When the traversal encounters an atom through which the current path has already passed, a phantom atom is generated in order to keep the tree finite. A single atom of the original molecule may appear in many places (some as phantoms, some not) in the tree.

2017年1月17日 · These “phantom atoms” are used solely for the purpose of determining CIP priority – they have no chemical meaning. Note that in the process of assigning phantom atoms to both atoms in a multiple bond involves the more distant …

First, examine at the atoms directly attached to the stereocenter of the compound. A substituent with a higher atomic number takes precedence over a substituent with a lower atomic number. Hydrogen is the lowest possible priority substituent, because it has the lowest atomic number.

These two atoms are known as phantom atoms and have an atomic number of zero. This level of rigor is only required in special cases. To assign the configuration of C 2, only the atoms in spheres 1 and 2 are required. In sphere 1, O > C 1 = C 3 > H. To distinguish between C 1 and C 3, their attachments in sphere 2 must be evaluated.

2019年7月9日 · directory of Chem Help ASAP videos: https://www.chemhelpasap.com/youtube/During atom prioritization for assigning stereochemical configurations, atoms with p...

This page describes how to treat small rings as substituents via the CIP method, how to convert cyclic compounds into acyclic digraphs and how to distinguish between duplicate and phantom atoms. The 2013 update of the 1982 Cahn-Ingold-Prelog rules is located here.

It is common to use simplified digraphs that do not show hydrogen or “phantom” atoms. However, from an implementation perspective, simplified digraphs must be used with caution. In complex examples, for instance, a critical aspect of the algorithm must be finding the first difference

2023年1月23日 · The carbonyl group places two oxygens (one phantom) on the adjacent carbon atom, so this methylene side is ranked ahead of the other. An interesting feature of the two examples shown here is that the R-configuration in both cases is levorotatory (-) …

Phantom atoms are less worth than real atoms but more worth than real atoms with lower atomic number.

2022年7月26日 · Rule 3: Atoms participating in a double or triple bond are considered to be bonded to an equivalent number of similar “phantom” atoms by single bonds. • That is, atoms of the double bond are duplicated, and atoms of a triple bond are triplicated.