Mechanism of decomposition of nitroaromatics. Laser-powered homogeneous pyrolysis of substituted nitrobenzenes

Gonzalez, Alicia C.; Larson, C. W.; McMillen, D.F.; Golden, David M.

doi:10.1021/j100268a030

Cited by 103 publications

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“…It can be seen from Table 8.1 that the energy for molecular dissociation in the gas phase is about 70 kcal mol −1 for both FOX-7 and TATB. This falls into the range of 61-70 kcal mol −1 reported for a wide variety of compounds [1] and is in general agreement with mass spectroscopy [133,134], laser-assisted pyrolysis [135], shock tube pyrolysis [136], and theoretical studies [107][108][109]119]. This is somewhat higher, however, than the differential calorimetry-based estimate for FOX-7, 58 kcal mol −1 [106].…”

Section: Shear-induced Decomposition In Fox-7 and Tatbsupporting

confidence: 82%

Modeling Defect-Induced Phenomena

Kuklja

Rashkeev

2009

Static Compression of Energetic Materials

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Elucidation of dissociation mechanisms, energy localization, and transfer phenomena in the course of explosive decomposition of energetic materials (EMs) are central for understanding, controlling, and enhancing the performance of these materials as fuels, propellants, and explosives. Quality of energetic materials is often judged using two main parameters: sensitivity to detonation and its performance. Low sensitivity is desired to make the material relatively stable to external stimuli, i.e., controllable and able of triggering rapid dissociation only when needed and not accidentally. Performance, on the other hand, is to be high to provide larger heat of the explosive reaction. These parameters do not necessarily correlate with each other and depend on many variables such as molecular and crystalline structures, history of samples, the particle size, crystal hardness and orientation, external stimuli, aging, storage conditions, and others. Mechanisms governing performance are fairly well understood whereas mechanisms of sensitivity are poorly known and need to be much more extensively studied. It is widely accepted though that the thermal decomposition reactions of the materials play a significant role in their sensitivity to mechanical stimuli and their explosive properties [1].The decomposition of energetic materials can be initiated with a mechanical impact, thermal heating, a shock wave, or a spark. Such events in solids generate molecules in highly excited vibronic and/or electronic states. Clearly, the decomposition of solid explosives under shock, spark, laser, or plasma ignition must include contributions from both ground and excited electronic states. Excitation in the UV can markedly reduce the power requirements for detonation of some secondary explosives. Therefore, establishing the initial steps of high explosive (HE) decomposition is an important goal to pursue. Decomposition triggered by excited electronic states seems appealing because electronic excitation of the system to an unstable potential energy surface can result in rapid dissociation of a molecule and consequent chain reaction.

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Section: Shear-induced Decomposition In Fox-7 and Tatbsupporting

confidence: 82%

Modeling Defect-Induced Phenomena

Kuklja

Rashkeev

2009

Static Compression of Energetic Materials

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“…The rate constants measured by Gonzalez et al 1 using the SF 6 as bath gas at 110 Torr pressure are evidently higher than those measured by Tsang and co-workers 2,3 using Ar as bath gas at 2700-3400 Torr. The values predicted for the conditions employed by Gonzalez et al 1 , represented by k 1 ) 1.5 × 10 15 exp[-30900/T] s -1 , though slightly lower than their experimental results given by k 1 ) 7.9 × 10 15 exp[-(33000 ( 1000)/ T] s -1 , are well within the given error bars as shown in the b. Production of Anthranil by Dehydration.…”

Section: Resultsmentioning

confidence: 53%

A Computational Study on the Kinetics and Mechanism for the Unimolecular Decomposition of o-Nitrotoluene

