RP10 Preparation of organic solids and liquids

Question 1

Main steps in producing pure organic solid

Answer 1

1. Synthesis of compound usually reflux, distillation
2. Filtration usually vacuum filtration
3. Purification recrystallisation

Question 2

Why is heating under reflux used

Answer 2

Allows heating for long period of time
Prevents flask from boiling dry
Prevents volatile reactants escaping
Ensures even heating

Question 3

How to filter under reduced pressure

Answer 3

Using a buchner funnel and buchner flask, connected by rubber tubing to vacuum source

Funnel contains a layer of filter paper
Pour the substance onto the filter paper and the liquid will be sucked through via vacuum filtration into the flask
Solid will remain on paper

Question 4

How do you purify a solid product

Answer 4

Recrystallisation
Add minimum amount of warm solvent to impure sample until dissolved
Allow to cool, crystals should form
When no more form you can filter under reduced pressure to obtain a dry crystalline solid

Question 5

How do you purify a liquid organic product

Answer 5

Use separating funnel to isolate organic layer from aq layer
Add anhydrous MgSO4 to organic product to get rid of all the water
Purify by distillation, separates substances by boiling point