Scientists solve the 50-year mystery of widely used high explosive TATB
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For the first time, scientists have determined the structure of (right) F1 (4,6-diamino-5,7-dinitro-benzo-furazan)—a chemical compound that forms when the high-explosive material known as (left) TATB (1,3,5-triamino-2,4,6-trinitrobenzene) decomposes.
A team of scientists at Lawrence Livermore National Laboratory (LLNL), in collaboration with the U.S. Naval Research Laboratory (NRL), has made a major breakthrough in understanding how one of the world’s safest and most widely used explosives, TATB, breaks down under extreme conditions.
TATB (1,3,5-triamino-2,4,6-trinitrobenzene) is a powerful explosive that is prized for its remarkable insensitivity. Unlike many explosives, TATB is very difficult to accidentally set off, making it a top choice for use in nuclear weapons and other sensitive military applications. However, when TATB is exposed to abnormal situations—like intense heat or physical shock—it can slowly break down, producing new chemical compounds. One of the most important of these intermediary compounds is known as F1 (4,6-diamino-5,7-dinitro-benzo-furazan).
Scientists have known for nearly 50 years that F1 forms when TATB decomposes, but until now, no one has been able to fully isolate and analyze this elusive compound. The main challenge was that previous methods for making F1 produced only tiny amounts, precluding the study of its properties in detail.
LLNL scientist Mao-Xi Zhang (now retired) developed a new, more efficient way to synthesize F1 in large enough quantities to allow for detailed studies. Using this new method, he was able to grow crystals of F1, and Andrew Kerr from NRL was then able to determine its exact structure using single-crystal x-ray diffraction. This is the first time the structure of F1 has been fully revealed.
According to Taylor Miller, research sponsor in LLNL’s Defense Technologies Engineering Division, “Understanding F1 is crucial because it is postulated to be more sensitive to thermal and mechanical insults than TATB itself.”
With F1 now in hand, LLNL researchers are studying its safety properties. “Early experiments indicate F1 is more thermally sensitive than TATB, and any compromised material could change the safety characteristics of TATB formulations,” said Alan J. DeHope, LLNL co-author of the research. This means that if TATB is damaged by fire or other accidents, the resulting material could pose new risks to workers and emergency responders.
With the ability to produce and study pure F1, scientists can now better understand how TATB decomposes, and update safety guidelines for manufacturing, storage, and emergency response. The new findings will also help refine computer models used by LLNL to predict how TATB will behave in real-world accidents, improving preparedness and critical safety margins.
[M.-X. Zhang, A.T. Kerr, A.J. DeHope, J.G. Reynolds, New Synthetic Route to4,6-Diamino-5,7-dinitro-benzo-furazan, Important Decomposition Product of 1,3,5-Triamino-2,4,6-trinitrobenzene, Propellants, Explosives, Pyrotechnics (2025), doi: 10.1002/prep.12080.]
–Physical and Life Sciences Communications Team
