Combination Energetic Materials Consisting of Strained Rings Combined with High Heat of Formation Tetrazoles.

The reaction of cyanogen azide with strained-ring containing primary and secondary amines led to the isolation of energetic molecules deriving their energy content from both strained rings as well as aminotetrazoles. Azo-coupling of these materials afforded novel high-nitrogen energetic materials of very high sensitivity. All compounds were chemically characterized by IR, NMR, single-crystal X-ray crystallography, and high-resolution mass spectrometry.

-selective Cyclopropanation of Nonconjugated Alkenes with Diverse Pronucleophiles via Directed Nucleopalladation.

A facile approach to obtaining densely functionalized cyclopropanes is described. The reaction proceeds under mild conditions via the directed nucleopalladation of nonconjugated alkenes with readily available pronucleophiles and gives excellent yields and good -selectivity using I and TBHP as oxidants. Pronucleophiles bearing a diverse collection of electron-withdrawing groups, including -CN, -COR, -COR, -SOPh, -CONHR, and -NO, are well tolerated.

Sequential, Electrochemical-Photochemical Synthesis of 1,2,4-Triazolo-[4,3-a]pyrazines.

1,2,4-triazolo-[4,3-a]pyrazine was prepared via a two-step electrochemical, photochemical process. First, a 5-substituted tetrazole is electrochemically coupled to 2,6-dimethoxypyrazine to yield 1,5- and 2,5- disubstituted tetrazoles. Subsequent photochemical excitation of the 2,5-disubstituted tetrazole species using an ultraviolet lamp releases nitrogen gas and produces a short-lived nitrilimine intermediate.

Synthesis and Energetic Characterization of Borane-Amines on High-Nitrogen Heterocycles.

Borane-amines have garnered attention over the last several decades in a variety of applications, ranging from hydrogen storage materials to hypergolic fuel systems. An investigation into the synthesis of borane-amines with high-nitrogen content heterocycles was undertaken in this work. Borane-amines were formed by the reaction of BH·MeS in tetrahydrofuran (THF) with the requisite nitrogen-containing heterocycle and isolated by placing the crude reaction mixture in hexanes to precipitate the product.

Nitrodiazene oxides: a unique nitrogen- and oxygen-containing functional group.

Nitrogen-/oxygen-containing functional groups (N/O groups) may be found in a wide variety of areas such as agriculture, drug design and energetic materials. Exploring the chemistry and synthesis of N/O groups is desirable as compounds containing their functionality may prove to be invaluable in a variety of fields. A unique N/O functional group which may offer additional insight into the design of high-heteroatom content systems is the 2-nitrodiazene-1--oxide group (NDO group).

Energetic Salts of a Tri-Annulated Ring System.

Energetic salts of a triazolyl-tetrazinyl-aminotriazine ring system are characterized as energetic materials. Previously known sodium, ammonium, hydrazinium, barium, and triaminoguanidinium salts as well as the parent free acid were synthesized according to literature procedures and fully characterized for the first time as energetic materials. The silver salt was also synthesized and characterized for the first time as an energetic material.

A Laboratory Preparation of High-Purity Calcium Cyanamide.

Calcium cyanamide is an important fertilizer and a chemical precursor. However, its large scale synthesis is extremely energy intensive via the historical Frank-Caro synthesis of fixing atmospheric nitrogen with calcium carbide at an elevated temperature, and the product material contains a large number of impurities. In this work, we prepare calcium cyanamide in a purity higher than that achievable by the Frank-Caro route in a convenient laboratory method.

Approach to High-Nitrogen Materials with Dual-Use Properties via Tetraaza-Nazarov Cyclization.

In this report, we describe the application of an electrocyclization toward the synthesis of a high-nitrogen heterocycle. It entails the synthesis of a novel, high-nitrogen, 2-3-disubstituted tetrazolium salt via the tetraaza-Nazarov cyclization (4π electrocyclization) of 3-bromo-1,5-bis(3-nitro-1,2,4-triazole-1-5-yl)-formazan (BDNF). The cyclization takes place under mild conditions using the oxidant phenyliodine(III) diacetate (PIDA).

3-Methyl-1,2,3-triazolium-1-dinitromethylylide and the strategy of zwitterionic dinitromethyl groups in energetic materials design.

3-Methyl-1,2,3-triazolium-1-dinitromethylylide, an exemplary zwitterionic energetic molecule, is the first fully-studied energetic material making use of the zwitterionic dinitromethyl functional group. This compound has impact and friction sensitivities of 8 J and 144-160 N respectively with a detonation velocity of 8162 m s.

