Organic Synthesis

Question 1

Outline Steps of preparation of an organic solid

Answer 1

• Filtration under reduced pressure
• recrystallisation
• Filtration under reduced pressure again
• Melting point determination to check purity

Question 2

Streps of filtration under reduced pressure

Answer 2

1. equipment (buchnerflask (side arm) funnel,filter paper,tap,tubing, filter pump)
2. Attach tubing to filter pump on water tap and other end to side arm of buchner flask with a tight fit
3. switch on tap check for suction over funnel w hand
4. wet filter paper w same solvent and place in funnel
5. Put in sample
6. Rinse formed crystals w more solvent then leave udner suctionto dry

Question 3

Steps of recrystallisation

Answer 3

Purpose to remove impurities from filtered solid

1. use water bath warm solvent in conical flask
2. put inpure sample in beaker
3. slowly add solvent until sample dissolves so minimum volume is added
4. Allow to cool then filter under reduced pressure again to obtain dry crystals

Question 4

Steps of melting point determination

Answer 4

1. make sure sample is dry and free flowing
2. hold one end of capillary tube over bunsen to seal then cool
3. add 3mm of crystals
4. place in electrically heated melting point apparatus
5. Recording melting point so u know approximate
6. New sample and very slowly heat just before melting point to obtain an accurate reading
7. compare to data

Question 5

How to melting points of pure solids compare to impure solids?

Answer 5

• pure solids have a very sharp range 1-2 degree , impure is wider
• impures have a lower melting point

Question 6

Steps to prepare an organic liquid?

Answer 6

Heating under reflux
Or
Distillation

Question 7

Steps for heating under reflux

Answer 7

1. Equipment (round flask,condenser,tubing,stand and clamp,bunsen

Question 8

Steps for distillation?

Answer 8

1. Equipment (round flask.condneser,tubing,stand and clamp,still head,thermometer, beaker)

Question 9

What do amri bumping granules do?

Answer 9

Ensure liquid boils smoothly, stops big bubbles

Question 10

How to use seperating funnel.

Answer 10

1. Put in a seperating funnel and invert to mix then allow to settle
2. Add water to see which imcreases in volume (aqueous layer)
3. open tap to remove lower layer into conical flask
4. collect organic layer

Question 11

How to rid acid impurities in organic liquid?

Answer 11

Add NaCO3 to seperating funnel and shake
Turn upside down and Slowly open tap to allow CO2 to escape
Release NaCO3 layer

Question 12

How to dry the organic product

Answer 12

1. Add drying agent such as CaCl2 to liquid in conical flask
2. add stopper and swirl
3. Keep adding until it stops clumping

Question 13

Steps of purifying an organic product

Answer 13

1. Seperating funnel
2. add drying agent
3. Distillation