Chapter 16 - Organic Synthesis Flashcards
Practical techniques in organic chemistry, Synthetic routes.
What equipment is necessary to heat under reflux?
Pear shaped flask Condenser Rubber tubing Stand and clamp Heat source (bunsen burner, tripod and gauze OR heating mantle)
Which method of heating is used when heating flammable liquids?
Heating mantle so there is no naked flame.
What is the purpose of heating under reflux?
Enables a liquid to be continually boiled whilst the reaction takes place. Prevents volatile components from escaping and the flask from boiling dry.
What is the equipment necessary for distillation?
Pear shaped flask Condenser Rubber tubing Heat source Stand and clamp Screw cap adaptor Receiver adaptor Still head Thermometer
What is the purpose of distillation?
Separate a pure liquid from its impurities.
How is an organic product purified?
Ensure the tap of the separating funnel is closed,
Pour the mixture of liquids, place a stopper in the top and invert to mix,
Allow the layers to settle.
Add some water to see which layer will increase in volume (aqueous layer)
Place a conical flask undeneath, remove the stopper and open the tap until the lower layer has left.
Place a second flask underneath to collect the organic layer
How can acid impurities be removed?
Adding aqueous sodium carbonate and shaking the mixture in the seperating funnel.
Carbon dioxide gas is made and must be released via the tap (funnel upside down).
Aqueous sodium carbonate layer is then removed and organic layer washed with water.
How can water be removed from organic products?
A drying agent is added (typically an anhydrous inorganic salt) and then mixed,
Place a stopper on the flask,
Leave for ten minutes,
Add more until some solid is dispersed as a fine powder,
Decant liquid into another flask.
What is a target molecule?
The compound that is being prepared by organic synthesis.
How would an aldehyde be formed from a halogenoalkane?
Stage 1: Add NaOH under reflux to form an alcohol
Stage 2: Oxidise with acidified potassium dichromate under gentle heat and distill off
How would a ketone be formed from an alkene?
Stage 1: Add steam with acid catalyst to form an alcohol
Stage 2: Oxidise with acidified potassium dichromate under reflux
What is ozonolysis?
A technique used to break open a C=C double bond. Useful for the preparation of aldehydes and ketones.
