| Abstract: | The mass spectra of 18 substituted 1-(p-R2-phyeyl)-3-R3-4-(p-R1-phenylimino)-2-pyrazolin-5-ones have been obtained. The major cleavages under electron bombardment take place in the pyrazoline nucleus, producing four major fragment ions whose abundance is related primarily to the electronic properties of R1. These ions appear to be produced from the molecular ion via an intermediate formed by the loss of CO. In most instances metastable ions are observed for the overall decomposition of the molecular ion to the four major fragment ions. A mechanism is proposed for these cleavages. |
