ALDEHYDES, KETONES & CARBOXYLIC
ACIDS
INTRODUCTION:
The classes of organic compounds containing carbonyl group as
the functional group are aldehydes, ketones, carboxylic acids and their
derivates. These are collectively called carbonyl compounds.
The general formulae of aldehydes and ketones are:
The functional group of aldehydes is called the aldehydic group
while
that of the ketones is called the ketonic group . … The carbonyl
compounds in
which the carbonyl group is attached to an – OH group are called carboxylic
acids.
Their general formula is The functional group of carboxylic acids
is
called carboxyl group .
Esters and acid anhydride are the derivatives of carboxylic acid.
Carbonyl compounds in which carbon atom is attached to halogen are called
acyl halide while in which carbon is attached to nitrogen are called amide.
(A) – ALDEHYDES AND KETONES NOMENCLATURE OF ALDEHYDES AND
KETONES:
Common Names:
a) The common names of aldehydes are derived from the common names of
the corresponding carboxylic acids by replacing the terminal, ‘ic acid’
from the common names of the corresponding carboxylic acids by the
suffix ‘aldehyde’.
𝐂𝐇𝟑 𝐂𝐇𝐎
Acetic acid – ic acid + aldehyde = Acetaldehyde
, Benzoic acid – ic acid + aldehyde =
Benzaldehyde
b) The common names of both aliphatic and aromatic ketones are obtained
by naming the two alkyl or aryl groups (in the alphabetical order)
attached to the keto group as two separate words and adding the suffix
‘ketone’. When the two alkyl or the aryl groups are the same, the prefix
‘di’ is attached to the name of the alkyl or the aryl group.
IUPAC Names:
a) The aliphatic aldehydes are called alkanals and the names of individual
members are derived by replacing the terminal ‘e’ from the name of the
corresponding alkane by the suffix ‘al’. In substituted aldehydes, the
parent carbon chain containing the aldehydic group is selected and the
positions of the substituent and the multiple bonds, if any, on the parent
chain are indicated by numbers, 1, 2, 3, - - - - -, etc.
b) When aldehyde group is directly attached to a ring (alicyclic or aromatic),
the suffix carbaldehyde is added to the full name of the hydrocarbon.
c) The ketones are named as alkanones. The names of the individual
members are derived by replacing the terminal ‘e’ from the name of the
corresponding alkane by the suffix ‘one’.
d) The aromatic ketones are known as phenones.
, STRUCTURE AND NATURE OF CARBONYL GROUP
STRUCTURE OF CARBONYL GROUP
According to the molecular orbital theory, the carbonyl carbon atom is
𝑠𝑝 − hybridised and forms three sigma (𝜎) bonds. The fourth valence electron
2
of carbon remain in its p = orbital and forms a 𝜋 − bond with oxygen by overlap
with p – orbital of an oxygen. In addition, the oxygen atomo also has two non –
bonding electron pairs. Thus, the carbonyl carbon and the three atoms attached
to it lie in the same plane and the 𝜋 −electron cloud is above and below this
plane. The bond angle is approximately 1200 as expected of a trigonal coplanar
structure.
NATURE OF CARBONYL GROUP:
Carbonyl carbon atom is carbonyl group is far more electronegative than
carbon atom. As a result, the oxygen atom tends to attract the electron cloud of
the 𝜋 − bond
towards itself, i.e., the 𝜋 − electron cloud of is unsymmetrical. In
other words, carbonyl carbon acquires a small positive charge and hence acts as
an electrophilic centre (Lewis acid) while the carbonyl oxygen carries a small
ACIDS
INTRODUCTION:
The classes of organic compounds containing carbonyl group as
the functional group are aldehydes, ketones, carboxylic acids and their
derivates. These are collectively called carbonyl compounds.
The general formulae of aldehydes and ketones are:
The functional group of aldehydes is called the aldehydic group
while
that of the ketones is called the ketonic group . … The carbonyl
compounds in
which the carbonyl group is attached to an – OH group are called carboxylic
acids.
Their general formula is The functional group of carboxylic acids
is
called carboxyl group .
Esters and acid anhydride are the derivatives of carboxylic acid.
Carbonyl compounds in which carbon atom is attached to halogen are called
acyl halide while in which carbon is attached to nitrogen are called amide.
(A) – ALDEHYDES AND KETONES NOMENCLATURE OF ALDEHYDES AND
KETONES:
Common Names:
a) The common names of aldehydes are derived from the common names of
the corresponding carboxylic acids by replacing the terminal, ‘ic acid’
from the common names of the corresponding carboxylic acids by the
suffix ‘aldehyde’.
𝐂𝐇𝟑 𝐂𝐇𝐎
Acetic acid – ic acid + aldehyde = Acetaldehyde
, Benzoic acid – ic acid + aldehyde =
Benzaldehyde
b) The common names of both aliphatic and aromatic ketones are obtained
by naming the two alkyl or aryl groups (in the alphabetical order)
attached to the keto group as two separate words and adding the suffix
‘ketone’. When the two alkyl or the aryl groups are the same, the prefix
‘di’ is attached to the name of the alkyl or the aryl group.
IUPAC Names:
a) The aliphatic aldehydes are called alkanals and the names of individual
members are derived by replacing the terminal ‘e’ from the name of the
corresponding alkane by the suffix ‘al’. In substituted aldehydes, the
parent carbon chain containing the aldehydic group is selected and the
positions of the substituent and the multiple bonds, if any, on the parent
chain are indicated by numbers, 1, 2, 3, - - - - -, etc.
b) When aldehyde group is directly attached to a ring (alicyclic or aromatic),
the suffix carbaldehyde is added to the full name of the hydrocarbon.
c) The ketones are named as alkanones. The names of the individual
members are derived by replacing the terminal ‘e’ from the name of the
corresponding alkane by the suffix ‘one’.
d) The aromatic ketones are known as phenones.
, STRUCTURE AND NATURE OF CARBONYL GROUP
STRUCTURE OF CARBONYL GROUP
According to the molecular orbital theory, the carbonyl carbon atom is
𝑠𝑝 − hybridised and forms three sigma (𝜎) bonds. The fourth valence electron
2
of carbon remain in its p = orbital and forms a 𝜋 − bond with oxygen by overlap
with p – orbital of an oxygen. In addition, the oxygen atomo also has two non –
bonding electron pairs. Thus, the carbonyl carbon and the three atoms attached
to it lie in the same plane and the 𝜋 −electron cloud is above and below this
plane. The bond angle is approximately 1200 as expected of a trigonal coplanar
structure.
NATURE OF CARBONYL GROUP:
Carbonyl carbon atom is carbonyl group is far more electronegative than
carbon atom. As a result, the oxygen atom tends to attract the electron cloud of
the 𝜋 − bond
towards itself, i.e., the 𝜋 − electron cloud of is unsymmetrical. In
other words, carbonyl carbon acquires a small positive charge and hence acts as
an electrophilic centre (Lewis acid) while the carbonyl oxygen carries a small
