23 Organic synthesis

Question 1

When a sample of Q synthesised in a laboratory was compared to a natural sample from olive oil, it was found that the therapeutic activity of the synthetic sample was lower.

Suggest a reason for this.

Ref: 9701/42/O/N/16

Answer 1

mixture of (two) optical / stereo isomer s formed

Question 2

Complete the following table to show the structures of the products formed when Q reacts with the three reagents.

Answer 2

all three reaction types

Question 3

Compounds V and W can be synthesised from bromobenzene by the following routes.

Suggest reagents for each of the steps 1– 4.

Answer 3

step 1, AlBr3 and CH3Br OR other suitable halogen instead of Br

step 2, KMnO4 or potassium manganate(VII)

step 3, conc. H2SO4 and conc. HNO3

step 4. Sn and (conc.) HCl (heat)

Question 4

Draw the structures of the two organic products from the reaction of V and W with LiAl H4.

Ref: 9701/42/O/N/16

Answer 4

1 mark for each correct structure

Question 5

V and W can be hydrolysed using hot HCl (aq).

(i) Draw the structures of the two organic products of the hydrolysis of W.

Answer 5

1 mark for each correct structure

Question 6

The products formed from the hydrolysis of W are soluble in aqueous acid, whereas a precipitate, X, is formed on hydrolysing V. Draw the structure of compound X.

Suggest why X is insoluble in water.

Answer 6

(precipitate) the compound is less polar/more non-polar/non-ionic resulting in less hydrogen bonding to water.

Question 7

What are the reactions and conditions for this step?

Answer 7

NaOH + I2/Cl2