Demos > Resolve CIP Stereochemistry

Stereochemistry is an important part of understanding a chemical structure. The CIP rules have long been the standard for assinging parity to stereocenters and are commonly taught in chemistry courses. Such instruction is often greatly simplified so that students can more easily understand it, as the CIP algorithm is incredibly complex, tedious and not without flaws. CIP rules have seen many revisions over the decades and more recently with the work of Paulina Mata and the work from NextMove Software (exemplified in the rule tests below). References can be found at the bottom of the page.

ChemDoodle 2D has an expert system to resolve stereochemistry. This demo will resolve CIP stereocenters for drawn 2D structures using the ChemDoodle 2D algorithms. Simply draw your stereocenter in the sketcher below and press the Resolve Stereochemistry button.

Rule Tests

These are the complex CIP edge case tests from NextMove Software.

See if you can determine how many stereocenters are present and what their configurations are. Then click on the molecule to see the answer. These stereocenters are resolved in real time by ChemDoodle 2D.


  1. Cahn, R. S.; Ingold, C. K. Specifcation of Configuration about Quadricovalent Asymmetric Atoms. J. Chem. Soc. 1951, 612-622.
  2. Cahn, R. S.; Ingold, C.; Prelog, V. Specification of Molecular Chirality. Angew. Chem., Int. Ed. 1966, 5, 385-415.
  3. Prelog, V.; Helmchen, G. Basic Principles of the CIP-System and Proposals for a Revision. Angew. Chem., Int. Ed. 1982, 21, 567-583.
  4. Mata, P.; Lobo, A. M. The CIP Sequence Rules: Analysis and Proposal for a Revision. Tetrahedron: Asymmetry 1993, 4, 657-668.
  5. Mata, P.; Lobo, A. M. Implementation of the Cahn-Ingold-Prelog System for Stereochemical Perception in the LHASA Program. J. Chem. Inf. Comput. Sci. 1994, 34, 491-504.
  6. Mata, P.; Lobo, A. M. Comparison of Constitutional Properties in the CIP System: The CIP Sequence Rule 1. Tetrahedron: Asymmetry 1995, 6, 693-696.
  7. Mata, P. The CIP System Again: Respecting Hierarchies Is Always a Must. J. Chem. Inf. Comput. Sci. 1999, 39, 1117-1118.
  8. May, J. W. CHEMINFORMATICS FOR GENOME-SCALE METABOLIC RECONSTRUCTIONS. Doctor of Philosophy, University of Cambridge, June 2014.
  9. Hanson, R. M.; Musacchio, S.; Mayfield, J. W.; Vainio, M. J.; Yerin, A.; Redkin, D. Algorithmic Analysis of Cahn−Ingold−Prelog Rules of Stereochemistry: Proposals for Revised Rules and a Guide for Machine Implementation. J. Chem. Inf. Model. 2018, 58, 1755-1765.

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