IR - The -N-H should be apparent. -NH one band, -NH2
two bands (symmetric and asymmetric)
Absorbance (cm-1)
Interpretation
3500 - 3100
NH stretch
1350 - 1000
C-N stretch
1H NMR - The -N-H proton(s) tend
to be broad peaks. N is less electronegative than O so it deshields less.
Resonance (ppm)
Interpretation
0.5 - 5.0 (broad, exchangeable)
-NH proton
1.5 - 3.0
CH2-NR2
13C NMR
C-N typically 35 - 50 ppm (deshielding due to N)
note: the deshielding is less than that observed in alcohols, C-O
= 50 - 65 ppm)
UV-VIS
maxima due to n®s* (190
nm)
n electron from N lone pair
s* antibonding C-N
Mass Spectrometry
Peak for the molecular ion, M+, is usually apparent.
The nitrogen rule : compounds composed of only C, H, O have an even
molecular weight.
If a compound contains an odd number of N atoms will have an
odd
molecular weight. (the Nitrogen rule).
Since N is very good at stabilising positive charge, cleavage at the
b-carbon
are common.
