Radicals,Ion Radicals, and Triplets

A course about the spin-bearing intermediates of organic chemistry

INSTRUCTOR:PROFESSOR NATHAN L. BAULD

OFFICE:WELCH 5.232; OFFICE HOURS W,Th 2-3

CLASS and TIME:CH 391; MWF 1 - 2

LECTURE ROOM: WELCH 4.224

REFERENCE TEXT (Optional):"RADICALS,ION RADICALS, AND TRIPLETS", WILEY-VCH, 1997.

EXAMS: TWO 100 POINT EXAMS (In class: April 14 and May 7)

PROBLEMS: SEVERAL ASSIGNED PROBLEM SETS: 50 POINTS MAX

NOTES: See NLB's CH 368 Web Page

Syllabus

• Basic concepts: MO picture; three electron bonding; charge and spin coupling and uncoupling in anion radicals; distonic anion radicals; the shape of the SOMO of anion radicals (TCNE anion radical).
• Stable and Persistent Anion Radicals: Examples; synthetic uses of persistent anion radicals.
• Anion Radicals in Familiar Organic Reaction Mechanisms: protonation of anion radicals (the Birch reaction; reductions of alkynes in liquid ammonia); coupling of anion radicals (pinacol reaction; acyloin condensation).
• ET vs Nucleophilic Reactions of Anion Radicals: The SRN1 mechanism; fullerene anion radicals and dianions.
• Cycloaddition Reactions of Anion Radicals.
• Anion Radical Cyclizations to Carbonyl Groups: natural product synthesis.

• Basic concepts: MO picture; comparisons with anion radicals (the Pairing Theorem); charge/spin coupling/uncoupling; distonic cation radicals; one electron bonding (dihydrogen cation; diphenylcyclopropane cation radical); three electron bonding (dihelium and dioxgen cation radicals).
• Structures of Cation Radicals: Long, 1 electron bond structures; pi cation radicals; distonic cation radicals; dissociative cation radicals.
• Stable and Persistent Cation Radicals: Examples; methods of generation/synthesis (Chemical, Photochemical, Electrochemical, etc.)
• Electron Transfer Reactions of Cation Radicals:
• Cation Radical Cycloadditions. Cyclobutanation and Diels-Alder Addition; cation radical chain mechanisms.
• Cation Radical Chain Cycloaddition Polymerization.

• Photosensitized electron transfer (PET); cation radicals, anion radicals and triplets via PET
• The Marcus Equation
• Thermal electron transfer (TET); stable ion radical pairs
• Intramolecular hole and electron transfer.

Unit 4: Radicals: General Concepts.

• Discovery and generation of radicals.
• Radical stabilizing effects.
• Stable and persistent radicals.
• Radical substituent constants.
• Polar effects in radical reactions.
• Radical scavengers; radical traps; radical inhibitors; radical probes and clocks.