CHAPTER 15

Aldehydes, Ketones &

Carboxylic Acids
 Classification of Carbonyl Compounds
General structure of carbonyl compounds:

Where, R - alkyl group or aryl group

Based on the types of Y let's classify carbonyl compounds.

 Classification of Carbonyl compounds

Class I Class II

Aldehyde Ketone Carboxylic Acid

 Classification of Carbonyl Compounds
Common day to day life examples of class 1 carbonyl compounds are:
(a) Bitter almond which is mainly composed of benzaldehyde molecules.
 Classification of Carbonyl Compounds

(b) Cinnamon which is mainly composed

of cinnamaldehyde molecules.

(c) Vanillin is used in flavouring of sweet dishes

like cakes and ice-creams in which aldehyde (-
CHO) group is also present along with hydroxyl
(-OH) group and ether (-O-CH3).
 Classification of Carbonyl Compounds

(d) Meadow sweet is a sweet

smelling plant which is mainly
composed of salicylaldehyde
which contains two main
functional groups, i.e.,
aldehyde (-CHO ) and alcohol
(-OH) groups.
 Classification of Carbonyl Compounds
Common day to day life examples of class 2 carbonyl compounds are:

(a) Aspirin can be used as an antipyretic and analgesic drug which is

composed of (-COOH) group as well as the anhydride (-OCOCH3) group.

O
 Classification of Carbonyl Compounds
Derivatives of carboxylic acid

Some common carboxylic acid derivatives are acyl halide, acid anhydride, acid
amide and esters.
General structural formula for carboxylic acid derivatives are as follows:-

Acyl halide Acid anhydride

Where Y is replaced by a halogen Where Y is replaced by anhydride (-
X. (X = F, Cl, Br, I) OCOR’) group
 Classification of Carbonyl Compounds

Amide Ester

Where Y is replaced by Where Y is replaced by

(NH2) group (-OR) group
 Nomenclature
Common names

Use of keyword acet as a prefix is very common in writing common names for
carbonyl compound and its derivatives having (CH3CO-) in the main chain.
E.g., acetic acid for ethanoic acid, acetaldehyde for ethanal etc.

Acetaldehyde Acetone Benzaldehyde Benzophenone

 Nomenclature
Common names by using position of substituent:

The location of the substituent in the

carbon chain is indicated by α, β, γ, δ, etc.
The α-carbon being the one directly linked
𝛾 β ⍺
to the aldehyde group, our group of
interest, β-carbon the next, and so on.
For example: Position of the substituent
 Write the common name of the following compound.

Solution

In the given figure (-CHO) is our group of interest and the substituent methyl (-
CH3) is at 𝛾 position with respect to the (-CHO) group. So common name of the
compound is 𝛾-methylcyclohexanecarbaldehyde.
 Write the common name of the following compound.
CH3-CH(OCH3)-CHO

Solution

In the given figure (-CHO) is our group of interest and the substituent
(-OCH3) is at ⍺ position with respect to the (-CHO) group. So common
name of the compound is ⍺-methoxypropionaldehyde.
Write the common name of the following compound.
(CH3)2-CHCHO

Solution

For substituent like methyl (-CH3) naming convention of iso, neo and n are
used. Iso is used for secondary and neo is used for tertiary carbon.
So, the common name for the given compound is isobutyraldehyde.
Match the following aldehydes with their common names.

a) CH3CH2CH2CH2CHO 1) m-bromobenzaldehyde

b) CH2=CHCHO 2) Phthalaldehyde

3) Valeraldehyde
c)

4) Acrolein
d)
Solution a) CH3CH2CH2CH2CHO 3) Valeraldehyde

b) CH2=CHCHO 4) Acrolein

c) 2) Phthalaldehyde

d)
1) m-bromobenzaldehyde
Match the following aldehydes with their common names.

a) CH3COCH2CH2CH3 1) ⍺-Methylcyclohexanone

b) (CH3)2CHCOCH(CH3)2 2) Mesityl oxide

c) 3) Methyl n-propyl ketone

d) (CH3)2C=CHCOCH3 4) Diisopropyl ketone

Solution a) CH3COCH2CH2CH3 3) Methyl n-propyl ketone

b) (CH3)2CHCOCH(CH3)2 4) Diisopropyl ketone

c) 1) ⍺-Methylcyclohexanone

d) (CH3)2C=CHCOCH3 2) Mesityl oxide

 Structure of Carbonyl Compounds

Carbonyl carbon of both aldehyde and ketones is sp2 –

hybridised.