Electrochemical Synthesis of High-Nitrogen Materials and Energetic Materials.

Electrochemical synthesis is a valuable method for the preparation of molecules. It is innately eco-friendly, as potentially hazardous oxidation and reduction agents are replaced with electrochemical potentials. Electrochemistry is commonly applied globally in the synthesis of numerous chemicals, but the energetic materials field lags in this regard.

4,4'-Dinitrimino-5,5'-diamino-3,3'-azo-bis-1,2,4-triazole: A High-Performing Zwitterionic Energetic Material.

Mixed acid nitration of electrochemically generated 4,4',5,5'-tetraamino-3,3'-azo-bis-1,2,4-triazole (TAABT) generated the novel energetic material 4,4'-dinitrimino-5,5'-diamino-3,3'-azo-bis-1,2,4-triazole (DNDAABT). Various energetic salts of DNDAABT were also prepared and characterized to confirm their structures and determine their explosive sensitivities and performances. The free acid of DNDAABT exists as a zwitterionic molecule that leads to a high-density material with predicted detonation parameters comparable to those of TKX-50 (bis(hydroxylammonium) 5,5'-bis(tetrazolate-1 -oxide).

1,3,4,5-Tetraamino-1,2,4-triazolium Cation: An Energetic Moiety.

The amination of 3,4,5-triamino-1,2,4-triazole with -tosylhydroxylamine yielded the nitrogen-rich 1,3,4,5-tetraamino-1,2,4-triazolium cation as its tosylate salt. Subsequent metathesis reactions produced energetic salts with various energetic anions, including perchlorate, nitrate, nitrotetrazolate, and bistetrazolate diolate. All energetic salts possess relatively high heats of formation, thermal sensitivities, and detonation velocities and pressures.

Heterocyclic Nitrilimines and Their Use in the Synthesis of Complex High-Nitrogen Materials.

We show the ability of a nitrilimine prepared from 3-amino-5-nitro-1,2,4-triazole to undergo various cyclization and rearrangement reactions, giving a beautiful diversity of nitrogen-rich heterocyclic products. This chemistry includes the first cyclization of a nitrilimine with a diazonium species, giving a tetrazole, a previously unknown transformation, as well as leading to the creation of several new energetic materials with backbones not available by traditional techniques. New materials prepared were characterized both chemically (multinuclear NMR, IR, mass spectrometry, and elemental analysis) and energetically, with sensitivities and performances reported.

Tailoring Energetic Sensitivity and Classification through Regioisomerism.

The azo-coupling of 1- and 2-amino-4-nitro-1,2,3-triazole yielded two new energetic compounds whose detonation properties compete with that of HMX. Though the calculated performances are impressive, the regioisomers have differing sensitivities and detonation behavior. One has sensitivities similar to a very sensitive primary explosive, while the other has sensitivities more comparable to a sensitive secondary explosive.

Nitroacetonitrile as a versatile precursor in energetic materials synthesis.

Nitroacetonitrile is the simplest α-nitronitrile; it possesses a single central carbon attached to two strong electronegative, electron-withdrawing groups allowing extensive chemistry through the active methylene center. Free nitroacetonitrile has purification and stability issues, however stable salts of nitroacetonitrile possess the same reactivity as the free acid and are much more stable. Nitroacetonitrile serves as a versatile synthetic precursor in the formation of heterocyclic and polyfunctional aliphatic products and can allow for straightforward conversion to amino, acyl, and other functional groups.

Synthesis of 5-Nitrotetrazolates by the Direct Oxidation of 5-Aminotetrazole in a Single-Pot Synthesis without Isolation of Explosive Intermediates.

A readily available oxidizer, potassium superoxide can be used for the oxidation of 5-amino-1H-tetrazole (5-AT) to 5-nitrotetrazole (5-NT) in high yields in a single-pot synthesis. This strategy reduces the synthesis of this important energetic material down to a single step and eliminates highly sensitive diazonium and copper salt primary explosive intermediates. Use of dimethyl sulfoxide along with molecular sieves and 18-crown-6 as phase transfer catalyst promoted faster reaction rates and greater yield.

Sensitive Energetics from the -Amination of 4-Nitro-1,2,3-Triazole.

Energetic N-amino-C-nitro compounds 1-amino-4-nitro-1,2,3-triazole and 2-amino-4-nitro-1,2,3-triazole are characterized for the first time as energetic materials. These compounds were characterized chemically by nuclear magnetic resonance (NMR), Infrared spectroscopy and X-ray crystallography. Compounds were also characterized energetically by differential scanning calorimetry (DSC), impact, and friction and found to possess sensitivities and performances classifying them as primary explosives with PETN-like performance.

