Chapter 16 organic synthesis

Question 1

Heating under reflux equipment

Answer 1

Round-bottom or pear-shaped flask
condenser
rubber tubing
stand and clamp
heat source

• heat allows reaction under reflux to be carried out at fixed temperature
  ( heat mantle when heating flammable liquids)

Question 2

Heating under reflux setting up

Answer 2

• flask is clamped by its neck (add reaction mixture and anti-bumping granules before fitting to condenser
  –> makes boiling smoother ( if not used, bubbles form and glassware vibrates or jumps violently)

–> thin layer of grease to ground-glass joint on condenser

–> liebig condenser: water in at bottom tube/ water out at top

Question 3

Distillation equipment

Answer 3

round-bottom or pear shaped flask
condenser
rubber tubing
heat source
stand and clamp
screw-cap adaptor
receiver adaptor
still head
thermometer

Question 4

Distillation set up

Answer 4

flask clamped by neck and still head (T shaped and two ground glass joints) connected to flask
–> second clamp is placed around receiver adaptor and condenser is fitted between tightly
water in from tube AWAY from heat/ water out from tube CLOSE to heat

–> thermometer is set up close to intersection of still head and condenser

Question 5

Purifying organic compound

Answer 5

1. ensure tap of separating funnel is closed
2. pour mixture of liquids into separating funnel, place a stopper in top of funnel and invert to mix contents
3. allow laters to settle
4. Add some water to see which layer increases in volume (aqueous layer)
5. Place conical flask under funnel and remove stopper. Open tap until whole lower layer has left tunnel
6. Place second conical flask to collect other layer

Question 6

Drying organic product

Answer 6

Traces of water can be removed with drying agents e.g. anhydrous inorganic salt

1. Add organic liquid to conical flask
2. Using spatula add some drying agent and gently swirl together
3. Place stopper on flask to prevent product from evaporating. Leave for 10 mins
4. If solid has stuck together in lump, add more drying agent till some solid is dispersed as fine power
5. Decant liquid from solid into another flask (if liquid is dry, it should be clear)

Then redistill the solution

Question 7

Organic synthesis

Answer 7

preparation of complex molecules from simple starting materials

Question 8

Predicting properties and reactions

Answer 8

After identifying functional groups of a compound, you can predict properties and reactions

e.g. if it is an alkene, it can form an alkane/ haloalkane/ alcohol
AND if it is a primary alcohol, it can form an alkene, haloalkane, aldehyde or carboxylic acid

Question 9

Target molecule

Answer 9

compound chemists are trying to prepare via organic synthesis