Unhybridized p-orbital of
carbonyl carbon form π-bond
with another half-filled p-
orbital of oxygen atom by sp2 hybridised
Trigonal planar
sideways overlapping.
 Structure of Carbonyl Compounds

Electronegativity of oxygen >> Electronegativity of carbon.

Therefore, bond is polarised bond.

Lewis acid 𝝳+
Electrophilic centre

𝝳−

Lewis base Nucleophilic centre

Physical Properties of Aldehydes & Ketones

Physical State

Odour
Physical properties

Boiling Point

Solubility
 Physical Properties of Aldehydes & Ketones

Physical State

Aldehydes and ketones are generally solids or liquids at room temperature.

Methanal is a gas at room temperature and ethanal is a volatile liquid.

Odour

• Lower aldehydes have a strong pungent smell. As the size of the

molecule increases, the odour becomes less pungent and more of a
fragrant type.
• Higher aldehydes find its application in the manufacture of deodorants,
air-freshners (room-freshners) etc.
 Physical Properties of Aldehydes & Ketones

Boiling Point
Case A
Aldehydes and ketones have lower boiling
points than alcohols since alcohols have
hydrogen bonds resulting in higher boiling
points. Case B
But aldehydes and ketones have higher
boiling points than hydrocarbons.
 Physical Properties of Aldehydes & Ketones

A graphical representation showing the boiling point trends of n-butane,

methoxyethane, propanal, acetone and propanol are given as follows:

Compounds
 Physical Properties of Aldehydes & Ketones

Solubility in water

• Lower members of aldehydes and ketones

are miscible in water in all proportions due
to the formation of hydrogen bonds with
water.
• Higher aldehyde and ketone is immiscible
in water because the longer alkyl group
attached prevents the hydrogen bond
formation as the alkyl part is hydrophobic.
 Physical Properties of Aldehydes & Ketones

Solubility in organic solvents

All aldehydes and ketones are

fairly soluble in organic solvents
like benzene, ether, methanol,
chloroform etc.
Arrange the following compounds in increasing order of their boiling
points: CH3CHO, CH3CH2OH, CH3OCH3, CH3CH2CH3
Arrange the following compounds in increasing order of their boiling
points: CH3CHO, CH3CH2OH, CH3OCH3, CH3CH2CH3

Solution

Due to the presence of intermolecular hydrogen bonds, CH3CH2OH has the

highest boiling point. Hydrocarbons have the least boiling points as they do
not have polarity. Hence, CH3CH2CH3 has the lowest boiling point.

Aldehydes have higher boiling points than ether due to the presence of strong
polar C=O bonds which can form strong dipole-dipole interactions. Hence,
CH3CHO has higher boiling points than CH3OCH3.

Hence, the increasing order of boiling points is:

CH3CH2CH3 < CH3OCH3 < CH3CHO < CH3CH2OH.
Preparation of Aldehydes & Ketones

Preparation via

Oxidation
of alcohols

Dehydrogenation
of alcohols
Ozonolysis
Hydrocarbons
Hydration
of alkynes
Oxidation by HIO4
 Preparation of Aldehydes & Ketones
Preparation via oxidation of alcohol

1O alcohol oxidizes in presence of mild oxidising agent such as Pyridinium

Chlorochromate (PCC) and Collins reagent (CrO3 in pyridine)and to give an
aldehyde, similarly 2O alcohol gives ketone and in 3O alcohol direct oxidation
is not possible.

Pyridinium chlorochromate
PCC is used as a mild oxidizing agent for higher yield.
 Preparation of Aldehydes & Ketones
Preparation via oxidation of alcohol

Example:
Conversion of secondary alcohol to ketone in the presence of mild oxidation
agents are given below:

PCC is used as a mild oxidizing agent for higher yield.

Name the reagent(s) required to bring about the following
transformation:
CH3CH2CH2CH2CH2CH2OH ⟶ CH3CH2CH2CH2CH2CHO
Name the reagent(s) required to bring about the following
transformation:
CH3CH2CH2CH2CH2CH2OH ⟶ CH3CH2CH2CH2CH2CHO

Solution

If a strong oxidising agent like acidified K2Cr2O7 or KMnO4 is used

then they will oxidise the alcohol into carboxylic acid.
Hence, a mild oxidising agent like PCC (Pyridinium chlorochromate) or
anhydrous CrO3 should be used.
But the yield is less while using anhydrous CrO3.

Hence, we can use PCC for better yield.

