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Theoretical study on the HACA chemistry of naphthalenyl radicals and acetylene: The formation of C 12 H 8 , C 14 H 8 , and C 14 H 10 species
Author(s) -
Chu TeChun,
Smith Mica C.,
Yang Jeehyun,
Liu Mengjie,
Green William H.
Publication year - 2020
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.21397
Subject(s) - chemistry , acenaphthylene , radical , acetylene , isomerization , hydrogen atom abstraction , computational chemistry , organic chemistry , catalysis , phenanthrene
The hydrogen‐abstraction‐C 2 H 2 ‐addition (HACA) chemistry of naphthalenyl radicals has been studied extensively, but there is a significant discrepancy in product distributions reported or predicted in literature regarding appearance of C 14 H 8 and C 14 H 10 species. Starting from ab initio calculations, a comprehensive theoretical model describing the HACA chemistry of both 1‐ and 2‐naphthalenyl radicals is generated. Pressure‐dependent kinetics are considered in the C 12 H 9 , C 14 H 9 , and C 14 H 11 potential energy surfaces including formally direct well‐skipping pathways. On the C 12 H 9 PES, reaction pathways were found connecting two entry points: 1‐naphthalenyl (1‐C 10 H 7 ) + acetylene (C 2 H 2 ) and 2‐C 10 H 7 + C 2 H 2 . A significant amount of acenaphthylene is predicted to be formed from 2‐C 10 H 7 + C 2 H 2 , and the appearance of C 14 H 8 isomers is predicted in the model simulation, consistent with high‐temperature experimental results from Parker et al. At 1500 K, 1‐C 10 H 7 + C 2 H 2 mostly generates acenaphthylene through a formally direct pathway, which predicted selectivity of 66% at 30 Torr and 56% at 300 Torr. The reaction of 2‐C 10 H 7 with C 2 H 2 at 1500 K yields 2‐ethynylnaphthalene as the most dominant product, followed by acenaphthylene mainly generated via isomerization of 2‐C 10 H 7 to 1‐C 10 H 7 . Both the 1‐C 10 H 7 and 2‐C 10 H 7 reactions with C 2 H 2 form some C 14 H 8 products, but negligible phenanthrene and anthracene formation is predicted at 1500 K. A rate‐of‐production analysis reveals that C 14 H 8 formation is strongly affected by the rates of H‐abstraction from acenaphthylene, 1‐ethynylnaphthalene, and 2‐ethynylnaphthalene, so the kinetics of these reactions are accurately calculated at the high level G3(MP2,CC)//B3LYP/6‐311G ** level of theory. At intermediate temperatures like 800 K, acenaphthylene + H are the leading bimolecular products of 1‐C 10 H 7 + C 2 H 2 , and 1‐acenaphthenyl radical is the most abundant C 12 H 9 isomer due to its stability. The predicted product distribution of 2‐C 10 H 7 + C 2 H 2 at 800 K, in contrast to the results of Parker et al is predicted to consist primarily of species containing three fused benzene rings—for example, phenanthrene and anthracene—as the leading products, indicating HACA chemistry is valid from two to three ring polycyclic aromatic hydrocarbons under some conditions. Further experiments are needed for validation.