6 - Organic synthesis practical techniques

Question 1

How Is a pure organic solid made?

Answer 1

1. Reagents in round bottom / pear shape flask with anti-bumping granules
2. Reflux
3. Filter impure product using a vacuum, place in conical flask
4. Recrystallise to remove impurities - add minimum amount of cold solvent, heat slowly until compound dissolves, allow to cool until product crystallises out
5. Vacuum filter pure product, wash with a little ice cold water
6. Purified product in oven to dry
7. Find melting point and compare to data base - the more impurities, the lower the melting point

Question 2

How is a pure organic liquid made? e.g. ester

Answer 2

1. Reagents in round bottom / pear shaped flask with antidumping pellets, reflux
2. Set up apparatus for distillation - ester will evaporate and condense into reaction vessel
3. Pour impure ester into separating funnel, add cold water, shake
4. More dense water layer with dissolved impurities forms under organic layer
5. Run off bottom aqueous layer
6. Add anhydrous calcium chloride into ester and shake to remove remaining water
7. further re-distillation