Organic synthesis
Cambridge A-Level Chemistry (9701) · Unit 21: Organic synthesis · 8 flashcards
Organic synthesis is topic 21.1 in the Cambridge A-Level Chemistry (9701) syllabus , positioned in Unit 21 — Organic synthesis . In one line: The molecule contains two functional groups: an alkene (C=C) and a carboxylic acid (-COOH).
Marked as A2 Level: examined at A Level in Paper 4 (A Level Structured Questions) and Paper 5 (Planning, Analysis and Evaluation). It is not tested on the AS-only papers (Papers 1, 2 and 3).
The deck below contains 8 flashcards — 4 definitions and 4 key concepts — covering the precise wording mark schemes reward. Use the 4 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
Some cards in this deck are on other syllabus topics: 36.1 Organic synthesis. Each card is labelled with its topic.
Identify the functional groups present in the molecule: CH3CH=CHCH2COOH
The molecule contains two functional groups: an alkene (C=C) and a carboxylic acid (-COOH).
What the Cambridge 9701 syllabus says
2025-2027 syllabus, in our words · A2 LevelWhat the syllabus expects you to be able to do in this topic, in plain English. For the exact wording, see the official syllabus (PDF).
- For an organic molecule with several functional groups: (a) identify its functional groups, using reactions from the syllabus; (b) predict its properties and reactions.
- Devise synthetic routes of more than one step to prepare organic molecules, using reactions from the syllabus.
- Analyse a given synthetic route, stating for each step the type of reaction and the reagents used, and identifying possible by-products.
Also in this deck: 36.1 Organic synthesis
- For an organic molecule with several functional groups: (a) identify its functional groups, using reactions from the syllabus; (b) predict its properties and reactions.
- Devise synthetic routes of more than one step to prepare organic molecules, using reactions from the syllabus.
- Analyse a given synthetic route, stating for each step the type of reaction and the reagents used, and identifying possible by-products.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9701 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in these topics
- › Work backwards: a hydroxynitrile is formed by nucleophilic addition of HCN to an aldehyde, which is formed by mild oxidation of a primary alcohol.
Topic 21.1 · Organic synthesis
Identify the functional groups present in the molecule: CH3CH=CHCH2COOH.
The molecule contains two functional groups: an alkene (C=C) and a carboxylic acid (-COOH).
Topic 21.1 · Organic synthesis
Describe a synthetic route to convert ethanol to ethanoic acid.
Ethanol can be oxidized to ethanoic acid in a two-step process. First, ethanol is oxidized to ethanal using acidified potassium dichromate(VI) with distillation to remove the aldehyde. Second, the ethanal is further oxidized to ethanoic acid using acidified potassium dichromate(VI) under reflux.
Topic 21.1 · Organic synthesis
Propose reagents and conditions for converting but-2-ene to butan-2-ol.
But-2-ene can be converted to butan-2-ol by hydration. This requires steam (H₂O(g)) and an acid catalyst, such as concentrated H₃PO₄.
Topic 36.1 · Organic synthesis
Outline the steps for converting benzene to nitrobenzene, then to phenylamine.
Step 1: Benzene to nitrobenzene requires nitration with concentrated nitric acid and concentrated sulfuric acid at 50-55°C. Step 2: Nitrobenzene to phenylamine requires reduction with tin and concentrated hydrochloric acid, followed by the addition of a base like NaOH.
Topic 21.1 · Organic synthesis
What type of reaction is used to convert an alcohol to an alkene?
This conversion involves elimination. Specifically, it's dehydration, requiring concentrated sulfuric acid and heat, or passing the alcohol vapor over a hot aluminum oxide catalyst.
Topic 36.1 · Organic synthesis
Starting with benzene, devise a two-step synthetic route to produce benzoic acid.
1. Friedel-Crafts alkylation: react benzene with chloromethane and an AlCl3 catalyst to form methylbenzene. 2. Side-chain oxidation: heat methylbenzene under reflux with hot alkaline KMnO4, then acidify with dilute acid, to form benzoic acid.
Topic 21.1 · Organic synthesis
What reagents are used to reduce a carboxylic acid to a primary alcohol?
Lithium aluminum hydride (LiAlH₄) in dry ether is used. Note: NaBH₄ is NOT strong enough to reduce carboxylic acids.
Topic 21.1 · Organic synthesis
Give reagents and conditions to convert a primary alcohol to a haloalkane.
To convert a primary alcohol to a haloalkane, use concentrated hydrohalic acid (e.g. HCl, HBr) or phosphorus halides (PCl₅, PBr₃). Alternatively, SOCl₂ can be used to form a chloroalkane.
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