Direct Detection of Products from the Pyrolysis of 2-Phenethyl Phenyl Ether

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• 作者：Mark W. Jarvis ; John W. Daily ; Hans-Heinrich Carstensen ; Anthony M. Dean ; Shantanu Sharma ; David C. Dayton ; David J. Robichaud ; Mark R. Nimlos
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：February 3, 2011
• 年：2011
• 卷：115
• 期：4
• 页码：428-438
• 全文大小：453K
• 年卷期：v.115,no.4(February 3, 2011)
• ISSN：1520-5215

文摘

The pyrolysis of 2-phenethyl phenyl ether (PPE, C₆H₅C₂H₄OC₆H₅) in a hyperthermal nozzle (300鈭?350 掳C) was studied to determine the importance of concerted and homolytic unimolecular decomposition pathways. Short residence times (<100 渭s) and low concentrations in this reactor allowed the direct detection of the initial reaction products from thermolysis. Reactants, radicals, and most products were detected with photoionization (10.5 eV) time-of-flight mass spectrometry (PIMS). Detection of phenoxy radical, cyclopentadienyl radical, benzyl radical, and benzene suggest the formation of product by the homolytic scission of the C₆H₅C₂H₄鈭扥C₆H₅ and C₆H₅CH₂鈭扖H₂OC₆H₅ bonds. The detection of phenol and styrene suggests decomposition by a concerted reaction mechanism. Phenyl ethyl ether (PEE, C₆H₅OC₂H₅) pyrolysis was also studied using PIMS and using cryogenic matrix-isolated infrared spectroscopy (matrix-IR). The results for PEE also indicate the presence of both homolytic bond breaking and concerted decomposition reactions. Quantum mechanical calculations using CBS-QB3 were conducted, and the results were used with transition state theory (TST) to estimate the rate constants for the different reaction pathways. The results are consistent with the experimental measurements and suggest that the concerted retro-ene and Maccoll reactions are dominant at low temperatures (below 1000 掳C), whereas the contribution of the C₆H₅C₂H₄鈭扥C₆H₅ homolytic bond scission reaction increases at higher temperatures (above 1000 掳C).