Journal of Hazardous Materials 145 (2007) 263–269 New method for calculating densities of nitroaromatic explosive compounds Mohammad Hossein Keshavarz ∗ Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr, P.O. Box 83145/115, Islamic Republic of Iran Received 26 November 2005; received in revised form 4 November 2006; accepted 13 November 2006 Available online 18 November 2006 Abstract A new model has been introduced for simple calculation of crystal density of an important class of organic explosives, namely nitroaromatic energetic compounds. This model is based on the fundamental correlation. The introduced procedure has been applied to 60 well-known and new synthesized organic nitroaromatic explosives. The results show that the present method gives comparable prediction respect to well-developed group additivity method for estimation of crystal density of organic explosives. The introduced simple method can be applied to any complex nitroaromatic explosive that contains the elements of carbon, hydrogen, nitrogen and oxygen with no difficulties. © 2006 Elsevier B.V. All rights reserved. Keywords: Crystal density; Correlation; Nitroaromatic explosive; Elemental composition; Safety 1. Introduction Simple methods can facilitate the discovery of new ener- getic materials that have significant advantages over materials currently in use. Properties such as density, heat of formation, detonation pressure, detonation velocity and sensitivity can help us to screen potential energetic candidates would permit the selection of only the most promising substances for laboratory synthesis, scale-up, testing, etc. However, predicting crystal den- sity is one of the most important properties of high explosives. The solid-state density is affected the amount of material that can be packed into a volume-limited warhead or propulsion config- uration. For most explosives, the detonation velocity increases linearly with density while the Chapman–Jouguet pressure is proportional to the square of the loading density [1]. To a chemist concerned with the synthesis of new high explo- sive compounds the ability to estimate crystal density and heat of formation from a given molecular structure is a problem of the utmost importance because they are usually needed to evaluate detonation properties by a computer code or empirical methods. The calculated detonation properties could be meaningful in the decision as to whether it is worth the effort to attempt a new and ∗ Tel.: +98 312 522 5071; fax: +98 312 522 5068. E-mail addresses: mhkir@yahoo.com, mhkeshavarz@mut-es.ac.ir. complex synthesis. The major goals of thermochemical codes and empirical methods apart from being developed as predic- tive tools, is to provide insight to understanding the molecules which are responsible for higher performance and which are not. An equilibrium complicated thermochemical code such as TIGER [2] and equations of state for detonation products can be used to estimate detonation parameters for explosives as well as parameters for other conditions such as a constant explo- sion. Each equation of state has a different set of data that mirrors the preferences of the workers that use it. Some well- known equations of state are Becker–Kistiakowsky–Wilson (BKW) [3], the Jacobs–Cowperthwaite–Zwisler (JCZ) [4,5] and Kihara–Hikita–Tanaka (KHT) [6]. New empirical methods were recently introduced for reliable detonation and thermochemical properties of ideal and non-ideal pure or mixed explosives of different classes [7–18]. Density and heat of formation usually are two parameters which are necessary in evaluating the performance of explo- sives by computer codes and empirical methods. Studies show that detonation velocity and pressure are greatly sensitive to density values, but somewhat less sensitive to the heat of for- mation [10,13,14]. Therefore, predicting the crystal density of unsynthesized organic explosives is one of the important data to explosive user for determining the performance of explosives. Molecular structure of an explosive can be related to its density [19]. Theoretical and empirical nature methods are two broad 0304-3894/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2006.11.023