- Studies in nitrosopyrazoles. Part 1. Preparative and spectroscopic studies of some 3,5-dialkyl-4-nitrosopyrazoles
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The preparations of a number of 3,5-disubstituted- and 1,3,5-trisubstituted-4-nitrosopyrazoles are described and a range of physical properties of these compounds are measured. Comparison is made with some 2,6-disubstituted nitrosobenzenes and it is shown from 13C NMR spectroscopy that the effects of substitution by flanking tert-butyl groups are moderated in the case of the pyrazoles from those in the aromatic C6 ring due to a lessening of steric hindrance. It is also suggested that steric effects are evident in the preparation of 1,3,5-substituted-4-nitrosopyrazoles when one of the flanking groups to the NO is tert-butyl or phenyl, there being no such effect for the corresponding case of the isobutyl group.
- Cameron, Mailer,Gowenlock, Brian G.,Boyd, Alan S. F.
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- Experimental standard molar enthalpies of formation of crystalline 3,5-dimethylpyrazole, 3,5-dimethyl-4-nitrosopyrazole, 1,3,5-trimethyl-4-nitrosopyrazole, and 3,5-dimethyl-1-phenyl-4-nitrosopyrazole
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Static-bomb calorimetry was used to measure standard molar enthalpies of combustion in oxygen for crystalline compounds. The standard molar enthalpies of formation of the crystalline compounds were derived using the measured values. The values of the stan
- Ribeiro da Silva, Maria D.M.C.,Ferreira, Susana C.C.,Rodrigues, Ivone A.P.,Da Silva, Luis C.M.,Acree Jr, William E.,Pandey, Siddharth,Roy, Lindsay E.
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- Thermally stable 3,6-dinitropyrazolo[4,3-c]pyrazole-based energetic materials
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3,6-Dinitropyrazolo[4,3-c]pyrazole was prepared using an efficient modified process. With selected cations, ten nitrogen-rich energetic salts and three metal salts were synthesized in high yield based on the 3,6-dinitropyrazolo[4,3-c]pyrazolate anion. These compounds were fully characterized by IR and multinuclear NMR spectroscopies, as well as elemental analyses. The structures of the neutral compounds 4 and its salt 16 were confirmed by single-crystal X-ray diffraction showing extensive hydrogen-bonding interactions. The neutral pyrazole precursor and its salts are remarkably thermally stable. Based on the calculated heats of formation and measured densities, detonation pressures (22.5-35.4 GPa) and velocities (7948-9005 ms-1) were determined, and they compare favorably with those of TNT and RDX. Their impact and friction sensitivities range from 12 to >40 J and 80 to 360 N, respectively. These properties make them competitive as insensitive and thermally stable highenergy density materials.
- Zhang, Jiaheng,Shreeve, Jean'ne M.,Parrish, Damon A.
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