QSPR models for the prediction of explosive properties of nitro compounds

International audienceThe evaluation of the explosibility of chemical substances essentially relies on the use of experimental tests according to international regulatory schemes (UN Manual of Tests and Criteria of the Recommendations on the transport of dangerous goods, regulation (EC) N°440/2008). The recent evolution of the European regulatory framework related to chemicals (REACH, CLP) implies a quantity of works incompatible with a complete systematic experimental characterization of hazardous properties (for reason of time and cost). For example, more than 140 000 existing substances could be under concern in the registration process of REACH. Moreover, the explosive intrinsic property of a substance ranks at the top of physico-chemical hazards that may be feared from the use of a given chemical. So, the development of methods allowing the identification of this hazardous property on the basis of chemical structures is of great interest not only for existing substances but also at the R&D stage in the development of new products. For these reasons, INERIS has been developing for several years predictive models (alternative or complementary to experimental approaches) for the evaluation of the explosive properties of hazardous substances and in particular for nitro compounds. The development of these predictive models lies on an original method combining the statistical tools used in quantitative structure property relationship method (QSPR), i.e. multilinear regressions, with quantum chemical calculations. Moreover, a strong validation process ensures the reliability of models in terms of fitting, robustness, predictive power and definition of the domain of applicability, according to the requirements of OECD for use in regulatory framework. Recent QSPR models developed for explosive properties (e.g. heat of decomposition and impact sensitivity) of nitro compounds (e.g. nitroaliphatics, nitroaromatics, nitramines) taking into account their decompositon process are presented. Once validated, models are expected to be used into a global process to estimate explosibility hazards of substances (for classification purposes) and the need for further experimental testing. They can also be used as tools for early identification of potential hazards in the development of new chemical compositions or in substitution studies