Cis-trans isomerism is a type of geometric isomerism that occurs in certain molecules that have restricted rotation around a bond, typically a double bond or a ring structure. This restriction allows for different spatial arrangements of the substituents attached to the carbon atoms involved in the double bond or within a ring.
In cis isomers, the similar or identifying groups are on the same side of the double bond or ring, while in trans isomers, these groups are on opposite sides. This difference in spatial orientation can lead to variations in physical and chemical properties, such as boiling points and solubility.
Two types of compounds that can exhibit cis-trans isomerism are:
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Alkenes: Alkenes possess at least one carbon-carbon double bond (C=C) and can display cis-trans isomerism when there are different substituents on each carbon of the double bond. For example, in 2-butene, the cis form has the two methyl groups on the same side, while the trans form has them on opposite sides.
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Cycloalkanes: Cycloalkanes that contain substituents can also exhibit cis-trans isomerism. In cyclohexane derivatives, for instance, if there are two substituents on adjacent carbon atoms in the ring, they can either be on the same face of the ring (cis) or on opposite faces (trans).
In summary, cis-trans isomerism is notable for its role in determining the properties of certain alkenes and cycloalkanes, influencing their reactivity and interaction in chemical contexts.
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