کد مقاله کد نشریه سال انتشار مقاله انگلیسی ترجمه فارسی نسخه تمام متن
12174274 905645 1998 8 صفحه PDF سفارش دهید دانلود کنید
عنوان انگلیسی مقاله ISI
Pyrolysis of cyclopentadiene: Rates for initial C−H bond fission and the decomposition of c-C5H5
موضوعات مرتبط
مهندسی و علوم پایه مهندسی انرژی مهندسی انرژی و فناوری های برق
پیش نمایش صفحه اول مقاله
Pyrolysis of cyclopentadiene: Rates for initial C−H bond fission and the decomposition of c-C5H5
چکیده انگلیسی
The pyrolysis of cyclopentadiene has been observed in shock waves with two complementary methods: time-of-flight mass spectrometry (TOFMS) and laser-schlieren (LS) densitometry. Experiments, encompassed the ranges 100-450 Torr and 1500-2500 K. The low-temperature LS experiments show brief, early maxima indicative of chain reaction initiated by C−H fission. Precise and consistent rate constants are obtained from both experiments for this reaction, and a very good Rice-Ramsperger-Kassel-Marcus (RRKM) fit is possible with standard parameters. The result is a barrier of 84±2 kcal/mol for C−H fission and a consequent ΔfHo298=65.3 kcal/mol for c-C5H5 radical Rate constants are also estimated for the important secondary reaction c-C5H5→C3H3+C2H2. These are also successfully RRKM-modeled with the aid of high-level density-functional calculations of the transition state for the 1,2 H-atom shift that controls the rate of this reaction. The large rates for this are shown to be a consequence of a newly calculated low barrier of 61.9 kcal/mol and a 10-fold reaction path degeneracy that arises from a facile pseudorotation in this Jahn-Teller molecule. The experiments and model reported here provide the first quantitative evidence for the H-atom shift mechanism for this reaction.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Symposium (International) on Combustion - Volume 27, Issue 1, 1998, Pages 143-150
نویسندگان
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