An approach to the construction of models for thermal decomposition of organic compounds based on recombination reaction networks was developed. Each species (molecule, ion. or radical) is considered as a potential reagent. It was suggested that the newly formed species can react with all other species which are already present in the reaction mixture. The results of reactions are represented as a bipartite graph whose vertices are formed either by species generated or by the descriptions of interactions, while the oriented edges determine the relations between the reagents and the reaction products. Based on analysis of the experimental data on the mechanisms of thermal decomposition, empirical rules were developed for simulating possible thermal decomposition reactions of the major classes of energetic compounds. The proposed approach allows one to describe the complete spectrum of reactions occurring in the course of thermal decomposition. The approach was realized in the CASB computer program and was exemplified by simulation of thermal decomposition of methyl, ethyl, and isopropyl nitrates. All stages of the mechanisms (some of which have been reported in the literature) were ~eproduced. A number of new decomposition reactions. which have not been studied experimentally, are suggested.

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SummaryAn approach to computer synthesis and retrosynthesis of organic compounds was formulated, and the CASB (Computer-Assisted Structure Building) software for its computer implementation was created. The approach was evaluated by the example of computer generation of probable routes for reactions of homolytic decomposition. Elementary steps of homolysis reactions were modeled with the use of the``retrosynthetic'' method. Each elementary reaction describes fragments that should be present in the structure and structural modi®cations that should be carried out to obtain reaction products. Target fragments are described in terms of production rules by specifying types of atoms, their formal charges and radical states, numbers of adjacent heteroatoms, hybridizations, etc. All possible intermediates of molecular homolysis reactions are generated by the program in a single step and then used in further search for probable pathways of decomposition during subsequent steps until the given maximum number of steps is achieved. Screening of advantageous pathways for these reactions was based on a set of empirical rules. The results obtained by the suggested approach and the corresponding program were illustrated by the example of some cyclic nitramines (RDX and HMX) and demonstrated good agreement with the experiment.