3.2.11 (HL)—NMR splitting patterns

Pattern	Typical neighbouring-hydrogen clue
Singlet	No equivalent neighbouring H in the coupling relationship
Doublet	One neighbouring H
Triplet	Two neighbouring H
Quartet	Three neighbouring H

Identify the relevant neighbouring proton set, predict n + 1, then compare with the actual pattern and cross-check shift/integration. Treat n + 1 as the introductory local rule: exchangeable protons may not show expected coupling, non-equivalent neighbour sets can give more complex patterns, and overlapping peaks can hide multiplicity. Do not force such evidence into a simple singlet/doublet/triplet/quartet label.

An ethyl fragment commonly gives a three-H triplet next to CH₂ and a two-H quartet next to CH₃. Apply the n + 1 pattern only to relevant neighbouring, non-equivalent hydrogens, then confirm the assignment with integration and chemical shift.

Representative question

[Maximum number: 1]

Bromoethane shows a signal in the 3.5-4.4 ppm region of its ${ }^{1} \mathrm{H}$ NMR spectrum.

Deduce the splitting pattern of this signal. Use section 21 of the data booklet.

Retrieve the route: translate formulae, identify functional groups and series, name and classify isomers, then use mass, IR, and NMR evidence together to determine structure.

Check connectivity, functional-group evidence, formula/mass constraint, shifts and integration, splitting neighbours, and agreement across every technique.

3.2.11 (HL)—NMR splitting patterns

NMR Splitting Patterns

Inferring Neighbouring Hydrogens

Assessment in practice

Organic Analysis Summary

Question 1