Mass-spectra of new heterocycles: XXV. electron impact study of <i>N</i>-[5-amino-2-thienyl]thioureas

Abstract

The mass spectra of previously unknown N -(5-amino-2-thienyl)thioureas obtained in one preparative step from propargylamines and isothiocyanates were studied for the first time, and the main patterns of their fragmentation under electron ionization conditions (70 eV) were revealed. All thienylthioureas studied form a molecular ion ( I rel 7-61%), whose general direction of fragmentation {with the exception of N -[5-(diethylamino)-2-thienyl]- N , N '-diphenylthiourea} is the breaking of the R1N-C(=S) bond with the formation of the [ M - R2NHCS]+ ion, the peak of which has a high intensity ( I rel 35-85%). The dominant direction of fragmentation of the molecular ion N -[5-(diethylamino)-2-thienyl]- N , N '-diphenylthiourea is associated with the degradation of the thiophene cycle by C2-S and C4-C5 bonds. For N -(5-pyrrolidine-1-yl-2-thienyl)- and N -(5-piperidine-1yl-2-thienyl)thioureas are characterized by the course of intensive specific rearrangement processes, manifested in the appearance of unexpected channels of primary fragmentation of the molecular ion, the main of which is the elimination of the molecule N , N '-dimethylcarbodiimide.