Thermische Zerfallsreaktionen von Nitroverbindungen I: Dissoziation von Nitromethan

Abstract

Summary. The thermal dccornposition of CH,NO, highly dilutcd in Ar has been studicd in shock waves a t 900 < T < 1500 K and 1.5. mol/cm3. Concentration profiles of CH,NO, and NO, were rccordcd. The unimolecular rcaction was found to be in its falloff range. Limiting low pressure rate constants of k, = [Ar] . 1017.1 exp( -4Z(kcal/mol)/RT) cm3/ mol sec in the range 900 < T < 1400 K and limiting high pressure rate constants of k , = 1016.25 exp ( -(.58.5 + 0.5 kcal/mol)/RTj sec-l have been dcrivcd. A rate constant o f 1.3 . lo1, cm3/mol sec was found for the first subsequent rcaction CH,+ NO, -+ CH,O + XO.

Nitromethane dissociation: Implications for the CH3 + NO2 reaction

“…The more recent of these studies, most of which involve detailed chemical kinetic modeling, indicate that the pyrolysis chemistry of nitromethane is much more complex than assumed by Glänzer and Troe, with secondary reactions consuming a major fraction of both CH 3 NO 2 and NO 2 . The two recent shock tube studies by Zaslonko et al [26] and by Zhang and Bauer [27] are consistent with the high and low pressure limit rate constants for (R1) determined by Glänzer and Troe [9]. However, Zhang and Bauer [27] point out that a redetermination of the rate constant for reaction (R14) should be undertaken.…”

“…These experiments, which covered the temperature range were interpreted in 1000 -1400 K, terms of a simplified reaction mechanism involving only reactions (R1) and (R14). The rate coefficients proposed by Glänzer and Troe [9,10] for CH 3 NO 2 dissociation (R1) and for reaction (R14) have largely been supported by subsequent work and have remained unchallenged. The rate constant reported by Glänzer and Troe [10] for the disproportionation step, cm 3 is in 13 Ϫ1 Ϫ1 k ϭ 1.3 · 10 mol s (1100 -1400 K), 14 good agreement with concurrent values of approximately cm 3 obtained at room tem-13 Ϫ1 Ϫ1…”

“…Nitromethane and other energetic materials are of interest as propellant fuels, and in addition to the work of Glänzer and Troe [9,10] numerous studies on nitromethane decomposition have been reported [13 -27] as part of an attempt to characterize and understand the chemistry of pure solid explosives. The more recent of these studies, most of which involve detailed chemical kinetic modeling, indicate that the pyrolysis chemistry of nitromethane is much more complex than assumed by Glänzer and Troe, with secondary reactions consuming a major fraction of both CH 3 NO 2 and NO 2 .…”

“…The rate constants for the disproportionation step (R14) and for CH 3 NO 2 dissociation (R1) have been determined from shock tube experiments on decomposition of highly diluted nitromethane by Glänzer and Troe [9,10]. These experiments, which covered the temperature range were interpreted in 1000 -1400 K, terms of a simplified reaction mechanism involving only reactions (R1) and (R14).…”

Vibrational energy transfer and pyrolysis of nitromethane by the variable-encounter method

“…A large amount of work [1][2][3][4][5][6] has been devoted to the study of the kinetics and mechanism of the thermal decomposition of nitromethane. However, virtually no attention has been paid to the study of vibrational energy transfer involving this species.…”