The instructions are reported at the bottom of the page

JME Editor courtesy of Peter Ertl, Novartis

Save on Disk

Useful commands in JSmol:

1) ALT + mouse --> rotate in the plan (x y)

2) CTRL+ ALT + mouse --> move to the screen plan (x y)

3) mouse wheel --> zoom in and out

4) left click and drag mouse --> rotate in the three dimensions

Background Colour


Choose Chirality

Check Answer

Show all Chiral Carbons


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

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

3) repeat the step 2 for each atom directly linked to the Chiral Carbon to assign CIP Priority

4) orient the molecule the molecule properly, with the priority 4 group point away from you

5) assign the chirality, R or S, by clicking on the chiral carbon and after on the proper "R" or "S" button

6) check your answer by clicking on the "Check Chirality" button


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.