Picryl derivatives of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one

Treatment of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one ( 1 ) with picryl fluoride (PkF) in 1-methyl-2-pyrrolidinone (NMP) gave a mixture of a monopicryl and a dipicryl derivative of 1 in a ratio of 2 :1 , respectively, regardless of the initial concentrations of 1 and PkF. The products were identified as 5-nitro-2-picryl-2,4-dihydro-3H-1,2,4-triazol-3-one ( 2 ) by X-ray crystallography and 5-nitro-2,4-dipicryl-2,4-dihydro-3H-1,2,4-triazol-3-one ( 4 ) by ¹⁵N labeling experiments.     

A density-functional theory investigation of 3-nitro-1,2,4-triazole-5-one dimers and crystal

Density-functional method with different basis sets was applied to the study of the highly efficient and low sensitive explosive 3-nitro-1,2,4-triazole-5-one (NTO) in both gaseous dimer and its bulk state. The binding energies have been corrected for the basis set superposition errors. Six stable dimers (II-VII) were located. The corrected binding energy of the most stable dimer VII is predicted to be -53.66 kJ/mol at the B3LYP/6-311++G(**) level. It was found that the structures of the more stable dimers (V-VII) are through the hydrogen bonding interaction between the carbonyl oxygen and the azole hydrogen of 3-nitro-1,2,4-triazole-5-one. The changes of Gibbs free energies (DeltaG) in the processes from the monomer to the dimers at 298.15 K are 8.51, 0.90, 0.35, -8.74, -10.67, and -11.06 kJ/mol for dimers from II to VII, respectively. Dimers V-VII, possessing cyclic structures, can be spontaneously produced from the isolated monomer at room temperature. The lattice energy is -156.14 kJ/mol, and this value becomes to -150.43 kJ/mol when a 50% correction of the basis set superposition error was adopted. The frontier bands are quite flat. Judged from the value of band gap of 4.0 eV, it may be predicted that 3-nitro-1,2,4-triazole-5-one is an insulator. Most atoms in NTO, with the exception of C(5) atom and the nitro atoms, make up the upper valence bands. In contrast, the lower conduction bands mainly consist of the nitro N and O atoms. The population of the C-NO(2) bond is much less than those of the other bonds and the detonation may be initiated by the breakdown of this bond.     

Kinetics of 2,4-dihydro-1,2,4-triazol-3-one nitration in nitric acid

The kinetics and mechanism of 2,4-dihydro-1,2,4-triazol-3-one nitration in nitric acid have been studied. The role of 2-nitro-2,4-dihydro-1,2,4-triazol-3-one as an intermediate has been determined.     

Condensation of 5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione with haloacetic acids

Reactions of triazolethiones with haloacetic acids were studied with 5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione as an example. It was proved for the first time by X-ray diffraction that the cyclocondensation of these compounds proceeds regiospecifically to give 2-(4-methylphenyl)[1,3]thiazolo[3,2-b][1,2,4]triazol-6(5H)-one rather than its isomer 3-(4-methylphenyl)[1,3]thiazolo[2,3-c][1,2,4]triazol-5(6H)-one.     

4-氨基-5-烃基-2,4-二氢-3H-1,2,4-三唑-3-硫酮席夫碱的简便合成

近年来,人们发现标题类杂环席夫碱能发生很多新颖的反应,且其中许多具有强的生物活性［１～７］．但其制备多以乙醇为反应介质,以酸或碱为催化剂,反应需经数小时,后处理也比较麻烦．本文报道了题示席夫碱的一种极为简便的合成方法,反应介质选用低级的脂肪酸（如冰醋...     

1-苯基-5-芳基-1,2-二氢-1,2,4-三唑-3-硫酮的合成

将取代苯甲酰氯1a～1f与硫氰酸钾反应, 得到的中间体不需纯化直接与苯肼反应, 成功地合成了1-苯基-5-芳 基-1,2-二氢-1,2,4-三唑-3-硫酮(2a～2f). 化合物2的结构通过红外光谱、核磁共振光谱和高分辨质谱进行了表征.     

Synthesis and properties of energetic salts based on 3-nitro-5-nitroimino-1,2,4-oxadiazole

A series of 3-nitro-5-nitroimino-1,2,4-oxadiazole-based energetic salts were synthesized from 3-nitro-5-nitroimino-1,2,4-oxadiazole anion and nitrogen-rich cations. They were fully characterized by IR,elemental analysis and NMR spectroscopy. The structure of triaminoguanidinium salt(1-e) was confirmed by single crystal X-ray diffraction. All salts showed good thermal stability with decomposed temperature ranging from 155 8C to 258 8C, and positive heats of formation from 226.0 k J/mol to554.1 k J/mol. Thus, the theoretic detonation pressure was predicted from 28.70 GPa to 37.60 GPa and velocities from 8526 m/s to 9354 m/s. Among them, guanidinium salt(1-c) exhibited both high decomposition temperature(258 8C) and detonation velocity(9319 m/s).     

