R/S and E/Z Configuration Exercises

Select a GROUP (R/S, E/Z or R/S-E/Z) from the top of the black panel. Exercises will appear in the black panel. Select a molecule; it will appear in the white panel. In examples under "Several Chiral Centers", the numbers in brackets indicate the number of chiral centers. Determine the R/S and/or E/Z-configurations. Click the respective green "show" button to display answers and any comments (Notes:). Atom Colors: carbon, gray; hydrogen, light blue; bromine, magenta; chlorine, green; nitrogen, blue; oxygen, red; lithium, pink; silicon, tan; sulfur, yellow. Caveat: Atom numbers (hovering) may not agree with nomenclature numbers. Read How to Manipulate JSmol Structures to navigate structures if you use the clockwise vs. counterclockwise method to determine R/S-configuration. There is a better (hand) method discussed in a primer on R/S-configuration. The double bonds in some substituted benzenoid rings will have different E/Z-designations depending upon which resonance structure is shown. These designations have no meaning in delocalized structures. [See the two vanillins in the E/Z-group.]