⚗️ Stereochemistry
CORN rule or Steering wheel method for R/S
R/S Configuration
Assign priorities 1-4 by atomic number. Place lowest priority (4) away from you. If 1→2→3 goes clockwise = R (like Right). Counterclockwise = S. Memory: R = Rotate Right = Clockwise.
⚗️ Stereochemistry
Enantiomers = mirror images, Diastereomers = not mirror images
Enantiomers vs Diastereomers
Enantiomers: non-superimposable mirror images — same physical properties except optical rotation. Diastereomers: stereoisomers that are NOT mirror images — different physical properties.
⚗️ Stereochemistry
'Meso = mirror image is superimposable — internal plane of symmetry'
Meso Compounds
A meso compound has chiral centers but an internal plane of symmetry making it achiral overall. It is its own mirror image. Example: meso-tartaric acid.
⚗️ Stereochemistry
(+) = dextrorotatory, (-) = levorotatory
Optical Activity
Enantiomers rotate plane-polarized light equally but in opposite directions. (+) or d = clockwise rotation. (-) or l = counterclockwise. A racemic mixture (50/50) = zero net rotation.
⚗️ Stereochemistry
Max stereoisomers = 2^n where n = chiral centers
Counting Stereoisomers
For n chiral centers, maximum possible stereoisomers = 2ⁿ. Meso compounds reduce this number. Always check for internal symmetry before applying 2ⁿ rule.