Synthesis and characterization of energetic 3-nitro-1,2,4-oxadiazoles

All new: 3-Nitro-5-guanidino-1,2,4-oxadiazole (NOG) was synthesized from diaminoglycoluril with in situ generated dimethyldioxirane (DMDO). The impact sensitivity of NOG is more than 40?J with a decomposition temperature of 290?°C. Some other energetic derivatives have been prepared and characterized.     

Effect of 2,4-dihydro-3H-1,2,4-triazole-3-thiones and thiosemicarbazones on iodide uptake by the mouse thyroid: the relationship between their structure and anti-thyroid activity.

Antithyroid activity of 2,4-dihydro-3H-1,2,4-triazole-3-thiones and thiosemicarbazones was tested by measuring the uptake ratio of thyroid: serum (T/S) of 125I through the mouse thyroid. Substitution with an alkyl group at the 5-position of the triazole nucleus remarkably increased the activity but substitution at the N-2 and/or N-4 positions caused a significant decrease in the activity, indicating the necessity of unsubstituted thioureylene moiety for the antithyroid activity. Thiosemicarbazone derivatives which are an open ring structure of triazoles showed comparable antithyroid activities to those in a ring form, but one thiosemicarbazone showed a much higher toxicity than the corresponding ring form compound. This suggests that the ring structure is not essential for the activity but is necessary to reduce toxic effect. Of fourteen compounds tested, 5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-thione was the most potent antithyroid compound with low toxicity, with a potency tenfold that of propylthiouracil, a drug currently used.     

5-amino-3,4-dihydro-2h-1,2,4-triazole-3-thiones. synthesis and chemosensor properties

The reaction of 4-arylalkyl- and 4-arylthiosemicarbazides with aroyl isothiocyanates gave substituted 1,2-bis(thiocarbamoyl)hydrazines, which readily cyclize to give previously unreported 4-aroyl 5-arylalkyl- and 4-aroyl-5-arylamino-2H-1,2,4-triazole-3-thiones, respectively. A spectral study of 9-anthrylmethylthiosemicarbazides and derived dihydrotriazolethione indicated the chemosensor activity of these compounds relative to a cation series.     

Application of ab initio molecular dynamics for a priori elucidation of the mechanism in unimolecular decomposition: the case of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO).

We have tested a new and general approach for the theoretical study of unimolecular decomposition. By combining the power of the ab initio molecular dynamics (MD) and ab initio molecular orbital (MO) methods, our approach requires no prior experimental knowledge or intuitive assumptions about the decomposition. Instead, the reaction channels are first sampled theoretically by simulating a molecule at high temperature in a number of trajectories, using the density functional theory (DFT) based ab initio MD method with a planewave basis set and pseudopotentials. Each type of these channels is then further examined by well-established ab initio MO method to locate the energy barrier and transition structure and to verify the ab initio MD results. The power of such an approach is demonstrated in a case study for the complicated unimolecular thermal decomposition of NTO (5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one), with several interesting new features uncovered. The C-NO2 homolysis is indeed the dominant channel at high temperature, while the departing NO2 could capture a H atom from the NTO ring to form HONO, by either a concerted bond breaking mechanism or by a bimolecular reaction between the NO2 group and the triazol ring. At lower temperature, the dissociation channels initiated by hydrogen migrations should be activated first. The channel with hydrogen migration followed by ring opening and then by HONO loss has an energy barrier of 38.0 kcal/mol at the rate-determining step, being the lowest among all the investigated dissociation paths and much lower than previously thought. The energy barrier for nitro-nitrite rearrangement is lower than that for the C-NO2 homolysis but makes only a minor contribution due to the entropy factor. And the NTO ring could rupture in the two C-N bonds connected to the carbonyl carbon, and the energy barriers for such processes are only 2-4 kcal/mol higher than that for the C-NO2 homolysis.     

Reactions of sulfur monochloride with some aromatic aldehyde semicarbazones and thiosemicarbazones: New syntheses of substituted 2,4-dihydro-1,2,4-triazol-3-ones, 2,4-dihydro-1,2,4-triazole-3-thiones and 2-amino-1,3,4-oxadiazoles

Treatment of various substituted semicarbazones of aromatic aldehydes with sulfur monochloride yields the corresponding substituted 2,4-dihydro-1,2,4-triazol-3-ones. With thiosemicarbazones, the products are derivatives either of the 2-amino-1,3,4 thiadiazole or of the 2,4-dihydro-1,2,4-triazole-3-thione depending on the experimental conditions.     

