Question

Infrared Unit 1500

Need help with identifying structure please.

Answer 1

Here we can apply method of elimination. Looking at the IR spectrum, we can predict that compound conains either O-H stretch or N-H stretch, C-H stretch and C=C stretch (aromatic).

Firstly, there is no peak at 2260-2220 cm^-1 is present, so no C$\equiv$N stretch, thus those compounds having CN functional groups can be eliminated.

Secondly, there is no peak at 1700 cm^-1 is present, so no C=O stretch, thus those compounds having -CO functional groups can be eliminated.

Thirdly, there is band at 1500 cm^-1 corresponding to C=C stretch, the compounds without C=C can be eliminated.

Finally, there is band at 3350 cm^-1 corresponding to either O-H or N-H stretch, the compounds without O-H or N-H can be eliminated.

Wavenumber (cm^-1) Functional group Vibration (stretch/Bend) Intensity (s, m, w)

3350 N-H stretch m

3030 C-H stretch m

1600 NH₂ bend s

1500 C=C stretch s

From this data, the IR spectrum of unknown compound is Aniline.

Structure of aniline:

Atiline Ime