review ketone aldehyde : : nucleophilic addition : - c=o very polar o
DESCRIPTION
Nucleophilic addition C O-H R O-H C O R .. H C = O R .. H+ C = O R .. + H+ H H+ hydrate or diol C O R .. H C R O-H O-R + H+ + H-OH O .. H R .. O H N H .. C = O R .. + H-OR hemi-ketal C R O - H N - H2 + H+ C R N H + H2O + H-NH2 Schiffs baseTRANSCRIPT
Review
aldehyde ketone
C=O very polar
++
-+
- H-Nu
H-OHH-ORH-NH2
H
Nu
O
C
H
Nu
O
C
: : O
C
: ::
+
-
O
C
: :
Nucleophilic addition
..OH H..
Nucleophilic addition
+
+
+
H-OH
H-OR
H-NH2
H+
H + H+
hydrate or diol
+ H+
hemi-ketalC = OR
R
..
..
C = OR
R
..
.. C = OR
R
..
..H+
C O
R
R.... H C O-H
R
RO-H
O..
HR ..C
R
R O-H
O-R
C O
R
R.... H
NH H H
..
C
R
R O - H
N - H2
+ H+
C
R R
N H+ H2O
Schiffs base
+ CH3OHH+
ketoneunstable
+ alcohol = ketal
aldehydeunstable
+ alcohol = acetal
C OH3CH3C
C OCH3
H3C
hemi-
H
Addition of alcoholH
hemi-
HOCH3
Nucleophilic
acetal
aldehyde + alcohol
hemi -
+ alcohol
+
H+ H+....
acetal
+ H+
condensation reaction
hemi-acetal + alcohol acetal + H2O
CH3C
H
OH
O - CH2 - CH3
OH - CH3 - CH2 ....
H
CH3C
H
OH
O - CH2 - CH3 H2O
O - CH2 - CH3
H ....
CH3C
H
O - CH2 - CH3
O - CH2 - CH3
..
..
substitution
acetal propanal +
stable
hemi- ketal 2-butanone +
unstable
2 equivalents ethanol
1 equivalent methanol
one
+
diol
H+
hemi-ketal
H+
ketal
H+....H
..
..
+ H2O
+ H+
cyclohexan ethane
Carboxylic acids
1o alcohol aldehyde carboxylic acid[O] [O]
methanol methanal methanoic acid
-
+
H-bond acceptor
H-bond donorvery high b.p.
2 H-bonds / molecule-
Carboxylic acidsNomenclature
1. Carboxyl group (COOH) always C1
2. Family name is longest C chain with COOH
3. Suffix is “-oic acid”
4. Carbonyl groups (C=O) called “oxo” Hydroxy groups (OH) called “hydroxy”
Carboxylic acids
oic acid1234 butan2-ethyl
oic acid
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hexan2-ethyl- 4-hydroxy
2-ethyl4-hydroxy
add [O]oic acidhexan2-ethyl- 4-oxo
CH3 – CH2 – CH – CH2 – CH – CO2H
OH CH2 – CH3O
CH3 – CH2 – CH – C
CH2 – CH3
O
OH
Carboxylic AcidsChemical properties
= C=O + OH = Bronsted acid H+ donor
weak acids, small dissociation
HA H+ + A-
+H+
Ka = [A-] [H+] Ka 1 x 10-5 pH 2.5 for 1M [HA]
Carboxylic Acids+H+
+H+
-
resonance structureanion stabilized
Carboxylic Acidsacidity also affects solubility
short chain acids soluble
long chain acids insoluble
add a strong base (OH-)
H-bonding
LDF
soluble
C
O
OH
C
O
OH-ion-dipole
benzoic acid
ReactionsAcid-base reactions:
octanoic acidinsoluble
+ NaOHNa+
+ H2Osodium octanoate + watersoluble
O O
-O
O
-O
O
-O
O
-O
O
-O
O
OO-
OO -
OO
-
OO
-
O O-
O
O
O
O
O
O-
OH
O
Reactions
Reduction:
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hexanoic acid5-oxo
LiAlH4
hexanediol1,5-
H2/ Pt
NaBH4
hexanoic acid5-hydroxy