ELECTRON IONISATION MASS SPECTRA OF SOME 
5-(2-PHENYLTHIAZOL-4-YL)-3-MERCAPTO-[1,2,4]TRIAZOLE AND
5-(2-PHENYL-4-METHYLTHIAZOL-5-YL)-3-MERCAPTO-[1,2,4]TRIAZOLE DERIVATIVES

N. Palibroda1, Z. Moldovan1, A. Pamula1, V. Zaharia2

1National Institute for Research and Development of 
Isotopic and Molecular Technologies Cluj-Napoca
2“Iuliu Hatieganu” University of Medicine and Pharmacy
Cluj-Napoca

The mass spectra under electron ionisation of some derivatives of 5-(2-phenylthiazol-4-yl)-3-mercapto-[1,2,4]triazole and 5-(2-phenyl-4-methylthiazol-5-yl)-3-mercapto-[1,2,4]triazole were investigated. 
Some of the derivatives were open thioethers, while other derivatives showed a cyclic thiazolyl-thiazolo[3,2-b][1,2,4]triazole structure. A total of seven structure groups were investigated. Open thioeters had four structure groups based as well on the 5-(2-phenylthiazol-4-yl)-triazole as on the 5-(2-phenyl-4-methylthiazol-5-yl)-triazole. The other three structure groups were based on the thiazolyl-thiazolo[3,2-b][1,2,4]triazole closed ring system having different substituents.
Mass spectra were recorded on a MAT 311 mass spectrometer with EI ion source, using the direct inlet probe under temperature programming of the sample crucible from room temperature to 300 oC. 
Molecular ions were present, representing in some cases the base peak of the spectrum. 
The abundance of fragment ions is strongly dependent on the structure of the compound. In compounds having acetyl substituents m/z 43 is always very intense and at the high mass end M - 42 ions dominate the spectrum. In the case of multiple substitution up to three consecutive losses 42 and 43 mass units could be observed.
As a rule, fragmentation of the single bond between the phenyl group and the rest of the molecule produced medium intensity ions with m/z = 77 but never M - 77 ions. Fragmentation of the single bond between the thiazole and the triazole rings was not observed, but instead a double fragmentation of the N-C and C-S in the thiazole ring did appear, producing characteristic ions with mass M - 103.
In the open thioether structures fragmentation of the sulphur bonds produced also characteristic ions.
Ion compositions were verified by exact mass determinations under high resolution R = 5000.