1 research outputs found
Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials
The evaluation of
new energetic nitroaromatic compounds (NACs)
for use in green munitions formulations requires models that can predict
their environmental fate. Previously invoked linear free energy relationships
(LFER) relating the log of the rate constant for this reaction (logÂ(<i>k</i>)) and one-electron reduction potentials for the NAC (<i>E</i><sup>1</sup><sub>NAC</sub>) normalized to 0.059 V have
been re-evaluated and compared to a new analysis using a (nonlinear)
free-energy relationship (FER) based on the Marcus theory of outer-sphere
electron transfer. For most reductants, the results are inconsistent
with simple rate limitation by an initial, outer-sphere electron transfer,
suggesting that the linear correlation between logÂ(<i>k</i>) and <i>E</i><sup>1</sup><sub>NAC</sub> is best regarded
as an empirical model. This correlation was used to calibrate a new
quantitative structure–activity relationship (QSAR) using previously
reported values of logÂ(<i>k</i>) for nonenergetic NAC reduction
by FeÂ(II) porphyrin and newly reported values of <i>E</i><sup>1</sup><sub>NAC</sub> determined using density functional theory
at the M06-2X/6-311++GÂ(2d,2p) level with the COSMO solvation model.
The QSAR was then validated for energetic NACs using newly measured
kinetic data for 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT),
and 2,4-dinitroanisole (DNAN). The data show close agreement with
the QSAR, supporting its applicability to other energetic NACs