IB Chemistry HL 3.2.12 Hl Combined Data Analysis Questions

Combine molecular, mass-spectral, infrared and ¹H NMR clues to constrain a formula, compare candidate structures and justify the final identification.

Exam points

Extract diagnostic structural or spectral features from mass spectrometry, IR and ¹H NMR data, including molecular ions, functional-group absorptions and proton environments.
Combine independent mass, IR and ¹H NMR observations to constrain the molecular formula and compare candidate structures.
Justify the final structure or identity by reconciling all available techniques and ruling out alternatives that fail one of the observations.

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This question is about carbon and chlorine compounds.

The mass and ${ }^{1} \mathrm{H}$ NMR spectra of product X are shown below. Deduce, giving your reasons, its structural formula and hence the name of the compound.

Mass spectrum:

Figure for Question IB Chemistry HL 3.2.12 Hl Combined Data Analysis Questions question 1 — IB Chemistry HL

${ }^{1} \mathrm{H}$ NMR spectrum:

molecular ion peak(s) about m/z 100 AND so $\mathrm{C}_{2}\mathrm{H}_{4}\mathrm{Cl}_{2}$ (isotopes of Cl)

two signals in ${ }^{1} \mathrm{H}$ NMR spectrum AND so $\mathrm{CH}_{3}\mathrm{CHCl}_{2}$

OR

signals in 3:1 ratio in ${ }^{1} \mathrm{H}$ NMR spectrum AND so $\mathrm{CH}_{3}\mathrm{CHCl}_{2}$

OR

one doublet and one quartet in ${ }^{1} \mathrm{H}$ NMR spectrum AND so $\mathrm{CH}_{3}\mathrm{CHCl}_{2}$

1,1-dichloroethane

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IB Chemistry HL 3.2.12 Hl Combined Data Analysis Questions question 1