Preparation of ADNBF with low-acidity by reactive crystallization

Acidity of ADNBF (7-amino-4,6-dinitrobenzofuroxan) crystallized from acetic acid taken as a reaction medium was found to be 0.14–0.2%, which is not acceptable in view of the long term stability of final products. Inclusion of acetic acid during azidation reaction of the TeNA (2,3,4,6-tetranitroaniline) to ATNA (3-azido-2,4,6-trinitroaniline) and formation of ADNBF crystals from ATNA in acetic acid was found to be the main reason for the high acidity of assynthesized ADNBF crystals. In the present experiments, to reduce the acidity of ADNBF, ATNA, which is an intermediate compound, was separated from acetic acid, and ADNBF crystals were obtained by thermolysis of ATNA from various solvents. The acidity of ADNBF crystals from ethanol was found to be 0.05–0.06%, and their shape and size distribution were cubic or tetragonal and 5–30 μm, respectively, which may be suitable for applying the explosive formulations.