Structures and energies of the tautomers of 1-nitroso-1,2,4-triazol-5-one-2-oxide: New triazol-5-one-n-oxides

Molecular orbital calculations at the DFT-B3LYP/aug-cc-pVDZ level are performed for the possible tautomers of 1-nitroso-1,2,4-triazol-5-one-2-oxide. We have examined the substitution effects of carbonyl, N-oxide, and nitroso groups by comparing the calculated geometries, relative energies, and electrostatic potentials of model molecules. The optimized structures, vibrational frequencies, and thermodynamic values for triazolone-N-oxides are obtained in the ground state. The results show that 1H, 4H tautomers are most stable. Detonation velocity and detonation pressure are evaluated by the Kamlet-Jacob equations based on the predicted density and the calculated heat of explosion. The explosive properties of the designed compounds seem to be promising compared with those of 1,3,5-trinitroperhydro-1,3,5-triazine (D 8.75 km/s, P 34.70 GPa), octahydro-1,3,5,7-tetrnitro-1,3,5,7-tetrazocine (D 9.10 km/s, P 39.3 GPa), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (D 9.20 km/s, P 42.0 GPa).     

Note on the use of the vacuum stability test in the study of initiation reactivity of attractive cyclic nitramines in Formex P1 matrix

The zero-order reaction rates (specific rate constants) of isothermal decomposition at 120 °C of plastic bonded explosives (PBXs) were measured by means of the Czech vacuum stability test, STABIL. The PBXs are based on 1,3,5-trinitro-1,3,5-triazinane (RDX), 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (BCHMX), and ε 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW, ε-CL-20) with 13 wt% of the Formex P1 type matrix, i.e., a matrix of the explosive with pentaerythritol tetranitrate (PETN) bound by 13 wt% of a mixture of 25 wt% of styrene–butadiene rubber and 75 wt% of an oily material. Dependencies were found between the specific rate constants mentioned and the detonation velocities of PBXs, and consequently between these constants and the impact and electric spark sensitivities of pure explosive fillers, i.e., RDX, HMX, HNIW, BCHMX, and PETN. It is stated that the higher impact or electric spark sensitivity of their pure explosive fillers corresponds to the higher thermal reactivity of the given PBXs.     

DFT study on the structure and detonation properties of amino,methyl, nitro,and nitroso substituted 3,4,5-trinitropyrazole-2-oxides: New high energy materials

The structure, band gap, thermodynamic properties and detonation properties of methyl, amino, nitro, and nitroso substituted 3,4,5-trinitropyrazole-2-oxides are explored using density functional theory at the B3LYP/aug-cc-pVDZ level. It is found that the NH₂ or CH₃ group substitution for the acidic proton at the N4 position of trinitropyrazole-2-oxide (P20) decreases the heat of detonation and crystal density. The density (2.20–2.50 g/cm³), detonation velocity (10.20–10.92 km/s), and detonation pressure (52.30–59.84 GPa) of the title compounds are higher compared with 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), and octanitrocubane (ONC).     

Notes on the use of the vacuum stability test in the study of initiation reactivity of attractive cyclic nitramines in the C4 matrix

The zero-order reaction rates (specific rate constants) for isothermal decomposition at 120 °C of plastic bonded explosives (PBXs) were measured by means of the Czech vacuum stability test, STABIL. The PBXs are based on 1,3,5-trinitro-1,3,5-triazinane (RDX), β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d] imidazole (BCHMX), and ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW, ε-CL-20) with 9 wt.% of the C4 type matrix, i.e., a matrix containing 25 wt.% of polyisobutylene, 59 wt.% of dioctyl sebacate and 16 wt.% of the oil HM46. Dependencies were found between the specific rate constants mentioned and the detonation velocities of the PBXs, and consequently between these constants and the impact of pure explosive fillers, i.e., RDX, β-HMX, ε-HNIW, RS-ε-HNIW, and BCHMX and, at the same time, the corresponding PBXs. The results obtained are compared with those from a recent analogous study of PBXs using an SBR (Formex P1) binder which could increase the PBXs’ reactivity in comparison with C4 matrix. These results also help to dispel a widely held view about HNIW being a relatively sensitive explosive.     

