Mass spectra of substituted pyrazolo[1,5‐a]‐1,3,5‐triazines

High resolution electron impact mass spectrometric measurements have been made on twelve pyrazolo[1,5‐a]‐1,3,5‐triazines. Substituents attached to carbon atoms 2, 4, 7, and 8 were used to label the various fragments. Three major ions were observed (a) the molecular ion, (b) an ion corresponding to M‐RCN where R is the substituent attached to C‐4 and (c) an aryl cyclopropenyl cation which was observed in 7‐aryl derivatives. Intensities and accurate mass‐measurements are given for all ions having intensities exceeding 2% of the base peak. Nine of the twelve pyrazolo‐[1,5‐a]‐1,3,5‐triazines included in this study are described here for the first time