Organic synthesis — common mistakes

In multi-step synthesis questions, always check the number of carbon atoms in the starting material and the final product. If the number of carbons increases by one, the nitrile route ($R-X \rightarrow R-CN \rightarrow R-COOH$) is a very common and important pathway to know at AS Level.

It comes down to practice and pattern recognition. A great strategy is to create your own reaction map or flowchart connecting all the functional groups. For each arrow between groups, write down the exact reagents and conditions. Using this visual aid during revision will build your fluency.

Reflux involves heating a reaction mixture with a condenser placed vertically above the flask. This allows the reaction to be heated for a long period without losing volatile substances, as they condense and drip back down. It's used to ensure a reaction goes to completion. Distillation is a separation technique. It's used either to purify a final liquid product or, crucially in synthesis, to remove a product as it forms if it's more volatile than the reactants (e.g., making an aldehyde from a primary alcohol).

Yes, for the most part. Reagents and conditions are intrinsically linked and are often worth separate marks in an exam. For example, stating 'acidified potassium dichromate(VI)' and 'heat under reflux' are two distinct pieces of information required to describe the full oxidation of a primary alcohol. Simply writing the reagent is not enough.