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Date November 2018 Marks available 2 Reference code 18N.2.hl.TZ0.8
Level HL Paper 2 Time zone TZ0
Command term Predict Question number 8 Adapted from N/A

Question

Carbon dioxide contributes significantly to global warming. It can be used as a raw material with methyloxirane to form polymers.

Suggest why the three-membered ring in methyloxirane is unstable.

[1]
a.

Draw two structural isomers of methyloxirane.

[2]
b.i.

State, giving a reason, whether methyloxirane can form cis-trans isomers.

[1]
b.ii.

Predict the chemical shift and splitting pattern of the signal produced by the hydrogen atoms labelled X in the 1H NMR spectrum of the polymer. Use section 27 of the data booklet.

[2]
c.

Markscheme

angle between bonds is 60°/strained/smaller than 109.5° ✔

a.

Any two of:
CH3COCH3

CH3CH2CHO ✔

CH2=CHCH2OH ✔

CH3OCH=CH2

 

Accept displayed or condensed structural formulas or skeletal formulas.

Accept CH(OH)=CHCH3 and CH2=C(OH)CH3.

b.i.

no AND only one «axial/methyl/CH3» substituent «at the ring»

OR

no AND two «axial» substituents required «for cis/trans-isomers» ✔

 

Accept “no AND «O in the ring and» one carbon has two H atoms”.

b.ii.

Chemical shift:
3.7–4.8 «ppm» ✔

Splitting pattern:
doublet ✔

c.

Examiners report

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

Syllabus sections

Additional higher level (AHL) » Topic 21: Measurement and analysis » 21.1 Spectroscopic identification of organic compounds
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Additional higher level (AHL) » Topic 21: Measurement and analysis
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