Unimolecular Dissociation in Allene and Propyne: The Effect of Isomerization on the Low-Pressure Rate
Unimolecular Dissociation in Allene and Propyne: The Effect of Isomerization on the Low-Pressure Rate
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丙二烯和丙炔的单分子解离：异构化对低压速率的影响
DOI：
10.1021/jp963314a
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
H. Chen
中科院分区：
文献类型：
--
作者：
J. Kiefer;P. S. Mudipalli;S. Sidhu;R. D. Kern;B. Jursic;K. Xie;H. Chen
用 激光纹影和飞行时间质谱仪两种互补激波管技术研究了C3H4同分异构体丙烯和丙炔的单分子解离。LS实验涵盖1800−2500K和70−650Torr，在1，2和4%丙炔/Kr和1和2%丙烯/Kr中，而在3%丙烯或丙炔中，飞行时间实验结果从1770和2081K扩展。用新的密度泛函理论计算了C3H4同分异构体体系中可能的单分子解离通道，并用新的密度泛函理论计算了几个C3H2插入H2的势垒，以评估作为解离途径消除H2的可能性。主要途径显然仍然是CH裂变，从任何一个异构体，如早期的工作所建议的，尽管一些少量的H2可能从联烯中消除。丙烯和丙炔的CH裂解速率常数是由通常的模型辅助外推到零时间，使用广泛的机理构造得到的。
The unimolecular dissociation of the C3H4 isomers allene and propyne has been examined using two complementary shock-tube techniques: laser schlieren (LS) and time-of-flight (TOF) mass spectrometry. The LS experiments cover 1800−2500 K and 70−650 Torr, in 1, 2, and 4% propyne/Kr and 1 and 2% allene/Kr, whereas the TOF results extend from 1770 and 2081 K in 3% allene or propyne in Ne. The possible channels for unimolecular dissociation in the C3H4 system of isomers are considered in detail, using new density functional theory calculations of the barriers for insertion of several C3H2 into H2 to evaluate the possibility of H2 elimination as a dissociation route. The dominant path clearly remains CH fission, from either isomer, as suggested in earlier work, although some small amount of H2 elimination may be possible from allene. Rate constants for the CH fission of both allene and propyne were obtained by the usual model-assisted extrapolation of LS profiles to zero time using an extensive mechanism constr...