Chapter 17 - Substitution Rxns @ a-C Flashcards
Ketones are involved in Addition or Substituion Rxns?
Addition
Aldehydes are involved in Addition or Substituion Rxns?
Addition
What happens to the carbonyl group during additon rxns?
The =O becomes an -OH
What determines whether an addition or substitution rxn will occur during carbonyl reactions?
If Y is a good leaving group, then a Substitution Rxn will occur.
If Y is not a good leaving group, then an addition rxn will occur and the =O will become an -OH.
Are Electronegative Atoms good or bad leaving groups?
Good Leaving Groups
Enolate Substitution
under BASIC conditions, the ALPHA C is DEPROTONATED creating an enolate anion where the E+ can bond to.
Enol Substitution
under ACIDIC conditions, the =O is protonated to form -OH with a C=C double bond.
Electrons from the C=C double bond can then bind to the E+
Enol Substitution
under ACIDIC conditions, the =O is protonated to form -OH with a C=C double bond.
Electrons from the C=C double bond can then bind to the E+
E+
Electrophile
Charge of reactants/products/intermediates under basic conditions
Neutral or (-)
Charge of reactants/products/intermediates under acidic conditions
Neutral or (+)
Tautomerization
transfers protons from one site to another via the solvent which is an intermediary
Keto-Enol Tautomerization under Basic Conditions
Alpha-C is deprotonated to form an enolate anion.
Resonance with negative O which reacts with water to form -OH and C=C double bond.
Keto-Enol Tautomerization under Acidic Conditions
=O is protonated to form =OH+
Then aplpha-C is depronated to form the C=C double bond.
1st step of tautomerization under basic conditions
deprotonation
