1H NMR, 13C NMR and mass spectral studies of some Schiff bases derived from 3-amino-1,2,4-triazole.

Heterocyclic Schiff bases derived from 3-amino-1,2,4-triazole and different substituted aromatic aldehydes are prepared and subjected to (1)H NMR, (13)C NMR and mass spectral analyses. (1)H NMR spectra in DMSO exhibit a sharp singlet within the 9.35-8.90ppm region which corresponds to the azomethine proton. The position of this signal is largely dependent on the nature of the substituents on the benzal moiety. It is observed that the shape, position and the integration value of the signal of the aromatic proton of the triazole ring ((5)C) are clearly affected by the rate of exchange, relaxation time, concentration of solution as well as the solvent used. (13)C NMR is taken as substantial support for the results reached from (1)H NMR studies. The mass spectral results are taken as a tool to confirm the structure of the investigated compounds. The base peak (100%), mostly the M-1 peak, indicates the facile loss of hydrogen radical. The fragmentation pattern of the unsubstituted Schiff base is taken as the general scheme. Differences in the other schemes result from the effect of the electronegativity of the substituents attached to the aromatic ring.