CHEM 2OA3 Chapter Notes - Chapter 9: Markovnikov'S Rule, Pi Bond, Racemic Mixture
30 Jun 2015
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Pi bonds can act as a base: pi bonds readily protonated. Pi bonds can act as a nucleophile: pi bonds attack electrophilic centers. Enthalpy term h: bonds broken bonds formed ; reaction favours the production of more stable compounds. Entropy term ts *always positive for addition reactions. *h is placed at the vinylic position already bearing the larger number of h = markovnikov"s addition. Hcl and hi: regioselective (markovnikov"s addition) with purified reagents. Mechanism pi bond is protonated = carbocation intermediate. The carbocation can form secondary or tertiary, but will always form the more stable carbocation. Involves the formation of a chirality center, with two different products (enantiomers) When carbocation rearrangements are possible, they occur. To decide on the major products: perform necessary carbocation rearrangements, determine shape of carbocation, determine if the p orbital can attack from the top or bottom (based on substituents attached and the shape)
