Improved Preparation of 3-Oximinooxetane - An Important Precursor to Energetic Oxetanes

Oximes represent an extremely versatile building block in energetic materials chemistry. While oxidation with peroxy acids affords the corresponding mononitro compounds, tandem oxidation-nitration reactions such as the Scholl reaction lead to geminal dinitro compounds. Furthermore, the corresponding amines can be obtained by reduction of the oxime group. Accordingly, 3-oximinooxetane represents a suitable precursor for 3-nitro- and 3,3-dinitrooxetane as well as 3-aminooxetane. 3-Oximinooxetane, which is poorly described in the literature, has now been extensively characterized by vibrational-, mass- and NMR spectroscopy, as well as elemental and thermal analysis. In addition, its synthesis has been significantly improved compared to literature. The molecular structure was elucidated by single-crystal X-ray diffraction. Since 3-oximinooxetane is energetic by itself, its performance was calculated using the EXPLO5 V6.04 thermochemical code, and its sensitivity towards external stimuli such as impact, friction, and electrostatic discharge was determined by BAM standard procedures

Oxetane Monomers Based On the Powerful Explosive LLM-116: Improved Performance, Insensitivity, and Thermostability

3-Bromomethyl-3-hydroxymethyloxetane represents an inexpensive and versatile precursor for the synthesis of 3,3-disubstituted oxetane derivatives. In the present work, its synthesis was improved and energetic oxetanes based on the explosive LLM-116 (4-amino-3,5-dinitro-1H-pyrazole) prepared. Reaching detonation velocities and pressures of up to 7335 ms(-1) and 20.9 GPa in combination with a high thermostability and insensitivity, these surpass the prior art by far. Next to a symmetric LLM-116 derivative, three asymmetric compounds were prepared using azido-, nitrato- and tetrazolyl-moieties. All compounds were intensively characterized by vibrational-, mass- and multinuclear (H-1, C-13, N-14) NMR spectroscopy, differential scanning calorimetry and elemental analysis. The molecular structures were elucidated by single crystal X-ray diffraction. Hirshfeld analysis allowed to estimate their sensitivity next to a practical evaluation using BAM standard procedures. Their performance was calculated using the EXPLO5 V6.04 code and a small-scale shock reactivity test and initiation test demonstrated their insensitivity and performance

Synthesis and characterization of allyl- and vinyl-substituted 1,2-bis(tetrazolo)ethanes as polymeric precursors

On the basis of 1,2-bis(5-tetrazolo)ethane (BTE) the corresponding twofold vinyl and allyl N-substituted derivatives were synthesized using 1,2-dibromoethane and allyl bromide, respectively. The compounds were obtained as two different constitutional isomers. Both species were analyzed using NMR and IR spectroscopy, elemental analysis, as well as mass spectrometry. In the case of the diallyl bistetrazoles, the two isomers were characterized using 2D NMR spectroscopy. The synthesis of the divinyl compounds gave crystals of the 2,2'-N-substituted isomer, which were analyzed by single-crystal X-ray diffraction. The thermal stability of the compounds was determined using differential scanning calorimetry (DSC) and gave decomposition temperatures around 190 degrees C and 230 degrees C. For the investigation of the inherent energetic potential, sensitivities toward physical stimuli and detonation parameters were determined. The compounds turned out to be insensitive toward friction and impact and possess moderate energetic properties

Nitrogen-Rich Oxetanes Based on the Combination of Azides and Tetrazoles

Literature known energetic oxetane derivatives have a nitrogen content of up to 49.98 %. Through the introduction of azide and tetrazole functionalities attached to an oxetane ring, energetic oxetanes with higher nitrogen contents than previously reported in the literature were obtained. The newly synthesized oxetane derivatives were extensively characterized via H-1 NMR, C-13{H-1} NMR, N-14 NMR, N-15 NMR, H-1-N-15 HMBC, FT-IR spectroscopy and/or DTA. Their crystal structures were elucidated using X-ray diffraction, their sensitivities towards impact, friction and electrostatic discharge were determined and their energetic properties were calculated using the EXPLO5 code

3-(Nitromethylene)oxetane: a very versatile and promising building block for energetic oxetane based monomers

In the field of energetic materials, older developments (e.g., RDX, ONC, CL20) are increasingly replaced by more environmentally benign, less expensive and likewise or more powerful compounds. This is mainly achieved through nitrogen-rich motifs like tetrazoles. However, such materials are mostly used as formulations containing polymeric energetic binders. Unfortunately, prior art binders show very poor performances and therefore reduce the overall performance. To address this problem, new monomers with enhanced performance are a prerequisite. Since the majority of energetic binders is oxetane-based, we chose 3-(nitromethylene)oxetane as a promising building block. It exhibits an explosophoric group, has recently become commercially available and provides suitable monomers by elegant and cost-efficient one-pot syntheses via conjugate addition. Herein, we report derivatives based on 1H-tetrazole, 1H-tetrazole-5-amine and the rather exotic but extremely powerful primary explosives 5-azido-1H-tetrazole (5AzT) and 5-nitro-2H-tetrazole (5NT). The sensitivities toward external stimuli like impact, friction, and electrostatic discharge were assessed by BAM standard procedures. As all molecular structures were elucidated by X-ray diffraction, Hirshfeld analysis was applied to explain the surprisingly low sensitivities found for the 5AzT- and 5NT-derivatives. Further, the compounds were studied by vibrational- and multinuclear NMR spectroscopy (H-1, C-13, N-14), differential scanning calorimetry, and elemental analysis. Their performance was calculated using the EXPLO5 V6.04 thermochemical code. Based on obtained values, the 5AzT- and 5NT-derivatives outperform prior art energetic oxetanes and TNT. Therefore, their performance was additionally demonstrated and evaluated by a small-scale shock reactivity test (SSRT)

