Stereoisomers and Chirality

What is a chiral molecule? (3 bullet points)

• A molecule that is non-superimposable on its mirror stage.

• Aka “handedness“

• Lacks an internal plane of symmetry

What is a chiral center? (2 bullet points)

• A center atom (usually C) bonding to four different substituents.

• One single chiral center = considered chiral

What are enantiomers? (2 bullet points)

• A pair of stereoisomers that are non--superimposable mirror images of each other.

• Identical bp and mp, EXCEPT the direction in which they rotate 180 degrees

What is achiral molecule? (3 bullet points)

• A molecule that is non-superimposable on its mirror stage.

• Has a plane of symmetry

• A C atom containing two or more identical substituents = achiral and cannot be a chiral center.

First step of the Cahn-Ingold-Prelog (CIP) systems for assigning configuration to a chiral center. (3 bullet points)

• Assigning priorities (1-4)

• Priority is based on atomic number of the atom bonded to the center.

• Higher atomic number = higher priority (1 > 2 >3 > 4)

How to determine if a chiral center is R or S? (4 bullet points)

• Cross the 4th prioritized substituent

• Trace the path from 1 to 3

• Curves to the right = R (Rectus)

• Curves to the left = S (Sinister)