Backbone Isomerization to Enhance Thermal Stability and Decrease Mechanical Sensitivities of 10 Nitro-Substituted Bipyrazoles
Jingwei Meng, Teng Fei, Jinxiong Cai, Qi Lai, Jinya Zhang, Siping Pang, Chunlin He
Abstract
The development of novel, environmentally friendly, and high-energy oxidizers remains interesting and challenging for replacing halogen-containing ammonium perchloride ( AP ). The trinitromethyl moiety is one of the most promising substituents for designing high-energy density oxidizers. In this study, a backbone isomerization strategy was utilized to manipulate the properties of 10 nitro group-substituted bipyrazoles containing the largest number of nitro groups among the bis-azole backbones so far. Another advanced high-energy density oxidizer, 3,3′,5,5′-tetranitro-1,1′-bis(trinitromethyl)-1 H,1′ H -4,4′-bipyrazole ( 3 ), was designed and synthesized. Compared to the isomer 4,4′,5,5′-tetranitro-2,2′-bis(trinitromethyl)-2 H,2′ H -3,3′-bipyrazole ( 4 ) ( T d = 125 °C), 3 possesses better thermostability ( T d = 156 °C), which is close to that of ammonium dinitramide ( ADN ) ( T d = 159 °C), and it possesses better mechanical sensitivity (impact sensitivity ( IS ) = 13 J and friction sensitivity ( FS ) = 240 N) than that of 4 ( IS = 9 J and FS = 215 N), thereby demonstrating a promising perspective for practical applications.