GENERAL INFORMATION ON NITRO COMPOUNDS 171la (with hydrogen bonds)IIa (with hydrogen bonds)Consequently the absorption curves of compounds I and II do not contain
maxima but only shoulders (Fig. 40). They are shifted towards longer wavelength
(bathochromic effect) as compared with the original nitroparaftlns.i
FIG. 40. Absorption spectra of nitroparaffins (I), and nitrodiols and aliphitic
aminonitro compounds (II) (T. Urbanski [ll]).
Thus 1-nitropropane shows a maximum at 270 mμ, and the diol (I) obtained
from the same compound by adding 2 mol. of formaldehyde shows a bend at 280mμ.
A shift of 8-20 mμ was also observed on the corresponding conversion of
other nitroparaffins to nitrodiols.
It is important to note that two hydroxyl groups reduce the intensity of the
absorption maximum of one nitro group and transform it into a shoulder. One