Some molecules have multiple 'chiral carbons
' where each chiral carbon
can exist in one of two configurations - thus there are multiple possible permutations.
For the second edition, Rao (former CEO of Chiral Carbon
Consultants in India) has revised the text and added two new indexes, on reaction type and reagents.
Next, tocopherols do have stereoisomers, which have the same molecular formula but differ configurationally based on the direction of the methyl groups at chiral carbon
atoms, the isomers are designated 2R, 4'R, 8'R; 2S, 4'R, 8'R; 2RS, 4'R, 8'R; 2R, 4'RS, 8'RS; 2S, 4'RS, 8'RS and rotate polarized light to varying degrees.
These pendant groups are located on a chiral carbon
and are always in the same stereo configuration, which implies the polymer is isotaetic and is therefore capable of crystallizing.
The Early History of Stereochemistry: From the Discovery of Molecular Asymmetry and the First Resolution of a Racemate by Pasteur to the Asymmetrical Chiral Carbon
of Van't Hoff and Le Bel.
Methylphenidate  contains two chiral carbons
, and so exists in four enantiomeric forms.
By convention the enantiomers with opposite stereochemistry around the chiral centres are designated ephedrine, while pseudoephedrine has same stereochemistry around the chiral carbons
Eribulin is the state of the art in modern synthetic chemistry, which has 826 of molecular weight, 62 steps of total synthetic route and 19 chiral carbons