- Synthesis, Characterization and Energetic Properties of 1,3,4-Oxadiazoles
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An efficient cyclization between nitro-substituted benzoic acids and nitro-substituted benzohydrazides affords 1,3,4-oxadiazoles. Facile synthesis and a broad substrate scope produce a range of compounds, some of them with potential as high-energy compounds. Heats of formation (ΔHf) and densities (ρ) were calculated, and heats of decomposition (ΔHd) and combustion (ΔHc) were determined experimentally. The densities of seven of the synthesized compounds were determined by gas pycnometry, and the respective values of detonation velocity (VD), detonation pressure (PD) and specific impulse (ISP) were calculated using the EXPLO5 program. An X-ray structure of 2-(2,4-dinitrophenyl)-5-(3,5-dinitrophenyl)-1,3,4-oxadiazole (4n) revealed the non-planarity of the molecule and afforded a crystal density of 1.698 (at 120 K), close to the pycnometric value of 1.64 at room temperature. Efficient cyclization between nitro-substituted benzohydrazides and nitro-substituted benzoic acids affords energetic 1,3,4-oxadiazoles.
- Wang, Zuoquan,Zhang, Hong,Killian, Benjamin J.,Jabeen, Farukh,Pillai, Girinath G.,Berman, Heather M.,Mathelier, Michael,Sibble, Ashani J.,Yeung, Justin,Zhou, Wenfeng,Steel, Peter J.,Hall, C. Dennis,Katritzky, Alan R.
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p. 5183 - 5188
(2015/08/18)
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- Substitution Reactions of Phenylated Aza-heterocycles. Part 1. Nitration of 2,5-Diphenyl-1,3,4-oxadiazole: a Product Study using High Performance Liquid Chromatography
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Contrary to a previous literature report, nitration of 2,5-diphenyl-1,3,4-oxadiazole (1) under various conditions gives a mixture of all six possible 2,5-bisnitrophenyl derivatives, which may be analysed quantitatively using high performance liquid chromatography.Nitration using nitric acid alone gives mainly the three isomers with p-nitrophenyl groups, i.e. (7), (9), and (10), whereas mixed acids and nitronium tetrafluoroborate give mainly meta-nitration products, i.e. (6), (8), and (9).Nitration of the three 2-(nitrophenyl)-5-phenyl-1,3,4-oxadiazoles also shows considerable variation of product ratio according to the conditions.
- Blackhall, Alexander,Brydon, Donald L.,Saga, Anthony J. G.,Smith, David M.
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p. 773 - 777
(2007/10/02)
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