The molecular ion peak is usually too weak to be observed. However, the loss of hydrogen radical will almost always produce an observable peak. For nitriles then, the M - 1 peak is usually more prominent than the M+ peak (see figure 53).
Figure 53. Loss of hydrogen radical.
McLafferty rearrangement can take place for nitriles (see figure 54).
Figure 54. McLafferty rearrangement of a nitrile.
The complete mass spectrum for pentanenitrile is given in figure 55, which illustrates most of these points.
Figure 55. Mass spectrum for pentanenitrile.
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