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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 19: Aromatic Transition States Cycloaddition and Electrocyclic Reactions

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Lecture Details

Freshman Organic Chemistry II (CHEM 125B)Cyclic conjugation that arises when p-orbitals touch one another can be as important for transition states as aromaticity is for stable molecules. It is the controlling factor in "pericyclic" reactions. Regiochemistry, stereochemistry, and kinetics show that two new sigma bonds are being formed simultaneously, if not symmetrically, in the 6-electron Diels-Alder cycloaddition. Although thermal dimerization of thymine residues in DNA is forbidden, photochemistry allows the 4-electron cycloaddition. "Electrocyclic" ring opening or closing chooses a conrotatory Möbius pathway, or a disrotatory Hückel pathway, according to the number of electron pairs involved and whether light is used in the process. Dewar benzene provides an example of a very unstable molecule that can be formed photochemically and then persists because of unfavorable orbital overlap in the transition state for ring opening.0000 - Chapter 1. Aromatic Ions0559 - Chapter 2. Pericyclic Reactions Cycloaddition, the Diels-Alder Reaction, and Photochemistry2815 - Chapter 3. Electrocyclic Stereochemistry 4427 - Chapter 4. How Bad is "Forbidden"? Opening Dewar BenzeneComplete course materials are available at the Open Yale Courses website httpoyc.yale.eduThis course was recorded in Spring 2011.