Download CH19 Aldehydes and Ketones

Ketones, Aldehydes
CH21 PS CLASS
Recall the many times we’ve
synthesized these! I command thee.
• Oxidation of R-OH
– (Periodinane, CrO3/Na2Cr2O7)
• Hydration of Alkynes (keto-enol tautomerism)
– H3O+/HgSO4, BH3/H2O2,OH-, etc…
• Friedel-Crafts ACYLation of Aromatics
– (acid halide + AlCl3)
REACTIONS OF ALDEHYDES/KETONES
• Oxidation of Aldehydes
• Nucleophilic Additions (overview)
– Hydride (H-) and Grignard (R-) as Nucleophiles
– Water addition (hydrate/diol/geminal diol
formation)
– Alcohol addition (acetal formation)
– Amine addition (imine formation)
• Conjugate Nucleophilic Addition Reactions
Major Synthesis
Major Synthesis
Major Synthesis
Major Synthesis
Major Synthesis
Major Synthesis
Major Synthesis
Oxidation of Aldehydes
Where [O] = CrO3 among others.
Nucleophilic
Addition Rxns
Slightly different
mechanisms in acid or
base. Neutral vs.
Negatively charged
Nucleophile
General picture
(basic):
Reactivity Notes:
Less steric hindrance
with aldehyde
Benzaldehyde less reactive due to resonance stabilization.
Reduction of Ketones/Aldehydes
Addition of Grignard Reagent
Grignard Reagents + carbonyls
Practice!
COME UP WITH
PAIRS, More than
one answer for
some.
Practice!
Hydrate formation/ Geminal Diols
Basic vs. Acidic
BASIC: Strong
nucleophile attacks,
as in Nu-
ACIDIC:
Carbonyl is
converted to a
stronger
ELECTROPHILE as
CABON BECOMES
MORE POSITIVE.
Problem
Acetal formation
ACID CATALYZED… AGAIN, CARBONYL MADE INTO BETTER ELECTROPHILE.
Acetal Formation
Acetal Formation
Acetal Formation
2 alcohols/ 1 diol can be used to ‘protect’ an
aldehyde or ketone from a reaction.
Nuc. Addition of Amines to form:
Imines (bisaya ka dong?)
Amine must have 2
protons, RNH2
Problems
Predict the
Products!
Problems
Conjugate Nucleophilic Addition Rxns
Conjugate Nucleophilic Addition Rxns
THE DOUBLE BOND IS EFFECTIVELY “POLARIZED” INTO A NEGATIVE REGION THAT’S
RESONANCE STABILIZED, AND A POSITIVE REGION AT THE BETA-CARBON.
Predict the product
+ HCN
Practice
Predict the Products
a.
b.
c.
d.
NaBH4/H3O+
NH2OH/HCl
2 CH3OH /acid
CH3MgBr then acid
Predict the Products
NaBH4/H3O+
2 CH3OH /acid
NH2OH/HCl
CH3MgBr then acid
Predict the Products
NaBH4/H3O+
2 CH3OH /acid
NH2OH/HCl
CH3MgBr then acid