Thermal behavior and decomposition kinetics of Formex-bonded explosives containing different cyclic nitramines

Thermal behavior and decomposition kinetics of Formex-bonded PBXs based on some attractive cyclic nitramines, such as 1,3,5-trinitro-1,3,5-triazinane (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). Actually, cis-1,3,4,6-tetranitrooctahy droimidazo-[4,5-d]imidazole (BCHMX) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10, 12-hexaazaisowurtzitane (CL-20), was investigated by means of nonisothermal thermogravimetry (TG) and differential scanning calorimetry (DSC). It was found that the mass loss rate of PBXs involved in this research depends greatly on heating rate and the residue of the decomposition of these PBXs decreases with the heating rate. The onset of the exotherms was noticed at 215.4, 278.7, 231.2 and 233.7 °C with the peak maximum at 235.1, 279.0, 231.2 and 233.7 °C for RDX-Formex, HMX-Formex, CL-20-Formex, and BCHMX-Formex, respectively. Their corresponding exothermic changes were 1788, 1237, 691, and 1583 J g^?1. It was also observed that the dependence on the heating rate for onset temperatures of HMX- and BCHMX-based PBXs was almost the same due to their similar molecular structure. In addition, based on nonisothermal TG data, the kinetic parameters for thermal decomposition of these PBXs were calculated by isoconversional methods. It was shown that the Formex base has great effects on the activation energy distribution of nitramines. It was further found that the kinetic compensation effects occurred during the thermal decomposition of nitramine-based PBXs, and they almost have the same compensation effects due to similar decomposition mechanism.     

Intermittent compression of N-alkyl-N,N-dimethylamine N-oxides encapsulated in a container with bis[2]catenane topology

Abstract

We report the encapsulation of a homologous series of N-alkyl-N,N-dimethylamine N-oxides in a molecular container with bis[2]catenane topology. N-oxides with short alkyl chains are co-encapsulated with one solvent molecule. Elongation of the alkyl chain from R = methyl to pentyl produced the progressive compression of the guest. The hexyl N-oxide reduces its compression by being singly encapsulated. Longer N-oxides (R = octyl to decyl) had to fold to adapt to the capsule’s dimensions and also experience a progressive compression. The mechanically interlocked nature of the container and the polar functionalisation of its cavity are responsible for the assembly of encapsulation complexes in solution displaying high packing coefficients (0.65–0.70). The high energy conformations adopted by the alkyl chains of the bound N-oxides are deduced from NMR experiments and molecular modelling studies.     

Cyclodextrin-assisted capillary electrophoresis for determination of the cyclic nitramine explosives RDX,HMX and CL-20 comparison with high-performance liquid chromatography

A sulfobutyl ether-beta-cyclodextrin-assisted electrokinetic chromatographic method was developed to rapidly resolve and detect the cyclic nitramine explosives 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and their related degradation intermediates in environmental samples. Development of the electrophoretic method required the measurement of the aqueous solubility of CL-20 which was determined to be 3.59 +/- 0.74 mg/l at 25 degrees C (95% confidence interval, n=3). The performance of the method was then compared to results obtained from existing high-performance liquid chromatography methods including US Environmental Protection Agency method 8330.     

Thermodynamics of formation of β-cyclodextrin inclusion complexes with four series of surfactant homologs

We report on a titration microcalorimetric study of the formation of β-cyclodextrin inclusion complexes with the members of series of anionic, cationic, and nonionic surfactant homologs containing even numbers of carbon atoms in the alkyl chains. n-Alkyltrimethylammonium bromides (C_xTAB, x = 6–16), sodium n-alkyl sulfates (SC_xS, x = 6–12), sodium n-alkanesulfonates (SC_xSN, x = 6–12), and N,N-dimethylalkylamine-N-oxides (DC_xAO, x = 8–12) were selected for use. The stoichiometry, the binding constant, and the changes in enthalpy, entropy, and Gibbs free energy of the complexation reactions were determined at 298 K. It was found in each case that the complexation is favored by both the enthalpy and the entropy changes and that the thermodynamics of the process is affected far more strongly by the length of the alkyl chain than by the nature of the headgroup.     

