By Cyril KimbiOrganic chemistry is where GCE Chemistry candidates most often decide they are bad at the subject. They are usually not. They are trying to memorise a body of material that is designed to be reasoned through, and memorising it is genuinely impossible.
Why memorising fails
A candidate trying to memorise organic chemistry is trying to hold hundreds of individual reactions. It cannot be done, and the attempt produces the familiar experience of recognising a question and having no idea how to start.
The subject is not hundreds of reactions. It is a handful of functional groups, each with predictable behaviour, combined in different arrangements. Once you know that an alcohol oxidises, that a halogenoalkane undergoes substitution, and that an alkene undergoes addition, an unfamiliar molecule becomes a familiar problem — you look at the group, not at the whole structure.
That shift, from recognising molecules to recognising groups, is the whole subject.
The functional groups to know cold
| Group | Characteristic behaviour |
|---|---|
| Alkane | Unreactive; substitution with halogens under UV |
| Alkene | Addition across the double bond |
| Halogenoalkane | Nucleophilic substitution; elimination |
| Alcohol | Oxidation, dehydration, esterification |
| Aldehyde and ketone | Addition; aldehydes oxidise further, ketones do not |
| Carboxylic acid | Acidic reactions; ester formation |
| Ester | Hydrolysis back to acid and alcohol |
| Amine | Basic; behaves as a nucleophile |
For each, three things must be automatic: how to recognise it in a structure, what it reacts with, and the reagent and conditions for each conversion. Conditions carry marks of their own — “heat under reflux with acidified potassium dichromate” is worth more than “oxidise”, and the difference between distilling and refluxing changes the product.
Reaction pathways are the real question
Paper 2 rarely asks for a single reaction. It gives you a starting material and a target, and asks how to get there — usually in two or three steps.
These are solved backwards, not forwards. Ask: what group does the product have, and what makes that group? An ester comes from an acid and an alcohol. An acid comes from oxidising a primary alcohol. A primary alcohol comes from a halogenoalkane. Work backwards to something you were given.
Build a single page for yourself — every group, with arrows showing what converts into what and the reagent on each arrow. One page covers most of the syllabus, and constructing it yourself is worth more than being handed one.
Mechanisms: draw everything
Mechanism marks are awarded for specific features, and candidates lose them on presentation rather than understanding.
- Curly arrows start at a lone pair or a bond, not at an atom, and point where the electrons go.
- Show the intermediate. Carbocations and the charges on them carry marks.
- Include partial charges where the mechanism depends on polarity.
- Name the mechanism if asked — nucleophilic substitution, electrophilic addition, free-radical substitution.
An arrow drawn from the wrong place is marked wrong even when you understand the reaction. Practise drawing them until the convention is automatic.
Naming and structures
Nomenclature looks like a small topic and is worth steady marks across the whole paper, because you cannot answer a question about a compound you cannot name or draw.
Practise in both directions: name to structure, and structure to name. Most candidates practise only one, and the exam asks for both. Isomers deserve specific attention — chain, position and functional group isomerism appear regularly and are easy marks once the pattern is familiar.
How to revise organic properly
- Build the pathway page yourself, from the syllabus, not from a textbook summary.
- Test yourself on conversions — given A and target B, write the reagents. Blank page, no notes.
- Draw twenty mechanisms from memory, then check each against the correct version.
- Work past-paper organic questions timed, then mark yourself strictly against the scheme. If the scheme required conditions and you wrote “oxidise”, you did not earn the mark.
- Log the recurring losses. After ten questions the list is short, and it is almost always conditions, arrows, or a missing intermediate.
The chemistry past papers supply the questions and schemes. Reading solutions feels productive and teaches very little; producing them is what moves the grade.
In the exam
Read the whole question before starting — later parts often reveal what the earlier ones were driving at. Write conditions every time, even when they feel obvious. Draw structures fully rather than abbreviating, since an ambiguous structure cannot be credited. And if a pathway will not come, write the first step you are sure of: partial credit is real, and a blank is the only guaranteed zero.
Frequently asked questions
How do I stop forgetting organic reactions?
Stop memorising reactions and learn functional-group behaviour instead. The reactions then follow from the group.
Do I need to write conditions?
Yes. Reagent and conditions frequently carry separate marks, and “heat under reflux” is not the same answer as “heat”.
How important are mechanisms?
They appear regularly and are heavily marked on presentation — arrows from the right place, intermediates shown, charges included.
How do I approach a multi-step synthesis?
Backwards. Identify the functional group in the product and ask what makes it, until you reach your starting material.
Is organic harder than physical chemistry?
It is differently structured. Physical rewards calculation; organic rewards pattern recognition. Candidates who treat organic as memorisation find it hardest.