Tetrazole Azasydnone (C N O H) And Its Salts: High-Performing Zwitterionic Energetic Materials Containing A Unique Explosophore.

This work reports the first compound containing both a tetrazole and an azasydnone ring, a unique energetic material. Several energetic salts of the tetrazole azasydnone were synthesized and characterized, leading to the creation of new secondary and primary explosives. Molecular structures are confirmed by H and C NMR, IR spectroscopy, and X-ray crystallographic analysis.

An Energetic Triazolo-1,2,4-Triazine and its N-Oxide.

The reaction of 3-amino-5-nitro-1,2,4-triazole with nitrous acid produces the corresponding diazonium salt. When the diazonium salt is treated with nitroacetonitrile, a subsequent condensation and cyclization reaction occurres to produced 4-amino-3,7-dinitrotriazolo-[5,1-c][1,2,4] triazine (DPX-26). X-ray crystallographic analysis shows that the DPX-26 has a density of 1.

Detection of high-energy compounds using photoluminescent silicon nanocrystal paper based sensors.

Luminescent silicon nanocrystals (Si-NCs) surface functionalized with dodecyl groups were exposed to solutions of nitroaromatic compounds including nitrobenzene, nitrotoluene, and dinitrotoluene. It was found that Si-NC luminescence was quenched upon exposure to nitroaromatics via an electron transfer mechanism as indicated by Stern-Volmer analysis. This quenching was exploited and a straightforward paper-based Si-NC sensor was developed.

Synthesis of 5-aminotetrazole-1N-oxide and its azo derivative: a key step in the development of new energetic materials.

1-Hydroxy-5-aminotetrazole (1), which is a long-desired starting material for the synthesis of hundreds of new energetic materials, was synthesized for the first time by the reaction of aqueous hydroxylamine with cyanogen azide. The use of this unique precursor was demonstrated by the preparation of several energetic compounds with equal or higher performance than that of commonly used explosives, such as hexogen (RDX). The prepared compounds, including energetic salts of 1-hydroxy-5-aminotetrazole (hydroxylammonium (2, two polymorphs) and ammonium (3)), azo-coupled derivatives (potassium (5), hydroxylammonium (6), ammonium (7), and hydrazinium 5,5'-azo-bis(1-N-oxidotetrazolate (8, two polymorphs)), as well as neutral compounds 5,5'-azo-bis(1-oxidotetrazole) (4) and 5,5'-bis(1-oxidotetrazole)hydrazine (9), were intensively characterized by low-temperature X-ray diffraction, IR, Raman, and multinuclear NMR spectroscopy, elemental analysis, and DSC.

1,3-Bis(nitroimido)-1,2,3-triazolate anion, the N-nitroimide moiety, and the strategy of alternating positive and negative charges in the design of energetic materials.

This unique study reports on the 1,3-bis(nitroimido)-1,2,3-triazolate anion. This compound provides unique insight into both academic and practical considerations surrounding high-nitrogen systems. The bonding in this energetic anion can be represented multiple ways, one of which includes a chain of alternating positive/negative charges nine atoms long.

A study of cyanotetrazole oxides and derivatives thereof.

In this work we report on the syntheses of energetic salts of cyanotetrazolate-1- and -2-oxides; this offers a unique ability to compare the effects of tetrazole 1- versus 2-oxidation. 5-Cyanotetrazolate-2-oxide can be synthesized by oxidation of the 5-cyanotetrazolate anion with Oxone, while the corresponding 1-oxide was synthesized by the rearrangement of azidoaminofurazan. Both chemical (multinuclear NMR, IR, and Raman spectroscopies, mass spectrometry, etc.

Amination of energetic anions: high-performing energetic materials.

The new energetic materials 2-amino-5-nitrotetrazole (ANT, 1), 1-amino-3,4-dinitro-1,2,4-triazole (ADNT, 2), and both 1,1'-diamino-5,5'-bistetrazole and 1,2'-diamino-5,5'-bistetrazole (11DABT, 3 and 12DABT, 4) have been prepared by the amination of the parent anion with O-tosylhydroxylamine. The 5-H-tetrazolate anion has also been aminated using hydroxylamine O-sulfonic acid to both 1-aminotetrazole and 2-aminotetrazole (1AT, 5 and 2AT, 6). The prepared materials have been characterized chemically (XRD (1-4, 6·AtNO(2), 8), multinuclear NMR, IR, Raman) and as explosives (mechanical and electrostatic sensitivity) and their explosive performances calculated using the EXPLO5 computer code.