Preparation of chiral bipyridine bis-N-oxides by oxidative dimerization of chiral pyridine N-oxides

The direct preparation of chiral 2,2′-bipyridine bis-N-oxides has been developed. The method involves two stages, first, the deprotonation of substituted chiral pyridine N-oxides and second, the oxidative dimerization of the resulting 2-lithiopyridine N-oxides. Optimization of the reaction conditions led to the selection of LiTMP in THF for the deprotonation and molecular iodine as the oxidant. The corresponding 2-iodopyridine N-oxide is invariably formed as a by-product. A series of 11 chiral pyridine N-oxides was prepared that bear substituents at the C(2) and C(5) positions. Oxidative dimerization of these mono-N-oxides proceeded in 33–77% yield. In all cases, the dimerization was highly diastereoselective for the formation of the P-configuration of the chiral axis.     

Specificity of 15N NMR chemical shifts to the nature of substituents and tautomerism in substituted pyridine N-oxides

¹H, ¹³C, and ¹⁵N NMR chemical shifts have been measured for 2-aminopyridine N-oxide (1), its eleven derivatives (2–10, 13, 14), and 3-Cl and 3-Br substituted 4-nitropyridine N-oxides (11, 12). δ(¹⁵N) of pyridine ring nitrogen in 2-acetylaminopyridine N-oxides are 5.9–11.5 ppm deshielded from those in 2-aminopyridine N-oxides. When amino and acetylamino substituents are in 4-position, δ(¹⁵N) of ring nitrogen is 21.3 ppm deshielded in the acetylated derivative. The strong resonance interaction between 2-amino and 5-nitro groups reflects in the decrease of amino nitrogen shielding about 5.3–17.9 ppm. Also, ¹H and ¹³C NMR spectral data are in agreement with ¹⁵N NMR results reflected as deshielded amino protons and carbons C-2 and C-5. The pyridine nitrogen chemical shift in all amino- and acetylamino derivatives vary between ?101.2 and ?126.7 ppm, which has been connected with the tautomeric balance in our earlier studies.     

New hybrids of clozapine and haloperidol and their isosteric analogues: synthesis,X-ray crystallography,conformational analysis and preliminary pharmacological evaluation

Schizophrenia is a debilitating mental disorder which affects approximately 1% of the world’s population. Clozapine is an atypical antipsychotic showing unmatched effectiveness in the control of treatment-resistant schizophrenia. Unlike typical antipsychotics, clozapine does not induce extrapyramidal side effects (EPS), tardive dyskinesia or elevate prolactin levels. However, clozapine can induce a potentially fatal blood disorder, agranulocytosis, in 1–2% of patients, severely limiting its clinical use. The model for antipsychotic activity under investigation is based on obtaining a clozapine-like profile with preferential dopamine D₄ and serotonin 5-HT_2A receptor affinity. Profiled herein are three unique members of a series of prospective antipsychotic agents. Compound (I) originated from the structural hybridization of the commercial therapeutics, clozapine and haloperidol, whilst compounds (II) and (III) possess an alternative tricyclic nucleus derived from JL13; a clozapine-like atypical antipsychotic developed by Liégeois et al. These compounds have been synthesized and characterized by means of elemental analysis, IR, ¹H and ¹³C-NMR spectroscopy, MS and X-ray diffraction. Compound (I) crystallizes in space group P(?1) with a = 10.5032(1), b = 10.6261(2), c = 12.6214(3) Å, α = 81.432(1)°, β = 83.292(1)°, γ = 61.604(1)°, Z = 2, V = 1223.62(4) Å³, C₂₈H₂₉ClN₄O, M _r = 473.00, D _c = 1.284 Mg/m³, μ = 0.185 mm^?1, F(000) = 500, R = 0.0506 and wR = 0.1304. Compound (II) crystallizes in the monoclinic space group P2₁/c with a = 10.8212(2), b = 9.3592(2), c = 22.9494(5) Å, β = 106.471(1)°, Z = 4, V = 2228.88(8) Å³, C₂₅H₂₅ClN₄O₂, M _r = 448.94, D _c = 1.338 Mg/m³, μ = 0.202 mm^?1, F(000) = 944, R = 0.0529 and wR = 0.1129. Compound (III) crystallizes in the monoclinic space group P2₁/c with a = 10.5174(2), b = 9.3112(2), c = 24.2949(5) Å, β = 98.666(1)°, Z = 4, V = 2352.03(8) Å³, C₂₅H₂₄Cl₂N₄O₂, M _r = 483.38, D _c = 1.365 Mg/m³, μ = 0.306 mm^?1, F(000) = 1008, R = 0.0478 and wR = 0.1067. The solid state conformations of (I), (II) and (III) exhibit the characteristic V-shaped buckled nature of the respective dibenzodiazepine and pyridobenzoxazepine nuclei with the central seven-membered heterocycle in a boat conformation. The molecules of (I) form a head-to-tail dimeric motif stabilized by hydrogen bonding. The results of a conformational analysis of compounds (I)–(III) investigating the effect of environment (in vacuo and aqueous solution) are presented. These analogues were tested for in vitro affinity for the dopamine D₄ and serotonin 5-HT_2A receptors and their comparative receptor binding profiles to clozapine and JL13 are reported.     

