Organic synthesis

• Describe how a Quickfit apparatus is connected:

  • Grease the joints using some petroleum jelly on the inside of the joints before connecting the pieces together
• • In a distillation setup it is necessary to have a continuous water flow around the condenser so that the water remains cool in order for the mixture to be distilled
• Method to separate immiscible liquids:

  • Pour the mixture into a separating funnel and some distilled water
  • Add the stopper and invert the flask to mix the mixture
  • Equalise the pressure by opening the stopper as required
  • Continue shaking until there is no whistle sound
  • To collect the water in lower layer, open the stopper and place a beaker under the sprout
  • Use another beaker to collect the desired organic layer
  • Shake the liquid with some drying agent
• • Magnesium sulphate and calcium chloride are both drying agents
• Using drying agents:

  • Add a selected drying agent to the organic product
  • If the drying agent forms clumps add some more until they are moving freely
  • Use gravity filtration to collect the dry product
  • Filtrate is the product
• Redistillation --> when a liquid is purified by using multiple distillations to separate the solvent from the solute
• Testing of hydrocarbons:

  • Use bromine water
  • Add a few drops of bromine water to the sample and mix well
  • Positive test - bromine water turns colourless
• Testing haloalkanes:

  • Reagents - silver nitrate, ethanol and water
  • Observations - chloro- : white precipitate
  • Bromo -: cream precipitate
  • Iodo -: yellow precipitate
• Reagents used to test carbonyls:

  • Acidified potassium dichromate
  • Fehlings's solution
  • Tollens' reagent
• Reaction of acidified potassium dichromate with ketones & aldehydes:

  • Ketones - no change
  • Aldehydes - turns from orange to green colour
• Reaction of Fehling's solution with ketones & aldehydes:

  • Ketones - no change
  • Aldehydes - dark red precipitate
• Reaction of Tollen's reagent with ketone & aldehydes:

  • Ketones - no silver mirror
  • Aldehydes - silver mirror
• Testing for carboxylic acid:

  • Universal indicator - pH of weak acid
  • Reactive metal - hydrogen effervescence
  • Metal carbonate - carbon dioxide effervescence
• Acidified potassium dichromate


  A common laboratory reagent used as an oxidizing agent
• Ketones

  Organic compound that contains a carbonyl group (C=O) bonded to two carbon atoms, and does not undergo oxidation easily
• Aldehydes

  Organic compound that contains a carbonyl group (C=O) bonded to one carbon atom and one hydrogen atom, and undergoes oxidation to a carboxylic acid group
• Oxidation


  The loss of electrons from a molecule, resulting in a more positive oxidation state