chapter 16 - organic synthesis

• heating under reflux is used to prepare an organic liquid without boiling off the solvent, reactants or products

  you need the following apparatus:

  • round bottom or pear shaped flask
  • condensor
  • rubber tubing
  • stand and clamp
  • heat source
• anti bumping granules ensure that there is a smooth boil, and the bubbles are not too large
• equipment for distillation

  • round bottom or pear shaped flask
  • condenser
  • rubber tubing
  • heat source
  • stand and clamp
  • screw cap adaptor
  • receiver adaptor
  • still head
  • thermometer
• How to use a separating funnel - identifying an organic layer

  1. Ensure the tap of the separating funnel is closed

  2. Pour the mixture of liquids into the separating funnel

  3. Place a stopper in the top of the funnel

  4. Invert to mix the contents

  5. Allow the layers to settle
• Identifying the aqueous layer

  Add some water to see which layer increases in volume - this is the aqueous
• Separating the organic and aqueous layers

  1. Place a conical flask under the separating funnel

  2. Remove the stopper and open the tap until the whole of the lower layer has left the funnel

  3. Place a second conical flask under the separating funnel to collect the other layer
• You will now have the conical flask with the organic layer, and one with the aqueous
• how to dry an organic product

  1. add the organic liquid to a conical flask
  2. using a spatula, add some of the drying agent to the liquid and gently swirl the contents to mix together
  3. place a stopper on the flask to prevent your product from evaporating away - leave for 10 mins
  4. if solid is clumped, water is still present, add more drying agent
  5. decant the liquid from the solid into another flask - should be clear
• to separate a product from impurities, distill again but with the boiling point of the compound you would like to collect
• target molecule is used to describe the compound that the chemist is attempting to prepare by organic synthesis
• to convert a molecule into the target molecule, you need to:

  • identify the functional groups in your starting and target molecules
  • identify the intermediate that links the starting and target molecules
  • state the reagents and conditions for each step