2 Energetic Compounds 1: Polynitropolycycloalkanes
This chapter is an extension of Chapter 1 and discusses the more recent research into energetic
compounds which contain strained or caged alicyclic skeletons in conjunction withC-nitro
functionality. This chapter complements Chapter 1 by providing case studies which show how
the same methods and principles that introduceC-nitro functionality into simple aliphatic com-
pounds can be used as part of complex synthetic routes towards caged polynitrocycloalkanes.
The chemistry used for the synthesis of caged structures can be complex but the introduction
ofC-nitro functionality follows the same principles as discussed in Chapter 1. It is suggested
that chemists who are not familiar with this field of chemistry consult Chapter 1 before reading
this chapter.
2.1 Caged structures as energetic materials
Many explosives in frequent use today derive their energy solely from the heat released on the
combustion of the carbon skeleton. Considerable research efforts have focused on synthesizing
explosives containing strained or caged structures which derive their energy from both the heat
of combustion of the carbon skeleton and the relief of molecular strain. Energetic materials with
caged structures also benefit from a decrease in molecular motion which often leads to higher
crystal density and a corresponding increase in explosive performance. Of equal importance
is the thermal and chemical stability of these new explosives; ideally, an increase in molecular
energy should not compromise stability.
The sensitivity of an explosive to impact and friction is a key factor in deciding whether it
finds practical use. Most developed countries have an ongoing program to gradually replace
current explosives and propellants with insensitive materials, a process which will greatly
reduce the risk of accidental detonation. At present these programs are still in their early phases.
The weakest bonds in an explosive will often determine its sensitivity to impact and such
bonds are usually present in the ‘explosophoric’ groups. Steric and electronic factors also
play an important role. Unsurprisingly, factors which increase explosive performance usually
have a detrimental effect on stability and sensitivity, and so a compromise must be made. As
the database of energetic materials and their properties is ever increasing this task becomes
Organic Chemistry of Explosives J. P. Agrawal and R. D. Hodgson
©C2007 John Wiley & Sons, Ltd.
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