Mass-spectrometric study of phthalazone, phthalazthione, and their methylation products

1. The mass-spectra of 1(2H)-phthalazone, 1(2H)-phthalazthione, and their oxo (thione) and hydroxy (mercapto) forms, fixed by methylation, were studied. 2. In a comparison of the mass spectra of these compounds with the spectra of a number of their deuteroanalogs, the basic general pathways and characteristic differences of the decomposition of oxy- and thio-derivatives of phthalazine, as well as methylated oxo (thione) and hydroxy (mercapto) forms of phthalazine derivatives, were established.