Organocatalytic chemoselective monoacylation of 1,n-linear disulfonamides

Predominant monoacylation of 1,n-linear disulfonamides took place in the presence of pyrrolidinopyridine-type organocatalysts when the chain length of the linear disulfonamides was n = 3, 4, or 5 (monoacylate/diacylate = up to 44). The chemoselectivity of the competitive acylation between N,N′-ditosyl-1,5-pentanediamine (n = 5) and N,N′-ditosyl-1,3-propanediamine (n = 3) was found to be 36, favoring the former substrate. Different chain length by only one carbon atom was discriminated in the competitive acylation between N,N′-ditosyl-1,5-pentanediamine (n = 5) and of N,N′-ditosyl-1,4-butanediamine (n = 4) with the relative acylation rate of 16 in the presence of the organocatalyst.     

Tuning the diglycolamides for modifier-free minor actinide partitioning

The unsymmetrical diglycolamides (DGAs) such as N,N-dihexyl-N′,N′-dioctyl-3-oxapentane-1,5-diamide (DHDODGA), N,N-didecyl-N′,N′-dioctyl-3-oxapentane-1,5-diamide (D²DODGA), N,N-didodecyl-N′,N′-dioctyl-3-oxapentane-1,5-diamide (D³DODGA), were synthesized, and characterized by IR, NMR, and mass spectroscopic techniques. The extraction behaviour of Am(III), Eu(III), and Sr(II) by the solutions of these unsymmetrical DGAs in n-dodecane was studied as a function of concentration of nitric acid and DGA. The distribution ratio of Am(III) and Eu(III) increased with increase in the concentration of nitric acid; whereas, the distribution ratio of Sr(II) reached a maximum at 4 M nitric acid followed by decrease at higher acidities. The extraction of Am(III) and Eu(III) in 0.1 M DGA/n-dodecane decreased in the order DHDODGA > D²DODGA > D³DODGA. However, the order changed upon lowering the concentration of DGA. The third-phase formation behaviour of nitric acid and neodymium(III) in 0.1 M DGA/n-dodecane was studied as a function of concentration of nitric acid. The limiting organic concentration of nitric acid and neodymium increased with increase in the chain length of alkyl group attached to amidic nitrogen. Near stoichiometric amount of neodymium(III) was loaded in 0.1 M D³DODGA/n-dodecane without the formation of third-phase from 3 to 4 M nitric acid medium. The study revealed that the unsymmetrical diglycolamides D²DODGA and D³DODGA are superior candidates for partitioning the minor actinides from high-level liquid waste.     

