Mass-spectra of new heterocycles: XXIV. Electron impact and chemical ionization study of <i>N</i>-[3-alkoxyand 3-(1<i>H</i>-pyrrol-1-yl)-2-thienyl]imidothiocarbamates

Abstract

The behavior of a wide range of previously unknown N -(2-thienyl)imidothiocarbamates synthesized in a single preparative step from heterosubstituted allenes (methoxy-, 1-ethoxyethoxy- and 1 H -pyrrol-1-ylallenes) and aliphatic, cycloaliphatic, and aromatic isothiocyanates was studied under conditions of electron (70 eV) and chemical (reagent gas - methane) ionization. Under the electron impact, the studied compounds form an unstable molecular ion, the main direction of fragmentation of which is associated with the breaking of the C-N bond in the imidoformamide fragment with charge localization at the imine nitrogen atom. A similar decay channel of a molecular ion is also observed in the chemical ionization mass spectra of the studied compounds. In this case, characteristic, but low-intensity ions in the electron ionization spectra of N -(3-methoxy-2-thienyl)imidothiocarbamates become dominant in the chemical ionization spectra. In the chemical ionization spectra of N -[3-(1 H -pyrrol-1-yl)-2-thienyl]imidothiocarbamates, the maximum intensity peak belongs to the [ M - SMe]+ ion. For N -[3-(1-ethoxyethoxy)-2-thienyl]imidothiocarbamate, the peak of the ion formed upon successive elimination of ethoxyethene and methanethiol molecules from the [ M + H]+ ion has the maximum intensity.