Future Energetics

Using the heat of explosion (g), the detonation velocity (D) and the detonation pressure (P) as a measure for the performance of a high explosive, one can clearly see from Fig. 9.30 that since the time NG was taken into service the performance of chemical explosives has improved substantially. 

In spite of the many years of research, there are limited possibilities to realize a substantial increase in performance from conventional C-H-N-O explosives. Recent advances in energetics energy output have come in improved processing or inclusion of energetic binders to increase overall formulation energy, but limited success has been realized in the development of novel energetics. One reason for this is that conventional nitramine and nitroaromatic explosives such as TNT, RDX, HMX and other similar molecules share the same three limitations (Table 9.11)  

The computed and predicted performance values not only exceed the first generation of high-nitrogen compounds e.g. HZT) but, in case of TKX-50, also the performance values of RDX and HMX (Fig. 9.33). 

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Recently, a method has been proposed to overcome the problems associated with calculating forces in both VMC and DMC [122], It has been suggested that the use of QMC in the near future to tackle the energetics of systems as challengmg as liquid binary iron alloys is not unthinkable [123],... 

Contents Introduction. - Experimental Techniques Production of Energetic Atoms. Radiochemical Separation Techniques. Special Physical Techniques. - Characteristics of Hot Atom Reactions Gas Phase Hot Atom Reactions. Liquid Phase Hot Atom Reactions. Solid Phase Hot Atom Reactions. - Applications of Hot Atom Chemistry and Related Topics Applications in Inorganic, Analytical and Geochemistry. Applications in Physical Chemistry. Applications in Biochemistry and Nuclear Medicine. Hot Atom Chemistry in Energy-Related Research. Current Topics Related to Hot Atom Chemistry and Future Scope. - Subject Index. 

It is to be hoped that measurements will be made in the near future which will put more substantial flesh on the skeleton of known bond enthalpy contributions in organo-transition metal compounds, so that a better understanding of the energetics of reactions such as olefin disproportionation (metathesis) and hydroformylation may be achieved. 

As such, a more thorough description of the energetics of nitroso compounds may well logically appear in a future Patai volume on functional groups devoted to carbon-containing double bonds such as monoalkenes, imines and ketones and aldehydes, since oximes would seem to belong with these functionalities. 

Finally, the theory for the bioenergetics and kinetics of microtubule assembly and disassembly of microtubules has been extended by Hill and Kirschner (1983). They consider the coupling of nucleotide hydrolysis in terms of the energetics of the [GTP]/[GDP][PJ mass action ratio, the possible effects of force imparted by attachment of tubules to barriers on the rate constants, and other intriguing aspects of protomer-polymer exchange kinetics and thermodynamics. Unfortunately, much of their theory remains to be tested, and an evaluation of its importance in revealing the subtleties of assembly/disassembly remains for future investigations. 

The reason for this behavior in the case of the double-bonded structures ( A -type phosphorus) is the easy dimerization of the P=C bond. Tricoordinate planar (or nearly planar) phosphorus ( B - and C -type bonding) can be stabilized by repyramidalization when the cyclic electron delocalization is disturbed or lost (e.g., in a chemical reaction). The fine balance between these energetic effects cannot easily be predicted by using analogies or other simple models. Such predictions, however, can be made by using the sophisticated methods of computational chemistry, leaving the field of the chemistry of the aromatic phosphorus compounds an interesting research area with unexpected results in the future. 

Preliminary evaluations of polynitropolycyclic compounds reveal that this class of energetic materials is relatively powerful and shock insensitive, and so, well suited for use in future explosive and propellant formulations. 

Chinese chemists have reported the synthesis of pentacyclo[4.3.0.0 , 0 ]nonane-2,4-bis(trinitroethyl ester) (88). This compound may find potential use as an energetic plastisizer in futuristic explosive and propellant formulations. The synthesis of (88) uses widely available hydroquinone (81) as a starting material. Thus, bromination of (81), followed by oxidation, Diels-Alder cycloaddition with cyclopentadiene, and photochemical [2 - - 2] cycloaddition, yields the dione (85) as a mixture of diastereoisomers, (85a) and (85b). Favorskii rearrangement of this mixture yields the dicarboxylic acid as a mixture of isomers, (86a) and (86b), which on further reaction with thionyl chloride, followed by treating the resulting acid chlorides with 2,2,2-trinitroethanol, gives the energetic plastisizer (88) as a mixture of isomers, (88a) and (88b). Improvements in the synthesis of nitroform, and hence 2,2,2-trinitroethanol, makes the future application of this product attractive. 

The effect which amino functionality has on the thermal and impact sensitivity of polyni-troarylenes (Section 4.8.1.4) makes amination by VNS a method with much future potential for energetic materials synthesis. Other carbon, nitrogen, oxygen and sulfur nucleophiles can displace aromatic hydrogen examples with 1,3-dinitrobenzene and 1,3,5-trinitrobenzene are extensive. 

A practical application of dinitrogen pentoxide in methylene chloride reagent involves the nitration of either ammonium carbamate or nitrourethane, followed by ammonolysis to yield ammonium dinitramide, an energetic oxidizer with enormous potential for use in future high performance propellant compositions. This important reaction is discussed in more detail in Chapter 9. 

Vast research efforts have been pooled into finding new energetic V-heterocycles over the past 30 years and, consequently, the number of reported compounds is huge. It is quite impossible to discuss all the materials reported in this area in the space available. We personally believe that V-heterocycles should be the subject of its own book and this may well be the case in the future. We draw the reader to a number of excellent reviews, which together cover most of the past and present literature on V-heterocycles. 

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