A Level Chemistry (AS Unit 2) notes including definitions and descriptions of the 3 types of structural isomerism as well as notes on geometric isomerism ( both cis-trans and E-Z)
This is portion of Bangalore university III B.Sc P-5 organic chemistry. The chapter name is Stereo isomerism. In this chapter Elements of symmetry: (Plane of symmetry: 2, 3-dichrolobutane, tartaric acid; Center of symmetry: trans-2, 4-dimethyl-trans-1, 3-cyclobutanedioic acid; Axis of symmetry: 1, 2, 3, 4-tetramethylcyclobutane).
Chiral molecules and achiral molecules (2-chloropropanol, 3-chloropentane).
Chirality, stereogenic center (lactic acid, tartaric acid and 2, 3-dichlorobutane).
Fischer projection formulae (lactic acid, 2-chlorobutane, tartaric acid and 2, 3-dichlorobutane).
Optical isomerism due to free rotation about single bonds: Enantiomers, optical activity (conditions for optically active compounds); absolute configuration of enantiomers (use of /–,d/l, D/L notations ( Glyceraldehyde and lactic acid).Cahn-Ingold-Prelog sequence rules (R and S system) of nomenclature with suitable examples. Properties of enantiomers.
Meso compounds: Explanation with examples of tartaric acid and 2, 3-dichlorobutane.
Diastereomers: Explanation with examples of tartaric acid 2-bromo-3-chlorobutane and properties. Relative configuration of threo and erythro nomenclature (using above examples).
Racemisation: Definition and explanation using lactic acid as an example.
Resolution of racemic mixture: Definition, explanation of resolution of racemic mixture of tartaric acid by chemical method and biochemical method.
Optical isomerism due to restricted rotation about single bonds- diphenyl systems: Explanation using 6, 6’-dinitrodiphenic acid as an example.
Geometric isomerism in alkenes: Definition, conditions and explanation using 2-butene and 1, 2-dichloroethene as examples.
Determination of configuration of geometric isomers: Cis and trans by (i) Physical methods(melting and boiling points, dipole moments, solubility) (ii)Spectroscopic methods(UV, IR evidences) (iii)chemical methods (cyclisation method: Ex-maleic acid to maleic anhydride, pKa values: Ex-maleic and fumaric acids). E and Z system of nomenclature (rules with suitable examples).
Geometric isomerism in oximes: Nomenclature of syn and anti isomers in oximes using benzaldoxime and acetophenone oxime as examples.
Alicyclic compounds: Conformations of four to eight membered cycloalkanes and disubstituted cyclohexanes (1, 2- , 1, 3- and 1, 4- dimethylcyclohexanes as examples).
Bicylic systems: Cis and trans- nomenclature and conformations of decalins and norbornane.