Synthesis and Chemistry of 1,3,5,7-Tetranitrocubane Including Measurement of Its Acidity, Formation of o-Nitro Anions, and the First Preparations of Pentanitrocubane and Hexanitrocubane¹

Abstract

Nitro groups on alternate corners of cubane enhance the acidity of cubyl hydrogen (pK a ∼21) and provide sufficient activation for ready anion formation. The sodium salt of 1,3,5,7-tetranitrocubane reacts easily with electrophiles and leads thereby to yet more highly substituted cubanes, like carbomethoxy- and (trimethylsilyl)tetranitrocubane. Anions from these species are also easily formed and are useful for further substitution on the cubane nucleus. Dinitrogen tetraoxide reacts with the anion of tetranitrocubane to give 1,2,3,5,7-pentanitrocubane, the first cubane to contain vicinal nitro groups. The reaction probably involves oxidation of the anion to the corresponding radical. Similarly, the anion of pentanitrocubane is used to prepare 1,2,3,4,5,7-hexanitrocubane, the most highly nitrated cubane made to date. Single-crystal X-ray structural information is given for both penta- and hexanitrocubane.

Application of DFT and EMS to the Study of Strained Organic Molecules

“…(Alkorta and Elguera 1997) and kinetic stability. In addition cubane has potential as a scaffold for combinatorial chemistry, and as an energetic material precursor (Bashir-Hashemi et al 1995;Lukin et al 1997). We report here our first preliminary studies on cubane, which is also the first EMS study on this unique molecule.…”

Análise térmica aplicada ao estudo de materiais energéticos

“…Neste trabalho, as temperaturas de decomposição térmica do mercúrio-5-nitrotetrazolato (MNT) e do explosivo primário azoteto de chumbo Pb(N 3 ) 2 , obtidas a partir de curvas DTA nas razões de aquecimento de 5 e 10 o C/min, foram utilizadas como parâmetro para comparar as estabilidades destes explosivos. Os autores concluíram que o azoteto de chumbo, com as temperaturas de decomposição de 327 e 345 o C, apresentava uma estabilidade térmica maior que o MNT, caracterizado pelas temperaturas de decomposição 228 e 230 o C. A temperatura de decomposição térmica não deve, entretanto, ser considerada um parâmetro determinante em estudos de materiais explosivos, uma vez que, dados relativos aos testes de compatibilidade química e estabilidade à fricção fornecem uma visão mais ampla quanto as características do material 23 . Uma confirmação sobre a compatibilidade química entre compostos participantes de uma formulação é obtida quando a temperatura de decomposição térmica da formulação resultante é menor em relação aos compostos originais.…”

Cubane: 50 Years Later

“…1,2,3,5,7-Pentanitrocubane (184) was found to be colorless and highly crystalline, showing no obvious shock sensitivity or special thermal sensitivity, with decomposition occurring only above 250°C. 150 When the bis(triethyllead) derivative (185) was treated with N 2 O 4 , followed by ozonolysis, a 40% isolated yield of a 40:60 mixture of pentanitrocubane (184) with hexanitrocubane (186) was obtained (Scheme 49). 150 The relative acidity of tetranitrocubane (170) proved to be the key to preparing the higher nitrocubane compounds.…”

“…150 When the bis(triethyllead) derivative (185) was treated with N 2 O 4 , followed by ozonolysis, a 40% isolated yield of a 40:60 mixture of pentanitrocubane (184) with hexanitrocubane (186) was obtained (Scheme 49). 150 The relative acidity of tetranitrocubane (170) proved to be the key to preparing the higher nitrocubane compounds. Anion formation with four equivalents NaN(SiMe 3 ) 2 followed by N 2 O 4 at −130°C gave a 74% yield of heptanitrocubane (154) on a 1 g scale.…”