Thermochemical and Energy Characteristics of Alkoxy-NNO-Azoxy Derivatives of Pyrazole and Nitropyrazoles

Abstract

The standard enthalpies of formation of the compounds 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)pyrazole, 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)-3-nitropyrazole, and 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)-4-nitropyrazole were measured experimentally to be 273.6 ± 6.7, 231.0 ± 3.3, and 213.8 ± 7.9 kJ/mol, respectively. These enthalpy values were used to determine the contribution of the replacement of the H atoms at the N atoms in the heterocycles by CH₂CH(N₂O₂Me)₂ groups (151.9 kJ/mol). Calculations have shown that 1-(2,2-bis(methoxy-NNO-azoxy)ethyl derivatives of pyrazole, 3- and 4-nitropyrazole, 3,4-dinitropyrazole, and 3,4,5-trinitropyrazole and the bis-derivative of bis-furazano[3,4-b;3′,4′-e]piperazine are inferior to HMX as gasifying components of solid composite propellants in metal-free compositions with an active binder. Only the derivative of 3,4-dinitropyrazole, which added in a small amount together with ammonium Perchlorate to aluminum-free propellant compositions provides a specific impulse of 249 s.