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Date May 2016 Marks available 2 Reference code 16M.3.hl.TZ0.26
Level HL Paper 3 Time zone TZ0
Command term Predict 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.

[1]
a.

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:

[2]
b.

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.

[3]
c.

Markscheme

ether

Do not accept “C-O-C”.

a.

Number of signals: 3 «signals»

Relative integration: 6:4:1

Accept any correct ratio order.

b.

(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”.

 

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Core » Topic 11: Measurement and data processing » 11.3 Spectroscopic identification of organic compounds
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