Preparation of Aldehydes

From hydrocarbon

Oxidation of methyl By chromyl

benzene chloride

Side chain chlorination By chromic

of methyl benzene oxide

Gattermann-Koch
reaction
What would be the product(s) of the given reaction?
Hg2+, H2SO4
HC CH
What would be the product(s) of the given reaction?
Hg2+, H2SO4
HC CH

The products of the given reaction would be:

Hg2+, H2SO4
2+
..

..
HC CH
⦀

-H+

Tautomerises
CH3CHO
The carbonyl compound obtained by reductive ozonolysis
of benzene is:

a) CH3CHO b) CH3CH2CHO c) d)
 The carbonyl compound obtained by reductive ozonolysis
of benzene is:

a) CH3CHO b) CH3CH2CHO c) d)

Solution

In the reductive ozonolysis of benzene, there will be the cleavage of the double bonds.
So, option (d) is the correct answer.
 Preparation of Aldehydes from Hydrocarbons
Oxidation of methyl benzene

By chromyl chloride(CrO2Cl2)
Chromyl chloride oxidises
methyl group to a chromium
complex, which on hydrolysis
gives corresponding
benzaldehyde.
This is known as Etard reaction. Reagents used

CrO2Cl2, CS2, H3O+

 Preparation of Aldehydes from Hydrocarbons
Oxidation of methyl benzene
 Preparation of Aldehydes from Hydrocarbons

Trick to remember

H3O+ -H2O

Unstable Benzaldehyde
 Preparation of Aldehydes from Hydrocarbons
Oxidation of methyl benzene

By chromic oxide (CrO3)

Toluene is converted to benzylidene
diacetate on treatment with chromic oxide
in acetic anhydride.
The benzylidene diacetate can be
hydrolysed to corresponding benzaldehyde Reagent used
with aqueous acid. Here, the intermediate
I. CrO3, (CH3CO)2O, 273-283 K
formed is benzylidene diacetate.
II. H3O+, Δ
 Preparation of Aldehydes from Hydrocarbons
Oxidation of methyl benzene

H3O+

Benzylidene
diacetate

Benzaldehyde
 Preparation of Aldehydes from Hydrocarbons

Trick to remember

H3O+ -H2O

Unstable Benzaldehyde
 Preparation of Aldehydes from Hydrocarbons

Side chain chlorination of methyl benzene

Side chain chlorination of

toluene gives benzal
chloride, which on h𝛎
hydrolysis gives + Cl2
benzaldehyde.

Reagent used: Benzal chloride

i) Cl2, h𝛎
H2O 373 K
ii) H2O, 373 K Benzaldehyde
 Preparation of Aldehydes from Hydrocarbons

Gattermann-Koch reaction

When benzene or its derivative is

treated with carbon monoxide
and hydrogen chloride in the
presence of anhydrous aluminium
chloride or cuprous chloride, it
Reagents used
gives benzaldehyde or
1) CO, HCl
substituted benzaldehyde.
2) Anhydrous AlCl3/CuCl
 Preparation of Aldehydes from Hydrocarbons

Gattermann-Koch reaction

Step 1: Formation of Electrophilic formyl cation

 Preparation of Aldehydes from Hydrocarbons

Gattermann-Koch reaction

Step 2: Electrophilic Aromatic Substitution

 Preparation of Aldehydes from Hydrocarbons

Oxidation of methane

Mo2O3
CH4 HCHO
 Preparation of Aldehydes from Nitriles

Stephen Reaction

Reagents used in Stephen reaction are: (i) SnCl2, HCl (ii) H3O+

The reaction is also possible by using DIBAL-H (Diisobutylaluminium

hydride), followed by hydrolysis
 Preparation of Ketones from Acyl Chloride

From dialkyl cadmium

Treatment of acyl chlorides with dialkyl cadmium (prepared by the reaction

of cadmium chloride with Grignard reagent) gives ketones.
Preparation of dialkyl cadmium

δ-δ+δ- δ+ δ-
2 XMgR + CdCl2 CdR2 + 2Mg(X)Cl
Dialkyl cadmium
 Preparation of Ketones from Acyl Chloride

From dialkyl cadmium

The reaction with acid chloride

2 + CdR2 + CdCl2
 Preparation of Ketones from Acyl Chloride

From dialkyl cadmium

Mechanisms:
 Preparation of Ketones from Nitriles

Using Grignard Reagent

Treating a nitrile with Grignard reagent followed by hydrolysis yields a

ketone.
Reagent used: (i) RMgBr (Grignard reagent ), dry ether (ii) H3O+
 Preparation of Ketones from Nitriles

Friedel-Crafts acylation

When Benzene reacts with RCOCl in presence of AlCl3 we get C6H5COR as

the product.

