Abstract
The kinetics and mechanisms for the unimolecular dissociation of nitrobenzene and related association reactions C 6H 5 + NO 2 and C 6H 5O + NO have been studied computationally at the G2M(RCC, MP2) level of theory in conjunction with rate constant prediction with multichannel RRKM calculations. Formation of C 6H 5 + NO 2 was found to be dominant above 850 K with its branching ratio > 0.78, whereas the formation of C 6H 5O + NO via the C 6H 5ONO intermediate was found to be competitive at lower temperatures, with its branching ratio increasing from 0.22 at 850 K to 0.97 at 500 K. The third energetically accessible channel producing C 6H 4 + HONO was found to be uncompetitive throughout the temperature range investigated, 500-2000 K. The predicted rate constants for C 6H 5NO 2 → C 6H 5 + NO 2 and C 6H 5O + NO → C 6H 5ONO under varying experimental conditions were found to be in good agreement with all existing experimental data. For C 6H 5 + NO 2, the combination processes producing C 6H 5ONO and C 6H 5NO 2 are dominant at low temperature and high pressure, while the disproportionation process giving C 6H 5O + NO via C 6H 5ONO becomes competitive at low pressure and dominant at temperatures above 1000 K.
Original language | English |
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Pages (from-to) | 8367-8373 |
Number of pages | 7 |
Journal | Journal of Physical Chemistry B |
Volume | 109 |
Issue number | 17 |
DOIs | |
State | Published - 5 May 2005 |