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Recent Advances in the Study of the Initiation of Nitramines by Impact Using Their 15N NMR Chemical Shifts

Jungová M., Zeman S., Yan Q.-L.

Central European Journal of Energetic Materials

2014

Vol. 11, no. 3

383--393

The relationship between the 15N NMR chemical shifts of aza nitrogen atoms in twelve nitramines and the impact sensitivity of these compounds, expressed as the drop energy, Edr, has been analyzed from the point of view of recently published findings. This relationship appears to be the best method for identifying the key atoms at the reaction centre of a given molecule. These atoms might be taken as “chemical hot spots”. The absence of any solid state influence on the chemical shifts, which were here determined in solution, does not have a fundamental influence on the reaction centre identification. The relationship discussed here confirms the close molecular structural dependence for drop energies (impact sensitivities) obtained for individual energetic materials (EMs) by means of a standard impact tester (Julius Peters) with the detection of the 50% probability of initiation based on acoustic detection. The dependence of impact sensitivity on specific crystal surfaces, using samples of individual EMs obtained by screening, should be investigated more extensively.

A Relationship between 15N NMR Chemical Shifts and Detonation Characteristics of Polynitro Derivatives of Arenes and Polyazaarenes

Zeman S., Pešková M.

Central European Journal of Energetic Materials

2005

Vol. 2, nr 3

71-84

The 15N NMR chemical shifts of eighteen polynitro arenes have been determined. The relationships were found and discussed between the characteristics of detonation and thermal decomposition, on the one hand, and 15N NMR chemical shifts of nitrogen atoms of the primarily split off nitro groups, on the other hand. Also the relationships are specified between the 15N NMR chemical shifts in the solid state of some polynitro derivatives of aminopyridines and aminopyrimidines, on the one hand, and squares of their detonation velocities, on the other. It has been stated that the chemical micromechanisms of primary fission processes of molecules of the studied compounds in the initiation by shock should be the same as in the case of their low-temperature thermal decomposition. Also mentioned is relevance of the modified Evans-Polanyi-Semenov relationship. On the basis of the findings presented it also has been stated that the detonation transformation itself of these polynitro compounds should be preceded by an induction period.