Topic 21: Measurement and analysis - 21.1 Spectroscopic identification of organic compounds

Nature of science: Improvements in modern instrumentation-advances in spectroscopic techniques (IR, 1H NMR and MS) have resulted in detailed knowledge of the structure of compounds. (1.8)


Essential idea: Although spectroscopic characterization techniques form the backbone of structural identification of compounds, typically no one technique results in a full structural identification of a molecule.

Structural identification of compounds involves several different analytical techniques including IR, 1H NMR and MS.

In a high resolution 1H NMR spectrum, single peaks present in low resolution can split into further clusters of peaks.

The structural technique of single crystal X-ray crystallography can be used to identify the bond lengths and bond angles of crystalline compounds.

Applications and skills

Explanation of the use of tetramethylsilane (TMS) as the reference standard.

Deduction of the structure of a compound given information from a range of analytical characterization techniques (X-ray crystallography, IR, 1H NMR and MS).


Students should be able to interpret the following from 1H NMR spectra: number of peaks, area under each peak, chemical shift and splitting patterns. Treatment of spin-spin coupling constants will not be assessed but students should be familiar with singlets, doublets, triplets and quartets.

High resolution 1H NMR should be covered.