Suggest two absorbances, other than the absorbances due to the ring structure and C–H bonds, that would be present in the infrared (IR) spectrum of aspirin.

State two techniques, other than IR spectroscopy, which could be used to confirm the identity of aspirin.

Any two of:

2500–3000 «cm^–1» / «absorbance» due to O–H in carboxyl

1700–1750 «cm^–1» / «absorbance» due to C=O in carboxyl/ethanoate

1050–1410 «cm^–1» / «absorbance» due to C–O bond in carboxyl/ethanoate

Accept “carboxylic acid” for “carboxyl”, “acetate/ester” for “ethanoate”.

Accept specific wavenumber once within indicated range.

Do not award mark if reference is made to an alcohol/ether.

[2 marks]

Any two of:

melting point

mass spectrometry/MS

high-performance liquid chromatography/HPLC

NMR/nuclear magnetic resonance

X-ray crystallography

elemental analysis

Accept “spectroscopy” instead of “spectrometry” where mentioned but not “spectrum”.

Accept “ultraviolet «-visible» spectroscopy/UV/UV-Vis”.

Do not accept “gas chromatography/GC”.

Accept “thin-layer chromatography/TLC” as an alternative to “HPLC”.

[2 marks]