Enhancing Energetic Properties and Sensitivity by Incorporating Amino and Nitramino Groups into a 1,2,4‐Oxadiazole Building Block

A single nitrogen‐rich heterocyclic ring with many energetic groups is expected to exhibit excellent detonation performance. We report an effective approach for the synthesis of 3‐amino‐5‐nitramino‐1,2,4‐oxadiazole, which has nitramino and amino groups in the same building block. The single‐crystal X‐ray structure shows layered hydrogen‐bonding pairs as well as the presence of a water molecule which ensure insensitivity. Through incorporation of a cation, the hydrazinium or hydroxylammonium salts exhibit good energetic performance and acceptable sensitivities.     

A convenient method for the synthesis of N-hydroxyureas

Treatment of amines with 1-(4-nitrophenol)-N-(O-benzylhydroxy)carbamate yields the O-benzyl protected N-hydroxyureas. Hydrogenation of the O-benzyl protected N-hydroxyureas over 5% Pd/BaSO₄ cleanly gives the N-hydroxyureas in good yield. In addition to primary and secondary aliphatic and aromatic amines, this method converts amino sugars to the corresponding N-hydroxyureas without extensive protecting group chemistry.     

Potassium 4,4′‐Bis(dinitromethyl)‐3,3′‐azofurazanate: A Highly Energetic 3D Metal–Organic Framework as a Promising Primary Explosive

Environmentally acceptable alternatives to toxic lead‐based primary explosives are becoming increasingly important for energetic materials. In this study, potassium 4,4′‐bis(dinitromethyl)‐3,3′‐azofurazanate, comprising two dinitromethyl groups and an azofurazan moiety, was synthesized and isolated as a new energetic 3D metal–organic framework (MOF). Several attractive properties, including a density of 2.039 g cm^?3, a decomposition temperature of 229 °C, a detonation velocity of 8138 m s^?1, a detonation pressure of 30.1 GPa, an impact sensitivity of 2 J, and friction sensitivity of 20 N make 4 a good candidate as a green primary explosive.     

Enantioselective synthesis of (2R,3R)- and (2S,3S)-2- [(3-chlorophenyl)-(2-methoxyphenoxy)methyl]morpholine

The enantioselective synthesis of the (R,R)- and (S,S)-enantiomers of 1 from commercially available 3-chlorocinnamic acid is reported. The Sharpless asymmetric epoxidation was used to establish the stereocenters in the synthesis of both enantiomers of 1.     

3-Azido-N-nitro-1H-1,2,4-triazol-5-amine-based energetic salts

Twelve energetic nitrogen‐rich salts based on 3‐azido‐N‐nitro‐1H‐1,2,4‐triazol‐5‐amine were prepared and fully characterized by ¹H, ¹³C NMR, and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. The crystal structures of the neutral compound 3‐azido‐N‐nitro‐1H‐1,2,4‐triazole‐5‐amine ( 1 ) and its triaminoguanidinium salt ( 13 ) were determined by single‐crystal X‐ray diffraction. The density of 1 and its twelve salts ranged from 1.57 to 1.79 g cm^?3, and the heat of formation was calculated with the Gaussian 03 suite of programs. Compounds 1 – 13 exhibit promising detonation performances (pressure: 25.3–39.3 GPa; velocity: 8159–9409 ms^?1; EXPLO 5.05). Impact sensitivities were also determined by hammer tests and resulted ranging from 2.5 J (very sensitive) to >40 J (insensitive).     

Yield phenomenon in oriented polyethylene terephthalate

The object of this investigation was to determine the origin of deformation bands in one-way oriented polyethylene terephthalate (PET) and their relation to the upper yield point. The tensile yield point was measured at room temperature as a function of the angle (θ) between the original draw direction and the tensile axis. The effect of strain rate was observed. The growth and geometry of deformation bands were studied. The results showed that the formation of a deformation band in PET cannot be interpreted as the strength-limiting yield mechanism for all θ and that the viscoelastic behavior plays the primary part in determining the yield point of this semicrystalline polymer.     

The NEMESIS planetary atmosphere radiative transfer and retrieval tool

With the exception of in situ atmospheric probes, the most useful way to study the atmospheres of other planets is to observe their electromagnetic spectra through remote observations, either from ground-based telescopes or from spacecraft. Atmospheric properties most consistent with these observed spectra are then derived with retrieval models. All retrieval models attempt to extract the maximum amount of atmospheric information from finite sets of data, but while the problem to be solved is fundamentally the same for any planetary atmosphere, until now all such models have been assembled ad hoc to address data from individual missions.In this paper, we describe a new general-purpose retrieval model, Non-linear Optimal Estimator for MultivariatE Spectral analySIS (NEMESIS), which was originally developed to interpret observations of Saturn and Titan from the composite infrared spectrometer on board the NASA Cassini spacecraft. NEMESIS has been constructed to be generally applicable to any planetary atmosphere and can be applied from the visible/near-infrared right out to microwave wavelengths, modelling both reflected sunlight and thermal emission in either scattering or non-scattering conditions. NEMESIS has now been successfully applied to the analysis of data from many planetary missions and also ground-based observations.     

Compressed liquid densities of ethane-propane mixtures between 10 and 49°C at pressures up to 9.6 MPa

Densities of compressed liquid ethane-propane mixtures are reported at five temperatures between 10.00 ad 48.90°C. For each isotherm the data cover eight compositions ranging between 30 and 95 mol% ethane at pressures up to 9.65 MPa. The excess volumes derived from the data are negative, extremely dependent on temperature and pressure, and can represent up to a 50% correction to the ideal mixture volume.