ALDEHYDES & KETONES
(ALKANALS & ALKANONES)
1
alkane
alcohol
reduction
reduction
aldehyde
ketone
oxidation
carboxylic acid
addition
product
nucleophilic
addition
Aldehydes and ketones are characterized by the
the carbonyl functional group (C=O).
Some common classes of carbonyl compounds
Carbon is sp2 hybridized. C=O bond is
shorter, stronger, and more polar than
C=C bond in alkenes.
Aldehydes are named by replacing the terminal -e of
the corresponding alkane name with –al
The parent chain must contain the CHO group
The CHO carbon is numbered possible minimum
number.
Replace the terminal -e of the alkane name with –
one
Parent chain is the longest one that contains the
ketone group
Numbering begins at the end nearer the carbonyl
carbon
Good solvent for alcohols.
Lone pair of electrons on oxygen of carbonyl can
accept a hydrogen bond from O-H or N-H.
Acetone and acetaldehyde are miscible in water.
Preparation of Aldehydes & ketones
1] Oxidation of 1& 2 alcohol :
RCH2OH
C2H5OH
O
R-C-H + H2O
CrO3 / pyridine
or, Cu /heat(week oxidi).
[O]
R
R-C-OH
H
CH3CHOHCH3
isopropanol
CH3CHO
[O]
CH3COOH
KMnO4
neutral
[O]
CH3COCH3
O
R-C-R
More polar, so boiling point higher than
corresponding alkane or ether.
Absence of H-bond, so boiling point lower than
corresponding alcohol.
A- 10 Alcohol gives aldehydes:
Cu/ 350 oC
CH3CH2OH
CH3CHO + H2
B- Secondary Alcohol gives Ketones:
OH
O
Cu/350oC
CH3CHCH3
CH3CCH3 + H2
3] Ozonolysis of alkenes:
CH3
C=CH2
CH3
1) O3
2)Zn, H2O
CH3
C=O
CH3
CH2O
H 2O/H 2SO 4
R C CH
R C CH 2
HgSO 4
OH
R C CH
1. 9-BBN
2. H 2O 2/OH
-
RCH CH
OH
R C CH 3
O
R CH 2 C H
O




A) If dihalogen are terminal:
H2O/NaOH
H2O
CH3CHCl2
CH3CH(OH)2
CH3CHO
acetaldehyde
B) If dihalogen aren’t terminal:
H2O/NaOH
CH3CCl2CH3
CH3COCH3 acetone


R-CO-Cl
CH3COCl
H2/Pd
H2/Pd
R-CHO +HCl
CH3CHO + HCl
1] Reactions with Grignard reagent:
R-CHO + R'-MgX
1)dry ether
2) H3O
R-CHOH-R'
1)dry ether
CH3-CHO + CH3-MgCl
2) H3O
R-CO-R' +R''-MgX
1)dry ether
2)H2O
CH3CO-CH3 +CH3-MgX
CH3CHOHCH3
R''
R-C-R'
OH
1)dry ether
2)H2O
OH
CH3-C-CH3
CH3
Nucleophilic addition to carbonyl:

O
C

+
Y Z
OY
C
Z
In presence of dry HCl aldehydes and ketones react
with two equivalent of alcohols to form acetals and
ketals
Acetal Formation
Acetals are geminal diethers- structurally related to hydrates,
which are geminal diols.
R
O
C
R
O
C
+
R
+ R'OH
H
- R'OH
aldehyde
R
O
C
+ R'OH
R
- R'OH
ketone
-
OH
R C OH
R
H2O
H2O
OH
H C OR'
R
+ R'OH
OH
R C OR'
R
+ R'OH
hydrate
(gem-diol)
OR'
H C OR' +
R
- R'OH
acetal
hemi-acetal
(gem-diether)
- R'OH
hemi-ketal
OR'
R C OR'
R
H2O
+ H2O
ketal
(gem-diether)
19
4-Reduction of Aldehydes/Ketones
 Hydrogenation
H2
R C H Pt
O
RCH 2OH Primary ROH
H2
R C R'
Pt
O
H
R C R'
OH
Secondary ROH

1- Hydroxylamine:
-C=O + NH2OH
-C=NOH + H2O (oxime)

CH3COCH3 + NH2OH




2- Hydrazine:
-C=O + H2N-NH2
CH3CHO +H2N-NH2
CH3-C=NOH
CH3
-C=N-NH2 + H2O
(hydrazone)
CH3CH=N.NH2+H2O
Aldol Condensation - Under the influence of
dilute base or dilute acid two molecules of an
aldehyde or a ketone may combine to form bhydroxaldehyde or b-hydroxyketone. This reaction
is called aldol condensation.

