Organic Synthesis | OCR A-Level Chemistry A (H432)
Organic Synthesis
- 52 questions
- 5 subtopics
- Module 4: Core organic chemistry
- Component 02 and Component 03
The practical and planning side: reflux, distillation, separation, drying, recrystallisation and melting point as a purity test, then devising a multi-stage route between functional groups..
It covers reflux, distillation and separating an organic layer, purifying an organic solid and testing its purity, planning a multi-stage synthetic route, functional group interconversions and lengthening the chain and esters, acyl chlorides, condensation polymers and racemic mixtures.
Sample questions from Organic Synthesis
Answer each one closed book first, then open the answer.
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Reflux, distillation and separating an organic layer
What is the purpose of heating under reflux using Quickfit apparatus?
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To heat a reaction mixture for an extended period without losing volatile reactants or products, as vapours condense and return to the flask. -
Reflux, distillation and separating an organic layer
When using a separating funnel, how do you determine which layer is the organic layer?
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By comparing densities; the organic layer floats on top if less dense than water, or sinks to the bottom if more dense than water. -
Purifying an organic solid and testing its purity
What two techniques are combined to purify an organic solid?
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Recrystallisation and filtration under reduced pressure. -
Purifying an organic solid and testing its purity
What physical property is measured to assess the purity of an organic solid?
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The melting point. -
Planning a multi-stage synthetic route
What is meant by a multi-stage synthetic route in organic chemistry?
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A planned sequence of reactions that converts a starting material into a target organic compound through multiple steps. -
Planning a multi-stage synthetic route
What approach should be taken when the target molecule contains a functional group that cannot be made directly from the starting material?
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Devise a multi-step synthetic route by identifying intermediate functional groups and applying a sequence of known transformations to progressively convert the starting material to the target product. -
Functional group interconversions and lengthening the chain
What happens to the carbon chain length when a carbonyl compound reacts with HCN?
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The carbon chain increases by one carbon atom. -
Functional group interconversions and lengthening the chain
Which type of reaction is used to convert benzene into a substituted aromatic compound by attaching alkyl or acyl groups?
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Friedel-Crafts reactions (alkylation or acylation).
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Reflux, distillation and separating an organic layer | Recall questions on Quickfit apparatus and the purpose of reflux, using a separating funnel and telling the layers apart, and drying with an anhydrous salt. | 9 |
| Purifying an organic solid and testing its purity | Recall questions on recrystallisation and the principle behind it, filtration under reduced pressure, and what a melting point reveals about purity. | 9 |
| Planning a multi-stage synthetic route | Recall questions on identifying the functional groups present, what a multi-stage route requires, retrosynthetic analysis, and choosing between alternative routes. | 11 |
| Functional group interconversions and lengthening the chain | Recall questions on haloalkane to amine and to nitrile, nitrile to amine and to carboxylic acid, and how HCN addition and Friedel-Crafts reactions change the carbon skeleton. | 12 |
| Esters, acyl chlorides, condensation polymers and racemic mixtures | Recall questions on forming an ester and an acyl chloride, the products with amines and alcohols, the monomers of polyesters and polyamides, and why HCN addition gives a racemic mixture. | 11 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby sections
OCR A-Level Chemistry A Active Recall Guide
Every section, not just this one. 1,913 questions with their answers.