How can you recognize geometric isomers?

1 Answer
Jul 23, 2016

Got models?


Cis-trans isomerism is fairly easy to appreciate and represent for an olefin or ring structure. It is less intuitive and much harder to represent stereoisomerism, where handedness is an issue.

The use of models as an aid to visualize geometry is widespread among professors of chemistry; it is less common among undergraduate students, who think they might be playing with toys. Of course, you still have to represent your model on the printed page, which is a non-trivial exercise.

I can offer one tip! Suppose you have represented your chiral centre, #CR_1R_2R_3R_4#, correctly on the printed page, or as a model in three dimensions. The interchange of ANY two substituents gives the enantiomer. Interchange again (ANY two substituents), and the original isomer is restored.