This drill requires the latest version of the Java platform.  You can get this (free download) by following the link at the bottom of the page.

This drill tests the practice of prioritizing substituents in organic chemistry according to the Cahn-Ingold-Prelog convention.  This  convention is used in various places, including E,Z-designation and R,S designations.  The highest priority substituent receives #1, while the lowest receives #4. 

To use this, click on the substituent windows in order from highest to lowest priority.  When you have selected the priority ranking for all four substituents, press OK (or just click the RMB).  This will reveal the answers.  Press Next (or hit RMB) for a new set of substituents. 

When you are comfortable with the C-I-P concept, you might want to try the following drill :

Fischer Projection Drill


This program determines the relative priorities of the substituents "on site", ie the priorities are not determined by us beforehand but rather by an algorithm "live".  While we have not yet seen it happen, there is always a chance that the algorithm may be flawed.  Use this knowledge at your own risk. 

If you do see any errors, inaccuracies, or bugs, please notify us immediately via feedback.  Also let us know if the program appears awkward on your machine, fonts are too big or small, etc.


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