound C (Problem 13.61) and has the following 13C NMR spectral data. Propose a structure.

Compound D

  • Broadband-decoupled 13C NMR: 9.7, 29.9, 74.4, 114.4, 141.4 δ
  • DEPT-90: 74.4, 141.4 δ
  • DEPT-135: positive peaks at 9.7, 74.4, 141.4 δ; negative peaks at 29.9, 114.4 δ
Problem 13-63

Propose a structure for compound E, C7H12O2, which has the following 13C NMR spectral data:

Compound E

  • Broadband-decoupled 13C NMR: 19.1, 28.0, 70.5, 129.0, 129.8, 165.8 δ
  • DEPT-90: 28.0, 129.8 δ
  • DEPT-135: positive peaks at 19.1, 28.0, 129.8 δ; negative peaks at 70.5, 129.0 δ
Problem 13-64

Compound F, a hydrocarbon with M+ = 96 in its mass spectrum, undergoes reaction with HBr to yield compound G. Propose structures for F and G, whose 13C NMR spectral data are given below.

Compound F

  • Broadband-decoupled 13C NMR: 27.6, 29.3, 32.2, 132.4 δ
  • DEPT-90: 132.4 δ
  • DEPT-135: positive peak at 132.4 δ; negative peaks at 27.6, 29.3, 32.2 δ

Compound G

  • Broadband-decoupled 13C NMR: 25.1, 27.7, 39.9, 56.0 δ
  • DEPT-90: 56.0 δ
  • DEPT-135: positive peak at 56.0 δ; negative peaks at 25.1, 27.7, 39.9 δ
Problem 13-65

3-Methyl-2-butanol has five signals in its 13C NMR spectrum at 17.90, 18.15, 20.00, 35.05, and 72.75 δ. Why are the two methyl groups attached to C3 nonequivalent? Making a molecular model should be helpful.

The structure of 2-methyl-2-butanol with main chain carbons numbered 1 through 4.
Problem 13-66

A 13C NMR spectrum of commercially available 2,4-pentanediol, shows five peaks at 23.3, 23.9, 46.5, 64.8, and 68.1 δ. Explain.

The structure of 2,4-pentanediol has a 5-carbon chain. C 2 and C 4 are each bonded to a hydroxyl group.
Problem 13-67

Carboxylic acids (RCO2H) react with alcohols (R′OH) in the presence of an acid catalyst. The reaction product of propanoic acid with methanol has the following spectroscopic properties. Propose a structure.

Propanoic acid reacts with methanol in the presence of hydrogen ion catalyst to form unknown product(s), depicted by a question mark.

MS: M+ = 88

IR: 1735 cm–1

1H NMR: 1.11 δ (3 H, triplet, J = 7 Hz); 2.32 δ (2 H, quartet, J = 7 Hz);

3.65 δ (3 H, singlet)

13C NMR: 9.3, 27.6, 51.4, 174.6 δ

Problem 13-68

Nitriles (RC N) react with Grignard reagents (R′MgBr). The reaction product from 2-methylpropanenitrile with methylmagnesium bromide has the following spectroscopic properties. Propose a structure.

2-Methylpropanenitrile reacts with methyl magnesium bromide in step 1 and hydronium ion in step 2 to form unknown product(s), depicted by a question mark.

MS: M+ = 86

IR: 1715 cm–1

1H NMR: 1.05 δ (6 H, doublet, J = 7 Hz); 2.12 δ (3 H, singlet);

2.67 δ (1 H, septet, J = 7 Hz)

13C NMR: 18.2, 27.2, 41.6, 211.2 δ

Problem 13-69

The proton NMR spectrum is shown for a compound with the formula C5H9NO4. The infrared spectrum displays strong bands at 1750 and 1562 cm–1 and a medium-intensity band at 1320 cm–1. The normal carbon-13 and the DEPT experimental results are tabulated. Draw the structure of this compound.

Normal Carbon DEPT-135 DEPT-90
    14 ppm Positive No peak
 16 Positive No peak
 63 Negative No peak
 83 Positive Positive
165 No peak No peak
Proton spectrum of C 5 H 9 N O 4 shifts: 0, 1.3 (triplet), 1.8 (doublet), 4.3 (quartet), and 5.2 (quartet). Relative areas of 3, 3, 2, and 0.92 respectively.
Problem 13-70

The proton NMR spectrum of a compound with the formula C5H10O is shown. The normal carbon-13 and the DEPT experimental results are tabulated. The infrared spectrum shows a broad peak at about 3340 cm–1 and a medium-sized peak at about 1651 cm–1. Draw the structure of this compound.

Normal Carbon DEPT-135 DEPT-90
    22.2 ppm Positive No peak
 40.9 Negative No peak
 60.2 Negative No peak
112.5 Negative No peak
142.3 No peak No peak
Proton spectrum of C 5 H 10 O shifts: 1.75 (singlet), 2.15 (singlet), 2.3 (triplet), 3.7 (triplet), and 4.8 (doublet). Relative areas of 3, 1.2, 2, 2.1, and 2.1 respectively.
Problem 13-71

The proton NMR spectrum of a compound with the formula C7H12O2 is shown. The infrared spectrum displays a strong band at 1738 cm–1 and a weak band at 1689 cm–1. The normal carbon-13 and the DEPT experimental results are tabulated. Draw the structure of this compound.

Normal Carbon DEPT-135 DEPT-90
    18 ppm Positive No peak
 21 Positive No peak
 26 Positive No peak
 61 Negative No peak
119 Positive Positive
139 No peak No peak
171 No peak No peak
Proton spectrum of C 7 H 12 O 2 shifts: 1.75 (doublet), 2.05 (singlet), 4.55 (doublet), and 5.35 (triplet). Relative areas of 5.7, 2.9, 2, and .96 respectively.
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