organic synthesis

Question 1

heating under reflux

Answer 1

• used to prepare an organic liwuid without boiling off the solvent, reactants or products
• leibig condenser
• round bottom or pear-shaped flask
• rubber tubing
• stand and clamp
• heat source
• add anti-bumping granules to the liquid so contents will boil smoothly. If granules arent used, large bubbles will from at the bottom of the liquid and make the glasswear vibrate or jump violently
• apply a thin layer of grease to the ground-glass joint on the condenser
• no stopper on the condenser otherwise pressure will build and apparatus will explode

Question 2

distillation

Answer 2

-seperate a pure liquid from impurities
* round bottom or pear shaped flask
* condenser
* rubber tubing
* heat source
* stand and clamp
* screw-cap adaptor
* still head
* thermometer

Question 3

purifying organic products

Answer 3

• to identify the organic layer add water to your mixture and the layer that gets bigger is the aquous layer
• add to seperating funnel and place a stopper at the top of the funnel and invert to mix the contents
• allow the layers to settle
• place a clonical flask under the separating funnel and remove the stopper, open the tap until the whole lower layer has left the funnel
• collect other layer in seperate clonical flask
• in preperation using acids, impure product may contain acid impurities, Add aqueous sodium carbonate and shake the mixture in the seperating funnel to remove these
• any acid present will react with sodium carbonate releasing C02. The tap needs to be slowly opened, holding the stoppered seperating funnel upside down to release any gas pressure that may build up

Question 4

drying the organic product

Answer 4

• may be some water left in organic product. These are removed by adding a drying agent to the organic liquid. Common ones are anhydrous calcium sulfate and anhydrous magnesium sulfate
• add organic layer to a clonical flask
• add some drying agent and gently swirl
• place a stopper on the flask to prevent the product from evapourating away and leave for 20 mins
• if solid has all stuck together in a lump, still some water present. Add more drying agent until some solid is dispered in solution as a fine powder
• decant tje liquid from the solid into another flask. If liquid is dry should be clear

Question 5

redystillation

Answer 5

-sometimes organic liquids have boiling points relatively close together so prepared sample may still contain some organic impurities
- distillation apparatus is cleaned and dried and set up again so that distillation can be carried out again. This time only collect the product with the boiling point of the compound you are trying to make. The narrower the boiling range, the purer the product. Now have seperated product from any impurities