Isomerism
Isomerism
The phenomenon
of existence of two or more compounds possessing the same molecular formula but
different properties is known as isomerism. Such compounds are called as
isomers. The following flow chart shows different types of isomerism.
Structural isomerism.
Compounds having
the same molecular formula but different structures (manners in which atoms are
linked) are classified as structural isomers. Some typical examples of
different types of structural isomerism are given below:
Chain
isomerism : When two or more compounds have similar molecular formula but
different carbon skeletons. These are referred to as chain isomers and the phenomenon
is termed as chain isomerism. For example C5H12 represents
three compounds:
Position isomerism
: When two or more compounds differ in the position of substituent atom or
functional group on the carbon skeleton, they are called position isomers and
this phenomenon is termed as position isomerism. For example, the molecular formula
C3H8O represents two alcohols:
Functional group
isomerism: Two or more compounds having the same molecular formula but
different functional groups are called functional isomers and this phenomenon
is termed as functional group isomerism. For example, the molecular formula C3H6O
represents an aldehyde and a ketone:
Metamerism:
It arises due o different alkyl chains on either side of the functional group in
the molecule. For example, C4H10O represents
methoxypropane (CH3OC3H7) and ethoxyethane (C2H5OC2H5).
Stereoisomerism
The compounds
that have the same constitution and sequence of covalent bonds but differ in
relative positions of their atoms or groups in apace are called stereoisomers. This
special type of isomerism is called as stereoisomerism and can be classified as
geometrical and optical isomerism.
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