Optical isomers

• Name of mechanism with HCN

  Nucleophillic addition
• considering the nucleophilic addition mechanism, explain why the product formed has no effect on plane polarised light?


  1. formation of product

  • nucleophilic attack on trigonal planar carbonyl
  • H-/ CN- attack on both sides
  • Exists as 2 enantiomers (racemic mixture)
  • Optical isomers rotate equally in opposite direction on plane polarised light
  • Racemate cancel effect
• How can you distinguish between 2 enantiomers?


  Plane polarised light, each enantiomers equally rotate in opposite directions
• 2 optical isomers are enantiomers . They have similar chemical properties and physical properties
• How to distinguish between 2 enantiomers?

  Plane polarised light. Rotate in opposite directions equally
• Relationship between 2 chiral carbons with similar structural formula

  non super imposable mirror images
• Racemic / racemate 


  • mixture containing 50/50 mix of 2 enantiomers
• Racemate don't rotate by plane polarized light
• Formation of a racemate

  • trigonal planar group is attacked from both side by attacking species
  • there are equal chances of either enantiomers forming
  • exists as a racemate
  • No optical activity is seen
• Optical isomers affected by plane polarised light. Racemate doesn't