PAG 5 - Synthesis of an organic liquid Synthesis of a haloalkane

Question 1

What type of reaction occurs when a

haloalkane is formed from an alcohol?

Answer 1

Nucleophilic substitution

Question 2

Write the word and chemical equations
for the formation of
2-chloro-2-methylpropane from
2-methylpropan-2-ol

Answer 2

2-methylpropan-2-ol + hydrochloric acid → 2-chloro-2-methylpropane + water
CH3C(CH3)2OH + HCl → CH3C(CH3)2Cl + H2O

Question 3

What are the 3 main stages in the
synthesis of a haloalkane from an
alcohol?

Answer 3

1. Preparation
2. Separation
3. Distillation

Question 4

Why do 2 layers form in the separating
funnel when synthesising a haloalkane
from an alcohol?

Answer 4

The aqueous and organic layers have
different densities and they are
immiscible

Question 5

What is the purpose of anti-bumping

granules?

Answer 5

To prevent the formation of large gas bubbles that
cause violent boiling.
During distillation, anti-bumping granules prevents
the mixture boiling over into the condenser meaning
impurities won’t contaminating the product.

Question 6

When producing a haloalkane from an
alcohol, why is sodium hydrogen
carbonate added to the organic layer
after it has been separated from the
aqueous layer?

Answer 6

To react with any leftover hydrochloric

acid

Question 7

Why is it important to open the stopper of

the separating funnel regularly?

Answer 7

To release the build up of pressure and

reduce the risk of apparatus breaking

Question 8

When producing a haloalkane from an
alcohol, why is anhydrous sodium sulfate
added to the organic mixture after
separation?

Answer 8

To remove water (small amounts only) -

acts as a drying agent

Question 9

Why is distillation used when
synthesising a haloalkane from an
alcohol?

Answer 9

To separate and purify the organic

product

Question 10

Describe the key features of the

apparatus set-up for distillation

Answer 10

● Tilt the condenser down so any liquids flow into the beaker
● The water must enter at the bottom of the condenser and leave at the
top for efficient cooling
● The collection flask should not be sealed to the condenser - it should
not be airtight as the hot air in the system could cause the apparatus
to crack
● Use a thermometer to identify when the desired product has
evaporated from the reaction mixture

Question 11

Why might a water bath or electric heater
be used instead of a Bunsen burner to
heat a reaction mixture?

Answer 11

If the reactants are flammable as using a

Bunsen burner would be a safety risk

Question 12

What safety precautions should be taken

when carrying out this practical

Answer 12

• 2-methylpropan-2-ol is highly flammable and harmful if inhaled. Keep away from naked flames and keep the lab well ventilated.
• Concentrated sulfuric acid causes severe skin burns and eye damage. Use a fume cupboard and wear safety goggles and
  gloves.
• Take care when heating apparatus. Move hot apparatus with tongs to avoid burns.