Question

What are geometric isomers? Give me an example

Answer 1

Molecules with the different groups "rotated" about the same double bond. These are technically constitutional isomers because double bonds cannot rotate.

Consider a simple case, cis and trans alkenes,

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The methyl groups are connected on different (`E`), and the same (`Z`) sides.

You will see more complicated iterations of the preceding, such as,

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where the former is `E` because its highest "priority" (same as absolute configuration scheme) groups are on different sides, and the latter is `Z` for the inverse of that reason.

`""^1` J. Org. Chem. 2017, 82, 10883-10897.