100 hiiai.#44 90 85 E75 70 65 60 C-o 4000 3500 3000 2500 2000 1500 1000 Wavenumb

Question

100 hiiai.#44 90 85 E75 70 65 60 C-o 4000 3500 3000 2500 2000 1500 1000 Wavenumbers (cm-1) Mon Nov 07 14:52:19 2016 (GMT-08:00) FIND PEAKS mai, #44 4000.12 Spectrum: Region Absolute threshold: 99.648 Sensitivity Peak list 550.10 50 Position: 668.44 Intensity: 95.830 Position: 923.11 Intensity: 95.234 Position: 944.66Intensity: 95.267 Position: 1041.37Intensity: 84.800 Position: 1148.66 Intensity: 87.700 Position: 1168.87 Intensity: 85.633 Position: 1219.36 Intensity: 94.693 Position: 1294.29 Intensity: 90.530

Explanation / Answer

Interpretation of spectra

IR

1709 cm-1 for C=O stretch

2850-2950 cm-1 for aliphatic C-H stretch

NMR

0.9 ppm (6H) for CH3's

2.1 ppm (4H) for CH2's next to an C=O group

The molecule is symmetrical with 6 : 4 or 3 : 2 ratio of CH3 and CH2

Possible compound structures

3-pentanone (with CH3 : CH2 = 6 : 4)

4-heptanone (with CH3 : CH2 = 6 : 4)

Absence of aromatic peaks in IR and NMR tells acetophenone absent

Symmetry in NMR spectra shows, 2-pentanone, 2-butranone, 2-heptanone, 2-hexanone, 4-methylpentanone, diisobutyl ketone are all absent.

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