Module 4.2.3- Organic synthesis

• Quickfit apparatus required for reflux


  Round-bottomed/ pear-shaped flask

  condenser

  rubber tubing

  stand and clamp

  heat source

  
• What apparatus can be used when heating flammable liquids to ensure safety


  heating mantle (so no naked flame is present)
• Anti-bumping granules


  added to the liquid so the contents would boil smoothly
• Heating under reflux apparatus


  water OUT on top

  water IN on bottom

  
• Quickfit apparatus required for distillation


  Round bottom flask

  condenser

  rubber tubing

  heat source

  stand and clamp

  screw cap adaptor

  receiver adaptor

  still head

  thermometer

  
• Apparatus set-up for distillation


  water OUT (closest to pear/round flask) water IN (closer to beaker)

  
• How to distinguish between an aqueous layer and an organic layer


  Add water and the layer that increases in volume is the aqueous layer
• Purifying organic products


  A separating funnel is used

  Allowing layers to settle in funnel

  Place a flask under the funnel and open the tap until the lower layer has left the funnel.

  Collect the other layer in another flask
• How would you remove any acid impurities if present in the separating funnel


  Add aqueous sodium carbonate and shake acid reacts with the sodium carbonate releasing CO2 gas in the separating funnel

  slowly open the tap, whilst funnel is upside down to prevent gas buildup and so it can escape

  remove aqueous sodium carbonate layer into another flask aswell as organic layer
• Drying the organic product


  Any water left after using a separating funnel then it is removed using a drying agent such as an anhydrous salt e.g. MgSO4 or CaCl2 Swirl contents together.

  Place stopper to prevent evaporation.

  Add drying agent until solid is dispersed in solution as fine powder.

  Decant the liquid from the solid into another flask.
• Examples of an anhydrous salt


  Anhydrous MgSO4 Anhydrous CaSO4 Anhydrous CaCl2
• Redistillation


  Purification of the product by distilling close to the desired product's boiling point
• Purifying an organic liquid summary


  Use separating funnel

  Collect organic liquid

  Add aqueous sodium carbonate (if acid present)

  Filter again

  Add anhydrous salt

  Decant liquid from solid

  Redistill

  Collect product
• Organic synthesis


  The process of making organic compounds from simpler starting materials
• Identifying functional groups in organic molecules

  
• Target molecule


  The compound that the chemist is attempting to prepare by organic synthesis
• Synthesis of propanal


  haloalkane -> INTERMEDIATE -> aldehyde

  think about what products can form an aldehyde such as a primary alcohol now think about the process of going from haloalkane to primary alcohol

  hydrolysis of haloalkane using NaOH under reflux

  then potassium (VI) dichromate and sulfuric acid distilling the product