Geometrical Isomerism PPT: Meaning, Types, Applications

Geometrical isomerism, also known as cis-trans isomerism, is a type of stereoisomerism where molecules have the same molecular formula but differ in the spatial arrangement of groups around a rigid structure, such as a double bond or a ring system. This rigidity prevents free rotation, leading to distinct isomers with unique properties.

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Geometrical Isomerism PPT: Meaning, Types, Applications

Causes of Geometrical Isomerism

Geometrical isomerism arises due to restricted rotation around a double bond or within a ring. In alkenes, the presence of a carbon-carbon double bond locks substituents in specific positions, giving rise to cis and trans forms. In cyclic compounds, the ring structure prevents rotation, causing similar isomeric behavior.

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Types of Geometrical Isomers

The two main types of geometrical isomers are:

Cis-Isomers: Substituents are on the same side of the reference plane (e.g., the double bond or ring).
Trans-Isomers: Substituents are on opposite sides of the reference plane.

These arrangements result in distinct physical and chemical properties.

Examples of Geometrical Isomerism

Alkenes: For example, in 2-butene, the cis-isomer has both methyl groups on the same side of the double bond, while the trans-isomer has them on opposite sides.
Cyclic Compounds: In cyclohexane derivatives, such as 1,2-dichlorocyclohexane, the cis and trans forms differ based on the positions of chlorine atoms.

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Applications of Geometrical Isomerism

Geometrical isomerism has significant implications in fields like medicine and materials science. In pharmaceuticals, different isomers can have vastly different biological activities. For instance, cisplatin (a cis-isomer) is a widely used anticancer drug, whereas its trans-isomer lacks similar efficacy. Understanding and controlling isomerism is crucial for designing functional molecules.