Cascade Transformations of Trifluoromethanesulfonamide in Reaction with Formaldehyde

Trifluoromethanesulfonamide reacts with paraformaldehyde in acid medium to give both open-chain and cyclic condensation products: bis(trifluoromethylsulfonylamino)methane, N, N-bis(trifluoromethylsulfonylaminomethyl)trifluoromethanesulfonamide, 5-(trifluoromethylsulfonyl)dihydro-1,3,5-dioxazine, 3,5-bis(trifluoromethylsulfonyl)tetrahydro-1,3,5-oxadiazine, 1,3,5-tris(trifluoromethylsulfonyl)hexahydro-1,3,5-triazine, 5,7-bis(trifluoromethylsulfonyl)-1,3,5,7-dioxadiazocane, and 5,7,9-tris(trifluoromethylsulfonyl)-1,3,5,7,9-dioxatriazecane. Amidoalkylation of acetonitrile in the system trifluoromethanesulfonamide-paraformaldehyde-phosphoric acid leads to formation of N-(trifluoromethylsulfonylaminomethyl)acetamide.     

Thermodynamic properties and heat capacities of Co (BTC)1/3 (DMF) (HCOO)

A novel metal organic framework [Co (BTC)_1/3 (DMF) (HCOO)] _n (CoMOF, BTC = 1,3,5-benzene tricarboxylate, DMF = N,N-dimethylformamide) has been synthesized solvothermally and characterized by single crystal X-ray diffraction, X-ray powder diffraction, and FT-IR spectra. The molar heat capacity of the compound was measured by modulated differential scanning calorimetry (MDSC) over the temperature range from 198 to 418 K for the first time. The thermodynamic parameters such as entropy and enthalpy versus 298.15 K based on the above molar heat capacity were calculated. Moreover, a four-step sequential thermal decomposition mechanism for the CoMOF was investigated through the thermogravimetry and mass spectrometer analysis (TG-DTG-MS) from 300 to 800 K. The apparent activation energy of the first decomposition step of the compound was calculated by the Kissinger method using experimental data of TG analysis.     

Structure-Property Relationships in the Basicity and Lipophilicity of Arylalkylamine Oxides

Homologous N,N-dimethyl-phenylalkylamine oxides and N,N-dimethyl-diphenylalkylamine oxides were prepared. Their basicity and lipophilicity (octan-1-ol/H₂O) were compared to those of the parent amines. In contrast to the amines, the basicity of all N,N-dimethyl-arylalkylamine oxides showed very limited pK_a variations (range 4.65 – 5.01) with increasing chain length and number of Ph groups. The N-oxides in their neutral form had a log P^N value lower by 2.77±0.34 (n=9) units than that of the parent amine. The log P^C of the cationic N,N-dimethyl-diphenylalkylamines was lower than that of their neutral form, with a decrement diff(log P^N−C) that increased from 3.25 to 4.21 in the homologous series. Unexpectedly, the decrement diff(log P^N−C) for the N-oxides was much smaller than for the tertiary amines, being 0.23 for the aliphatic N,N-dimethyl-pentylamine oxide, 0.47±0.13 for the phenylalkylamine oxides, and 0.80±0.07 for the diphenylalkylamine oxides. In fact, the protonated N-oxides had log P^C values that were quite comparable to those of the protonated parent amines. Because of the differences in basicity, the difference in distribution coefficients at physiological pH (log D^7.4) between a tertiary arylalkylamine and its N-oxide was 0.82±0.66 (n=9). The pharmacokinetic implication is that N-oxygenation may have a smaller effect on the urinary excretion of tertiary amines than usually assumed.     

