ch 16 organic synthesis

Question 2

condesner

Answer 2

(Liebig)
Condenser

Question 3

Heating mantle

Answer 3

• safer when working with flamables

Question 4

Separating
funnel

Answer 4

can be tapped off

Question 5

boss

Answer 5

thing that secures the clamp to a clamp stand

Question 6

Receiver

Answer 6

– used to accurately
deliver the distillate to a
collection vessel.

Question 7

(Liebig) condenser

Answer 7

(water in at the
bottom, out at the
top)

Question 8

Still head

Answer 8

(connects the
condenser to the
round-bottom flask – allows
for a thermometer to be
attached)

Question 9

Why heat under reflux?

Answer 9

At room temperature many organic reactions are slow. To speed these reactions up, and
to ensure the reactants can overcome the high activation energy the reaction is heated.

It is used so as the solvent, in which the organic reaction is taking place, the reactants
and any products are not boiled off.

Question 10

Set-up for reflux:

Answer 10

Round-bottom/pear-shaped flask

(Liebig) condenser)

Rubber tubing (one connected from tap to the
bottom of the condenser, one connected from
the top and finishing in the sink)

Stand and clamp

Heat source (bunsen/tripod/gauze or heating
mantle)

Question 11

Points to remember when completing heating under reflux:

Answer 11

Heating:

→ if a reaction can be done below 100oC a
water bath is used.

→ Flammable liquids can be kept away
from naked flames by used the heating
mantle.

Anti-bumping granules: Anti-bumping granules are
added to the reaction mixture to promote smooth
boiling.

Grease: apply a thin layer of grease to the
‘ground-glass’ joint on the condenser (where the two
pieces of glassware meet). Place condenser into the
flask and rotate slightly. This allows for the seal to be
airtight (and ensure they come apart easily).

Clamping of condenser: Condenser is kept in the
upright position

Question 12

Distillation is a common method of

Answer 12

separating a pure liquid from any impurities.

Question 13

Many organic compounds are oily and therefore immiscible in water (N.B.– short
chain alcohols are miscible due to hydrogen bonding with water)

Answer 13

The organic compound will often float on the water as it is less dense and can be
separated from the water. To confirm which layer is which, add a few drops of water
to the mixture. Whichever layer gets bigger is the aqueous layer.

Question 14

Drying agents

Answer 14

Inorganic salts such as magnesium sulfate (MgSO4), calcium sulfate and
calcium chloride (CaCl2) absorb water to become hydrated.

Question 15

Procedure for drying an organic product:

Answer 15

• Place the organic layer into a conical flask, and add your drying agent.

Swirl gently, stopper and leave for 10 minutes.

If the drying agent clumps together, add more. Add until the solid drying agent
resembles a fine powder.

Filter to leave a clear organic layer.