Cahn-Ingold-Prelog Priority Rules

Requires a Wolfram Notebook System
Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.
This Demonstration describes the rules of Cahn, Ingold and Prelog (CIP) to assign priority to the substituents associated with double bonds and chiral carbon atoms. The first case leads to the classification (for geometric isomerism), the second to the
classification (optical isomerism). The method assigns the following order of priority [1, 2]:
Contributed by: D. Meliga, A. Ratti, L. Lavagnino and S. Z. Lavagnino (August 2022)
Open content licensed under CC BY-NC-SA
Snapshots
Details
Snapshot 1: double and triple bonds are formally converted into single bonds
Snapshot 2: Moving along the chain of the substituent in the branch associated with oxygen (element with the highest atomic number), the methyl carbon introduces the first difference between the two structures and causes the prioritization. Forming oxygen, only two bonds are introduced, with virtual bonds with phantom atoms of zero atomic number.
Snapshot 3: after the formal transformation of multiple bonds into an equivalent number of single bonds (the duplicated atom is enclosed in square brackets), the priority is assigned according to the criterion of the first difference
Reference
[1] H. Hart, L. E. Craine and D. J. Hart, Organic Chemistry: A Short Course, 10th ed., Boston: Houghton Mifflin, Co., 1999.
[2] Wikipedia. "Cahn–Ingold–Prelog Priority Rules." (Feb 15, 2022) https://en.wikipedia.org/wiki/Cahn%E2%80%93Ingold%E2%80%93Prelog_priority_rules.
Permanent Citation