Lecture Description
A difficult exam question shows how visible and NMR spectroscopy related to long-term misassignment of the structure for the triphenylmethyl dimer. Evidence from 1970 shows that Friedel-Crafts propylation involves an SN2 mechanism, not a protonated cyclopropane. Assigning oxidation states from -4 to +4 to the carbon atoms of proposed starting material and product allows choosing whether a reagent that is oxidizing or reducing or neither is appropriate. Beyond belonging to the appropriate redox class, the reagent must have an appropriate mechanism. Alcohol oxidations by elemental bromine and by Cr+6 reagents are shown to involve familiar substitution, elimination, and addition mechanisms. Mechanistic understanding allows adjusting conditions to make oxidation selective.
Course Index
- Mechanism: How Energies and Kinetic Order Influence Reaction Rates
- Peculiar Rate Laws, Bond Dissociation Energies, and Relative Reactivities
- Rate and Selectivity in Radical-Chain Reactions
- Electronegativity, Bond Strength, Electrostatics, and Non-Bonded Interactions
- Solvation, H-Bonding, and Ionophores
- Brønsted Acidity and the Generality of Nucleophilic Substitution
- Nucleophilic Substitution Tools - Stereochemistry, Rate Law, Substrate, Nucleophile, Leaving Group
- Solvent, Leaving Group, Bridgehead Substitution, and Pentavalent Carbon
- Pentavalent Carbon? E2, SN1, E1
- Cation Intermediates - Alkenes: Formation, Addition, and Stability
- Carbocations and the Mechanism of Electrophilic Addition to Alkenes and Alkynes
- Nucleophilic Participation During Electrophilic Addition to Alkenes: Halogen, Carbene, and Borane
- Addition to Form Three-Membered Rings: Carbenoids and Epoxidation
- Epoxide Opening, Dipolar Cycloaddition, and Ozonolysis
- Metals and Catalysis in Alkene Oxidation, Hydrogenation, Metathesis, and Polymerization
- Isoprenoids, Rubber, and Tuning Polymer Properties
- Alkynes; Conjugation in Allylic Intermediates and Dienes
- Linear and Cyclic Conjugation Theory; 4n+2 Aromaticity
- Aromatic Transition States: Cycloaddition and Electrocyclic Reactions
- Electronic and Vibrational Spectroscopy
- Functional Groups and Fingerprints in IR Spectroscopy; Precession of Magnetic Nuclei
- Medical MRI and Chemical NMR
- Diamagnetic Anisotropy and Spin-Spin Splitting
- Higher-Order Effects, Dynamics, and the NMR Time Scale
- C-13 and 2D NMR - Electrophilic Aromatic Substitution
- Aromatic Substitution in Synthesis: Friedel-Crafts and Moses Gomberg
- Triphenylmethyl and an Introduction to Carbonyl Chemistry
- Mechanism and Equilibrium of Carbonyl Reactions
- Imines and Enamines; Oxidation and Reduction
- Oxidation States and Mechanisms
- Periodate Cleavage, Retrosynthesis, and Green Chemistry
- Measuring Bond Energies: Guest Lecture by Prof. G. Barney Ellison
- Green Chemistry; Acids and Acid Derivatives
- Acids and Acid Derivatives
- Acyl Insertions and a-Reactivity
- α-Reactivity and Condensation Reactions
- Proving the Configuration of Glucose and Synthesizing Two Unnatural Products
- 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.