The Aldol Condensation
ald
+
ol
O
R CH2 C H
OH
+
base
O
R CH2 C CH C H
O
H R
an aldol
(b-hydroxyaldehyde)
R CH2 C H
H3O+
- H2 O
O
aldols easily lose
water to form a
double bond
R CH2 CH C C H
R
a,b-unsaturated aldehyde
Aldol Condensation -- Mechanism
: O:
_ ..
+ :O
.. H
CH3 C H
fast
: O:
slow
CH3 C H
_
..
CH2
: O:
.. _
: O:
CH3 C CH2 C H
H
+ H2O
: O:
_
..
CH2 C H
fast
: O:
..
:O H
forms new
C-C bond
: O:
CH3 C CH2 C
H
C H
enolate ion
.. _
: O:
CH3 C H
H2C
CH2 C H
C H
: O:
.. _
:O:
H
_ ..
+ :OH
..

1-
CH3COCH3
3I
2
Cl3COCH3
2- Cannizzaro’s reaction:
2CH2O + NaOH
NaOH
CHI3 + CH3CO2Na
CH3OH + HCOONa
Cannizzaro’s reaction
Add ammonia solution to AgNO3 solution until
precipitate dissolves.
Aldehyde reaction forms a silver mirror.
O
R C H + 2
+
H3)2
_
+
3 OH
+
Ag(NH3)2
O
_
+
H2O
3 OH
O
H2O
2 Ag + R C O
2 Ag + R C O
_
+
_
+
4 NH3 + 2 H2O
4 N
KMNO
4
RCHO 
 RCOOH
or K 2Cr2O7 , H
Tollen’s test

RCHO  2Ag NH3 2  3OH  RCOO  2Ag  4NH3  2H2O
(Silver mirror)
(ammonical silver nitrate solution)
Fehling’s test
RCHO  2CuO  RCOOH
Blue
Schiff’s test

Cu2O
Re d ppt. (Cuprousoxide)
Schiff's Test for aldehydes. Use 2 mL Schiff's reagent
+ 3 drops unknown. Positive test showing a magenta
color after ten minutes.
A carboxylic acid
 Contains a carboxyl group, which is a carbonyl
group (C=O) attached to a hydroxyl group (—
OH).
 Has the carboxyl group on carbon 1.
carbonyl group
O

CH3 — C—OH hydroxyl group or CH3COOH
carboxyl group
29
The IUPAC names of carboxylic acids

Replace the -e in the alkane name with -oic acid.
CH4 methane
CH3—CH3 ethane

HCOOH methanoic acid
CH3—COOH ethanoic acid
Number substituents from the carboxyl carbon 1.
CH3
O
|
║
CH3—CH—CH2—C—OH
4
3
2
1
3-methylbutanoic acid
30
Carboxylic acid
R-COOH
Aliphatic (carboxylic cid)
Ar-COOH
aromatic (benzoic acid)
Nomenclature :
1) replace
ane
by
-ic acid
No. C
Formula
IUPAC
Common
1
HCOOH
Methanoic acid
Formic acid
2
CH3COOH
Ethanoic acid
Acetic acid
3
CH3CH2COOH
Prpanoic acid
Prpionic acid
4
CH3(CH2)2COOH
Butanoic acid
Butyric acid
5
CH3(CH2)3COOH
Pentanoc acid
valeric acid
2) Longest continuous chain
CH3CH2CHCH2CH2COOH
4-Methyl hexanoic acid
CH3
   ba
C-C-C-C-C-COOH
CH3CH2CHCH2CH2COOH
CH3
γ-Methyl hexenoic acid
CH3 CH3
CH3-CH-CH-COOH
commmone:
IUPAC:
a-b- Dimethyl butyric acid
2,3-Dimethyl butanoic a
CH3-CHBr-CHCl-CO2H
3-Bromo-2-chlorobutnoic acid
Methanoic acid (formic acid)
O
║
H─C─OH
ethanoic acid (acetic acid)
O
║
CH3─C─OH
33
Physical properties:
1] They form hydrogen
2] comp. 1-7 soli in H2O .
3] mor than 7 carbon less soli. (bec. R increased)
4] Aromatic acids insoluble. In H2O
5] BP. Acid > Alcohol
Carboxylic acids
 Are strongly polar.
 Have two polar groups:
hydroxyl (−OH) and
carbonyl (C=O).
δO
║δ+ δ- δ+
CH3CO H
35
The boiling points of carboxylic acids
 Are higher than alcohols, ketones, and aldehydes
of similar mass.

