38 episodes

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.

Freshman Organic Chemistry ‪2‬ Yale University

    • Science
    • 3.4 • 14 Ratings

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.

    1. Mechanism: How Energies and Kinetic Order Influence Reaction Rates

    1. Mechanism: How Energies and Kinetic Order Influence Reaction Rates

    This second semester of Freshman Organic Chemistry builds on the first semester’s treatment of molecular structure and energy* to discuss how reaction mechanisms have been discovered and understood. It also treats the spectroscopy and synthesis of organic molecules. Reactions and their rates can be understood in terms of reaction-coordinate diagrams involving the passage of a set of atoms through the “transition state” on the potential-energy surface. Analysis of bond-dissociation energies suggests a chain mechanism for free-radical halogenation of alkanes. Experimental determination of kinetic order provides insight into complex reaction schemes, especially when one step is rate-limiting.

    Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

    This course was recorded in Spring 2011.

    • 48 min
    2. Peculiar Rate Laws, Bond Dissociation Energies, and Relative Reactivities

    2. Peculiar Rate Laws, Bond Dissociation Energies, and Relative Reactivities

    Curious kinetic orders can be mechanistically informative. Fractional kinetic orders suggest dissociation of a dominant aggregate to give a smaller reactive species. An apparent negative kinetic order, due to competition with a second-order process, leads to spontaneous deracemization of chiral crystals. Changes in bond dissociation energies can be due to differences in bonds or in radicals. Although it is often said that the order of alkyl radical stability is tertiary > secondary > primary, careful analysis suggests that the order of bond dissociation energies may be due to differences in the alkanes rather than in the radicals. Hammond helped organic chemists begin to think sytematically about predicting relative reaction rates by suggesting that the transition states of more exothermic reactions should lie closer to the starting materials in structure and energy.

    Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

    This course was recorded in Spring 2011.

    • 48 min
    3. Rate and Selectivity in Radical-Chain Reactions

    3. Rate and Selectivity in Radical-Chain Reactions

    The reactivity-selectivity principle explains why bromine atoms are more selective that chlorine atoms in abstracting hydrogen atoms from carbon. A free-radical mechanism for adding HBr to alkenes explains its anti-Markovnikov regiospecificity. Careful analysis is required to understand kinetic order for reactions involving catalysts. Termination of radical-chain reactions can make their rate half-order in the initiator. Selectivity due to protonation of radicals and their reaction partners illustrates the importance of ionic charge in determining reaction rates.

    Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

    This course was recorded in Spring 2011.

    • 46 min
    4. Electronegativity, Bond Strength, Electrostatics, and Non-Bonded Interactions

    4. Electronegativity, Bond Strength, Electrostatics, and Non-Bonded Interactions

    A student provides insight on fractional-order rate laws. Bonds involving atoms with lone-pair electrons are weakened by electron-pair repulsion. Electronegativity differences between atoms make ionic dissociation (heterolysis) easier and radical dissociation (homolysis) harder, although Pauling’s definition of electronegativity makes the logic of the latter effect somewhat circular. The course transitions from free-radical reactions to ionic reactions by discussing solvent properties, in particular the electrostatic properties of alkyl halides and alkanes..

    Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

    This course was recorded in Spring 2011.

    • 50 min
    5. Solvation, H-Bonding, and Ionophores

    5. Solvation, H-Bonding, and Ionophores

    Most organic reactions occur in solution, and particularly in the case of ions, one must consider non-bonded interactions with neighboring molecules. Non-bonded interactions, including hydrogen-bonding, also determine such physical properties as boiling point. For the most part these interactions may be understood in terms of electrostatics and polarizability. Artificial or natural ion carriers (ionophores) can be tailored to bind specific ions. Energetically the ionic dissociation of water in the gas phase is prohibitively expensive.

    Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

    This course was recorded in Spring 2011.

    • 47 min
    6. Brønsted Acidity and the Generality of Nucleophilic Substitution

    6. Brønsted Acidity and the Generality of Nucleophilic Substitution

    The coincidentally substantial extent of ionic dissociation of water provides an example of Brønsted acidity, or nucleophilic substitution at hydrogen. Relative pKa values are insensitive enough to solvent that they provide insight on the role of energy-match, overlap, and resonance in ionic dissociation. The titration of alanine in water illustrates the experimental determination of pKa values and the phenomenon of buffering. The limited pKa scale in water can be extended dramatically by titration in other solvents, providing one of the best ways to measure many “effects” in organic chemistry. A wide range of important organic reactions discovered in the 19th century and many biochemical reactions can be understood under the rubric of nucleophilic substitution.

    Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

    This course was recorded in Spring 2011.

    • 46 min

Customer Reviews

3.4 out of 5
14 Ratings

14 Ratings

6600599 ,

Freshman Organic Chemistry 2

Where is Freshman Organic Chemistry 1? I'd like to start at the beginning.

pjongray ,

I also cannot find that first course

Where is freshman chemistry 1

Top Podcasts In Science

Listeners Also Subscribed To

More by Yale University