EXO-TRICYCLO5.2.1.0~(2,6)DECANE (TCD OR JP-10) DECOMPOSITION: THERMOCHEMOSTRY AND KINETICS OF RING OPENING AND FORMED INTERMEDIATES

摘要

Exo-tricyclo[5.2.1.0~(2,6)]decane (TCD) or exo-tetrahydro-dicyclopentadiene is an interesting, strained ring compound and the near single component in the high-energy density, hydrocarbon fuel known as JP-10. Important initial reactions of TCD at high temperatures would cleave the strained carbon-carbon (C-C) bonds in the ring creating diradicals constrained by the remaining ring system, or reactions similar to reverse Diels Alder dissociations This study determines the thermochemistry and kinetic parameters of these of TCD unimolecular decompositions, formed intermediates and diradicals. Thermochemical properties including enthalpies (ΔH°_f 298), entropies (S(T)), heat capacities (C_p(T)), and C-H and C-C BDEs for the parent (TCD-H2 m-n), radical (TCD-H2 mj-n and mnj), diradical (TCD-H2 mj-nj), are determined. Ring opening (C3a- C4, numbering below) and posterior H-shift has been shown to account for the formation of 3-cyclopentylcyclopentene. In this study CBS-QB3 and G3MP2 calculations were used to study the ring opening reaction barriers and structures of TCD followed by H-shifts for the cleavage of the competitive C-C bonds (C4-C8, C4-C5) and reaction to olefins. Formation of reported products 1,3- cyclooctadiene (1,3 COD·) and methylheptahydroindene is explained, loss of ethane from 1,3-COD· to benzene is evaluated. Kinetic parameters are derived and a mechanism to describe the initial decomposition of TCD is developed.