Mass spectra of some 1,2,4-triazole derivatives

Fragmentation of various 1,2,4-triazole derivatives occurs by two predominant pathways involving the loss of RCN originating from both C₃ and C₅ positions. The resulting diazirinium radical cation was observed to lose a nitrogen atom to give a nitrilium ion whose substitution pattern was dependent upon the original substituents in the nucleus.     

Electron ionization induced fragmentation of some oxadiazole and thiadiazole derivatives

The mass spectrometric behaviour under electron ionization of several 3,4-(alkyl/aryl)-disubstituted 1,2,4-oxadiazole-5(4H)-ones (1-13) and 1,2,4-thiadiazole-5(4H)-thiones (14-17), and that of 3-aryl-5-alkyl- or arylthio-1,2,4-thiadiazoles (18-24), was studied. These five-membered rings split similarly to the corresponding 1,2,4-thiadiazole-5(4H)-ones, although substitution has also a clear effect on the routes of fragmentation and the magnitude of secondary processes. In particular, the fragmentation of 1,2,4-oxadiazole-5(4H)-ones (1-6), which do not bear aromatic substituents, was, in addition to the ring ruptures, fairly complicated. The other compounds fragmented more systematically and relatively few unpredictable fragmentations occurred.     

Electron impact fragmentation of some tetramethyl derivatives of thiathrene and phenoxathiin

Mass spectra of thiathrene and three tetramethylthiathrenes (II), (III) and (IV) are reported and discussed. The principal mode of fragmentation of these compounds consists of the loss of sulphur to give the corresponding dibenzothiophene ion. The general pattern of electronolytic decomposition among the tetramethylthianthrenes is, however, much more complex. The mass spectrum of 2,3,7,8-tetramethylphenoxathiin (VI) is also reported and compared with the spectrum of the corresponding thianthrene derivatives.     

Synthesis and antimicrobial activities of some novel 1,2,4-triazole derivatives

In the present investigation, a series of new Schiff bases 4a–f were synthesized by the condensation of N-[(4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-4-substituted-benzamides 3a–b with various substituted aromatic aldehydes in ethanol–dioxane mixture using catalytic amount of sulfuric acid. The starting materials 3a–b were in turn synthesized by the fusion of benzoyl glycine/substituted benzoylglycine with thiocarbohydrazide. Newly synthesized compounds were characterized by IR, NMR, mass spectra and elemental analyses. All the compounds were evaluated for their antibacterial and antifungal activity using the Minimum Inhibition Concentration (MIC) method by serial dilution technique. Few of the compounds were found to be biologically active.     

Electron impact fragmentation of some mixed cyclotetraphosphazenes

The electron impact fragmentations of some cyclotetraphosphazenes are reported and discussed. The major fragmentation path involves loss of two amine radicals and one chlorine radical in the series P₄N₄Cl_8-n(NMe₂)_n when n=2, and subsequent stages involve a ring contraction process with elimination of a P = N fragment, when n = 5 loss of amine radicals predominates on statistical grounds with little evidence of ring contraction. In the series P₄N₄F_8-n(NMe₂)_n fragmentation is dominated by loss of amino radicals when n = 4 and loss of fluorine radicals predominates on statistical grounds when n = 2. In the series P₄N₄F_8-nX_n (n = 2 or 4, X = Cl or Br), when n = 2 and X = Br the major fragmentation path is the loss of two bromine radicals, whereas when X = Cl the more favoured path is the loss of two chlorine radicals. In both, subsequent stages involve ring contraction reactions with elimination of a PN fragment. When n = 4 and X = Br or Cl on bond energy grounds the more favoured fragmentation pattern is the loss of bromine or chlorine radicals, respectively.     

Synthesis of some substituted 1,2,4-triazole and 1,3,4-thiadiazole derivatives

New S-substituted 1,2,4-triazole and 1,3,4-thiadiazole derivatives have been prepared. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1712–1715, November, 2008.     

