Hexanitrohexaazaisowurtzitane (HNIW) is a polycyclic cage nitramine and the most powerful high energy density compound (HEDC) ever tested. the authors have synthesized HNIW in a yield of 82% in a yield of 72% by the nitrolysis of tetraacetyldiformylhexaazaisowurtzitane (TADFIW) using a complex nitrating agent. condensation of two benzyl groups at the six-membered ring of tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) into two formyl groups in formic acid gave TADFIW in 72% yield. As described in the literature, TADBIW was prepared from hexabenzyl-hexaazaisowurtzitane (HBIW) via hydrogenolysis in the presence of Pd(OH)~2 catalyst. It was found that the HNIW thus obtained contained a small amount (2%～3%) of incompletely-nitrated product, which was later separated and characterized as pentanitromonoformylhexa-azaisowurtzitane (PNMFIW). The separation of PNMFIW from crude HNIW was carried out using a chromatographic column packed with silica-gel, with acetone as solvent and petroleum benzine (b.p. 90～120℃)/ethyl acetate (4:1, V:V) mixture as extracting agent respectively. The analytic results for all the involved compounds are summarized in Table 1. The simple HNIW synthetic method possesses the following advantages: low consumption of catalyst, mild reaction conditions and high yielding.

Key words: CAGE STRUCTURE, NITRAMINE