AQA assesses n + 1 formation of doublets, triplets and quartets in aliphatic compounds. Proton NMR samples use a deuterated solvent or CCl4. D2O exchange practice appears on the OCR A route.
Year 13 · AQA + OCR A
A-level NMR questions and structure deduction
Practise carbon-13 and proton NMR: environments, chemical shifts, integration, splitting and full structure deduction. For structure deduction, every signal has to fit the structure you draw.
Prefer structure deduction? Start a mystery compound → · Review IR first
Pick your board once. Shared chemistry stays shared; AQA/OCR differences change the questions and reference data.
Example evidenceC4H8O2
| δ / ppm | Integration | Splitting |
|---|---|---|
| 4.10 | 2 | quartet |
| 2.05 | 3 | singlet |
| 1.25 | 3 | triplet |
signal count→δ→integration→splitting→structure
OCR A can assess a wider range of splitting patterns. OCR also requires proton exchange with D2O to identify O–H and N–H, and its Data Sheet presents shift regions graphically.
Expect structure deduction from combined evidence. Recent AQA questions can be substantial multi-signal mysteries too, so the harder deduction route applies to both boards.
Choose an NMR skill
NMR basicsGet the foundations secure: TMS, chemical shift, deuterated solvents and what carbon-13 and proton NMR actually tell you.
TMS and δdata-sheet use13C vs 1H
AQA · OCR A
Carbon-13 NMRCount carbon environments, use symmetry and chemical-shift evidence, then distinguish plausible structures.
carbon environmentssymmetry13C chemical shifts
AQA · OCR A
Environments & integrationCount proton environments and turn integrations into useful structural evidence without losing sight of equivalent hydrogens.
proton environmentsintegrationequivalent H
AQA · OCR A
Splitting patternsUse adjacent non-equivalent protons and the n + 1 rule. Board-aware practice keeps AQA inside its specified splitting limits.
n + 1 ruleadjacent protonsfragment recognition
AQA · OCR A
Predict NMR dataWork from a displayed or condensed structure to the number, shift region, integration and splitting of expected signals.
predict signalschemical shiftssplitting + integration
AQA · OCR A
Structure deductionDeduce whole structures from molecular formulae and curated 13C and 1H NMR evidence tables, with progressive clues when needed.
combine NMR evidencededuce fragmentscheck whole structure
AQA · OCR A
Mixed NMR practiceNew · 16 Aug 2026A balanced run across carbon-13, proton environments, integration, splitting, prediction and structure deduction, with OCR-only D2O questions included only when OCR A is selected.
mixed retrievalboard-aware NMRstructure reasoning
AQA · OCR A
Hard NMR mysteriesLarge exam-style mystery compounds combining molecular formula, IR or other analytical evidence, carbon-13 NMR and proton NMR.
multi-technique deductionNMR reasoningconstraint checking
AQA · OCR A
D2O proton-exchange practice appears on the OCR A route because OCR A specifies it.
Quick reference
Read the spectrum before choosing a structure
Chemical shifts move with solvent, concentration and substituents. Use the ranges as structural evidence, then check that signal count, integration, splitting and the molecular formula all fit the same structure.
What each clue tells you
- Number of signals
- Number of distinct carbon or proton environments.
- Chemical shift, δ
- What sort of environment that nucleus is in.
- Integration
- Relative numbers of protons in each 1H environment.
- Splitting
- Neighbouring non-equivalent protons, using n + 1 where appropriate.
High-value regions
- ~9–10 ppm 1H: aldehyde proton.
- ~10–12 ppm 1H: carboxylic-acid O–H.
- ~4–6 ppm 1H: alkene H; C–H attached to O/halogen is often further downfield than ordinary alkyl H.
- ~160–220 ppm 13C: carbonyl region, with acids/esters lower than aldehydes/ketones.
- ~100–160 ppm 13C: unsaturated/aromatic carbon region.
Working through a structure deduction
- Write down what each signal tells you.
- Spot obvious fragments such as triplet + quartet.
- Use shifts to decide what those fragments are attached to.
- Fit the carbon environments.
- Accept the final structure once all the evidence fits.
Board detail
AQA and OCR A details
Which n + 1 patterns does AQA assess?
AQA assesses doublet, triplet and quartet formation in aliphatic compounds.
What is different about D2O on OCR A?
OCR A requires identification of O–H and N–H protons by proton exchange using D2O. These questions are shown only when OCR A is selected.
Do the harder questions apply to AQA too?
Yes. AQA can use substantial structure-deduction questions combining molecular formula, IR, carbon-13 NMR and proton NMR.