Are high because they form dimers in which
hydrogen bonds form between the polar groups in
the two carboxyl groups.
O
H—O
||
|
CH3—C
C—CH3
|
||
O—H
O
A dimer of acetic acid
36
Carboxylic acids
 Form hydrogen
bonds with many
water molecules.

Water molecules
With 1-4 carbon
atoms are very
soluble in water.
37
Preparation of carboxylic acid
1] Oxidation
a) 1 alcohols & Aldehydes
CH3CH2OH
KMnO4 / H+
CH2OH
KMnO4 / H+
or K2Cr2O7 /H+
CH3CHO
heat
CH3COOH
COOH
CHO
heat
Cu / Heat
or CrO3 / pyridine
R-CHO
RCH2OH
K2Cr2O7 / H+
or KMnO4 / H+
RCOOH


Carboxylic acids can be prepared by oxidizing
primary alcohols or aldehydes.
The oxidation of ethanol produces ethanoic acid
(acetic acid).
OH
O
|
[O]
||
CH3—CH2
CH3—C—H
O
[O]
||
CH3—C—OH
ethanol
ethanal
ethanoic acid
(ethyl alcohol) (acetaldehyde) (acetic acid)
39
2] Carbonation of Grignard reagent:
R-Mg X
1) CO2
R-COOMgX
1)CO2
CH3-Mg Br
2) H3O
RCOOH
2) H3O CH COOH
3
CH3-COOMgBr
+ Mg(OH)Br
RMgX +
O
C
O
O
R C
O-
H+
+
+MgX
O
R C
OH
Reactions of acids
1)Salt formation:
it react with strong base & we can use Ca or K
RCOOH + KOH
RCOOH + NaOH
It reacts with weak base
RCOOH + NaHCO3
RCOOK + H2O
RCOONa + H2O
sodi. acetate
RCOONa + CO2 + H2O
Sodium bicarb. Can be used to distinguish between
carboxylic acid and phenols
OH
+ NaHCO3
NO reaction
2) Formation of Ester:
nucleophilic substitution
R C
O
+ H O R
OH
carboxylic acid
alcohol
H+
R C
O
+ H2O
O R
ester
condensation reaction
reverse = hydrolysis
ester + H2O
H+
carboxylic acid+ alcohol
2) Formation of Ester:
RCOOH
R'-OH / H+
heat
OH
COOH
R-COO-R' + H2O
OH
COOC2H5
CH3CH2OH
H+ / heat
3) Formation of acid chloride:
2 RCOOH
2 CH3COOH
SOCl3 , PCl3
or PCl5
2
SOCl3 , PCl3
or PCl5
O
R-C-Cl
2
O
CH3-C-Cl
4) Formation of acid anhydride:
2RCOOH + P2O5
(RCO)2O + H2O
2CH3COOH + P2O5
(CH3CO)2O + H2O
5- Reduction:
RCO2H + LiAlH4; then H+  RCH2OH
LiAlH4
1o alcohol
H+
CH3CH2CH2CH2CH2CH2CH2COOH
Octanoic acid
(Caprylic acid)
CH3CH2CH2CH2CH2CH2CH2CH2OH
1-Octanol
6- Decarboxylation:( Soda lime)
CH3COOH + NaOH/CaO
CH4 + Na2CO3 Alkane
ketone
aldehyde
ROR
ROH
RCOOH
alkene
Alcohols are
central to
organic
syntheses
RX
RH
alkyne