CIE A Level Chemistry
CIE A Level Chemistry Organic Synthesis Exam Questions
Free CIE A Level Chemistry exam questions for Organic Synthesis, with a mark scheme for every pack. Covers identifying functional groups, planning multi-step synthetic routes, reagents and conditions, chain lengthening, and predicting properties and reactions of unfamiliar molecules.
Organic Synthesis exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About CIE A Level Chemistry Organic Synthesis
Organic synthesis in Cambridge International 9701 asks you to use everything from the organic topics together. You need to identify functional groups in complex molecules, predict their reactions, and devise synthetic routes of up to several steps, stating reagents, conditions and intermediates. The A Level part extends this to routes involving arenes, phenols, amines, acyl chlorides and amides, and to analysing given routes, for example spotting where a chiral centre forms or where a step changes the carbon chain length. This topic is synoptic and is a common source of longer questions in Paper 4. Examiners reward precise conditions, such as reflux, distillation, catalysts and concentrations, and clearly drawn intermediates.
What you need to know
- Functional group recognition Identify alkenes, alcohols (primary, secondary, tertiary), halogenoalkanes, aldehydes, ketones, carboxylic acids, esters, acyl chlorides, amines, amides, nitriles and arenes in complex structures.
- Key conversions Learn the reagents and conditions for each conversion, for example alcohol to halogenoalkane, halogenoalkane to nitrile, nitrile to acid or amine, alcohol to aldehyde, ketone or acid, and alkene to alcohol or dibromide.
- Changing chain length Reaction with KCN (halogenoalkanes) or HCN/KCN (carbonyls) adds one carbon. Friedel-Crafts alkylation or acylation adds carbon to a benzene ring.
- Aromatic routes (A Level) Benzene to nitrobenzene to phenylamine to diazonium salt to azo dye, and methylbenzene to benzoic acid by hot alkaline KMnO4 then acidification.
- Planning a route Work backwards from the target to known starting materials, then check each step is compatible with other groups in the molecule, for example oxidising agents also attack alcohols and aldehydes elsewhere.
- Unfamiliar molecules Apply known reactions of each functional group to a new molecule, and count how many groups react with a reagent such as NaOH, Na or Br2.
Common mistakes in Organic Synthesis
- Giving vague conditions such as heat; examiners expect specific detail like heat under reflux, distil, or in ethanol.
- Forgetting that a strong oxidising agent will also oxidise other alcohol or aldehyde groups in the molecule.
- Using HCN alone without KCN, or KCN in water when ethanol is needed for halogenoalkanes.
- Missing that NaOH reacts with phenol and carboxylic acid groups but not with alcohols.
- Writing a route that skips a step, for example going from an alkane directly to an alcohol in one step.
Try three Organic Synthesis exam-style questions
1. Suggest a two-step synthesis of propanoic acid from bromoethane, giving reagents and conditions. (4 marks)
Show the mark scheme answer
Step 1: KCN in ethanol, heat under reflux; gives propanenitrile, CH3CH2CN; Step 2: heat under reflux with dilute HCl (or H2SO4); hydrolysis gives CH3CH2COOH.
2. A molecule contains a phenol group, a primary alcohol and a carboxylic acid group. State how many moles of NaOH and of Na react with one mole. (2 marks)
Show the mark scheme answer
NaOH: 2 mol (phenol and carboxylic acid); Na: 3 mol of Na atoms (all three OH groups).
3. Describe how benzene can be converted into phenylamine, giving reagents and conditions. (4 marks)
Show the mark scheme answer
Concentrated HNO3 and concentrated H2SO4 at about 50 °C; forms nitrobenzene; then Sn and concentrated HCl, heat under reflux; followed by NaOH(aq) to release phenylamine.
Organic Synthesis FAQs
What does Cambridge AS & A Level Chemistry Organic synthesis cover?
It covers recognising functional groups, predicting reactions of unfamiliar compounds and planning multi-step synthetic routes with reagents and conditions.
How do I revise Organic synthesis?
Build a complete reaction map for AS and A Level functional groups, then practise past questions that ask for two or three step routes.
What should I write for conditions in synthesis questions?
State the reagent, its state or solvent (aqueous, ethanolic, concentrated or dilute), temperature or heating method, and any catalyst.
