Very‐low‐pressure pyrolysis of nitroso‐ and pentafluoronitrosobenzene C-NO bond dissociation energies

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Abstract
The high‐pressure absolute rate constants for the decomposition of nitrosobenzene and pentafluoronitrosobenzene were determined using the very‐low‐pressure pyrolysis (VLPP) technique.Bond dissociation energies of DH0(C6H5NO) = 51.5 ± 1 kcal/mole and DH0 (C6F5NO) = 50.5 ± 1 kcal/mole could be deduced if the radical combination rate constant is set at log kr(M−1·sec−1) = 10.0 ± 0.5 for both systems and the activation energy for combination is taken as 0 kcal/mole at 298°K. δHf0(C6H5NO), δHf0(C6F5NO), and δHf0(C6F5) could be estimated from our kinetic data and group additivity. The values are 48.1 ± 1, –160 ± 2, and – 130.9 ± 2 kcal/mole, respectively. C–X bond dissociation energies of several perfluorinated phenyl compounds, DH0(C6F5–X), were obtained from the reported values of δHf0(C6F5X) and our estimated δHf0(C6F5) [X = H, CH3, NO, Cl, F, CF3, I, and OH].
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