Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm
| Autor: | Stephen J. Klippenstein, David H. Bross, Andreas V. Copan, Daniel P. Zaleski, Sarah N. Elliott, Branko Ruscic, Nathan A. Seifert, Lawrence B. Harding, Kevin B. Moore, Hailey R. Weller, Kirill Prozument, Robert W. Field, Raghu Sivaramakrishnan |
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| Rok vydání: | 2021 |
| Předmět: |
Substitution reaction
Chemistry Ab initio Ketene General Chemistry 010402 general chemistry Propyne 01 natural sciences Biochemistry Catalysis 0104 chemical sciences chemistry.chemical_compound Transition state theory Colloid and Surface Chemistry Reaction rate constant Computational chemistry Thermochemistry Rotational spectroscopy |
| Zdroj: | Journal of the American Chemical Society. 143:3124-3142 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/jacs.0c11677 |
| Popis: | The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations. Broadband rotational spectroscopy offers quantitative and isomer-specific detection by which branching ratios of polar reaction products may be obtained. Using this technique, we observe and characterize products arising from H atom substitution reactions in the flash pyrolysis of acetone (CH3C(O)CH3) at a nominal temperature of 1800 K. The major product observed is ketene (CH2CO). Minor products identified include acetaldehyde (CH3CHO), propyne (CH3CCH), propene (CH2CHCH3), and water (HDO). Literature mechanisms for the pyrolysis of acetone do not adequately describe the minor products. The inclusion of a variety of substitution reactions, with rate constants and thermochemistry obtained from automated ab initio kinetics predictions and Active Thermochemical Tables analyses, demonstrates an important role for such processes. The pathway to acetaldehyde is shown to be a direct result of substitution of acetone's methyl group by a free H atom, while propene formation arises from OH substitution in the enol form of acetone by a free H atom. |
| Databáze: | OpenAIRE |
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