Rules:

It is possibile to use the already available examples or draw your own molecules.

1) to assign the priority, click on "Initialize".

2) click on the chiral carbon in JSMol and click on the "Chiral Carbon" button

3) repeat the the step 2 assigninig the priority to all the first atoms linked to the chiral Carbon

4) orient the molecule to place the group having priorirty 4 far from the observer

5) Assign the chirality R or S to the molecule

Save on Disk Background

Priority

Chirality

Answer

Save on Disk Background

Priority

Chirality

Answer

Left

(LE)

Chiral Carbon

Tartaric Acid

Threose

Glucose

Right

(RI)

Chiral Carbon

Tartaric Acid

Erithrose

Glucose

Enantiomers

Sequence Rules

Sequence Rules

 

 

Assign the priority order to the susbtituents on the asymmetric carbon according to the Cahn-Ingold-Prelog rules.

 

  1. For every substituent, look at the first atom linked to the asymmetric carbon: the atom having the highest atomic number has the highest priority
  2. If it is not possible to define all the priorities in this way, look at the second atom away form the double bond carbon atom, and so on, until a point of difference can be found.
  3. The atoms having multiple bonds are equivalents to the same number of atoms linked by single bonds.