Question

(a) Explain Geometrical Isomerism found in organic compounds with suitable examples.
(b) What is the action of heat on Oxalic acid and Succinic acid?

Answer 1

(a) Geometrical Isomerism: Isomerism that arises out of the difference in the spatial arrangement of atoms or groups about the doubly bonded carbon atoms is called Geometrical Isomerism.
These isomers are not mirrored images of each other. Rotation about $C=C$ is not possible under normal conditions, and hence the isomers are isolable.
If different atoms or groups are bonded to the '$C=C$' bond in a molecule, more than one spatial arrangement is possible.
For example, 2 - butene exists in two isomeric forms.
The isomer in which similar groups lie on the same side is called 'Cis isomer' (I). The other in which similar group lie in opposite direction is called 'Trans isomer' (II). This isomerism is called 'Cis-Trans' isomerism. The two groups attached to the carbon atoms need not be the same, it may be different also,
This isomerism arises out of the hindrance to rotation about the $C=C$ bond in such molecules.
(b) Oxalic acid on heating at 373 K - 378 K loses water of hydration. On further heating, it decomposes to formic acid and carbon dioxide.
succinic acid on heating to ${300}^{o}C$ losses a molecule of water to form an anhydride.