Chloro derivatives of 1,2,4-triazole

5-Substituted 3-chloro-1,2,4-triazoles were synthesized by diazotization of 5-substituted 3-amino-1,2,4-triazoles in hydrochloric acid. In addition to replacement of the amino group by a chloro group, diazotization of 5-aryl-3-aminotriazoles at high temperatures leads to chlorination of the aromatic ring.Translated from Khimiya Geterotsiklicheskikh Soedinenli, No. 3, pp. 421–423, March, 1976.     

Spectroscopic identification of some derivatives of 3,4-diamino-4H-1,2,4-triazole and 3-Hydrazino-4H-1,2,4-triazole

Spectroscopic methods (ir, ¹H- and ¹³C-nmr, ms and uv) have been used for the structural elucidation and identification of different isomeric 1,2,4-triazole derivatives, obtained by cyclisation reactions from appropriate diaminoguanidines. The four compounds 3,4-diamino-4H-1,2,4-triazole, 3-hydrazino-4H-1,2,4-triazole, 3-amino-4-(2,6-dichlorobenzylideneamino)-4H-1,2,4-triazole and 3-(2,6-dichlorobenzylidenehydrazino)-4H-1,2,4-triazole, were chosen as representative structures to illustrate the general spectroscopic properties for 3,4-diamino- and 3-hydrazino-substituted 4H-1,2,4-triazoles and the corresponding hydrazones, with different substituents in the 5-position of the triazole ring (alkyl-, aralkyl-, mercapto-, hydroxy- and amino-groups). Nmr and uv spectroscopy were found to be the best methods for confirmation of the different series of hydrazones, while ir and nmr were found to be suitable for the structural elucidation of compounds in the series of 3,4-diamino- and 3-hydrazino-4H-1,2,4-triazoles, respectively.     

Electron impact fragmentation of 2-arylhydrazonopropandioic acid derivatives

Examination of the mass spectra of eleven 2-arylhydrazonopropandioic acid derivatives reveals that a radical ion which is tentatively formulated as a 1H-diazirine species is produced in each case (except for the diphenyl este) by more than one process. Formation of what is formally the aryl amine radical ion occurs by a novel hydrogen rearrangement. Simple cleavage of the bonds β to either the aromatic ring or the C?N moiety also produces abundant ions. The diphenyl ester behaves anomalously yielding the phenol ion instead of the amine. The proposed mechanisms were confirmed by metastable studies, deuterium labelling and exact mass measurements.     

Electron impact fragmentation of some cyclohexyl thiophosphororganic amides

This paper presents the mass spectra, fragmentation pathways and structures of ions obtained by electron impact from methyl cyclohexyl phosphinomorpholinylamidothioate (1), cyclohexyl phosphonomorpholinylamidochloridothioate (2), cyclohexyl morpholinylamidophosphonothioic acid (3) and O-methyl cyclohexyl phosphonomorpholinylamidothioate (4). The fragmentation pathways and ion structures were established by exact mass determinations on compound 1 and by metastable transitions of all the compounds.     

Synthesis and biological activities of some fluorine-and piperazine-containing 1,2,4-triazole thione derivatives

A series of fluorine-and piperazine-containing 1,2,4-triazole thione derivatives were synthesized by the Mannich reaction of triazole intermediates with various substituted piperazines and formaldehyde in high yields. Structures of title compounds were confirmed by melting points, IR, ¹H NMR, ¹³C NMR and elemental analysis. The preliminary bioassays for 17 novel title compounds showed that several compounds have significant fungicidal activity against Cercospora arachidicola, Physalospora piricola and Rhizoctonia cerealis at 50μg/mL.     

Electron impact induced fragmentation of dibenzo-18-crown-6 polyether and its nitro derivatives

The mass spectra of dibenzo-18-crown-6 polyether and three of its nitro derivatives have been determined. The fragmentation pathways of all the compounds suggested that ring contraction was taking place. The molecular ion of the polyether dissociated by three competing processes, mainly through loss of C₂H₄O units. The molecular ions of the three derivatives dissociated with ring contraction, as well as through losses of O, No and NO₂.     

Formation of N-vinyl derivatives of 1,2,4-triazole

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, p. 856, June, 1989.