RCOCl
Anhyd. AlCl3
What would be the product(s) of the given reaction?

Anhydrous AlCl3
+ C2H5COCl
CS2
What would be the product(s) of the given reaction?

Anhydrous AlCl3
+ C2H5COCl
CS2

Solution This is an example of Friedel-Crafts acylation.

Anhydrous AlCl3
+ C2H5COCl + HCl
CS2
What would be the product(s) of the given reaction?

CH3

1. CrO2Cl2 H3O+
2. CS2

NH2
What would be the product(s) of the given reaction?

Solution H
Cl2(OH)CrO OCr(OH)Cl2
CH3
C CHO
1. CrO2Cl2 H 3 O+

2. CS2

NH2
NH2 NH2
Name the reagent(s) required to bring about the following
transformation.

?
Name the reagent(s) required to bring about the following
transformation.

Solution
CrO3 in the presence of
acetic anhydride

OR
1. CrO2Cl2 2. H3O+
The oxidation of toluene to benzaldehyde by chromyl
chloride is called:

a) Etard reaction b) Reimer-Tiemann reaction

c) Wurtz reaction d) Cannizzaro's reaction

The oxidation of toluene to benzaldehyde by chromyl
chloride is called:

a) Etard reaction b) Reimer-Tiemann reaction

c) Wurtz reaction d) Cannizzaro's reaction

Solution

The oxidation of toluene to benzaldehyde by chromyl chloride is called

Etard reaction.
So, option (a) is the correct answer.
 Preparation of Ketones from Gem-dihalides

Hydrolysis of Gem-Dihalides

Hydrolysis of geminal dihalides

results in the formation of
carbonyl compounds, specifically NaOH

aldehydes or ketones.

This occurs because the initial hydrolysis step yields a geminal diol, which is
unstable and undergoes dehydration to form the carbonyl compound and
water.
 Preparation of Ketones from Nitroalkanes

Nef Reaction

The Nef reaction is a chemical

process in organic chemistry
where a nitroalkane is
converted into a carbonyl
compound (aldehyde or ketone)
under acidic conditions.
 Preparation of Ketones from Nitroalkanes

Nef Reaction

Mechanisms:
 Preparation of Ketones from Nitroalkanes

Oxo Process

Addition of carbon monoxide (CO) and hydrogen (H2) to an alkene to form

an aldehyde.
Catalyst: Cobalt or Rhodium complexes.
 Preparation of Ketones from Alkenes

Wacker Process

Oxidation of alkenes (especially ethylene) to aldehydes or ketones.

Catalyst: Palladium chloride (PdCl₂) and Copper chloride (CuCl₂).
 Preparation of Ketones from Alkenes

Wacker Process

Mechanisms:
 Preparation of Ketones from Carboxylates

Dry Distillation with Calcium salt

 Preparation of Ketones from Carboxylates

Reactions of Acids with MnO

 Preparation of Ketones from Alcohol

Oppenaeur Oxidation
 Preparation of Ketones from Alcohol

Oppenaeur Oxidation

Mechanisms:
Question – 1

Question – 2

Question – 3 Question – 4
Question – 1

Question – 2

Question – 3 Question – 4
Chemical Properties of Aldehydes and Ketones
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

The carbonyl group is polar due to the

electronegativity difference between carbon and
oxygen. Hence, carbon attains a partial positive
charge and oxygen attains a partial negative
charge.
Carbon of the carbonyl group is an
electrophilic centre and oxygen of the carbonyl
group is a nucleophilic centre.
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

A general reaction for the nucleophilic addition to a carbonyl group is given as follows.
It can be observed that a nucleophile attacks the carbonyl carbon and forms a carbon-
nucleophile bond.

+
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Step 1: Addition of nucleophile

 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Step 2: Abstraction of proton

 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Stereochemistry

Nucleophilic addition of formaldehyde and acetone can’t

form a racemic mixture as the products formed are achiral.
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Stereochemistry

Nucleophilic addition of formaldehyde and acetone can’t

form a racemic mixture as the products formed are achiral.
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Aldehyde vs ketone towards nucleophilic addition reaction:

Relative reactivity of aldehydesand ketones can be explained considering two
factors given as follows:

Aldehyde vs Ketone

Steric factor Electronic factor

 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Steric factor:
Sterically, the presence of two relatively large substituents in ketones hinders
the approach of nucleophile to carbonyl carbon than in aldehydes.
Hence, aldehydes are more reactive towards nucleophilic addition reaction
than ketones.

