New Synthetic Route to 4,6‐Diamino‐5,7‐dinitro‐benzo‐furazan, Important Decomposition Product of 1,3,5‐Triamino‐2,4,6‐trinitrobenzene

ABSTRACT The important 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) decomposition byproduct, 4,6‐diamino‐5,7‐dinitro‐benzo‐furazan (F 1 ), was prepared in a four‐step reaction sequence starting with commercially available materials through a key intermediate, 4,6‐dichloro‐5,7‐dinitro‐benzo‐furazan. The introduction of azido to 4,6‐dichloro‐benzo‐furazan, followed by nitration and amination gave F 1 in good yield. This new method showed a greatly improved yield and ease of purification than previous methods (the total yield was 30%–40% in seven steps). F 1 is a stable yellow solid with a melting point of 308.7°C and a thermal decomposing temperature of 310.3°C (differential scanning calorimetry at 10°C/min heating rate). The solid‐state structure was solved by single‐crystal X‐ray analyses at low temperatures (100 K). The compound crystallizes in a P 2 1 c space group with the formula C 6 H 4 N 6 O 5 •H 2 O with 12 molecules of F 1 /H 2 O in the unit cell. This compound has eluded complete characterization for almost 50 years. With this information, more advanced decomposition models can be created to further improve critical safety margins in handling the energetic material, TATB.