Heats of fusion of polynitro derivatives of polyazaisowurtzitane
Introduction
The nitramines continue to be a source of new explosives characterized by high energy content [1], [2], [3], [4]. An important point in selection and exploitation of explosives of this kind is, inter alia, studies of their physical stability [5]. A significant characteristics affecting this stability is the heat of fusion, which-to a certain extent-represents intermolecular interactions in nitramine crystals. In order to determine this quantity, one can apply differential scanning calorimetry (DSC) as a convenient method [5]. However, for the nitramines, which are thermolysed in solid, phase the heat of fusion ΔHm,tr is only accessible by means of prediction methods. At present, the said type of attractive nitramines involves derivatives of polyazaisowurzitane, particularly 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW) and 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX), the prediction of which was the topic of a preliminary study [6]. Results of this study were reinvestigated including a largest number of nitramines.
Section snippets
Substances and data sources
Table 1 presents a set of the nitramines whose data were used to predict the ΔHm,tr values of HNIW and TEX. The heat of fusion ΔHm,tr defined as a sum of all heats of the polymorphous transitions and of the heat of melting [7] was determined with a DSC-7 apparatus of Perkin-Elmer [5] or predicted in the sense of [5]: the ΔHm,tr values given in Table 1 are the average of at least three measurements from [5]. The 15N NMR chemical shifts of nitrogen atoms of nitramine groupings were mostly
Results and discussion
Physical properties of polyfunctional molecules are influenced by the character and intensity of local interactions, i.e. by magnitude, number, distances and orientation of group dipoles within a molecule. The factors mentioned are directly connected with the size of a molecule, its conformation, symmetry and with the quality and quantity of the substituents present [7], [22].
Conclusions
The results presented show that we can obtain real heat of fusion (ΔHm,tr) values for 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW) by applying the prediction relationships involving, first of all, the 1,3-diazacyclopentane and 1,3,5-triazacycloheptane structures (i.e. the dependence C and the point of intersection of the dependences G and H) or the comparable effect of intermolecular interactions on the length and cis-orientation in space of N–N bonds in molecular crystals
References (27)
Thermochim. Acta
(1997)Thermochim. Acta
(1999)- et al.
Chem. Phys. Lett.
(1991) - et al.
J. Mol. Struct. (THEOCHEM)
(1990) Chem. Eng. News
(1994)- G.A. Olah, D.R. Squire, Chemistry of Energetic Materials, Academic Press, San Diego,...
- R.I. Simpson, R.G. Garza, M.F. Foltz, D.I. Ornellas P.A. Utriev, Characterization of Tnaz, Rep. UCRL-ID-119572,...
- A. Sanderson, The Characterization and Development of New Energetic Materials, Proc. 27th Int. Annual Conf. ICT,...
- Z. Jalový, S. Zeman, Prediction of Heat of Fusion of Polynitro Derivatives of Polyazaisowurtzitane, in: Proc. 3rd Int....
- A. Bondi, Physical Properties of Molecular Crystals, Liquids, and Glasses, Wiley, London,...
Org. Magn. Reson.
Cited by (31)
A reliable method for prediction of enthalpy of fusion in energetic materials using their molecular structures
2016, Fluid Phase EquilibriaImproved method for reliable predicting enthalpy of fusion of energetic compounds
2012, Fluid Phase EquilibriaSimple method for prediction of activation energies of the thermal decomposition of nitramines
2009, Journal of Hazardous MaterialsPrediction of physicochemical properties of energetic materials
2008, Fluid Phase EquilibriaNew aspects of initiation reactivities of energetic materials demonstrated on nitramines
2006, Journal of Hazardous MaterialsA study of chemical micro-mechanisms of initiation of organic polynitro compounds
2003, Theoretical and Computational ChemistryCitation Excerpt :The thermal decomposition of RDX and HMX (from this group of nitramines) could consist in their primary depolymerisation to 1-nitro-1-azaethylene (DIGEN, see below). We also made molecular-dynamic simulation of thermal decomposition of some individual energetic materials, including RDX, at extremely high temperatures [93,94]. It turned out that the primary fragmentation mechanism at these conditions is entirely different from the low-temperature variant.