Geometrical isomerism: cis–trans, E–Z notation
Isomerism and Stereochemistry · Chemistry
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Let's label But-2-ene: CH3-CH=CH-CH3. 1. Draw the C=C bond in the center. 2. Attach one H and one CH3 to the first carbon. 3. Attach one H and one CH3 to the second carbon. 4. In the 'Cis' version, place both CH3 groups on the top side. In the 'Trans' version, place one CH3 on the top left and one CH3 on the bottom right. Because the carbons cannot rotate, the Cis molecule cannot become the Trans molecule without breaking the bond.