Syllabus Edition

First teaching 2023

First exams 2025

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Organic Synthesis (AL) (CIE A Level Chemistry)

Exam Questions

2 hours14 questions
1a2 marks

Morphine is a naturally occurring opiate found in opium from poppies. Heroin is a synthetic opiate that can be synthesised from morphine. Fig. 1.1 shows the chemical structure of morphine and heroin.

heroin-corrected-structure

Fig. 1.1

What functional groups are found in morphine?

1b1 mark

Identify the functional group(s) present in heroin, but not in morphine.

1c2 marks

State the reagents and conditions needed to turn morphine into heroin.

1d3 marks

Predict and explain what you would see if morphine and heroin were separately reacted with warm acidified potassium dichromate solution.


Observation ..................................................................................


Explanation ................................................................................................

                    ................................................................................................

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2a2 marks

This question is about farnesol, a chemical found in essential oils and used in perfumes, especially in lilac perfumes. The structure of farnesol is shown in Fig. 2.1

6-8-q3a-farnesol

Fig. 2.1

Identify two different functional groups found in farnesol and identify their locations in Fig. 2.1.

2b1 mark

Describe how you would expect farnesol to react if shaken with a little bromine water. 

2c1 mark

Farnesol is an important starting compound in organic synthesis. Fig. 2.2 shows a two-step synthesis of a compound made from farnesol.


screenshot-2022-11-03-112824
Fig. 2.2


Suggest a new functional group present in the product of the first step.

2d1 mark

Suggest a functional group present in the final product, but not in farnesol.

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3a3 marks

The four step synthesis to form propan-1-ol from a ketone is outlined in Fig. 3.1.

2

Fig. 3.1 

i)
Name a possible halogenoalkane, D, that undergoes nucleophilic substitution in step to form propan-1-ol.

[1]

ii)
Give the reagents and conditions for step 4.

[2]

3b1 mark

Deduce the identity of the alkene, C, in Fig. 3.1 in part (a).

3c1 mark

Suggest why the electrophilic addition reaction in step 3, in Fig. 3.1 in part (a), might not be favourable in an industrial multistep reaction. You should not include economic considerations.

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4a3 marks

Benzene and its derivatives are used in various industrial applications, including the production of plastics, synthetic fibres, rubber, dyes, and detergents.

Fig. 4.1 shows three compounds, AB and C, which are all derivatives of benzene.

A

benzoic-acid

B

phenylamine

C

1-3-dimethylbenzene

Fig. 4.1

Give the systematic names of compounds AB and C.

Compound A ..................................................

Compound B ..................................................

Compound C ..................................................

4b2 marks

Different functional groups attached to the benzene ring activate specific carbons within the ring structure and make them more likely to react.

State the positions that are activated for the following compounds in part (a).

Compound A ..............................

Compound B ..............................

4c4 marks

Compounds A and B can be synthesised from benzene by the routes shown in Fig. 4.2.

l4T8YRDB_2-benzene-reactions-blank-scheme7-8-4c-e-2-benzene-reactions-blank-scheme

Fig. 4.2

i)
Suggest the reagents for steps 1 - 4.
 
step 1 ................................................................................
 
step 2 ................................................................................
 
step 3 ................................................................................
 
step 4 ................................................................................
 
[4]
 
ii)
Draw the structures of compounds D and E in the boxes.
 
[2]
4d3 marks

The route shown in Fig. 4.3 is proposed for the synthesis of compound C.

foDY9Bu1_benzene-methylation-unlikely7-8-4d-e-benzene-methylation-unlikely

Fig. 4.3

i)
Suggest one set of reagents and conditions that could be used for both steps.
 
reagents ............................................................
 
conditions ............................................................
 
[2]
 
ii)
Suggest why step 2 is less likely to occur.
 
[1]

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5a4 marks

1-(3-aminophenyl)ethanol can be synthesised from benzene by the route shown in Fig. 5.1.

synthesis-of-1-3-aminophenylethanol

Fig. 5.1

Step 1 involves a reaction with concentrated nitric acid and concentrated sulfuric acid.

i)
Name compound and state the reaction conditions for step 1.
 
compound A ................................................................................
 
reaction conditions ................................................................................
 
[2]
 
ii)
Name the mechanism for the conversion of benzene into compound A and identify the specific species that reacts with benzene. 
 
mechanism ................................................................................
 
species ................................................................................
 
[2] 

 

5b1 mark

Step 2, in Fig. 5.1 in part (a), is the reaction of compound A with ethanoyl chloride, CH3COCl, in the presence of a suitable catalyst.

Identify the catalyst required for this reaction and write an equation to show how the catalyst forms the electrophile for this reaction. 

5c1 mark

Step 3, in Fig. 5.1 in part (a), is the reaction of compound B with tin and hydrochloric acid, converting a nitro group into an amino group.