Relative reactivity > >

 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

Electronic factor

Electronically, aldehydes are more

reactive than ketones because two
Decreasing Reactivity
alkyl groups in ketones reduce the
electrophilicity of the carbonyl ẟ- ẟ- ẟ-
carbon more effectively than in ẟ+ ẟ+ ẟ+
aldehydes.
Decreasing Reactivity
Compare the reactivity:
CH3CH2CHO
Compare the reactivity:
CH3CH2CHO

Solution

Resonance effect is present in benzaldehyde. This resonance stabilisation

has reduced the polarity between carbon and oxygen and has decreased
the reactivity of benzaldehyde towards nucleophilic addition reaction.
Compare the reactivity:
Compare the reactivity:
Compare the reactivity:

Solution

• In benzophenone, the carbonyl carbon is more resonance stabilised by

two benzene rings.
• Also due to two bulky phenyl groups in benzophenone it is difficult for
the nucleophile to attack the carbonyl carbon.
• Hence, considering the electronic and steric effects, we can say that,
benzaldehyde is more reactive.
Arrange the following compounds in increasing order of
reactivity:

A B C D

E
 Solution

• Due to steric hindrance caused by two bulky phenyl groups in

benzophenone, it is less reactive than acetone.
• Also the positive charge in carbonyl carbon of benzophenone (C) is
stabilised by resonance effect but positive charge in carbonyl carbon of
acetone (E) is stabilised by inductive effect.
• Hence, we can conclude that benzophenone is less reactive towards
nucleophilic addition reactions when compared to acetone.

A < B < C < D < E

 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

 Nucleophilic addition reactions

HCN Addition

Cyanohydrins are very useful compounds in synthesizing

many other organic compounds such as
⍺-hydroxy acids, amino acids etc.
 Nucleophilic addition reactions

HCN Addition

Mechanism of
Addition of HCN
 Nucleophilic addition reactions

HCN Addition

Nucleophilic attack on
Step 1
carbonyl carbon
 Nucleophilic addition reactions

HCN Addition

Formation of a strong Tetrahedral

Step 2 intermediate
nucleophile
_ _
CN
δ+ δ- Slow
 Nucleophilic addition reactions

HCN Addition

Formation of
Step 3
Adduct Cyanohydrin
_

H+
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

 Nucleophilic addition reactions
Base catalysation is not needed here, as there is
NaHSO3 Addition
already presence of a strong naked nucleophile.

This method can be used for the purification of aldehydes

from other organic compounds as NaHSO3 attacks
aldehyde selectively.
 Nucleophilic addition reactions

NaHSO3 Addition

Mechanism of
Addition of NaHSO3
 Nucleophilic addition reactions

NaHSO3 Addition

Nucleophilic attack
Step 1
on carbonyl carbon

S site is more
nucleophilic than O- site
due to the engagement
of O- in resonance
..
_
+
 Nucleophilic addition reactions

NaHSO3 Addition

Formation of
Step 2
Adduct
_
 Nucleophilic addition reactions

NaHSO3 Addition
 Nucleophilic addition reactions

NaHSO3 Addition

Aldehydes and ketones combine with sodium bisulfite to for well-crystallized

water-soluble products known as “aldehyde bisulfite” and “ketone bisulfite”.
 Nucleophilic addition reactions

NaHSO3 Addition

Collected crystalline product (bisulphite

Filtration process where crystalline
salt) can be again back to aldehyde
bisulphite salt of aldehyde product
which will be pure aldehyde by treating it
are being filtered.
with Dilute mineral acid.
 Nucleophilic addition reactions

NaHSO3 Addition

+ .. _ +

More steric Lesser accessibility Equilibrium shifts

hindrance for nucleophile to LHS
 Nucleophilic addition reactions

NaHSO3 Addition

But why do diethylketones

and acetophenones do not Due to the bulkier groups
undergo this reaction? present in these ketones,

Nucleophiles are less approachable

to the carbonyl carbon.
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

 Nucleophilic addition reactions

Grignard Reagent
 Nucleophilic addition reactions

Grignard Reagent

Excess [H+] triggers NH3 controls the excess [H+] by

elimination reaction. forming NH4Cl and facilitates
nucleophilic addition.
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

 Nucleophilic addition reactions

Alcohol Addition

Ether Ether

Alcohol Ether
Hemiacetal Acetal
 Nucleophilic addition reactions

Alcohol Addition

Ether Ether

Alcohol Ether

Hemiketal Ketal
 Nucleophilic addition reactions

Alcohol Addition

Mechanism of
Addition of Alcohol
to Aldehydes
 Nucleophilic addition reactions

Alcohol Addition

Formation of a
Step 1
hemiacetal
 Nucleophilic addition reactions

Alcohol Addition

Formation of an
Step 2
acetal
 Nucleophilic addition reactions

Alcohol Addition

Formation of an
Step 2
acetal
Acetal
 Nucleophilic addition reactions

Alcohol Addition

Cyclic acetals and ketals are formed in the presence of dihydric or

trihydric alcohols.

