Organic synthesis

• Describe how a Quickfit apparatus is connected:

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

  • Pour the mixture into a separating funnel with distilled water
  • Add the stopper and invert the flask to mix the mixture
  • Equalize pressure by opening the stopper as required
  • Continue shaking until no ‘whistle’ sound
  • To collect the water in the lower layer, open the stopper and place a beaker under the spout
  • Use another beaker to collect the desired organic layer
  • Shake the liquid with a drying agent
• Drying agents:

  • Magnesium sulphate
  • Calcium chloride
• How to use drying agents:

  • Add a selected drying agent to the organic product
  • If clumps form, add more until they move freely
  • Use gravity filtration to collect the dry product
  • Filtrate is the product
• Re-distillation means purifying a liquid by using multiple distillations
• To test unsaturated hydrocarbons, use bromine water:

  • Add a few drops to the sample and mix well
  • Positive test: bromine water turns colorless
• Reagents to test haloalkanes and observations:

  • Reagents: silver nitrate, ethanol, water
  • Observations: chloro- : white precipitate, bromo- : cream precipitate, iodo- : yellow precipitate
• Reagents to test carbonyls:

  • Acidified potassium dichromate
  • Fehling’s solution
  • Tollens’ reagent
• Observations when acidified potassium dichromate reacts with ketones and aldehydes:

  • Ketones: no change
  • Aldehydes: orange to green color
• Observations when Fehling’s solution reacts with ketones and aldehydes:

  • Ketones: no change
  • Aldehydes: dark red precipitate
• Observations when Tollens’ reagent reacts with ketones and aldehydes:

  • Ketones: no silver mirror
  • Aldehydes: silver mirror
• Reagents to test carboxylic acid and corresponding observations:

  • Universal indicator: pH of weak acid
  • Reactive metal: hydrogen effervescence
  • Metal carbonate: carbon dioxide effervescence