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.
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This course was recorded in Spring 2011.