HCl gas
+ H2O
+
⇌
dil.HCl

Ethylene glycol ketal

 Nucleophilic addition reactions

Alcohol Addition

Cyclic acetals and ketals are formed in the presence of dihydric or

trihydric alcohols.

Cyclic acetal Cyclic ketal

 Nucleophilic Addition Reactions
Can acetals and ketals
transform back to the
respective aldehydes and Using mineral
ketones? Yes!
acids

Example

CH3CH2CHO
H3O+

⇌ +
2 CH3CH2OH
 Chemical Properties of Aldehydes & Ketones

Nucleophilic addition reactions

 Nucleophilic addition reactions

Ammonia and its derivatives

+ ⇌
⇌
+ H2O
Tetrahedral
Short trick Intermediate

+ ⇌ + H O
2
 Nucleophilic addition reactions

Alcohol Addition

Mechanism of
Addition of Alcohol
to Aldehydes
 Nucleophilic addition reactions

Ammonia and its derivatives

Ammonia Imine

Amine
Substituted imine
Schiff’s base
Nucleophilic Addition
Reactions

Hydroxylamin Oxime
e

⇌
Hydrazine Hydrazone

⇌
Phenylhydrazin Phenylhydrazone
e
Nucleophilic Addition
Reactions

Semicarbazide Semicarbazone

2,4- 2,4-
Dinitrophenylhydrazine Dinitrophenylhydrazone
 Formaldehyde when reacted with methyl magnesium
bromide followed by hydrolysis gives:

a) CH CH OH b) c) CH3CHO d) HCOOH
3 2 CH3COOH

Solution

δ δ+ δ- +
δ + -
H ≡
+

Hence, option (a) is the correct answer.

 Addition Reactions of Ammonia and its Derivatives

General reaction

Examples of ammonia derivatives by changing Z substituent :

Addition Reactions of Ammonia and its Derivatives
Addition Reactions of Ammonia and its Derivatives
 Addition Reactions of Ammonia and its Derivatives

Short
trick
⇌
+

2,4-
dinitrophenylhydrazine

+ H2O

2,4-
dinitrophenylhydrazone
 2,4-Dinitrophenylhydrazine

2,4-DNP is used for identification of aldehydes and

ketones.

Organic compound aldehyde or Yellow orange solid gets

Ketone is taken in a test tube deposited and confirms
few drops of 2,4-DNP is poured the presence of an
in aldehyde or ketone aldehyde or ketone 2,4-DNP
test tube using dropper
 Which one is the most reactive to
nucleophilic addition reaction?

(a (b
) )

(c (d
) )
 Solution

The reactivity of the carbonyl group towards the nucleophilic addition

reactions depends upon the magnitude of the positive charge on the
carbonyl carbon atom.
Aromatic aldehydes are more reactive than alkyl aryl ketones due to more +I
effect of alkyl group in ketones. Electron withdrawing group (—NO2) due to -M
and -I effect, increases the magnitude of positive charge on carbonyl carbon
and increases the reactivity towards nucleophilic addition reactions whereas,
electron donating group (—CH3) due to its +I effect decrease the magnitude of
positive charge on carbonyl carbon and decreases the reactivity towards
nucleophilic addition reactions. Hence, p-nitrobenzaldehyde is the most
reactive.

Thus, option c is the correct answer.

 Nucleophilic addition reaction will
be most favoured in:
(a) CH CHO (b) (c) (d
3 CH3CH2CHO
CH3COC )
H3
Solution

The reactivity of the carbonyl group towards the addition reactions depends
upon the magnitude of the positive charge on the carbonyl carbon atom.
The introduction of alkyl groups (+I effect), decreases the magnitude of
positive charge on carbonyl carbon, hence more number of alkyl group less
will be the reactivity and vice versa. Therefore, the least (+ I) effect exists
in option a with a single alkyl group and offers least steric hindrance to
incoming nucleophile .

