C-13 and 2D NMR - Electrophilic Aromatic Substitution 
C-13 and 2D NMR - Electrophilic Aromatic Substitution
by Yale / J. Michael McBride
Video Lecture 25 of 38
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Date Added: July 5, 2012

Lecture Description

Proton decoupling simplifies C-13 NMR spectra. Dilute double labeling with C-13 confirmed the complex rearrangement scheme in steroid biosynthesis. Two-dimensional NMR yields correlations between NMR signals that underlie structural determination of proteins and identification of the mechanism of a rapid carbocation rearrangement. Substitution of an electrophile for a proton on an aromatic ring proceeds by a two-step association-dissociation mechanism involving a cyclohexadienyl cation intermediate. The relative rates of forming various products from substituted benzenes correlates with the substituents' influences on the stability of the various cyclohexadienyl cation intermediates. The spectrum of electrophile reactivities is very broad. Important contributions for activating electrophiles were made by Friedel and Crafts working in Paris.

Course Index

  1. Mechanism: How Energies and Kinetic Order Influence Reaction Rates
  2. Peculiar Rate Laws, Bond Dissociation Energies, and Relative Reactivities
  3. Rate and Selectivity in Radical-Chain Reactions
  4. Electronegativity, Bond Strength, Electrostatics, and Non-Bonded Interactions
  5. Solvation, H-Bonding, and Ionophores
  6. Brønsted Acidity and the Generality of Nucleophilic Substitution
  7. Nucleophilic Substitution Tools - Stereochemistry, Rate Law, Substrate, Nucleophile, Leaving Group
  8. Solvent, Leaving Group, Bridgehead Substitution, and Pentavalent Carbon
  9. Pentavalent Carbon? E2, SN1, E1
  10. Cation Intermediates - Alkenes: Formation, Addition, and Stability
  11. Carbocations and the Mechanism of Electrophilic Addition to Alkenes and Alkynes
  12. Nucleophilic Participation During Electrophilic Addition to Alkenes: Halogen, Carbene, and Borane
  13. Addition to Form Three-Membered Rings: Carbenoids and Epoxidation
  14. Epoxide Opening, Dipolar Cycloaddition, and Ozonolysis
  15. Metals and Catalysis in Alkene Oxidation, Hydrogenation, Metathesis, and Polymerization
  16. Isoprenoids, Rubber, and Tuning Polymer Properties
  17. Alkynes; Conjugation in Allylic Intermediates and Dienes
  18. Linear and Cyclic Conjugation Theory; 4n+2 Aromaticity
  19. Aromatic Transition States: Cycloaddition and Electrocyclic Reactions
  20. Electronic and Vibrational Spectroscopy
  21. Functional Groups and Fingerprints in IR Spectroscopy; Precession of Magnetic Nuclei
  22. Medical MRI and Chemical NMR
  23. Diamagnetic Anisotropy and Spin-Spin Splitting
  24. Higher-Order Effects, Dynamics, and the NMR Time Scale
  25. C-13 and 2D NMR - Electrophilic Aromatic Substitution
  26. Aromatic Substitution in Synthesis: Friedel-Crafts and Moses Gomberg
  27. Triphenylmethyl and an Introduction to Carbonyl Chemistry
  28. Mechanism and Equilibrium of Carbonyl Reactions
  29. Imines and Enamines; Oxidation and Reduction
  30. Oxidation States and Mechanisms
  31. Periodate Cleavage, Retrosynthesis, and Green Chemistry
  32. Measuring Bond Energies: Guest Lecture by Prof. G. Barney Ellison
  33. Green Chemistry; Acids and Acid Derivatives
  34. Acids and Acid Derivatives
  35. Acyl Insertions and a-Reactivity
  36. α-Reactivity and Condensation Reactions
  37. Proving the Configuration of Glucose and Synthesizing Two Unnatural Products
  38. Review: Synthesis of Cortisone

Course Description

This is a continuation of Freshman Organic Chemistry I (CHEM 125a), the introductory course on current theories of structure and mechanism in organic chemistry for students with excellent preparation in chemistry and physics. This semester treats simple and complex reaction mechanisms, spectroscopy, organic synthesis, and some molecules of nature.

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