2-Diphenylphosphinomethyl-3-methylpyrazine

The lateral metalation-electrophilic trapping reaction of alkyl-substituted pyrazines has always been challenging and poorly regioselective, with the corresponding derivatives often being isolated in moderate yield. In this contribution, we first report on the preparation of an unsymmetrically-substituted pyrazine, that is 2-diphenylphosphinomethyl-3-methylpyrazine, by subjecting to metalation with n-BuLi the commercially available 2,3-dimethylpyrazine, followed by interception of the putative lithiated benzyl-type intermediate with Ph2PCl. Such a functionalization has been successfully carried out in the absence of additional ligands, working either in THF at −78 °C or in a more environmentally friendly solvent like cyclopentyl methyl ether at 0 °C, with the desired phosphine derivative being isolated in 70–85% yield. The newly synthesized adduct has been fully characterized by means of multinuclear magnetic resonance spectroscopic techniques, and also by preparing a selenium derivative, which furnished single crystals that were suitable for X-ray analysis

Ferrocenes with a Persulfurated Cyclopentadienyl Ring: Synthesis, Structural Studies, and Optoelectronic Properties

Persulfurated arenes are a fascinating class of functional molecules with a wide range of potential applications. Ferrocenes are also a multifaceted class of aromatic compounds that can easily be finetuned for an enormous variety of desired properties. A combination of both substance classes might yield an even wider field of applications. Herein, we describe the synthesis of two ferrocenes with one persulfurated cyclopentadienyl ring [C5(SR)5], with R=Me or Ph, together with their crystal structures, optical, and electrochemical properties. Both crystal structures show significant intramolecular sulfur‐iron interactions as well as weak intermolecular sulfur– contacts. Cyclovoltammetry of the [C5(SPh)5] compound shows a high oxidation potential of 651 mV vs. FcH/FcH+

TYK2 Kinase Activity Is Required for Functional Type I Interferon Responses In Vivo

Tyrosine kinase 2 (TYK2) is a member of the Janus kinase (JAK) family and is involved in cytokine signalling. In vitro analyses suggest that TYK2 also has kinase-independent, i.e., non-canonical, functions. We have generated gene-targeted mice harbouring a mutation in the ATP-binding pocket of the kinase domain. The Tyk2 kinase-inactive (Tyk2K923E) mice are viable and show no gross abnormalities. We show that kinase-active TYK2 is required for full-fledged type I interferon- (IFN) induced activation of the transcription factors STAT1-4 and for the in vivo antiviral defence against viruses primarily controlled through type I IFN actions. In addition, TYK2 kinase activity was found to be required for the protein’s stability. An inhibitory function was only observed upon over-expression of TYK2K923E in vitro. Tyk2K923E mice represent the first model for studying the kinase-independent function of a JAK in vivo and for assessing the consequences of side effects of JAK inhibitors

Metal–organic fireworks: MOFs as integrated structural scaffolds for pyrotechnic materials

A new approach to formulating pyrotechnic materials is presented whereby constituent ingredients are bound together in a solid-state lattice. This reduces the batch inconsistencies arising from the traditional approach of combining powders by ensuring the key ingredients are ‘mixed’ in appropriate quantities and are in intimate contact. Further benefits of these types of material are increased safety levels as well as simpler logistics, storage and manufacture. A systematic series of new frameworks comprising fuel and oxidiser agents (group 1 and 2 metal nodes & terephthalic acid derivatives as linkers) has been synthesised and structurally characterised. These new materials have been assessed for pyrotechnic effect by calorimetry and burn tests. Results indicate that these materials exhibit the desired pyrotechnic material properties and the effect can be correlated to the dimensionality of the structure. A new approach to formulating pyrotechnic materials is proposed whereby constituent ingredients are bound together in a solid-state lattice. A series of Metal–organic framework frameworks comprising fuel and oxidiser agents exhibits the desired properties of a pyrotechnic material and this effect is correlated to the dimensionality of the structure

The Janus kinases (Jaks)

The Janus kinase (Jak) family is one of ten recognized families of non-receptor tyrosine kinases. Mammals have four members of this family, Jak1, Jak2, Jak3 and Tyrosine kinase 2 (Tyk2). Birds, fish and insects also have Jaks. Each protein has a kinase domain and a catalytically inactive pseudo-kinase domain, and they each bind cytokine receptors through amino-terminal FERM (Band-4.1, ezrin, radixin, moesin) domains. Upon binding of cytokines to their receptors, Jaks are activated and phosphorylate the receptors, creating docking sites for signaling molecules, especially members of the signal transducer and activator of transcription (Stat) family. Mutations of the Drosophila Jak (Hopscotch) have revealed developmental defects, and constitutive activation of Jaks in flies and humans is associated with leukemia-like syndromes. Through the generation of Jak-deficient cell lines and gene-targeted mice, the essential, nonredundant functions of Jaks in cytokine signaling have been established. Importantly, deficiency of Jak3 is the basis of human autosomal recessive severe combined immunodeficiency (SCID); accordingly, a selective Jak3 inhibitor has been developed, forming a new class of immunosuppressive drugs