抄録
Mass spectra (MS) of the condensed diazinecarbonitriles such as2-quinoxalinecarbonitrile(I), 4-quinazolinecarbonitrile(II), 1-methyl-(IIIa), 1-phenyl-1H-pyrazolo[3, 4-d]pyrimidine-4-carbonitrile(IIIb), 9-methyl-(IVa)and9-phenyl-9H-purine-6-carbonitrile(IVb)were examined. The initial fragmentation of I and II is the decomposition of diazine ring, that is, the consecutive losses of cyanogen and hydrogen cyanide or those of hydrogen cyanide and two cyano radicals from the molecular ion(M+). MS of III and IV show the similar patterns. The dissociation pattern of III, the consecutive losses of two hydrogen cyanides or those of hydrogen radical, cyanogen and cyano radical from M+, is almost similar to that of IV except for the little difference between IIIa and IVa in the initial dissociation of pyrazole and imidazole ring. For the stability of ring system caused by the effect of the substituent at the 1-position of III or at the 9-position of IV, the relative intensity of (M-·EH)+and(M-HCN)+· Especies in III a or IVa is greater than that in IIIb or IVb, respectively. The main fragmentation of the condensed pyrimidinecarbonitriles such as II, III and IV, is the initial dissociation ofpyrimidine ring with the loss of cyanogen or hydrogen cyanide.
