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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 23: Diamagnetic Anisotropy and Spin-Spin Splitting

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Lecture Details

Freshman Organic Chemistry II (CHEM 125B)Through-space interaction between magnets of fixed strength and orientation averages to zero during random molecular tumbling, suggesting that the local field about a proton should be sensitive only to electrons that orbit about itself. The chemical shift can be sensitive to electrons orbiting elsewhere if the amount of orbiting varies with molecular orientation. This "diamagnetic anisotropy" is commonly used to rationalize the unusual chemical shifts of protons in acetylene and in aromatic and antiaromatic compounds. The other source of a protons local field is nearby magnetic nuclei, which can be counted by the splitting multiplicity. Unlike chemical shift, which is measured in fractional units because it depends on the strength of the applied field, this spin-spin splitting (J), measured in Hz, is dependent only on molecular structure. J depends not on spatial proximity, but on orbital overlap, which, remarkably, is larger for anti- than for eclipsed conformations.0000 - Chapter 1. Diamagnetic Anisotropy and Aromaticity2050 - Chapter 2. Multiplicity in Spin-Spin Splitting 3605 - Chapter 3. Tumbling, Orbitals, and the Magnitude of J Complete course materials are available at the Open Yale Courses website httpoyc.yale.eduThis course was recorded in Spring 2011.