“…As molecular volume is (very roughly) a group additive property, highly nitrated cubanes can be predicted to be very dense, and hence they are expected to be very powerful explosives. Octanitrocubane ( 1 ) is calculated to be 15−30% better than HMX, an important explosive produced and used in large quantity. …”
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.
“…As molecular volume is (very roughly) a group additive property, highly nitrated cubanes can be predicted to be very dense, and hence they are expected to be very powerful explosives. Octanitrocubane ( 1 ) is calculated to be 15−30% better than HMX, an important explosive produced and used in large quantity. …”
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.
ABSTRACT:For five prototypical energetic molecules (nitrobenzene, methyl azide, methyl nitrate, nitromethane, and dimethylnitramine), we examine computationally the effects of external electric fields upon their "trigger linkage" bonds, the breaking of which is believed to play a key role in detonation initiation. The bonds are, respectively, CONO 2 , NON 2 , OONO 2 , CONO 2 , and NONO 2 . The calculations are at the B3PW91/ 6 -31G** level. We find that fields along these bonds that reinforce the molecules' intrinsic polarities also lower their energies and increase the bonds' stretching vibration frequencies. This suggests a strengthening of the bonds. Fields in the opposite direction do the reverse.
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