Chen

Diau

et al. 2006

J. Phys. Chem. A

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The kinetics and mechanism for the unimolecular decomposition of o-nitrotoluene (o-CH(3)C(6)H(4)NO(2)) have been studied computationally at the G2M(RCC, MP2)//B3LYP/6-311G(d, p) level of theory in conjunction with rate constant predictions with RRKM and TST calculations. The results of the calculations reveal 10 decomposition channels for o-nitrotoluene and its six isomeric intermediates, among them four channels give major products: CH(3)C(6)H(4) + NO(2), C(6)H(4)C(H)ON (anthranil) + H(2)O, CH(3)C(6)H(4)O (o-methyl phenoxy) + NO, and C(6)H(4)C(H(2))NO + OH. The predicted rate constants in the 500-2000 K temperature range indicate that anthranil production, taking place initially by intramolecular H-abstraction from the CH(3) group by NO(2) followed by five-membered ring formation and dehydration, dominates at temperatures below 1000 K, whereas NO(2) elimination becomes predominant above 1100 K and CH(3)C(6)H(4)O formation by the nitro-nitrite isomerization/decomposition process accounts for only 5-11% of the total product yield in the middle temperature range 800-1300 K. The branching ratio for CH(2)C(6)H(4)NO formation by the decomposition process of CH(2)C(6)H(4)N(O)OH is negligible. The predicted high-pressure-limit rate constants with the rate expression of 4.10 x 10(17) exp[-37000/T] s(-1) for the NO(2) elimination channel and 9.09 x 10(12) exp[-25800/T] s(-1) for the H(2)O elimination channel generally agree reasonably with available experimental data. The predicted high-pressure-limit rate constants for the NO and OH elimination channels are represented as 1.49 x 10(14) exp[-30000/T] and 1.31 x 10(15) exp[-38000/T] s(-1), respectively.

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“…Another experiment (3) on the same compound, which mass spectrometrically sampled the initial products, reported observation of NO and fragment ions of the nitroxyl radical (CH3),N0, presumably formed from the nitrite. However, a recent IRMPD study (4) of dimethylnitramine reported no evidence of the isomerh n c d In Canada nitrobenzene, detection of C,H,OH in the presence of radical scavenger, has also been reported (5).…”

Section: Introductionmentioning

confidence: 97%

Theoretical study of nitro–nitrite rearrangement of CH₃NO₂

Saxon¹,

Yoshimine²

1992

Can. J. Chem.

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This paper is dedicated to Professor Sigerzi Hzizinc~gc~ otz the occasion of his 65th birthdayROBERTA P. SAXON and MEGUMU YOSHIMINE. Can. J . Chem. 70, 572 (1992). Calculations designed to characterize the transition state and determine the barrier height for rearrangement of nitromethane to methyl nitrite are reported. Structures of CH,NO,, C H 3 0 N 0 , dissociation products, CH3 + NOz and CH,O + NO, and the transition state for nitro-nitrite rearrangement have been optimized at the MCSCF/4-31G level. The geometry of the transition state may be approximately described as separated CH3 and NO, species with extremely long C-N and C 4 bond lengths, 3.396 and 3.654 A, respectively. Energies have been obtained by large-scale multireference single-and double-excitation CI calculations (6-3 lG:+ basis). The transition state is calculated to lie 56.7 kcal/mol above nitromethane (with zero-point energy). A C-N bond dissociation energy of 51.7 kcal/mol is obtained. Results are compared with the infrared multiphoton dissociation experiment of Wodtke, Hintsa, and Lee.

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Mechanism of decomposition of nitroaromatics. Laser-powered homogeneous pyrolysis of substituted nitrobenzenes

Cited by 103 publications

References 0 publications

Modeling Defect-Induced Phenomena

Modeling Defect-Induced Phenomena

A Computational Study on the Kinetics and Mechanism for the Unimolecular Decomposition of o-Nitrotoluene

Theoretical study of nitro–nitrite rearrangement of CH₃NO₂

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Mechanism of decomposition of nitroaromatics. Laser-powered homogeneous pyrolysis of substituted nitrobenzenes

Cited by 103 publications

References 0 publications

Modeling Defect-Induced Phenomena

Modeling Defect-Induced Phenomena

A Computational Study on the Kinetics and Mechanism for the Unimolecular Decomposition of o-Nitrotoluene

Theoretical study of nitro–nitrite rearrangement of CH3NO2

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Theoretical study of nitro–nitrite rearrangement of CH₃NO₂