| Date | May 2017 | Marks available | 2 | Reference code | 17M.3.hl.TZ2.20 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | State | Question number | 20 | Adapted from | N/A |
Question
Aspirin is one of the most widely used drugs in the world.
Aspirin was synthesized from 2.65 g of salicylic acid (2-hydroxybenzoic acid) (Mr = 138.13) and 2.51 g of ethanoic anhydride (Mr = 102.10).
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.
Markscheme
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]
