Synthesis, Characterization and Energetic Properties of 1,3,4‐Oxadiazoles

Abstract 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 (Δ H f ) and densities ( ρ ) were calculated, and heats of decomposition (Δ H d ) and combustion (Δ H c ) were determined experimentally. The densities of seven of the synthesized compounds were determined by gas pycnometry, and the respective values of detonation velocity ( V D ), detonation pressure ( P D ) and specific impulse ( I SP ) 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.