Reactions of AlkenesSince σbonds are strongerthan πbonds, double bonds tend to react to convert the double bond into σbonds + X-YYXThis is an additionreaction. (Other types of reaction have been substitution and elimination). Addition reactions are typically exothermic. Electrophilic AdditionThe πbond is localized above and below the C-C σbond. The πelectrons are relatively far away from the nuclei and are therefore looselybound. An electrophilewill attract those electrons, and can pull them away to form a new bond. This leaves one carbon with only 3 bonds and a +ve charge (carbocation). The double bond acts as a nucleophile(attacks the electrophile). In most cases, the cation produced will react with another nucleophile to produce the final overall electrophilic addition product. Ch08 Reacns of Alkenes.doc Page1
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