| Date | May 2016 | Marks available | 3 | Reference code | 16M.3.hl.TZ0.26 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain and Identify | Question number | 26 | Adapted from | N/A |
Question
In recent years several antiviral medications have been produced. One of these medications is oseltamivir (Tamiflu).
Identify the functional group circled in the structure of oseltamivir.
Predict the number of signals and relative integration you would expect to see in the nuclear magnetic resonance spectroscopy (1H NMR) spectrum for the circled portion in the structure.
Number of signals:
Relative integration:
Oseltamivir is a chiral compound.
(i) Identify an apparatus that can be used to distinguish between its enantiomers.
(ii) Explain how the differentiation between the enantiomers is obtained using this apparatus.
Markscheme
ether
Do not accept “C-O-C”.
Number of signals: 3 «signals»
Relative integration: 6:4:1
Accept any correct ratio order.
(i)
polarimeter
Accept other alternative techniques such as “GC/HLPC/chromatography using a chiral column”.
Do not accept just “polarizer”.
(ii)
«plane-»polarized light passed through sample
analyzer/second polarizer determines the angle of rotation of the plane of polarized light
OR
each enantiomer will rotate plane «of plane-»polarized light in opposite directions «by the same angle»
Accept explanation related to other alternative techniques such as GC/ HLPC/chromatography using a chiral column.
Award [2] for “(+)/d rotates plane of polarization to the right AND (-)/l rotates plane of polarization to the left”.
