This is the IR of sulfanilamide. Help me answer the question number 4 please. Ma
ID: 490300 • Letter: T
Question
This is the IR of sulfanilamide. Help me answer the question number 4 please.Mai Luu 30 3500 Wave numbers (cm-1) Tue Feb 21 14:38:41 2017 (GMT 08:00) FIND PEAKS: Spectrum Mai Luu 4000.12 550.10 Region Absolute threshold: 90.107 Sensitivity: 50 Peak list. Position 676.99 Intensity: 49.881 Position: 787.68 Intensity: 54.107 Position: 824.16 Intensity: 50.862 Position 853.23 Intensity: 52.185 Position 922.56 Intensity: 66.371 Position: 1010.25 Intensity: 76.726 Position 1092.59 Intensity: 45.587 Position 1143.98 Intensity: 32.045 1500 1000
Explanation / Answer
Assign the important peaks. The compound is sulfanilic acid and has two free NH2 groups. Primary NH2 groups display two stretching peaks between 3200-3500 cm-1 corresponding to N-H stretching. The spectrum you obtained shows notable peaks at 3462 cm-1 and 3552 cm-1 corresponding to NH2 group. N-H bending vibrations occur around 1600 cm-1 and the compound and the spectrum you obtained shows a noticeable peak at 1595 cm-1 and 1627 cm-1, most likely due to N-H bending vibrations. In both the cases, the vibrations for the N-H group attached to the SO2 group will be slightly shifted to lower wavelengths due to the electronic pull of the SO2 group. C-N vibrations of amine groups are medium intensity peaks occurring between 1100-1350 cm-1 and the spectrum you obtain contains a bunch of peaks in the said region.
Sulfanilic acid is an aromatic compound and the C=C vibrations of aromatic rings occur at 1400-1600 cm-1. These are weak peaks and are often not observed. C-H stretching vibrations occur near 3000 cm-1.
The spectrum you obtained matches the spectrum of sulfanilic acid to a good degree. The intensity of the peaks in the compound you obtained is low possibly because the yield of the product was lower. Moreover, the spectrum you obtained appears to be clean, since there are no interfering peaks due to contaminations.
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