Dheeraj Kumar

A Highly Stable and Insensitive Fused Triazolo–Triazine Explosive (TTX)

A fused-ring conjugated energetic molecule, 4-amino-3,7-dinitro-[1,2,4]triazolo[5,1-c] [1,2,4]triazine (TTX), has been synthesized in good yield in a two-step process starting from the known 5-amino-3-nitro-1H-1,2,4-triazole (ANTA). Characterization of TTX shows that it possesses energetic properties approaching those of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but with a higher thermal stability and lower sensitivity towards impact and friction.

Connecting energetic nitropyrazole and aminotetrazole moieties with N,N′-ethylene bridges: A promising approach for fine tuning energetic properties

A new approach for fine tuning the properties of energetic compounds through bonding of energetic pyrazoles with tetrazole moieties by means of N,N′-ethylene bridges is described. Reactions of various pyrazole derivatives with 2-haloethylamines, followed by reaction with cyanogen azide resulted in the formation of compounds having ethylene-bridged 5-aminotetrazole and nitropyrazole. Further reactions on this basic framework resulted in various energetic compounds having mono, di or tri nitro-substituted pyrazole moieties, and an amino or nitroimino-substituted tetrazole ring. All the compounds were thoroughly characterized by IR, and NMR [1H, 13C{1H}, 15N] spectra, elemental analysis, and differential scanning calorimetry (DSC). Some of them were also structurally characterized with single-crystal X-ray diffraction studies. Heats of formation and detonation performance for all the energetic compounds were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively. Initial studies showed that the properties of energetic compounds can indeed be fine-tuned by careful selection of the number and nature of energetic groups on the pyrazole and tetrazole rings.

Asymmetric N,N′-ethylene-bridged azole-based compounds: Two way control of the energetic properties of compounds

Reactions of various energetic pyrazole, triazole and tetrazole salts with 1-(2-bromoethyl)-5-aminotetrazole, in the presence of a phase transfer catalyst, resulted in new asymmetric N,N′-ethylene-bridged azole-based energetic compounds having diversified functionalities and properties. The availability of the aminotetrazole moiety for conversion to nitroimino(tetrazole) provides a route for further modifying energetic properties. All the compounds were thoroughly characterized by IR, NMR [1H, 13C{1H}, 15N], elemental analyses, and differential scanning calorimetry (DSC). Some were also further characterized using single-crystal X-ray diffraction studies. Impact and friction sensitivities were measured and heats of formation and detonation performances were calculated. Results show that combination of different energetic heterocycles broadens options for the design of desirable energetic compounds.

3,4,5-Trinitro-1-(nitromethyl)-1H-pyrazole (TNNMP): a perchlorate free high energy density oxidizer with high thermal stability

A superior oxidizer, a derivative of trinitropyrazole, 3,4,5-trinitro-1-(nitromethyl)-1H-pyrazole (TNNMP), was obtained in good yield by the reaction of ammonium 4-amino-3,5-dinitropyrazolate with bromonitromethane followed by oxidation with a mixture of H2O2/H2SO4. Characterization of TNNMP shows that in addition to having good oxygen balance (+18.3%) and detonation performance (Dv = 8858 m s−1; P = 35.1 GPa), it concomitantly has high thermal stability (Td = 202 °C) and acceptable sensitivities (IS = 14 J; FS = 120 N). These attractive properties suggest TNNMP as a promising perchlorate free high energy density oxidizer and a potential replacement for ammonium perchlorate.

N-Acetonitrile Functionalized Nitropyrazoles: Precursors to Insensitive Asymmetric N-Methylene-C Linked Azoles

Properties of energetic compounds obtained by linking energetic pyrazoles to tetrazoles by means of N-methylene-C bridges can be fine-tuned. Reactions of pyrazole derivatives with chloroacetonitrile followed by conversion of the cyano group to tetrazole using click reactions in the presence of zinc chloride result in asymmetric N-methylene-C bridged azole-based energetic compounds. All the compounds were thoroughly characterized by IR and NMR [1 H, 13 C {1 H}, 15 N] spectroscopy, elemental analysis, and differential scanning calorimetry (DSC), and for two compounds, further supported by single-crystal X-ray diffraction studies. Heats of formation and detonation performances were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively. Initial studies show that this new approach is promising for synthesizing less sensitive energetic compounds with fine-tuned properties.

Aminoacetonitrile as precursor for nitrogen rich stable and insensitive asymmetric N-methylene-C linked tetrazole-based energetic compounds

Reaction of aminoacetonitrile with cyanogen azide resulted in acetonitrile derivative of amino(tetrazole), 1, which on further reaction with sodium azide in the presence of ammonium chloride resulted in compound 2 with N-methylene-C bridged tetrazole and amino-tetrazole moieties. Reaction of 2 with 100% nitric acid resulted in N-(1-((1H-tetrazol-5-yl)methyl)-1H-tetrazol-5(4H)-ylidene)nitramide (4) having N-methylene-C bridged nitroimino-tetrazole and tetrazole moieties. Various energetic salts based on these three types of tetrazole derivatives (tetrazole, amino-tetrazole and nitroimino-tetrazole) in 2 and 4 were obtained. All the compounds were thoroughly characterized by IR, NMR [1H, 13C{1H}, 15N], elemental analysis, and differential scanning calorimetry (DSC). Some of them were also structurally characterized with single-crystal X-ray diffraction studies. Heats of formation and detonation performances for all the energetic compounds were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively.

Resolving synthetic challenges faced in the syntheses of asymmetric N,N′-ethylene-bridged energetic compounds

Synthetic challenges faced during the syntheses of asymmetric N,N′-ethylene-bridged energetic compounds due to the differences in the reactivity and stability of various types of energetic rings are addressed. The elusive asymmetric compounds, 12 (in which nitramino-pyrazole is bonded to nitroimino-tetrazole via an N,N′-ethylene-bridge), and 15 and 17 (in which azido-pyrazole is bonded to nitroimino-tetrazole via an N,N′-ethylene-bridge), were obtained in good yields. All the compounds were thoroughly characterized using IR, NMR [1H, 13C{1H}, 15N], elemental analysis and differential scanning calorimetry (DSC). The structures of 13 and 14 were further confirmed via X-ray crystal analysis. Heats of formation and the detonation properties of all the energetic compounds were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively. Impact and friction sensitivities were determined using the standard BAM technology.