Question

How figure out R/S in a molecule with multiple stereocenters

Answer 1

To determine R/S configuration in a molecule, assign priorities based on atomic number, orient the lowest priority group away, draw an arrow from priority 1 to 2 to 3, and assign R/S based on the arrow direction. Repeat for each stereocenter.

Step-by-step explanation:

To figure out R/S configuration in a molecule with multiple stereocenters, you must follow a systematic process:

1. Determine the Lewis structure of the molecule.
2. Identify all the stereocenters in the molecule.
3. Assign priorities to the substituents at each stereocenter based on atomic number.
4. For each stereocenter, visualize the substituents in space with the lowest priority (4) pointing away from you.
5. Draw an arrow from priority 1 to 2 to 3. If the arrow goes clockwise, and the lowest priority group is away from you, the configuration is R. If counterclockwise, then it is S.
6. If the lowest priority group is not away from you, first determine the sequence as if it were and then reverse the R/S assignment.
7. Once each stereocenter is assigned an R or S, you can write the full IUPAC name with the appropriate R/S designation before each stereocenter's locant number.

If a molecule has multiple stereocenters, repeat this process for each one to determine the overall stereochemistry of the molecule.