AS Level · Chemistry 9701 · Organic chemistry

Organic synthesis: AS Level Chemistry questions with answers

Free Organic synthesis questions for AS Level Chemistry (9701), part of Organic chemistry. Each question has the answer and the marking points an examiner would look for.

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Organic synthesis practice questions

Question 1Multiple choice · 1 mark

Which test distinguishes an aldehyde from a ketone?

  1. A bromine water
  2. B sodium metal
  3. C 2,4-DNPH
  4. D Tollens’ reagent
Show answer

Answer: D

Question 2Multiple choice · 1 mark

Which statement describes chiral centre?

  1. A A carbon atom bonded to four different groups
  2. B Resistance to decomposition, which increases down the group
  3. C Distance moved by a spot ÷ distance moved by the solvent front
  4. D The –CONH– link formed between amino acids
Show answer

Answer: A

Question 3Multiple choice · 1 mark

Which reagent converts ethene into ethanol?

  1. A LiAlH₄
  2. B aqueous NaOH
  3. C HBr
  4. D steam with phosphoric acid catalyst
Show answer

Answer: D

Question 4Structured · 8 marksA* challenge

Lactic acid, CH₃CH(OH)COOH, can be made from ethene in four steps: ethene → ethanol → ethanal → 2-hydroxypropanenitrile → lactic acid.

(a)

Give the reagents and conditions for each step.

[4]
(b)

State the type of reaction in step 3.

[1]
(c)

Calculate the atom economy for making ethanol from bromoethane: C₂H₅Br + NaOH → C₂H₅OH + NaBr.

[2]
(d)

Explain why the lactic acid made is optically inactive.

[1]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)steam/H₃PO₄; Cr₂O₇²⁻/H⁺ distil; HCN/KCN; dilute acid heat
steam with H₃PO₄ catalyst, high T and p B1
acidified K₂Cr₂O₇, distil B1
HCN with KCN catalyst B1
heat with dilute HCl/H₂SO₄ B1
4
(b)nucleophilic addition
nucleophilic addition B1
1
(c)30.9%
46.0/(109.0 + 40.0) × 100 M1
= 30.9% A1
2
(d)racemic mixture
equal amounts of both enantiomers form (racemic mixture) B1
1
Question 5Structured · 6 marksA* challenge

Organic synthesis often involves several steps.

(a)

Suggest a two-step synthesis of propanoic acid from bromoethane, giving reagents and conditions.

[4]
(b)

Identify the functional groups in the intermediate and the product.

[2]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)KCN ethanol reflux; then acid hydrolysis
step 1: KCN in ethanol B1
heat under reflux B1
step 2: dilute acid B1
heat under reflux (hydrolysis) B1
4
(b)nitrile; carboxylic acid
nitrile (–CN) B1
carboxylic acid (–COOH) B1
2
Question 6Structured · 4 marks

Plan a synthesis of ethyl ethanoate from ethanol only.

Describe the two routes needed and how they are combined.

[4]
Show answers and mark scheme
PartAnswer and marking pointsMarks
oxidise some ethanol to ethanoic acid; esterify
oxidise ethanol to ethanoic acid B1
acidified dichromate, heat under reflux B1
react ethanoic acid with ethanol B1
concentrated H₂SO₄ catalyst, heat B1
4

More Organic chemistry questions

Introduction to organic chemistryHydrocarbonsHalogen compoundsHydroxy compoundsCarbonyl compoundsCarboxylic acids & derivativesNitrogen compoundsPolymerisationAnalytical techniques

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Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in