CH 630

Fall, 2008
 

Course Syllabus

Reading assignments are noted at the end of each major section.   Miller refers to Writing Reaction Mechanisms in Organic Chemistry, by Audrey Miller and Philippa H. Solomon; C&S refers to Advanced Organic Chemistry, Part A by Francis A. Carey and Richard J. Sundberg. 

I. Introduction: Properties of Organic Molecules

• A. What is a reaction mechanism?
• B. Conventions in organic chemistry.
 
• 1. Drawing structures: cyclohexane and the diamond lattice; bicyclic structures; Newman/Fischer projections; depiction of stereochemistry.
• 2. Rules for drawing resonance structures.  The relationship between resonance structures and valence bond theory and MO theory.
• 3. Stereochemical principles. (C&S Ch. 2)
• a. Enantiomers
• b. Diastereomers
• c. Prochiral relationships
• 4.  Conformational properties of organic molecules (C&S Ch. 2)
  • Energetic impact of changing molecular geometry
  • Preferred conformations of simple molecules
  • Cyclohexane derivatives
  • Impact of conformations on reactivity:  Baldwin's rules, ring strain, the anomeric effect
• 5. "Electron pushing:" electronegativity and electron flow in reaction processes.

• C. Introduction to mechanistic principles: potential energy diagrams, the Hammond postulate; the Curtin-Hammett principle; microscopic reversibility.

Reading:
Miller, Ch. 1, Ch 2, Ch. 3.
C&S secs. 1.1, 1.2, 2.1-2.6, 3.1-3.3.

II. Carbocations
 

• A. Structure and general elements of stabilization, pi donation(3.4.1, 4.4.1, 4.2.5, 4.4.1)
• B. Generation: heterolysis of R-X; addition of electrophiles to multiple bonds. (4.1.1, 5.1-5.3)
• C. Factors which promote or inhibit formation of carbocations.
• 1. Structure of R: electron donating/releasing substituents; resonance effects; neighboring group participation; nonclassical ions. (4.4)
• 2. Leaving group ability, and activation of poor leaving groups. (4.2.3)
• 3. Solvent effects (4.2.2)
• 4.  Ion pairing; effects on kinetic and stereochemical outcome (4.1.3)
• D.  Reactions of carbocations.
  • Polar addition to alkenes; source of Markownikov' rule (5.1-5.3)
  • Isotope effects
    • Primary KIE's:  basis from Transition State Theory (3.5)
    • Secondary KIE's
    • Solvent and other KIE's
  • Substituent effects:  Hammett relationship and LFER's (3.6)

• E. Reactions of carbocations with nucleophiles
• a. Competition of different nucleophiles
• b. Sn1 vs. Sn2 reactivity (4.1)
• F. Loss of H⁺ from carbocations: E1 elimination (5.10)
• a. Direction of elimination 
• b. Comparison with E2, E1cb mechanisms 
• G. Rearrangements and migratory aptitudes. (4.4.4)

Reading: Miller, Secs. 3.1, 3.2, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6;
C&S Ch. 4 and 5; also 3.4, 3.5, 3.6.

III. Carbanions
 

• A. C-H acidity as a function of structure.
• B. Other methods of generation
• C. Structure & effect on reactivity (particularly aggregation effects and enolate/enamine structure)
• D. Reactions
• 1. Sn2; discussion of nucleophilicity.
• 2. Addition to C=O
• 3. Reprotonation
• 4. Other electrophiles

Reading: C&S Ch. 6.

IV. Carbenes
 

• A. Structure: comparison of singlet vs. triplet.
• B. Generation
• 1. a-elimination
• 2. From diazo compounds
• 3. Carbenoids
• 4. Stable carbenes.
• C. Reactions
• 1. Cyclopropanation
• 2. C-H insertion
• 3. Rearrangements

Reading: March Ch. 5 (handout);
Miller, Secs. 4.8, 4.9.

V. Free Radicals
 

• A. Structure; stable radicals and radical anions
• B. Generation: homolysis & bond strengths; photolysis.
• C. Reactions
• 1. Atom abstraction
• 2. Addition to multiple bonds
• 3. Fragmentation
• D. Chain reactions

Reading: Miller, Ch. 5. 
C&S Ch. 11

Grading

Homework: 20 points each, 120 points total

Midterm exams:  100 points each, 200 points total

Final exam:  200 points

Letter grade will be assigned based on points earned out of 520 points total.

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Last updated:  09/18/2008
Comments to K. Gable