The presentation covers basic reactions of aldehydes and ketones

1. Pharmaceutical Organic Chemistry-I
(BP202T)
Unit-4
Carbonyl Compounds
(Aldehydes & Ketones)
Mr. Krishan Kr. Verma, Assistant Professor
Ram-Eesh Institute of Vocational & Technical Education

2. • Carbonyl compounds are compounds that contain the carbonyl group
(C=O).
• Include aldehydes, ketones, carboxylic acid and its derivatives.
SP2 hybrid
Z = H R OH X
Z = OR NH2/NHR/NHR2 OCOR
R Z
O

3. IUPAC Nomanclature
• The name of the parent hydrocarbon (alkane or alkene or
alkyne) is determined while counting the carbonyl carbon as a
methyl group for aldehydes and as a methylene group for
ketones.
• The substituents are named as it is done for the hydrocarbon.
• The name of the alkane is modified to alkanal for an aldehyde.
• In case of ketones, the name is modified to alkanone. The
position of the carbonyl group is denoted as numerical prefix
to –one.

4. • When both the aldehyde and keto functionalities are present
in the same molecule, the aldehyde gets preference and the
molecule is suffixed with an –al. The position of the keto
group is denoted by a numerical prefix and is denoted by
used of the word oxo.

5. Methods for Preparation Aldehydes and Ketones
1. Oxidation of Alcohols:
Ketones may be prepared by the oxidation of secondary alcohols
in the presence of acid dichromate.
In case of primary alcohol, this process may lead to oxidation of
the alcohol to carboxylic acid.
This problem is overcome by using mild oxidizing agent. e.g.
pyridinium Chlorochromate and pyridinium dichromate.
R OH
R O
PCC/PDC
CH2Cl2

6. • The ketones may also be generated from the secondary
alcohols using aluminium t-butoxide / aluminium
isopropoxide in the presence of acetone.
• This reaction is known as Oppenauer Oxidation.

7. 2. Reduction of acid chlorides
• Aldehydes can also be prepared by the reduction of acid
chloride with hydrogen using a palladium catalyst suspended
on barium Sulphate.
• This reaction is known as Rosenmund reduction.
3. Oxidative Cleavage of Alkenes (Ozonolysis of Alkenes)
• Both aldehydes and ketones may be formed by ozonolysis of
suitable alkenes.
R Cl
R H
Pd/BaSO4
O
O

8. • The ozonolysis of alkenes of the type RCH=CHR1 leads to the
formation of aldehydes while the tetrasubstituted alkenes will
give ketones as product.
(i) O3
R
R 1
(ii) H3O+
R H
O
R1 H
O
(i) O3
R
R
3
(ii) H3O+
R
1
R
2
O
R
R
1
O
R
3
R
2

9. 4. Hydration of Alkynes
• The hydration of alkynes by the mercuration-demercuration
procedure can be utilized to prepare acetaldehyde and ketones.
• The hydration of acetylene gives acetaldehyde while the
hydration of any other alkyne leads to formation of ketones.

10. 5. Acylation of Arenes (Friedel-Craft acylation)
• Friedel Craft acylation may be used to prepare alkyl aryl
ketones or diaryl ketones.
• In this process, an arene is usually treated with an acid halide
or acid anhydride in the presence of a Lewis acid catalyst.

11. Physical Properties
• They have dipole moment as oxygen is more electronegative
than carbon.
• This implies that the carbonyl carbon is slightly positively
charged and the carbonyl oxygen is slightly negatively
charged.
• This makes the carbon susceptible to nucleophilic attack while
the oxygen should be susceptible to attack by electrophiles.

12. Chemical Reactions
1. Nucleophilic Addition Reactions:
• The nucleophilic addition to the carbonyl group is the most
important reaction of aldehydes and ketones.
• Several nucleophiles such as water, alcohols, cyanide etc
attack the carbonyl carbon.
• The reaction can be catalyzed by the presence of both acids
and bases.