State two changes that occur to compound B during this reaction to show that reduction has taken place.

5d2 marks

Step 4, in Fig. 5.1 in part (a), is the reduction of compound C to 1-(3-aminophenyl)ethanol using NaBH4.

The structure of 1-(3-aminophenyl)ethanol is repeated in Fig. 5.2.

EyNKNJ3E_1-3-aminophenylethanol

Fig. 5.2

i)
Draw a circle around the aliphatic functional group that is formed after the reaction of compound C with NaBH4.
 
[1]
 
ii)
Draw the structure of compound C.
 
[1]

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1a2 marks

Ibuprofen and paracetamol are pain-relief drugs.

fig-8-1-9701-y22-sp-4-cie-ial-chem

Fig. 1.1

Ibuprofen and paracetamol both contain the aryl (benzene) functional group.

Name the other functional groups present in each molecule.

ibuprofen .........................................................................

paracetamol ...................................................................

1b2 marks

Ibuprofen contains a chiral centre and has two enantiomers.

i)
State one similarity and one difference in the physical or chemical properties between the two enantiomers.

   similarity.......................................

   difference.....................................

[1]

ii)
Explain what is meant by racemic mixture.

[1]

1c3 marks

Paracetamol reacts separately with the two reagents shown in the table.

Complete Table 1.1 by:
• drawing the structures of the organic products formed,
• stating the types of reaction.

Table 1.1

reagent organic product structure type of reaction
LiAlH4    
an excess of Br2(aq)    

1d5 marks

One of the steps in the manufacture of ibuprofen is shown in Fig. 1.2.


fig-8-2-9701-y22-sp-4-cie-ial-chem
Fig. 1.2

i)
Write an equation to show how AlCl3 generates the electrophile for the conversion of X into Y.

[1]

ii)

Draw the mechanism for the conversion of X into Y. Include all necessary curly arrows and charges.

[3]

iii)
Write an equation to show how the AlCl3 is regenerated. 

[1]

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2a4 marks

Cuminyl alcohol can be synthesised from benzene by the following route shown in Fig. 2.1.

7-8-2a-m-formation-of-cuminyl-alcohol

Fig. 2.1

Suggest reagents and conditions for steps 1–4.

step 1 ...................................................

step 2 ...................................................

step 3 ...................................................

step 4 ...................................................
2b2 marks

Name the mechanism of step 2 and state the type of reaction in step 4.


Mechanism of step 2 ..........................................................................................................


Type of reaction in step 4 ....................................................................................................

2c4 marks

Draw the reaction mechanism for step 2.

2d1 mark

Deduce the number of peaks that would be present in the 13C NMR spectrum of cuminyl alcohol.

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3a9 marks

Outline how ethanal can be synthesised from ethane in three steps.

ethane space rightwards arrow with step space 1 on top chloroethane rightwards arrow with step space 2 on top ethanol rightwards arrow with step space 3 on top ethanal

State the reaction conditions and reagents and name the type of reaction taking place.

i)
Step 1

Reagents ..........................................................................................................

Conditions ..........................................................................................................

Reaction type ..........................................................................................................
[3]

ii)
Step 2

Reagents ..........................................................................................................

Conditions ..........................................................................................................

Reaction type ..........................................................................................................
[3]

iii)
Step 3

Reagents ..........................................................................................................

Conditions ..........................................................................................................

Reaction type ..........................................................................................................
[3]
3b3 marks

The following reaction pathway in Fig. 3.1 used to produce compounds A and B, which when reacted together, form a branched ester molecule, compound C

Suggest suitable reagents and conditions for the synthesis of compound A via step 1 and give the name for this type of reaction.

q2a_20-2_ib_hl_medium_sq

Fig. 3.1

3c3 marks

The ketone in part (a), must be converted to compound B to produce the ester.

i)

Name the molecule that is produced from step 2

[1]

ii)

Name of the type of reaction that is involved in step 2 and suggest suitable reagents and conditions for this step.

[2]

3d1 mark

Draw the skeletal formula of the ester formed from the reaction scheme.

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4a3 marks

Noradrenaline shown in Fig. 4.1 is a hormone and neurotransmitter, which is released during stress to stimulate the heart and increase blood pressure.

7-8-4a-m-noradrenaline-a

Fig. 4.1

State the names of three functional groups in the noradrenaline molecule.

4b3 marks

Consider the following two step synthesis of noradrenaline from dihydroxybenzaldehyde in Fig. 4.2. 

 
screen-shot-2023-03-06-at-11-48-21
 
Fig. 4.2
 

Draw the structure of the intermediate Z in the box.

Suggest reagents for steps 1 and 2.

 

step 1 ..................................................................................................................................

 

step 2 ..................................................................................................................................

