After studying this Unit, you will be
able to
write the common and IUPAC
names of aldehydes, ketones and
carboxylic acids;
write the structures of the
compounds containing functional
groups namely carbonyl and
carboxyl groups;
describe the important methods
of preparation and reactions of
these classes of compounds;
correlate physical properties and
chemical reactions of aldehydes,
ketones and carboxylic acids,
with their structures;
explain the mechanism of a few
selected reactions of aldehydes
and ketones;
understand various factors
affecting the acidity of carboxylic
acids and their reactions;
describe the uses of aldehydes,
ketones and carboxylic acids.
Objectives
Carbonyl compounds are of utmost importance to organic
chemistry. They are constituents of fabrics, flavourings, plastics
and drugs.
12
Unit
Unit
Unit
Unit
Unit
12
Aldehydes
Aldehydes
Aldehydes
Aldehydes
Aldehydes
,,
,,
,
KK
KK
K
ee
ee
e
tonestones
tonestones
tones
andand
andand
and
CarboxylicCarboxylic
CarboxylicCarboxylic
Carboxylic
AA
AA
A
cidscids
cidscids
cids
AldehydesAldehydes
AldehydesAldehydes
Aldehydes
,,
,,
,
KK
KK
K
ee
ee
e
tonestones
tonestones
tones
andand
andand
and
CarboxylicCarboxylic
CarboxylicCarboxylic
Carboxylic
AA
AA
A
cidscids
cidscids
cids
In the previous Unit, you have studied organic
compounds with functional groups containing carbon-
oxygen single bond. In this Unit, we will study about the
organic compounds containing carbon-oxygen double
bond (>C=O) called carbonyl group, which is one of the
most important functional groups in organic chemistry.
In aldehydes, the carbonyl group is bonded to a
carbon and hydrogen while in the ketones, it is bonded
to two carbon atoms. The carbonyl compounds in which
carbon of carbonyl group is bonded to carbon or
hydrogen and oxygen of hydroxyl moiety (-OH) are
known as carboxylic acids, while in compounds where
carbon is attached to carbon or hydrogen and nitrogen
of -NH
2
moiety or to halogens are called amides and
acyl halides respectively. Esters and anhydrides are
derivatives of carboxylic acids. The general formulas of
these classes of compounds are given below:
2020-21
358Chemistry
Aldehydes, ketones and carboxylic acids are widespread in plants
and animal kingdom. They play an important role in biochemical
processes of life. They add fragrance and flavour to nature, for example,
vanillin (from vanilla beans), salicylaldehyde (from meadow sweet) and
cinnamaldehyde (from cinnamon) have very pleasant fragrances.
12.1.1
Nomenclature
I. Aldehydes and ketones
Aldehydes and ketones are the simplest and most important carbonyl
compounds.
There are two systems of nomenclature of aldehydes and ketones.
(a) Common names
Aldehydes and ketones are often called by their common names
instead of IUPAC names. The common names of most aldehydes are
derived from the common names of the corresponding carboxylic
acids [Section 12.6.1] by replacing the ending –ic of acid with aldehyde.
At the same time, the names reflect the Latin or Greek term for the
original source of the acid or aldehyde. The location of the substituent
in the carbon chain is indicated by Greek letters α, β, γ, δ, etc. The
α-carbon being the one directly linked to the aldehyde group, β-
carbon the next, and so on. For example
12.1
12.1
12.112.1
12.1
Nomenclature and Structure of Carbonyl GroupNomenclature and Structure of Carbonyl Group
Nomenclature and Structure of Carbonyl GroupNomenclature and Structure of Carbonyl Group
Nomenclature and Structure of Carbonyl Group
They are used in many food products and pharmaceuticals to add
flavours. Some of these families are manufactured for use as solvents
(i.e., acetone) and for preparing materials like adhesives, paints, resins,
perfumes, plastics, fabrics, etc.
2020-21