3.3.7.1 optical isomers

• what is optical isomerism?

  type of stereoisomerism when molecules have the same molecular formula but a different spatial arrangement of atoms in space
• when does optical isomerism occur?

  when there is an asymmetrical carbon within an organic molecule known as the chiral centre
• chiral centres


  a carbon atom with 4 different groups bonded around it so there is no line of symmetry to the molecule
• what does the presence of a chiral centre lead to?

  the presence of 2 possible isomers that are mirror images of each other - these are optical isomers
• optical isomers

  
• what are enantiomers?


  two different isomers and are unique due to their effect on plane polarised light
• what does each enantiomer cause?

  the rotation of plane polarised light by 90 degrees in opposite directions
• formation of enantiomers

  
• how is a racemate formed?

  when optical isomers are produced as a pair of enantiomers in a 1:1 ratio
• what does the optical rotational effect on polarised light caused by each enantiomer cause?

  the overall effect to be zero as the opposite directions of rotation cancel out
• have happens to the mixture?

  the mixture produced is optically inactive - a racemic mixture
• nucleophilic addition mechanism