13. Acid Catalyzed Nucleophilic Additions Mechanism
O
H+
O
H
OH
:Nu-
OH
Nu
Base Catalyzed Nucleophilic Additions Mechanism
O
:Nu-
O
Nu
OH
Nu
H+

14. Relative Reactivities of Aldehydes & Ketones for
Nucleophilic Additions
• Any group that increases the positive charge on carbonyl
carbon increases the reactivity of carbonyl group towards
nucleophilic additions.
• Therefore, electron releasing groups tend to neutralize the
positive charge of carbonyl carbon and decrease the reactivity.
• Whereas, electron withdrawing groups enhance the positive
charge of carbonyl carbon and increase the reactivity.

15. Questions
1. Why Aldehydes are more reactive than ketones in nucleophilic
addition additions?
2. Why formaldehydeis more reactive than acetaldehyde?
3. Why aromatic aldehydes and ketones are less reactive than
aliphatic aldehydes and ketones towards nucleophilic addition?

16. Nucleophilic Addition Reactions
1. Addition of Grignard reagent.
2. Addition of HCN.
O
R
1
R
R2
Mg
X
O
R
1
R
R
2
MgX
OH
R
1
R
R
2
H3O+
O
R
1
R
OH
R
1
R
CN
OH
R
1
R
2H2OHCN
Cyanohydrin
HCl
COOH
Hydroxy Acid

17. 3. Addition of Sodium Bisulphite.
4. Addition of Water (Hydration).
5. Addition of Alcohols.
O
H
OH
H
SO3Na
NaHSO3
Sodium Bisulphite Adduct
O
R
1
R
OH
R
1
R
OH
HOH
gem-diols
O
H
R
OH
H
R
OR1
R1OH
Hemiacetals
OR2
H
R
OR1
Acetals
R2OHH+
O
R
3
R
OH
R
3
R
OR1
R1OH
Hemiketals
OR2
R
3
R
OR1
Ketals
R2OHH+

18. 2. Reduction Reactions:
• LiAlH4 or NaBH4 can be used to reduce both aldehydes and
ketones to their corresponding alcohols.
Meerwein Pondorf Verley (MPV) Reduction:
• This method is used to reduce ketones to alcohols reversibly in
presence of aluminium isopropoxide and isopropanol solvent.
This is reverse of Oppenauer oxidation.
R-CHO H2 R-CH2OH
LiAlH4 / NaBH4
OR
R
1
OH Al-(OCHMe2)3
OHR
R
1
O
Ketone Alcohol isopropanoneIsopropanol
(solvent)

19. Wolff Kishner Reduction:
• The Wolff–Kishner reduction reaction is used to
convert carbonyl functionalities into methylene groups.
Clemmensen Reduction:
• This method is used to reduce carbonyl group to methylene
group in presence of zinc amalgam and hydrochloric acid.
NH2NH2
OR
R
1
Base
R
R
1
H
H
Zn / Hg
OR
R
1
HCl
R
R
1
H
H

20. 3. Condensation Reactions
• The aldehydes and ketones undergo another class of reactions
which may be called addition elimination reaction or
condensation reactions. In these reactions, they react with a
reagent to form an adduct, which may then under suitable
conditions undergo elimination of a water molecule to form
the product.
(i) Aldol Condensation:
Two molecules of aldehydes or ketone having α hydrogen atom
combine together i.p.o. base to form β- hydroxy aldehyde or β-
hydroxy ketone that further upon dehydration yields α, β-
unsaturated carbonyl compound.

21. O
H
O
H OH
O
H
OH-
H+
O
H
Acetaldehyde Acetaldehyde
ß-hydroxy Aldehyde (Aldol)
3-hydroxy butanal
H2O
2- butenal

22. O O O
OH-
H+
O
Acetone Acetone
ß-hydroxy Ketone
4-hydroxy - 4-methyl- 2-pentanone
H2O
4-methyl- 3-pentenone
OH

23. Mechanism of Aldol Condensation
• The reaction involves formation of carbanion that acts as
neucleophile and attacks second aldehyde molecule.
H
H
O
H
H
OH-
-H2O
CH2CHOH
O
+
O
CHO
CH2CHO
O
CHO + H2O
OH
CHO
-OH-
OH
CHO
-H2O
CHO

