, MODULE IV
Stereochemistry and Polymer Chemistry
Stereochemistry:
Stereochemistry is the branch of chemistry which deals with the spatial arrangement of atoms
or groups in a molecule. Organic compounds with same molecular formula but different
structures are called isomers. This phenomenon is called isomerism. Isomers differ in their
physical and chemical properties.
Structural isomerism
Isomerism arises due to the difference in the arrangement of atoms within the molecule and
is independent of the position of atoms in the space around the molecule. Structural isomerism is
of different types.
1. Chain (nuclear) isomerism:
It arises due to the different arrangement of carbon atoms in a carbon chain or skeleton, for
example in C4H10 has two chain isomers and in C5H12 has three chain isomers.
2. Position isomerism
It arises due to the different position of atoms or groups in a carbon chain.
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,3. Functional isomerism
It arises due to the difference in the functional groups attached to the carbon chain.
4. Metamerism
It arises due to the unequal distribution of carbon atoms on either side of the functional
group.
5. Tautomerism
It is a type of functional isomerism. When two isomers are mutually interconvertable and
exit in dynamic equilibrium, they are called tautomers and this phenomenon is called
tautomerism.
II. Stereo isomerism:
Isomerism arises due to the difference in the spatial arrangement of atoms is called stereo
isomerism. This can divided into conformational isomerism and configurational isomerism. In
conformational isomerism, the isomers go on changing into another rapidly due to the rotation
about single covalent bonds and cannot be separated. In configurational isomerism, the isomers
do not change into one another automatically. These isomers can be interconverted only by
breaking and remaking of covalent bonds. Configurational isomerism can be divided into
geometrical isomerism and optical isomerism.
1. Geometrical isomerism:
Isomerism arises due to the different spatial arrangement of atoms or groups around a
double bond or ring structure is called geometrical isomerism.
a) Geometrical isomerism in double bonds:
When carbon atoms are joined by a double bond, free rotation about the bond is restricted
and the two substituents on each carbon atom are different, geometrical isomerism arises.
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, b) Geometrical isomerism in cyclic structures:
Geometrical isomerism arises in cyclic structures or ring compounds due to the restricted
free rotation of carbon atoms about their axis.
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Stereochemistry and Polymer Chemistry
Stereochemistry:
Stereochemistry is the branch of chemistry which deals with the spatial arrangement of atoms
or groups in a molecule. Organic compounds with same molecular formula but different
structures are called isomers. This phenomenon is called isomerism. Isomers differ in their
physical and chemical properties.
Structural isomerism
Isomerism arises due to the difference in the arrangement of atoms within the molecule and
is independent of the position of atoms in the space around the molecule. Structural isomerism is
of different types.
1. Chain (nuclear) isomerism:
It arises due to the different arrangement of carbon atoms in a carbon chain or skeleton, for
example in C4H10 has two chain isomers and in C5H12 has three chain isomers.
2. Position isomerism
It arises due to the different position of atoms or groups in a carbon chain.
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,3. Functional isomerism
It arises due to the difference in the functional groups attached to the carbon chain.
4. Metamerism
It arises due to the unequal distribution of carbon atoms on either side of the functional
group.
5. Tautomerism
It is a type of functional isomerism. When two isomers are mutually interconvertable and
exit in dynamic equilibrium, they are called tautomers and this phenomenon is called
tautomerism.
II. Stereo isomerism:
Isomerism arises due to the difference in the spatial arrangement of atoms is called stereo
isomerism. This can divided into conformational isomerism and configurational isomerism. In
conformational isomerism, the isomers go on changing into another rapidly due to the rotation
about single covalent bonds and cannot be separated. In configurational isomerism, the isomers
do not change into one another automatically. These isomers can be interconverted only by
breaking and remaking of covalent bonds. Configurational isomerism can be divided into
geometrical isomerism and optical isomerism.
1. Geometrical isomerism:
Isomerism arises due to the different spatial arrangement of atoms or groups around a
double bond or ring structure is called geometrical isomerism.
a) Geometrical isomerism in double bonds:
When carbon atoms are joined by a double bond, free rotation about the bond is restricted
and the two substituents on each carbon atom are different, geometrical isomerism arises.
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, b) Geometrical isomerism in cyclic structures:
Geometrical isomerism arises in cyclic structures or ring compounds due to the restricted
free rotation of carbon atoms about their axis.
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