Theoretical Study on the Mechanism of the CH₃OH + ·XH₃ (X = C, Si) Reactions
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Abstract
The mechanism for the reactions of methanol (CH₃OH) with ·XH₃ (X = C, Si) radicals have been investigated by ab initio molecular orbital theory based on the CCSD(T)//B3LYP/aug-cc-pVTZ method. For the CH₃OH + ·CH₃ reaction, the major product pathways channels are H-abstraction forming PR1 (·CH₂OH + ·CH₄; 0 kcal·mol⁻¹) and PR2 (·CH₂OH + CH₄; -8.1 kcal·mol⁻¹) via transition states TS1 and TS2 lying 12.0 and 12.8 kcal·mol⁻¹ above the reactants, respectively. While for the CH₃OH + ·SiH₃ reaction, the major product pathways channels are the H-abstraction forming PR7 (·CH₂OH + SiH₄; 3.4 kcal·mol⁻¹) and substitution channels forming PR8 (H + CH₃OSiH₃; -0.3 kcal·mol⁻¹) and PR9 (·CH₃ + SiH₃OH; -28.7 kcal·mol⁻¹) via transition states TS7 (16.2 kcal·mol⁻¹), TS8 (16.5 kcal·mol⁻¹) and TS9 (17.0 kcal·mol⁻¹), respectively. The predicted geometry parameters for the species in the PESs and the heats of reaction in this work are in good agreement with available experimental data.
Keywords
Reaction mechanism, silyl radical (·SiH₃), methyl radical (·CH₃), methanol (CH₃OH), PES
Article Details
References
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[3] C. Anastasi, D. U. Hancock, Reaction of CH₃ radicals with methanol in the range 525 < T/K < 603, J. Chem. Soc. Faraday Trans., 86 (1990), 2553–2555.
[4] T. W. Shannon, A. G. Harrison, The reaction of methyl radicals with methanol at high temperatures, Ber. Bunsenges. Phys. Chem., 93 (1989), 633–637.
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[6] S. L. Peukert, J. V. Michael, High-Temperature Shock Tube and Modeling Studies on the Reactions of Methanol with D-Atoms and CH₃-Radicals, J. Phys. Chem. A, 117 (2013), 10186–10195.
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[9] N. H. Thọ, N. X. Sáng, Động học phản ứng của gốc metyl với metanol, Tạp chí Khoa học Tự nhiên và Công nghệ, 34 (2018), 111–117.
[10] M. J. Frisch, G. W. Trucks, H. B. Schlegel, J. A. Pople, Gaussian, Inc., Pittsburgh PA, (2003).
[11] E. E. Baroody, G. A. Carpenter, Heats of formation of propellant compounds (U), Rpt. Naval Ordnance Systems Command Task No. 331-003/067-1/UR2402-001 for Naval Ordnance Station, Indian Head, MD, (1972), 1–9.
[12] H. B. Schlegel, Heats of Formation of Fluorine-Substituted Silylenes, Silyl Radicals, and Silanes, J. Phys. Chem., 88 (1984), 6254–6258.
[13] W. Tsang, Heats of Formation of Organic Free Radicals by Kinetic Methods in Energetics of Organic Free Radicals, Blackie Academic and Professional, London, (1996), 22–58.
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