24. Crossed Aldol Condensation
• Between two different aldehydes and ketones.
CH3CHO + CH3COCH3
CH3CH(OH)CH2COCH3
CH3CH(OH)CH2CHO
(CH3)2C(OH)CH2COCH3
(CH3)2C(OH)CH2CHO

25. 2. Claisen Schmidt Reaction

26. 3. Claisen Reaction

27. 4. Perkin Reaction

29. Ar
O
H
CH2 O
O O
Ar
O
H
O
O
O

30. Ar
O
H
O
O
O
O
O
H
Ar
O
O
O
O
H
Ar
O
O
H
H
-CH3COOH
O
H Ar
O
H
OH
Ar O
H+

31. 5. Benzoin Condensation

33. 6. Reformatsky Reaction

34. Condensation with ammonia derivarives

35. Mannich Reaction

37. 4. Hydride Transfer Reaction
Cannizaro Reaction
Aldehydes without α hydrogen atom undergo disportionation
i.p.o. strong base to form equal amounts of corresponding
alcohol and carboxylic acid salt.
One aldehyde acts as hydride (H-) donor whereas other
aldehyde acts as hydride acceptor.

39. 5. Oxidation Reactions

40. Electromeric Effect
• It is an temporary effect observed in unsaturated compounds
only in presence of some reagent available nearby.
• Electromeric effect involves complete transfer of π electrons of
multiple bond. e.g. during attack on a carbonyl group by
nucleophile, the π electron pair of C=O bond is transferred
completely to oxygen (due to greater electro-negativity of
oxygen), and therefore polarize the carbonyl group.
• The positevely charged carbon is then attacked by nuclephile.
O O

41. “ The complete transfer of shared pair of electrons of a multiple
bond to the more electronegative atom of the bonded atoms due
to the requirements of an attacking reagent is called
electromeric effect ”.
Electromeric effect is of two types- +E effect and –E effect
+E Effect : when the transfer of π electrons take place towards
the attacking reagent (Electrophile).
-E Effect : when the transfer of π electrons take place away
from the attacking reagent (Nucleophile).

42. O O
Nu
Nu
E
E

43. STRUCTURE AND USES
1. Formaldehyde
Structure:
Uses:
• It is used as an general antiseptic.
• It is used as local anesthetic.
• It is used in preservation of biological specimens.
• It is used in the manufacturing of plastics such as bakellite.
O
H
H

44. 2. Paraldehyde
Structure: it is a cyclic trimer of acetaldehyde
Uses:
• It is used as in the manufacturing of resins.
• It is used as CNS depressant, sedative and hypnotic.
• It is used as expectorant.
O O
O

45. 3. Acetone
Structure:
Uses:
• It is used as a organic solvent.
• It is used in the synthesis of chloroform.
• It is used in the synthesis of iodoform.
• It is used in the preparation of thermo softening plastic,
perspex.
O
CH3
H3C

46. 4. Chloral Hydrate
Structure:
Uses:
• It is used as insecticide.
• It is used as hypnotic.
• It is used in the preparation of DDT.
OH
OHCl
Cl
Cl

47. 5. Hexamine
Structure:
Uses:
• It is used as a urinary antiseptic.
• It is used as disinfectant.
• It is used as absorbent for absorbing poisonous gases.
• Hexamine nitrate is used to get explosive cyclonite or RDX.
• Used in adhesives, coating and sealing compounds.
N
N
N
N

48. 6. Benzaldehyde
Structure:
Uses:
• It is used in the manufacturing of cinnamic acid.
• It is used in the preparation of malachite green dye.
• It is used as flavoring agent.
• It is used as bee repellent.
OH

49. 7. Vanillin
Structure:
Uses:
• It is used as flavoring agent in ice creams and chocolates.
• It is used in perfume industry.
• It is used to mask the unpleasant taste of medicines.
O
H
HO
O CH3