CAIE A-Level Chemistry A2 37.3.2 Carbon 13 Nmr Peak Count Questions

Practise predicting carbon-13 NMR peak counts by grouping equivalent carbons through molecular symmetry.

Exam points

label every carbon in the structure and group carbons related by molecular symmetry into one environment
count one 13C peak per distinct environment, not one per carbon atom or carbon type name
compare isomers by finding the symmetry change that makes their predicted peak counts different

[Maximum number: 1]

Asparagine is an amino acid that contains a chiral carbon atom and displays stereoisomerism.

Separate samples of asparagine are dissolved in $\mathrm{CDCl}_{3}$ and analysed using carbon-13 and proton $\left({ }^{1} \mathrm{H}\right)$ NMR spectroscopy.

Fig. 6.1

Predict the number of peaks seen in the carbon-13 and proton ( ${ }^{1} \mathrm{H}$ ) NMR spectra of asparagine.

Table for Question CAIE A-Level Chemistry A2 37.3.2 Carbon 13 Nmr Peak Count Questions question 1 — CAIE A-Level Chemistry A2

	carbon-13 NMR	proton NMR
number of peaks in $\mathrm{CDCl}_{3}$	4	5

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CAIE A-Level Chemistry A2 37.3.2 Carbon 13 Nmr Peak Count Questions question 1