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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Contrasting Photolytic and Thermal Decomposition of Phenyl Azidoformate: The Curtius Rearrangement Versus Intramolecular C-H Amination
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Contrasting Photolytic and Thermal Decomposition of Phenyl Azidoformate: The Curtius Rearrangement Versus Intramolecular C-H Amination

机译：对比光解和苯基的热分解壬酸酯：Curtius重排与分子内C-H胺化

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摘要

The decomposition of phenyl azidoformate, PhOC(O)N-3, was studied by combining matrix isolation spectroscopy and quantum chemical calculations. Upon UV laser photolysis (193 and 266 nm), the azide isolated in cryogenic noble gas matrices (Ne and Ar, 2.8 K) decomposes into N2 and a novel oxycarbonylnitrene PhOC(O)N, which was identified by matrix-isolation IR spectroscopy (with 15N labeling) and EPR spectroscopy (vertical bar D/hc vertical bar = 1.620 cm(-1) and IE/hcl = 0.024 cm(-1)). Subsequent visible-light irradiation (532 nm) causes rearrangement of the nitrene into phenoxy isocyanate PhONCO with complex secondary fragmentation (PhO center dot + center dot NCO) and radical recombination species in matrices. The observation of PhONCO provides solid evidence for the Curtius rearrangement of phenyl azidoformate. In sharp contrast, flash vacuum pyrolysis (FVP) of PhOC(O)N-3 at 550 K yields N-2 and exclusively the intramolecular C-H amination product 3H-benzooxazol-2-one. FVP at higher temperature (700 K) leads to further dissociation into CO2, HNCO, and ring-contraction products. To account for the very different photolytic and thermal decomposition products, the underlying mechanisms for the Curtius rearrangement (concerted and stepwise) of PhOC(O)N-3 and the intramolecular C-H amination of the nitrene in both singlet and triplet states are discussed with the aid of quantum chemical calculations using the B3LYP, CBS-QB3, and CASPT2 methods.
机译：通过组合基质分离光谱和量子化学计算来研究苯基壬酸苯基丙酯，PHOC（O）N-3的分解。在UV激光光解（193和266nm）时，在低温惰性气体基质（NE和Ar，2.8k）中分离的叠氮化物分解成N 2和新的氧化羰基硝基PHOC（O）N，其通过基质隔离IR光谱鉴定（具有15N标记）和EPR光谱（垂直条D / HC垂直杆= 1.620cm（-1）和IE / HCl = 0.024cm（-1））。随后的可见光照射（532nm）导致硝酸硝酸苯氧乙烯与基质中复合二次碎裂（PHO中心点+中心点NCO）和自由基重组物种重新排列成苯氧异氰酸酯寄粥。 Phonco的观察为苯基吡吡甲酸苯基的凝避重排提供了坚实的证据。在鲜明的对比度下，PHOC（O）N-3的闪光真空热解（FVP）在550k下产生N-2，仅为分子内C-H胺化产物3H-苯并恶唑-2-一体。在较高温度下（700 k）的FVP导致进一步解离CO 2，HNCO和铃声产物。为了考虑非常不同的光溶解和热分解产物，讨论了PHOC（O）N-3和硝基在单态和三重态态中硝基的分子内CH胺化的底层重排（互相）的下面机制使用B3LYP，CBS-QB3和CASPT2方法辅助量子化学计算。

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