Mass spectra and structure in the gas phase of isomeric 2-aroylbenzamides

The electron-impact mass spectra of various derivatives of 2-aroylbenzamides were studied. The principal pathways of fragmentation of the open and ring isomeric forms were described on the basis of an analysis of the high-resolution spectra and the DADI spectra. It is shown that peaks of ions formed in the fragmentation of the ring form, the intensities of which decrease as the volume of the substituent increases, are observed in the spectra of compounds with substituents R¹ = H, CH₃, and C₂H₅. Thermal isomerization of the ring form was proved on the basis of a study of the temperature effect on the intensities of the peaks of ions due to fragmentation of the open and ring forms when the samples are introduced through an inlet cylinder.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 666–670, May, 1982.