Synthesis, Characterisation and Crystal Structures of Two Bi‐oxadiazole Derivatives Featuring the Trifluoromethyl Group

Abstract

The synthesis, characterisation, and crystal structure determination of the closely related compounds 3,3'-bi-(5-trifluoromethyl-1,2,4-oxadiazole) and 5,5'-bi-(2-trifluoromethyl-1,3,4-oxadiazole) are reported. These two compounds are known for their bioactivity; however, in this study they serve as model compounds to evaluate the suitability of the heterocyclic oxadiazole ring system for energetic materials when the fluorine atoms in the exocyclic CF3 groups are substituted successively by nitro groups. Quantum chemical calculations for the bi-1,3,4-oxadiazole derivatives with difluoronitromethyl, fluorodinitromethyl, and trinitromethyl groups have been carried out and predict promising energetic performances for both explosive and propulsive applications.

New efficient synthesis of bis-1,2,4-oxadiazole derivatives via subsequent Staudinger/aza-Wittig reaction

“…There were many synthetic methods [16][17][18][19][20] of oxadiazole, but there were only few literatures on the synthesis of bisoxadiazole ring. diaminoglyoxime, as the only basic starting material, was used to obtain bis-1,2,4oxadiazole derivatives through condensation and cyclization reaction with various reagents, such as triethyl orthoformate 21,22 , triethyl orthoacetate 21 , trifluoroacetic acid 21 , trifluoroacetic anhydride 23 or acetoxyacyl chloride 23,36 and chloroacyl chloride 24 in the existed literatures. A frequently applied strategy is to modify the substituents of bis-1,2,4-oxadiazole with nitrogenous groups to design metal complexes 21 or energetic materials 24,36 , but the substituents on the bis-1,2,4-oxadiazole ring are very limited.…”

5-Nitrotetrazol and 1,2,4-Oxadiazole Methylene-Bridged Energetic Compounds: Synthesis, Crystal Structures and Performances

“…In the past decade, significant progress has been made in the field of melt cast explosives. Researchers have found that the 1,2,4-oxadiazole skeleton is promising for the construction of new high explosives with balanced detonation and safety properties [ 7 , 8 , 9 , 10 ]. A lot of melt cast energetic materials have been synthesized based on 1,2,4-oxadiazole, such as 3,5-bis(4-nitrofurazan-3-yl)-1,2,4-oxadiazole (LLM-191) [ 11 ], 3-(4-amino-1,2,5-oxadiazol-3-yl)-5-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazole (LLM-192) [ 11 ], 3-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazol-5-amine (LLM-201) [ 12 ], bis(1,2,4-oxadiazolyl)furoxan (BOF) [ 13 ] and bis(1,2,4-oxadiazole)bis(methylene) dinitrate (BODN) [ 14 ] ( Figure 1 a).…”

Theoretical design and prediction of properties for dinitromethyl, fluorodinitromethyl, and (difluoroamino)dinitromethyl derivatives of triazole and tetrazole

“…19 Furthermore, it has been found that partially uorinated nitro groups exhibit potential for applications in the eld of energetic materials. [19][20][21][22][23] Molecules in which the uorodinitromethyl moiety [-CF(NO 2 ) 2 ] is attached via a carbon atom to an aliphatic, aromatic, or heterocyclic skeleton have been revealed to have useful energetic properties and stabilities. 22,[24][25][26] Notably, the incorporation of the (diuoroamino)dinitromethyl moiety [-C(NF 2 )(NO 2 ) 2 ] is another effective tool for constructing energetic compounds, as it provides a high energy content while maintaining a high density and acceptable thermal and processing properties.…”