Thus, option a is the correct answer

 Acetone is treated with excess of ethanol in the presence of
hydrochloric acid. The product obtained is:

(a (b
) )

(c (d
) )

Solution
Formation of acetal and
Ketal
Acetals
•In excess are geminal-diether derivatives of aldehydes or ketones, formed
of alcohol
reaction
by with two equivalents (or an excess amount) of an alcohol and
elimination of water.
 Solution

Ketone derivatives of this kind were once called ketals, but modern usage has
dropped that term. It is important to note that a hemiacetal is formed as an
intermediate during the formation of an acetal.

General reaction

+ 2

Aldehyde or Aceta
Ketone l
The product obtained
is:

HCl
+ (g)
Δ

Thus, option d is the correct

answer.
 A carbonyl compound reacts with hydrogen cyanide to form
cyanohydrin, which on hydrolysis, forms a racemic mixture of
𝛼-hydroxy acid. The carbonyl compound is:

(a) Formaldehyde (b) Acetaldehyde

(c) Acetone (d) Diethyl Ketone
Solution

Nucleophilic addition of cyanide ion on carbonyl carbon having two different

groups attached on either side leading to formation of racemic mixture.
+

+ + +
Clearly for option b nucleophilic attack of CN- ion produces a cyanohydrin
(2-hydroxypropanenitrile) with a chiral carbon. which on further hydrolysis
produces ɑ-hydroxy acid and it occurs as a racemic mixture i.e. a 50-50
mixture of optical isomers.
• The reason for the formation of equal amounts of two isomers lies in the
way the ethanal gets attacked.
• Ethanal is a planar molecule, and attack by a cyanide ion will either be
from above the plane of the molecule, or from below. There is an equal
chance of either happening.
• Attack from one side will lead to one of the two isomers, and attack from
the other side will lead to the other.

All aldehydes except formaldehyde and unsymmetrical ketones will

form a racemic mixture in this way.
Thus, option b is the correct answer.
 The order of stability of the following tautomeric compound is:

(I (II
) )

(III)
Solution

Generally, keto form is more stable than enol, because C=O is more stable
than C=C. But if enol is form is stablized by some other factors like
conjugation and intramolecular H bonding as given in III.
 Intramolecular hydrogen bonding

It will make it more stable than keto. No such factor is there in

compound I, hence II is more stable than I.

Thus, order of stability is III > II > I

 Friedel Craft Alkylation

Anhyd. AlCl3
+ Br
- HBr

We get a rearranged product due to the

formation of more stable 2o carbocation Isopropyl benzene
than a 1o carbocation. (Cumene)

In order to prevent this formation of

rearranged product we can use Friedel Major (Rearranged
Crafts Acylation to form n-propylbenzene product)
 Friedel Craft Alkylation

Anhyd. AlCl3
+
+ HCl

Friedel Crafts Acylation is a process used

to form ketones, so if we can reduce >C=O Ethyl phenyl ketone
to CH2 n-propylbenzene benzene can be
formed. Reductio
n
n-propylbenzene
 Reduction of Aldehyde and Ketones

Reduction of aldehydes and ketones

Reduction to hydrocarbon Reduction to alcohol

Clemmensen reduction Acidic condition

Wolff-Kishner reduction Basic condition

 Reduction of Aldehyde and Ketones

Clemmensen reduction General

reaction

The reaction of aldehydes and

ketones with zinc amalgam
(Zn/Hg alloy) in concentrated
hydrochloric acid, which reduces Aldehyde/
Hydrocarbon
the aldehyde or ketone to a Ketone
hydrocarbon, is called
Clemmensen reduction.
Reagent used Zn-Hg, HCl
 Reduction of Aldehyde and Ketones

Examples:
Zn-Hg
+ H2O
HCl

Zn-Hg
+ H2O
HCl
 Which of the following reducing agent is used for the
following conversion? [H]
CH3COCH2COOC2H5 CH3CH2CH2COOC2H5

LiAlH4 (b) NaBH (c) DIBAL-H

(a) 4 Zn-Hg/HCl (d)

Solution

If the reduction is done using LiAlH4, It can reduce both ester group and C=O
to alcohol. On the other hand, NaBH4 can reduce ketone to alcohol and
DIBAL-H reduces ester to -CHO group.
Thus, the reaction of aldehydes and ketones with zinc amalgam (Zn/Hg alloy)
in concentrated hydrochloric acid, which reduces the aldehyde or ketone to
a hydrocarbon, is called Clemmensen reduction.

