Module 4: Organic Synthesis IPS (4.2.3)

Question 1

Heating Under Reflux Apparatus

Answer 1

Liquid continually boiled whilst reaction takes place.

1. Pear shaped flask
2. Condenser
3. Rubber Tubing
4. Clamp and stand
5. Tripod, gauze and Bunsen burner

Question 2

Method to heat under reflux

Answer 2

1. Clamp flask by neck
2. Add reaction mixture and anti bumping granules to prevent forming large bubbles
3. Apply thin layer of grease to round glass joint on condenser
4. Place condenser onto flask and rotate back and forth to ensure good seal
5. Keep condenser upright and clamp loosely
6. No stopper on condenser as pressure will build from hot air expansion.
7. Rubber tubing connects condenser to tap and outlet to sink

Question 3

Distillation Apparatus

Answer 3

• Separate pure liquid from its impurities.
• Different liquids have different boiling points.
• Lowest and most volatile will boil first.
  1. Round bottom flask
  2. Condenser
  3. Rubber tubing
  4. Screw cap adaptor
  5. Receiver adaptor
  6. Still head
  7. Thermometer
  8. Clamp and stand
  9. Tripod, gauze and Bunsen burner

Question 4

Method to Distil

Answer 4

1. Clamp flask by neck and connect sill head to flask
2. Grease both joints of still head and connect condenser and screw cap adaptor
3. Clamp receiver adaptor and connect to condenser
4. Rubber tubing connects condenser to tap and outlet to sink
5. Collecting flask at end of receiver to collect distillate so distillation apparatus is not completely air tight.

Question 5

Purification of Organic Compounds

Answer 5

1. Ensure tap of separating funnel is closed
2. Pour mixture of liquids into separating funnel, place stopper and invert to mix contents
3. Allow layers to settle
4. Add water to see which layer increases volume; aqueous layer
5. Place conical flask under separating funnel, remove stopper and open tap until lower layer has left funnel.
6. Place 2nd conical flash under funnel to collect other layer

Question 6

Drying organic product

Answer 6

Drying agent is anhydrous inorganic salt which readily takes up water to become hydrated.
CaCl₂, CaSO₄, MgSO₄
1. Add organic liquid to conical flask
2. Add drying agent using spatula and swirl contents
3. Place stopper to prevent evaporation and leave 10 minutes
4. Solid stuck together = water present, add more drying agent until some solid is dispersed as a fine powder
5. Decant liquid from solution into another flask.
6. Colourless = dry

Question 7

Distillation

Answer 7

1. Distil a 2nd time

2. Only collect product with boiling point of desired compound