Thermal Stability Characteristics of Nitroaromatic Compounds.
Final rept. 1 Jun 83-30 Aug 86,
NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD CHEMICAL KINETICS DIV
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A single pulse shock tube has been used to determine the rates and mechanisms of the initial processes during the decomposition of a number of nitroaromatic compounds at temperatures near 1100 K. For nitrobenzene and p-nitrotoluene, the primary decomposition pathways involve the breaking of the C-NO2 bond and the isomerization of the NO2 group to form the nitrite, followed by rapid cleavage of the weak CO-NO bond. In the case of o-nitrotoluene, although these channels also make contributions, the principal pyrolytic mechanism involve an intermolecular rearrangement leading to the formation and rapid decomposition of anthranil. This represents the first report of such a process occuring purely in the gas phase and thus without the aid of acid, base or photon catalysis. It is clear that the presence of a methyl ortho to the nitro group in nitroaromatic compounds introduces a new element into the decomposition behavior of such compounds. Inasmuch as these are low activation energy processes, we expect that such reactions will be of even more importance in the lower temperature regions where ignition behavior is intimately related to the chemical kinetics. We describe in detail the unique features of single pulse shock tube experiments and the systematic studies which permit unambiguous determination of the reaction mechanisms and the elucidation of high accuracy rate constants and expressions.
- Organic Chemistry
- Atomic and Molecular Physics and Spectroscopy