Organic synthesis

Question 1

What is Quickfit apparatus? (2 points).

Answer 1

1. Apparatus designed to fit together and provide a good seal.
2. Each joint is thinly layered in grease to allow a good fit but ensures the equipment comes apart easily afterwards.

Question 2

Definition of reflux (3 points).

Answer 2

1. Continuous evaporation and condensation.
2. Heating under reflux enables a liquid to be continuously boiled whilst the reaction takes place.
3. This prevents components from escaping the flask from boiling dry.

Question 3

Why are anti-bumping granules added?

Answer 3

To ensure the boiling is smooth.

Question 4

Draw a labelled diagram of quick-fit apparatus for a reflux experiment

Answer 4

*Refer to organic synsthesis notes

Question 5

Why is water going into the condensor at the bottom?

Answer 5

For more efficient cooling.

Question 6

Definition of distillation

Answer 6

A method used to separate a pure liquid from impurities.

Question 7

Draw a labelled diagram for a distillation experiment

Answer 7

*Refer to organic synsthesis notes

Question 8

What is the separated liquid in distillation called?

Answer 8

The distillate

Question 9

What are the 3 steps for the preparation and purification of an organic liquid?

Answer 9

1. Use of a separating funnel.
2. Drying with an anhydrous salt.
3. Redistillation.

Question 10

What are the two layers seen when preparing an organic liquid?

Answer 10

Organic and a water layer.

Question 11

What peice of equipment is used to separate the two layers?

Answer 11

A separting funnel

Question 12

Describe how to separate the organic and water layer (3 points).

Answer 12

1. To confirm which layer is which, add distilled water and observe which layer gets bigger.
2. Once the layers are separate, place a beaker or conical flask under the tap of the funnel and open the tap to allow the bottom layer to run out.
3. Use a separate beaker to collect the other layer in the same way. (The densities of the liquids will depend which layer is at the bottom).

Question 13

Describe how to clean the product by removing any acid (4 points).

Answer 13

1. Place the organic layer back into the separating funnel and add aqueous sodium carbonate solution to neutralise any acid present.
2. Place the stopper in the neck of the funnel and shake to mix the aqueous and organic layers.
3. The stopper needs to be released frequently as gas (carbon dioxide) is being produced, so the pressure needs to be released.
4. Clamp the funnel in an upright position and leave the liquids to separate. Run off the organic layer as before.

Question 14

Defintion of a drying agent

Answer 14

An anhydrous inorganic salt that readily takes up water to become hydrated.

Question 15

What are the 3 examples of drying agents?

Answer 15

1. Anhydrous calcium chloride (CaCl2).
2. Anhydrous calcium sulfate (CaSO4).
3. Anhydrous magnesium sulfate (MgSO4).

Question 16

Describe how to dry the product (6 points).

Answer 16

1. Using a spatula, add some of the drying agent to the organic liquid in the beaker.
2. Mix the contents and cover the beaker if the liquid is volatile.
3. Leave for about 10 minutes.
4. If the solid has formed into a lump, there is still some water present, so add more solid and mix again.
5. Do this until some solid remains as powder.
6. The solid could be removed once drying has taken place by filtration.

Question 17

Describe how the product would be re-distilled (5 points).

Answer 17

1. The product may need to be distilled again as organic liquids sometimes have similiar boiling points.
2. The distillation apparatus is cleaned, dried and set up as before.
3. During the distillation, only the target product is collected.
4. To ensure this, only collect the product using the boiling point of the desired product.
5. The narrower the boiling point range, the purer the product.

Question 18

EXAM: Describe the preparation and purification of organic liquids

Answer 18

1. Separate the two layers
   Use a separating funnel.
   Two layers: organic and aqueous.
   Look out for densities; lower density is upper layer and higher density will sink, so is the lower layer. If necessary- remove any acid.
   Add aqueous sodium carbonate.
   Open stopper frequently to avoid build up of pressure- build up of gas (CO2(g)).
2. Add a drying agent.
   Anhydrous: HAVE TO NAME.
   Remove by filtration.
3. Distillation.
   To separate organic product.
   Only collect liquid at a temperature of biling point of desired product.

Question 19

Definition of organic synthesis

Answer 19

The preparation of complex molecules from simple starting materials.

Question 20

Definition of target molecule

Answer 20

Describes the compound that the chemist is attempting to prepare by organic synthesis.