Chapter 5 - Chapter 5: Addi.on Reac.ons of Alkenes...

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Unformatted text preview: Chapter 5: Addi.on Reac.ons of Alkenes Addi.on reac.on and Markovnikov’s rule Markovnikov’s Rule In the addi.on of a pro.c acid, such as H ­X, to an alkene, the acid hydrogen (H) becomes aFached to the carbon atom with the greatest number of hydrogens, and the halide (X) group becomes aFached to the carbon with the fewest hydrogens. More alkene addi.on reac.ons Modified Markovnikov’s rule In the addi.on reac.ons, when the two groups that add are different, the carbon of the double bond with fewer alkyl subs.tuents becomes bonded to the less electronega.ve group, and the carbon of the double bond with more alkyl subs.tuents becomes bonded to the more electronega.ve group. Electrophilic addi.on Alkenes with halogens (Cl, Br) Products: Vicinal dihalides Percentage yield Catalyst, solvent wriFen over the arrow How about reac.on with F2 and I2? Chapter 5.3 “wri.ng org. rxn” Bromine addi.on halohydrins Halodrin regioselec.vity Oxymercura.on ­Reduc.on of Alkenes furan mechanism Conversion of Oxymercura.on Adducts into Alcohols Shorthand equa.on Employed to avoid rearrangement Hydrobora.on of alkenes Concerted mechanism Fic..ous mechanism (used to understand regioselec.vity) Single step mechanism (in concert) Hydrobora.on ­oxida.on Laboratory synthesis of alcohols Markovnikov product An. ­Markovnikov product Industrial method for alcohol prepara.on Ozone Ozone deple.on Ozone cracking Ozonolysis Reduc.ve vs. Oxida.ve condi.ons Reduc.ve oxida.ve Free ­radical addi.on of hydrogen bromide to alkenes See aFached lecture notes from: Carolynn Chin (10/2) Bond dissocia.on energy Free ­radical polymeriza.on of alkenes Addi.on polymer Industrial use of alkenes Key points •  Modified Markovnikov’s rule; •  Electrophilic addi.on; •  Regioselec.vity of bromine addic.on and halohydrin forma.on; •  Oxymercura.on ­reduc.on reac.on; •  Hydrobora.on ­oxida.on; •  Concerted mechanism; •  Ozonolysis; •  Free radical addi.on of hydrogen bromide; •  Bond dissocia.on energy, ΔH calcula.on; •  Free ­radical polymeriza.on of ethylene. ...
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This note was uploaded on 08/24/2010 for the course CHEM 3351 at Colorado.

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