3.7 optical isomerism

• what is an unsymmetrical carbon?

  when there are 4 different groups attached to the carbon
• what are chiral molecules?

  any molecule that contains a chiral centre
• what is a chiral centre/ carbon?

  atom attached to 4 different groups
• what are enantiomers?

  mirror images of chiral molecules that are non-superimposable
• what are optical isomers?

  same structural formula but in 3d the atoms are arranged differently in space
• what is plane polarised light?

  light waves arranged in at the same angle
• what is a racemate or racemic mixture?

  when there is 50/50 of each optical enantiomer
• what kind of enantiomers do you find in nature?

  naturally occuring enantiomers have a chiral carbon and usually found as pure enantiomers
• what are the similiarities and differences of optical isomers?

  they have the same boiling point, melting point and react the same however the rotate plane polarised light in different directions
• how do enantiomers rotate plane polarised light?

  one enantiomer rotates it one direction and the other rotates it the opposite direction the same amount
• will a racemic mixture rotate plane polarised light?

  no
• how do racemates form?

  when a trigonal planar molecule or intermediate is attacked from either side , there is an equal chance of either enantiomer forming
• outline the nucleophilic addition reaction of aldehydes or ketones by HCN

  nucleophilic addition

  
• how else other than nucleophilic addition can a racemic mixture be forms?

  the electrophilic addition of unsymetrical alkenes
• what are two drugs known for their enantiomers?

  thaliomide (used in morning sickness pills) and ibuprofen