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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Elucidating the decomposition mechanism of energetic materials with geminal dinitro groups using 2-bromo-2-nitropropane photodissociation
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Elucidating the decomposition mechanism of energetic materials with geminal dinitro groups using 2-bromo-2-nitropropane photodissociation

机译：用2-溴-2-硝基丙烷光解离阐明含双硝基二元基的高能材料的分解机理

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摘要

These experiments photolytically generate two key intermediates in the decomposition mechanisms of energetic materials with nitro substituents, 2-nitropropene, and 2-nitro-2-propyl radicals. These intermediates are produced at high internal energies and access a number of competing unimolecular dissociation channels investigated herein. We use a combination of crossed laser-molecular beam scattering and velocity map imaging to study the photodissociation of 2-bromo-2-nitropropane at 193 nm and the subsequent unimolecular dissociation of the intermediates above. Our results demonstrate that 2-bromo-2-nitropropane has four primary photodissociation pathways: C-Br bond fission yielding the 2-nitro-2-propyl radical, HBr elimination yielding 2-nitropropene, C-N bond fission yielding the 2-bromo-2-propyl radical, and HONO elimination yielding 2-bromopropene. The photofragments are formed with significant internal energy and undergo many secondary dissociation events, including the exothermic dissociation of 2-nitro-2-propyl radicals to NO + acetone. Calculations at the G4//B3LYP/6-311++g(3df,2p) level show that the presence of a radical at a nitroalkyl center changes the mechanism for and substantially lowers the barrier to NO loss. This mechanism involves an intermediate with a three-center ring rather than the intermediate formed during the traditional nitro-nitrite isomerization. The observed dissociation pathways of the 2-nitro-2-propyl radical and 2-nitropropene help elucidate the decomposition mechanism of larger energetic materials with geminal dinitro groups.
机译：这些实验在具有硝基取代基的高能材料的分解机理中，通过光解生成了两个关键中间体，即2-硝基丙烯和2-硝基-2-丙基。这些中间体以高内能产生，并进入本文研究的许多竞争性单分子解离通道。我们使用交叉激光分子束散射和速度图成像的组合来研究2-溴-2-硝基丙烷在193 nm处的光解离，以及随后的上述中间体的单分子解离。我们的结果表明2-溴-2-硝基丙烷具有四个主要的光解离途径：C-Br键裂变产生2-硝基-2-丙基自由基，HBr消除产生2-硝基丙烯，CN键裂变产生2-溴-2 -丙基和HONO消除生成2-溴丙烯。形成的光碎片具有显着的内部能量，并经历许多次要的离解事件，包括将2-硝基-2-丙基自由基放热分解为NO +丙酮。在G4 // B3LYP / 6-311 ++ g（3df，2p）水平上的计算表明，在硝基烷基中心存在自由基会改变机理，并大大降低了NO损失的障碍。该机理涉及具有三中心环的中间体，而不是传统的亚硝酸盐异构化过程中形成的中间体。观察到的2-硝基-2-丙基自由基和2-硝基丙烯的解离途径有助于阐明具有双二硝基基团的较大含能材料的分解机理。

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