aldehydes and ketones - carbonyl compounds carbonyl group - structure, bonding and physical...
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Aldehydes and Ketones - carbonyl compounds
carbonyl group -structure, bonding and physical
properties
Review of methods of preparation of aldehydes and ketones
hydration of alkynesFriedel-Crafts acylation of
aromatic compounds
Overview of reactions of carbonyl compounds
reduction to alcoholsaddition of organometallic
reagentsaddition of oxygen, nitrogen, sulfur
and phosphorus nucleophilesreduction of carbonyl to methylene
(Clemmensen or Wolff-Kishner)
Nucleophilic addition to carbonyls
Nucleophilic addition to carbonyls
Synthesis of Alcohols
Reduction of Carbonyl Compounds
Synthesis of Alcohols
Reduction of Carbonyl Compounds
H2/cat., NaBH4, LiAlH4
Synthesis of Alcohols
Reduction of Carbonyl Compounds
CO
reducing agent COH
H
lithium aluminum hydride (LAH)
OHO1. LiAlH4/ether2. H2O
-+LiAlH3
HO
Li+
-O H
AlH3-
+LiAlH3
HO
CH3CH2CCH2CH2COCH2CH3
O O
2. H2O
1. LiAlH4/ether
CH3CH2CHCH2CH2CH2OH
OH
sodium borohydride
CH3CH2CCH2CH2COCH2CH3
O O
NaBH4/H2O
CH3CH2CHCH2CH2COCH2CH3
OH
O
Synthesis of Alcohols Using Organometallic Reagents
++-
RMgX C
O MgX
RCO
C
OH
R
H3O
MgX
RCO
++-
RMgX C
O MgX
RCO
C
OH
R
H3O
+2. H3O
1. ether
CH3(CH2)8CH2MgBr +
CH3(CH2)8CH2CH2OH
HCHO
+
CCH3
OH
CH3
COCH3 + O
2. H3O
1. ether
2 CH3MgBr
CH3
OC OCH3
+MgBr-
CH3 MgBr
COCH3 O
-OCH3CH3
OC
CH3
OC OCH3
+MgBr-
CH3 MgBr
COCH3 O
CH3
OCCH3
CH3 MgBr
CH3
OC
+MgBr-
+H
CH3
OCCH3
CH3 MgBr
CH3
OC
+MgBr-
CCH3
OH
CH3
CH2CH2OHMgBr+
1. THF
2. H3O+
O
Hydration of aldehydes and ketones
An example
Addition of alcohols: hemiacetal and acetal formation
Addition of alcohols: hemiacetal and acetal formation
hemiacetalor hemiketal
O
+ROH H3O+
OH
OR
Addition of alcohols: hemiacetal and acetal formation
hemiacetalacetal
+ROH H3O+
OH
OR
OR
OR
Mechanism of acetal formation
O H OH2+ OH
+
O R
H
O
OHH
R
+
OR+
OR
H
Mechanism of acetal formation
OR+
OR
H
OR
OR
H+
OHHOR
ORH3O
++
An example
O +
HO
HO
pTosOH
tolueneO
O
Addition of ammonia and amines: imine and enamine formation
O+ R NH2
H+
NH
OH
R
NR
Examples
N
O
+CH3NH2
H3O+
N
N CH3
Examples
Examples
The Wittig Reaction
R CH2X + Ph3P: RCH2 PPh3+
X-
B:
RCH PPh3+
YLIDE
O
R
H
An example
The mechanism
Br Ph3P:+PPh3
HBr
Mechanism, cont.
PPh3 ylidePPh3
HBr
OH
Mechanism, cont.
+
O
O
PPh3
oxaphosphetane
PPh3
Mechanism, cont.
O
PPh3
Formation of cyanohydrins
O1) CN
-
2) H3O+
C
OH
N
Example
Glc Glc O
H C N
Reduction of carbonyls to alkanes
Clemmensen reductionWolff-Kishner reductionDesulfurization of thioketals
Nucleophilic Addition to a,b-Unsaturated Carbonyls
O
+ Nuc
Nuc
OH
Nuc OH
Nucleophilic Addition to a,b-Unsaturated Carbonyls
Strong nucleophiles add 1,2 kinetic control
Weaker nucleophiles add 1,4thermodynamic control
Nucleophilic Addition to a,b-Unsaturated Carbonyls
O
KCN
H2O
Nucleophilic Addition to a,b-Unsaturated Carbonyls
NC
OHO
KCNH2O
O
NC
Nucleophilic Addition to a,b-Unsaturated Carbonyls
O
+ CH3CH2( )2CuLiEt2O
H2O
Nucleophilic Addition to a,b-Unsaturated Carbonyls
O
CH3CH2
O
+ CH3CH2( )2CuLiEt2O
H2O