BRAINCAKEPlanning Multi-Stage Syntheses
A multi-stage synthesis converts a starting material into a target molecule through two or more steps. OCR exam questions ask for up to about four steps, with the reagents and conditions for each step and the structure of every intermediate.
A systematic approach:
1. Compare the starting material and the target: which functional groups change, and are they aliphatic or aromatic?
2. Count the carbon atoms. If the chain gets one carbon longer, a nitrile step (KCN with a haloalkane, or NaCN/H+ with a carbonyl) is needed. On a benzene ring, a Friedel-Crafts reaction adds carbon.
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More in Organic Synthesis
- Practical Techniques in Organic Synthesis
- Quickfit Apparatus
- Filtration under Reduced Pressure
- Recrystallisation
- Melting Point Determination
- Identifying Functional Groups
- Aliphatic Synthetic Routes
- Aromatic Synthetic Routes
All 9 lessons in Organic Synthesis · All OCR A-level Organic Chemistry topics