Synthesis and Physicochemical Properties of Energetic 1,2,4,5-Tetrazinyl Derivatives of 5-Nitro-2,4-dihydro-1,2,4-triazol-3-one

By replacing the pyrazolyl fragment in 3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine with 3-nitro-1,2,4-triazol-5-one (NTO), both mono- and disubstitution products have been synthesized. Further interaction of the obtained compounds with O- and N-nucleophiles led to the preparation of a number of polynitrogen tetrazine derivatives, including 2-[6-amino-1,2,4,5-tetrazin-3-yl]-5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one and 5-nitro-2- [6-(1H-tetrazol-5-ylamino)-1,2,4,5-tetrazine-3-yl]-2,4-dihydro-3H-1,2,4-triazol-3-one. The reactions of nucleophilic substitution of symmetrically substituted tetrazine were shown to proceed more selectively. The resulting compounds were identified using H-1, (CNMR)-C-13 spectroscopy, FTIR, LC-MS, and elemental analysis, as well as using X-ray diffraction analysis. The thermal stability of the new compounds was evaluated under isothermal and non-isothermal conditions and their energy characteristics were calculated. An unusual drop in stability was found on going from symmetrically substituted tetrazines to asymmetric ones.

Automated summary

The reaction involving the replacement of the pyrazolyl fragment in 3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine with 3-nitro-1,2,4-triazol-5-one (NTO) led to the synthesis of mono- and disubstitution products. Further interaction with O- and N-nucleophiles resulted in the preparation of various polynitrogen tetrazine derivatives. The stability of the new compounds showed a surprising decrease when transitioning from symmetrically substituted tetrazines to asymmetric ones.