Chapter 17 - Substitution Rxns @ a-C Flashcards
(17 cards)
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
1st step of tautomerization under acidic conditions
protonation
Which is more stable? Cycloketone or Phenol?
Phenol
