Organic Synthesis (A Level Only) | CIE A Level Chemistry Structured Questions 2022

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.

Fig. 1.1

What functional groups are found in morphine?

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1b1 mark

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

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1c2 marks

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

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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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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, A, B and C, which are all derivatives of benzene.

A

benzoic-acid 7-8-4a-e-benzoic-acid

B

phenylamine 7-8-4a-e-phenylamine-and

C

1-3-dimethylbenzene 7-8-4a-e-13-dimethylbenzene

Fig. 4.1

Give the systematic names of compounds A, B and C.

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

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

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

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

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4c4 marks

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

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]

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4d3 marks

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

foDY9Bu1_benzene-methylation-unlikely 7-8-4d-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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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.

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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]

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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]

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1d4 marks

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

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

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

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

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1e2 marks

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

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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1a2 marks

Ibuprofen and paracetamol are pain-relief drugs.

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

Fig. 8.1

Ibuprofen and paracetamol both contain the aryl (benzene) functional group.
Name the other functional groups present in each molecule.

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

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

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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]

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1c3 marks

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

Complete Table 8.1 by:
• drawing the structures of the organic products formed,
• stating the types of reaction.

Table 8.1

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

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1d5 marks

One of the steps in the manufacture of ibuprofen is shown in Fig. 8.2.

Fig. 8.2

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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3a9 marks

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

$ethane \overset{step 1}{\to} chloroethane \overset{step 2}{\to} ethanol \overset{step 3}{\to} ethanal$

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]

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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