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Unformatted text preview: ssary to complete this substitution. 2. Draw a complete mechanism. OH
racemic Page 12 of 24 C341/Fall 2011 Chapter 7: Nucleophilic Substitution Reactions 4. Determining Which Mechanism Predominates A. Steric hindrance at the electrophilic site B. The stability of the resulting carbocation Alkyl Allyl Benzyl C. The quality of the nucleophile “Strong” or “weak” nucleophiles dictate different reactions Nucleophilicity increases down a column; why? HS‐ > HO‐ I > Br > Cl‐ > F‐ ‐ ‐ Compare the SIZE of the nucleophile (molecule) as a whole: O O Page 13 of 24 O C341/Fall 2011 Chapter 7: Nucleophilic Substitution Reactions What are some general trends about Nu‐ you can make using the pKa table? Acids CB
10 -9 Page 14 of 24 C341/Fall 2011 Chapter 7: Nucleophilic Substitution Reactions D. The solvent The solvent surrounds each species in the mechanism including the transition state. How does that help to facilitate the reaction? δ
δ δ δ δ δ δ
δ δ δδ δ
δ δ δ
δ δ δ δ δ δ δ δ δ To specifically promote SN2, what role should the solvent play? Page 15 of 24 δ C341/Fall 2011 Chapter 7: Nucleophilic Substit...
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