THEORETICAL-STUDY ON PYROLYSIS AND SENSITIVITY OF ENERGETIC COMPOUNDS- PART 4 - NITRO-DERIVATIVES OF PHENOLS

The UHFSCF-AM1 MO method was applied to the study of two kinds of pyro lysis reactions of six nitro derivatives of phenols (homolysis reactio n by rupture of the C-NO2 bond into radicals and isomerization reactio n involving phenolic hydrogen transferring to oxygen on the NO2 group) . The molecular geometries of reactants, transition states and product s were fully optimized. The potential energy curves and activation ene rgies were first obtained. The results show that this category of comp ounds is more easily initiated via isomerization reactions than by hom olysis reactions. The parallel relationship among the Wiberg bond orde r of the pyrolysis-initiation H-O bond in the molecule of a reactant, the activation energy of the isomerization reaction breaking the H-O b ond and impact sensitivity of the reactant gives 'the principle of the smallest bond order' (PSBO) powerful support. The sensitizing effect of a phenol group was elucidated based on calculation results. The dif ferent influences of OH and NO2 groups on the heat of formation of a m olecule are discussed. (C) 1998 John Wiley & Sons, Ltd.