CHEM 237 Lecture Notes - Lecture 5: Protic Solvent, Nucleophilic Addition, Stereoselectivity
Document Summary
Substitution reactions exchange an atom or substituent with each other. The more positive the electrophile, the more likely it is an electron acceptor. The weaker the base (unreactive/stable), the better the lg. Any nucleophile will do since c is very electron deficient! Attack on either face of the planar sp2 carbocation - 2 enantiomer products (other than lg) Rate limiting step depends on electrophile only! (unimolecular) One product other than lg; stereoselective; inversion of configuration. Rate limiting step includes electrophile and nucleophile (bimolecular) Attack the carbonyl c, and break pi bond to the o, yielding both electrons to that oxygen. Protonated by acid workup, yielding in an alcohol. Any time a pi bond disappears from reactant to product, this is an addition reaction! Acid catalysts protonates the carbonyl o due to partial negative charge. Positively charged o is a stronger electron withdrawing species, making the carbonyl c more positive and susceptible to nucleophilic attack.
