New High Secondary Explosives

CL-20 (1987, A. Nielsen) and ONC (1997, Eaton) are without doubt the most prominent recent explosives based on molecules with considerable cage-strain. 

While CL-20 is now already produced in 100 kg quantities (e.g. by SNPE, France or Thiokol, USA) on industrial pilot scale plants, ONC is only available on a mg to g scale because of its very difficult synthesis. Despite the great enthusiasm for CL-20 since its discovery over 20 years ago it has to be mentioned that even today most of the high explosive formulations are based on RDX (see Tab. 1.2). There are several reasons why CL-20 despite its great performance has not yet been introduced successfully  

Interconversion of the s form into a more stable but perhaps also more sensitive other polymorph would result in a loss of performance and an increase in sentitivity. 

CL-20 is obtained by the condension of glyoxal with benzylamine in an acid catalyzed reaction to yield hexabenzylhexaaxaisowurtzitane (Fig. 1.8). Afterwards the benzyl groups are replaced under reducing conditions (Pd-C catalyst) by easily removable acetyl substituents. Nitration to form CL-20 takes place in the final reaction step. 

Another very insensitive high explosive which is structurally closely related to CL-20 is 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX, see Fig. 1.7), which was first described by Ramakrishnan and his co-workers in 1990. It displays one of the highest densities of all nitramines (2.008 g cm ) [Ic]. 

---