4.2.3 Organic synthesis

• round-bottom / pear-shaped flask • receiver • screw-tap adaptor • condenser • still head

• reaction mixture + anti-bumping granules added to flask • apply grease (vaseline) to joint of condenser + put into flask > condenser in upright poistion > water out at top + water in at bottom • condenser clamped loosely to clamp stand • flask heated

• so contents boil smoothly

• prevents volatile components from escaping + flask from boiling dry

• vapour from mixture rises up inner tube of condenser until it meets outer jacket containing cold water • vapour condenses + drips back into flask

• you make a close system + pressure will build up ad heated air expands > can lead to apparatus exploding

• separating a pure liquid from its impurities

• flask clamped by neck > still head attached to flask (T shaped + has 2 ground-glass joints) > condenser attached to still head adaptor + screw cap adaptor (with thermometer) • second clamp around receiver adaptor which attached to condenser • water enters at lower end + leavs at top • flask used to collect distillate • flask heated

• diff liquids in mixture have diff bp > liquid with lowest bp is most volatile + boils first • vapour moves out flask + reaches cold condenser, condenses + becomes liquid > liquid drips into collecting flask

• bunsen burner • water bath (less than 100) • heating mantle for flammable liquids

• pour mixture of liquids into separating funnel • tap is closed + invert to mix contents • allow layers to settle • place conical flask under separating tunnel, remove stopper, open tap, until whole of lower layer has left funnel

• add aqueous sodium carbonate + shake mixture in separating funnel > any acid present will react with sodium carbonate releasing CO2 gas

• add drying agent > anhydrous inorganic salt that readily takes up water to become hydrated

• anhydrous magnesium sulfate (Mg SO4): general drying • anhydrous calcium chloride (CaCl2): drying hydrocarbons

• add drying agent to liquid + swirl to mix contents • add stopper to prevent evaporation of products + leave for 10 mins • if solid stuck together in lump, there is still water present > add more drying agent until some solid is dispersed in the solution as fine powder • pour liquid from solid in another flask + if liquid dry it should be clear

• the liquid should be clear

• if organic liquids have similiar bp then prepared sample may have impurities > distillation clean + dry + set up again so 2nd distillation is carried out > this time only collect product with bp of compound you are trying to make

• preparation of complex molecules from simple starting molecules

• compound that chemist is trying to prepare by organic synthesis

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

• halogen • UV light • free radical substitution

• hydrogen halide • room temp • electrophilic addition

• H2 • nickel catalyst • 150C • 5 atom • addition

• aqueous alkali (NaOH) • reflux • nucleophilic substitution