 

4c2 marks

Dihydroxybenzaldehyde reacts with Br2 (aq).

 
  • Describe what you would see during this reaction
  • Draw the structure of the product
 

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5a2 marks

Compound G is a naturally occurring aromatic compound that is present in raspberries.

7-8-5a-m-compound-g-q5-

Identify the functional groups present in compound G.

 
5b9 marks

Complete Table 5.1 with information about the reactions of the three stated reagents with compound G.


Table 5.1

Reagent Observation Structure of organic product Type of reaction
Na (s)




   
Br2 (aq)





   
I2 / NaOH (aq)





   

5c5 marks

The dye H can be made from compound G by the route shown below in Fig. 5.1.

7-8-5c-m-cie-ial-7-8-m-q5-fig--5-1-a

Fig. 5.1

i)
Draw the structures of the amine J and the intermediate K in the boxes above.

[2]

ii)
Suggest reagents and conditions for

step 1 ........................................................................................................................

step 2 ........................................................................................................................

[3]

5d2 marks

Explain why dye H is very stable.

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1a1 mark

Benzocaine is an ester based compound that is used medicinally as a local anaesthetic in pain relievers and cough drops. One of the first industrial processes to manufacture benzocaine was the five-step reaction shown in Fig. 1.1.

_uvCi8Ff_benzocaine-synthesis-adapted

Fig. 1.1

Give the systematic name of benzocaine.

1b4 marks

Step 1 involves the reaction of benzene with bromomethane.

i)
State a suitable catalyst for step 1.
 
[1]
 
ii)
Draw a mechanism for step 1. Include all necessary curly arrows, charges and the structure of A.
 
[3]
1c5 marks

Concentrated sulphuric acid and concentrated nitric acid are used to form the ion required for step 2.

The following equilibrium is the first step in the formation of the ion:

H2SO4 + HNO3 ⇋ HSO4 + H2NO3+

i)
State the roles of each acid in this reaction.
 
[2]
 
ii)
Use your answer to part (i) to suggest the relative strengths of the acids.
 
[1]
 
iii)
Different isomers with the molecular formula C7H7NO2 can be formed during step 2.
 
Draw the structure of the isomer B. Explain your answer.
 
[2]
1d4 marks

Suggest reagents and conditions for steps 3 - 5 of the synthesis.

   step 3 ................................................................................

   step 4 ................................................................................

   step 5 ................................................................................

1e2 marks

Fig. 1.2 shows an alternative reaction scheme for the production of benzocaine.

3-3

Fig. 1.2

i)
Suggest why this reaction scheme is an improvement.
 
[1]
 
ii)
Suggest why this reaction scheme may not work.
 
[1]

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2a5 marks

Propanone can be synthesised from 2-bromopropane according to the reaction scheme shown in Fig. 2.1.

WIh2OJPZ_5-2

Fig. 2.1

Step 1 is not completed in acidic conditions.

Suggest reagents and conditions for each of steps 1 to 3.
  
 
step 1 ................................................................................
 
step 2 ................................................................................
 
step 3 ................................................................................
2b2 marks

Suggest one reaction, including reagents and conditions, to replace steps 1 and 2.

2c1 mark

Using structural formulae, write an equation for the reaction of compound B with an oxidising agent, [O], to form propanone.

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3a2 marks

Ethene is used in the radical-free synthesis of 1-aminopropane as shown.

ethene rightwards arrow with step space 1 on top compound A rightwards arrow with step space 2 on top compound B rightwards arrow with step space 3 on top propylamine

Identify which step of the reaction scheme could use hydrogen cyanide. Explain your answer.

3b2 marks

Draw the skeletal structure of compound A and state the reagents required for its formation.

3c2 marks

The final step of the reaction scheme forms 1-aminopropane from compound B.

Name compound B and identify the type of reaction that compound B undergoes to form propylamine. Explain your answer.

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4a4 marks

Sudan II is an azo dye that was used as a colourant in chilli powder until it was banned due to its links to an increased risk of cancer.  It can be synthesised from 1,3-dimethylbenzene by the route shown in Fig. 4.1

H56sLkF6_sudan-ii-synthetic-route

Fig. 4.1

Draw the structures of the organic compounds A, B, C and D in the boxes.

4b4 marks
i)
Write an equation to show the formation of an appropriate reactive species to react with 1,3-dimethylbenzene to form compound A.
 
[1]
 
ii)
Draw the mechanism for this reaction. Include all necessary curly arrows and charges.
 
[2]
4c1 mark

Two other structural isomers of compound A could have been formed from the mononitration of 1,3-dimethylbenzene, as shown in Fig.4.2.

13-dimethylbenzene-mononitration-isomers

Fig. 4.2

Suggest, with the aid of suitable diagrams, why 1,3-dimethyl-2-nitrobenzene is likely to be the more abundant product.

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