Theoretical study on the small carbon nano-ladders

1,3-Butadiyne, 1,3,5-hexatriyne, 1,3,5,7-octatetrayne, and 1,3,5,7,9-decapentayne are small oligomeric forms of acetylene. These oligomers participate in cyclization reactions to form ladder-like structures. Enthalpies, ?H, and Gibbs free energies, ?G, of the cyclization reactions were calculated employing MP2 and B3LYP methods. The calculated ?H and ?G were positive, and their variation versus carbon atoms number, n, was fitted in linear functions as ?H(n) = a+bn. The calculations were performed on the structures with carbon numbers up to 20. Also, consecutive cyclization reactions between acetylene molecules were studied. During these consecutive reactions, two different structures, zigzag-ladder-like and cyclic molecules with tetragonal rings, were produced. Among the cyclic structures, the hexagonal form was the most stable structure. The calculated ?H and ?G of formation of zigzag-ladder-like molecules were excellently fitted in linear functions. The obtained functions for ?H and ?G calculated by MP2 method are ?H(n) = 139.67?126.44n and ?G(n) = 80.987?75.684n, respectively.     

Molecular dynamics simulation studies of the ε-CL-20/HMX co-crystal-based PBXs with HTPB

Molecular dynamics simulations were carried out to explore a ε-CL-20/HMX (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazaisowurtzitane/1,3,5,7-tetranitro-1,3,5,7- tetrazacyclooctane) co-crystal-based polymer-bonded explosive (PBX) with HTPB (hydroxyl-terminated polybutadiene). The binding energies, pair correlation functions, and mechanical properties of the PBXs were reported. From the calculated binding energy, it was found that the order of the binding energies per unit surface between the crystalline surface and HTPB is (0 1 0) > (1 0 0) > (0 0 1). The pair correlation function revealed that the H···O and H···N H-bonds exist on the interfaces between the crystalline surfaces and HTPB, and the number of H???O hydrogen bonds (H-bonds) atom pairs is ten times more than that of H???N H-bonds. Additionally, the calculated mechanical data indicated that the stiffness of the co-crystal/HTPB PBX is weaker and its ductility is better than those of the co-crystal.     

X-ray and computational structural study of neutral <Emphasis Type="Italic">bis</Emphasis>(<Emphasis Type="Italic">N,N,N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-tetramethylthiophosphoramidoyl)-methylamine

The structure of bis(N,N,N′,N′-tetramethylthiophosphoramidoyl)-methylamine 1 has been determined by single-crystal X-ray diffraction. The compound 1 crystallizes in the monoclinic system, with a space group P2₁/c, a = 11.836(2) Å, b = 11.659(2) Å, c = 12.796(5) Å and β = 95.28(3)°, V = 1758.3(5) Å³ and Z = 4. The X-ray crystallographic data have been assessed by semi-empirical and ab-initio density functional theory and by Hartree–Fock molecular orbital methods. A comparative study of the results of the different methods is given.     

Synthesis,crystal structure,and thermodynamics of a high-nitrogen copper complex with <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-bis-(1(2)H-tetrazol-5-yl) amine

A new high-nitrogen complex [Cu(Hbta)₂]·4H₂O (H₂bta = N,N-bis-(1(2)H-tetrazol-5-yl) amine) was synthesized and characterized by elemental analysis, single crystal X-ray diffraction and thermogravimetric analyses. X-ray structural analyses revealed that the crystal was monoclinic, space group P2(1)/c with lattice parameters a = 14.695(3) Å, b = 6.975(2) Å, c = 18.807(3) Å, β = 126.603(1)°, Z = 4, D _c = 1.888 g cm^?3, and F(000) = 892. The complex exhibits a 3D supermolecular structure which is built up from 1D zigzag chains. The enthalpy change of the reaction of formation for the complex was determined by an RD496–III microcalorimeter at 25 °C with the value of ?47.905 ± 0.021 kJ mol^?1. In addition, the thermodynamics of the reaction of formation of the complex was investigated and the fundamental parameters k, E, n, \( \Updelta S_{ \ne }^{{{\uptheta}}} \), \( \Updelta H_{ \ne }^{{{\uptheta}}} \), and \( \Updelta G_{ \ne }^{{{\uptheta}}} \) were obtained. The effects of the complex on the thermal decomposition behaviors of the main component of solid propellant (HMX and RDX) indicated that the complex possessed good performance for HMX and RDX.