Thermal properties of 1,2,4-triazole-3-one and copper nitrate mixtures

1,2,4-Triazole-3-one (TO) is anticipated to have applications as a high performance alternative gas generating agent, while basic copper nitrate (BCN) is typically used as the oxidizing agent in air bag systems. In order to obtain a better understanding of the thermal properties of TO/BCN mixtures, thermal behavior was investigated using the differential scanning calorimetry. Mixtures of TO with copper, copper oxide, and trihydrated copper nitrate (Cu(NO₃)₂·3H₂O) were also examined for comparison purposes. Samples were prepared at TO/BCN ratios (on a per mass basis) of 10/0, 7/3, 5/5, 3/7, 2/8, 1.6/8.4, 1/9, and 0/10. The endothermic onset temperatures for TO/BCN mixtures were lower than those for either pure TO or pure BCN. TO/BCN mixtures exhibited an initial exothermic peak immediately after an endothermic peak, in the range of 219–234 °C. TO/BCN mixtures with ratios of 3/7, 2/8, 1.6/8.4, and 1/9 displayed a second series of exothermic peaks in the range of 260–300 °C, which appear to result from the oxidation–reduction reaction of previously formed intermediate species with NO₂ and NO generated by unreacted BCN. The TO/CuO mixtures are believed to undergo reaction between molten TO and CuO at approximately 230 °C. In general, the presence of copper was shown to be effective at promoting the decomposition of TO. The reaction between TO and Cu(NO₃)₂·3H₂O seems to be initiated by the melting of Cu(NO₃)₂·3H₂O, following which TO reacts with nitric acid resulting from the dissociation of Cu(NO₃)₂·3H₂O. Overall, the triggering event for the reaction between TO and each of the copper nitrate species is a phase change of one of the two mixture components.     

Synthesis of new derivatives of 4-amino-2,4-dihydro-1,2,4-triazol-3-one as potential antibacterial agents

Thirty new 2-substituted-4-amino-5-alkyl or aryl-2,4-dihydro-1,2,4-triazol-3-ones and ten 2-substituted-5-alkyl or aryl-4-(5-nitro-2-furfurylidene)amino-2,4-dihydro-1,2,4-triazol-3-ones were synthesized and characterised by their sharp melting points, elemental analysis, ir and ¹H nmr spectra. These new derivatives of 5-nitro-2-furaldehyde were screened for their antibacterial activities. Most of the compounds showed good activity against one test organism, Staphylococcus aureus. For a few compounds, C.M.I. ranged from 4 to 8 μg/ml (higher results than nitrofurantoin).     

Thermal decomposition properties of 1,2,4-triazole-3-one and guanidine nitrate mixtures

1,2,4-triazole-3-one (TO) and guanidine nitrate (GN) have the potential to be used as alternative gas-generating agents. To obtain a better understanding of thermal decomposition properties of TO/GN mixtures, sealed cell differential scanning calorimetry, thermogravimetry–differential thermal analysis–infrared spectroscopy (TG–DTA–IR), and thermogravimetry–differential thermal analysis–mass spectrometry (TG–DTA–MS) were carried out. The endothermic peak and onset temperatures of TO/GN mixtures were lower than those of individual TO and GN. TG–DTA–IR and TG–DTA–MS showed that the mass of TO/GN mixtures decreased with heat generation and N₂ evolved as the major gas during thermal decomposition. The interaction between TO and nitric acid from the dissociation of GN is proposed for the thermal decomposition of TO/GN mixtures.     

Thermal behavior and evolved gases analysis of 1,2,4-triazole-3-one derivatives

In order to obtain a better understanding of thermal substituent effects in 1,2,4-triazole-3-one (TO), the thermal behavior of 1,2,4-triazole, TO, as well as urazole and the decomposition mechanism of TO were investigated. Thermal substituent effects were considered using thermogravimetry/differential thermal analysis, sealed cell differential scanning calorimetry, and molecular orbital calculations. The onset temperature of 1,2,4-triazole was higher than that of TO and urazole. Analyses of evolved decomposition gases were carried out using thermogravimetry–infrared spectroscopy and thermogravimetry–mass spectrometry. The gases evolved from TO were determined as HNCO, HCN, N₂, NH₃, CO₂, and N₂O.     

Trinitromethyl-substituted 5-nitro- or 3-azo-1,2,4-triazoles: synthesis, characterization, and energetic properties

Various new polynitro-1,2,4-triazoles containing a trinitromethyl group were synthesized by straightforward routes. These high nitrogen and oxygen-rich compounds were fully characterized using IR and multinuclear NMR spectroscopy, elemental analysis, natural bonding orbital (NBO) analysis, and differential scanning calorimetry (DSC) and, in the case of 12, with single crystal X-ray structuring. The heats of formation for all compounds were calculated with Gaussian 03 (revision D.01) and then combined with experimentally determined densities to determine detonation pressures (P) and velocities (D) of the energetic materials (Cheetah 5.0). They exhibit high density, good thermal stability, acceptable oxygen balance, positive heat of formation, and excellent detonation properties, which, in some cases, are superior to those of TNT, RDX, and HMX.