4.2.3 - organic synthesis

Cards (12)

  • In distillation, a continuous water flow is needed so the water remains cool in order for the mixture to be distilled.
  • To separate immiscible liquids:
    • Pour mixture into separating funnel, and distilled water
    • add stopper and invert the flask
    • equalise the pressure by opening the stopper
    • continue shaking until there is no ‘whistle’ sound
    • open the stopper and place a beaker under the spout
    • use another beaker to collect desired organic layer
    • shake liquid with drying agent
  • Two drying agents are:
    magnesium sulfate
    calcium chloride
  • To use drying agents you add it to the organic product. Add some more until the clumps are moving freely. Use filtration to collect the dry product.
  • Re-distillation is when a liquid is purified by using multiple distillations.
  • Unsaturated hydrocarbons can be tested using bromine water.
    Add a few drops to the sample, positive result shows colour change from brown to colourless.
  • to test for haloalkanes add silver nitrate, ethanol and water. observe:
    Chloro - white precipitate
    bromo - cream precipitate
    iodo - yellow precipitate
  • 3 reagents used to test for carbonyls are
    acidified potassium dichromate
    fehlings solution
    tollens reagent
  • When acidified potassium dichromate is added to ketones there is no change. But when it is added to aldehydes it turns from orange to green colour.
  • When feelings solution is reacted with ketones there is no change. But when it is reacted with aldehydes it forms a dark red precipitate.
  • When tollens reagent is reacted with ketones no silver mirror is formed. When it is reacted with aldehydes it forms a silver mirror.
  • To test for a carboxylic acid.
    Universal indicator gives the ph of a weak acid
    reactive metal gives hydrogen effervescence
    metal carbonate gives carbon dioxide effervescence