Benzonitrile mass spectrum

No evidence is available which indicates whether the neutral fragment eliminated in (1) is cyanic, isocyanic, or even fulminic acid or whether the neutral fragment eliminated in (3) is phenyl isocyanide or benzonitrile. These features of the mass spectrum of... 

A benzenoid ylid has been recently generated in the gas phase by collisional reduction of an ylid isomer of benzonitrile cation-radical [154]. Dissociative ionization of o-cyanobenzaldehyde produced a cation-radical (36+ ) that was distinguished by ion-molecule reactions from its conventional [benzonitrile]+ isomer. In particular, 36+ reacts with tert-butylnitrite by NO transfer to form 2-nitrosobenzonitrile, while [benzonitrile] reacts by proton transfer. Collisional reduction of 36 provided a +NR+ mass spectrum that was distinctly different from that of benzonitrile (Fig. 7). 

On being heated, the oxadiazoles (39, 40) both yielded phenyl isocyanate and benzonitrile, but only the mass spectrum of (39) showed strong peaks corresponding to these pyrolysis products at m/e 103, 119 (J. L. Cotter and Knight, 1966). 

Jones and Paisley have reported the ionic and thermal fragmentation of 4,6-diphenyl-l,2,3,5-oxathiadiazine-2,2-dioxide, 26. Thermal decomposition of 26 in the solid state leads to formation of benzonitrile and a brown-colored intractable glass. The major ionic decomposition pathways for 26 are shown in Eq. (17). The failure of 26 to eliminate SO 2 on thermolysis lysis may reflect a heteroatom effect it may also be due to a medium effect with the SO 2 being trapped before it could escape the solid. It should be noted that the only volatile pyrolysis product, benzonitrile, appears as an intense ion, mfe 103, in the mass spectrum of 26. 

The strongest peak in the mass spectrum of an aromatic nitrile is the molecular ion peak. Loss of cyanide occurs, giving, in the case of benzonitrile (Fig. 8.44), the ion at mIe = 77. More important fragmentation involves loss of the elements of hydrogen cyanide. In benzonitrile, this gives rise to a peak at mie = 76. 

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