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Freshman Organic Chemistry I

Yale,, Spring 2011 , Prof. Michael McBride

Updated On 02 Feb, 19

Overview

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 - Brnsted Acidity and the Generality of Nucleophilic Substitution - Nucleophilic Substitution Tools - Stereochemistry, Rate Law, Substrate, Nucleophile - 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 - 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 [gr]α-Reactivity - [gr]α-Reactivity and Condensation Reactions - Proving the Configuration of Glucose and Synthesizing Two Unnatural Products - Review: Synthesis of Cortisone.

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Lecture 18: Linear and Cyclic Conjugation Theory. 4n+2 Aromaticity

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Lecture Details

Freshman Organic Chemistry II (CHEM 125B)Despite the substantial change in the energy of individual orbitals, the overall pi-electron energy and orbital shape changes little upon linear conjugation of two double bonds. Conjugation energy of polyenes and allylic systems may be predicted by means of a semicircle mnemonic. The much greater stabilization in "aromatic" conjugated rings, and Hückels 4n+2 rule, derive from alternating stabilization and destabilization of successive orbitals when the ends of a conjugated chain overlap as it is closed to form a ring. A circle mnemonic predicts orbital energies for conjugated rings. This aromaticity concept is generalized to heteroaromatic compounds like furan and imidazole, to polycyclic compounds like naphthalene, and to hydrocarbon ions like cyclopentadienide.0000 - Chapter 1. Why is Diene Stabilization Small? Orbital Mixing and the Semicircle Mnemonic2236 - Chapter 2. Benzene, Hückels 4n+2 Rule, and the Circle Mnemonic 3559 - Chapter 3. Generalization Nonbenzenoid Aromaticity Complete course materials are available at the Open Yale Courses website httpoyc.yale.eduThis course was recorded in Spring 2011.