1- Nitropropane mass spectrum

The molecular ion peak for an aliphatic nitro compound is seldom observed. The mass spectrum is the result of fragmentation of the hydrocarbon part of the molecule. However, the mass spectra of nitro compounds may show a moderate peak at mie = 30, corresponding to the NO" ion, and a weaker peak at m e = 46, corresponding to the NOa" ion. These peaks appear in the mass spectrum of 1-nitropropane (Fig. 8.45). The intense peak at m e = 43 is due to the ion. 

FIGURE 4. Neutralization/reionization mass spectrum of [M — C2H4]+ ion of 1-nitropropane ... 

Nitroalkane behavior is illustrated by the mass spectrum of nitropropane. A y-H rearrangement can initiate decomposition, leading to eliminations of OH-or ethylene (Equation 9.50 Hindawi et al. 1986). Although these rearrangements compete poorly with the loss of NO2 from the molecular ion, they retain some significance for structure assignment the presence in the spectrum of an ion at mjz 61 clearly shows that the peak at m/z 72 (the highest mass detected) cannot be due to the molecular ion. Nitroaromatics show characteristic losses of NO... 

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