Ketone Hydrocarbon

Reagent used Zn-Hg, HCl

Thus, option c is the correct

answer.
 Reduction of Aldehyde and Ketones

Wolff-Kishner reduction

The reduction of aldehydes and General

ketones to alkanes. Condensation reaction
of the carbonyl compound with
hydrazine forms the hydrazone, 1. NH2-NH2
treatment with base and on
and
heating induces the reduction of 2. KOH/ethylene
the carbon coupled with oxidation glycol/Δ
of the hydrazine to gaseous
+ N
nitrogen, to yield the 2
corresponding alkane.
↑
 Reduction of Aldehyde and Ketones

Short
trick
H2NNH2
+ H2O

KOH/ethylene
Hydrazone glycol/Δ
intermediat
e

Unstable + N2 ↑
 Reduction of Aldehyde and Ketones
Examples:

NH2NH 2 KOH/Ethylene glycol

Δ
+HO + N (g)
2 2

NH2NH2
KOH/Δ
+ N2(g)
+ H2O
 What will be the products A and B in
the given reaction?

N2H4 NaOH
A B
Δ

Solution

Clearly According to Wolff - Kishner reaction Ketone reacts with hydrazine to

form hydrazone intermediate and treatment with base and heating induces
the reduction of the carbon coupled with oxidation of the hydrazine to gaseous
nitrogen, to yield cyclohexane.
The products A and B are
as:

N2H4 NaOH
Δ

A B
 Clemmensen reduction of a ketone is carried out in the presence
of which of the following?

(a) Glycol with KOH (b) Zn-Hg with HCl (c) (d) H2 and Pt as
LiAlH catalyst
4
Solution

Clemmensen reduction:
The reaction of aldehydes and
ketones with zinc amalgam (Zn/Hg
alloy) in concentrated hydrochloric
acid, which reduces the aldehyde or Ketone Hydrocarbon
ketone to a hydrocarbon, is called
Clemmensen reduction. Reagent
used Zn-Hg, HCl
Thus, option b is the correct
answer.
 Reduction of aldehydes and ketones into hydrocarbons using
zinc amalgam and conc. HCl is called:

(a) Cope reduction (b) Dow reduction

(c) Wolff-Kishner reduction (d) Clemmensen reduction

Solution
Clemmensen reduction:
The reaction of aldehydes and ketones with zinc amalgam (Zn/Hg alloy) in
concentrated hydrochloric acid, which reduces the aldehyde or ketone to a
hydrocarbon, is called Clemmensen reduction.

Thus option (d) is the correct answer.

 Reduction to Alcohol

[H]
Aldehyde 1° Alcohol
Reduction
[H]
Ketones 2° Alcohol
Reduction

Reduction

Aldehyde 1° Alcohol
 Reduction to Alcohol

Reduction of aldehydes
and ketones to
alcohols

Catalytic
Using LiAlH 4 Using NaBH 4
hydrogenatio
n
 Reduction to Alcohol

Reduction using LiAlH4

LiAlH4 is a strong reducing agent. It is mostly used in reduction of

acid/ester
along with aldehydes and ketones to an
alcohol Example:

1.LiAlH4 in dry ether

2. H2O

1.LiAlH4 in dry ether

2. H2O
 Reduction to Alcohol

Reduction using NaBH4

Example:

1.NaBH4
2. H2O

1.NaBH4
2. H2O
 Reduction to Alcohol
Catalytic hydrogenation

Catalytic hydrogenation is treatment with hydrogen in the presence of a

catalyst such as nickel, palladium or platinum. Hydrogenation reduces double
and triple bonds in hydrocarbons. Catalytic hydrogenation can also convert
aldehyde and ketones to alcohols.
Example:
H2 H2
Pd, Ni, Pt Pd, Ni, Pt

Aldehyde 1° Alcohol Aldehyde 1° Alcohol

 Reduction to Alcohol
Catalytic hydrogenation

H2 ,Pd/ Ni/ Pt
Which of the following reducing agent is used for the
following conversion?

[H]

(a) LiAlH4 (b) NaBH4

(c) (d) DIBAL-H

Zn-Hg/HCl
NaBH4 is a moderate reducing agent used to reduce aldehydes and ketones
to alcohols but it cannot reduce acids and esters and clearly only the
ketone group is reduced in the given reaction. So, the correct reagent is
NaBH4

Thus, option (b) is the correct answer.

 Reactions of Aldehydes & Ketones
Addition of Diazomethane
Wittig Reaction
Wittig Reaction
Beckmann Rearrangement
 Reactions of Aldehydes & Ketones
Michael Addition
 Reactions of Aldehydes & Ketones
Michael Addition
 Reactions of Aldehydes & Ketones
Michael Addition