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A Free‐Radical Pathway to Hydrogenated Phenanthrene in Molecular Clouds—Low Temperature Growth of Polycyclic Aromatic Hydrocarbons
Author(s) -
Thomas Aaron M.,
Lucas Michael,
Yang Tao,
Kaiser Ralf I.,
Fuentes Luis,
BelisarioLara Daniel,
Mebel Alexander M.
Publication year - 2017
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201700515
Subject(s) - coronene , phenanthrene , murchison meteorite , chemistry , phenanthrenes , anthracene , photochemistry , biphenyl , triphenylene , aryne , polycyclic aromatic hydrocarbon , organic chemistry , astrobiology , meteorite , molecule , physics , chondrite
Abstract The hydrogen‐abstraction/acetylene‐addition mechanism has been fundamental to unravelling the synthesis of polycyclic aromatic hydrocarbons (PAHs) detected in combustion flames and carbonaceous meteorites like Orgueil and Murchison. However, the fundamental reaction pathways accounting for the synthesis of complex PAHs, such as the tricyclic anthracene and phenanthrene along with their dihydrogenated counterparts, remain elusive to date. By investigating the hitherto unknown chemistry of the 1‐naphthyl radical with 1,3‐butadiene, we reveal a facile barrierless synthesis of dihydrophenanthrene adaptable to low temperatures. These aryl‐type radical additions to conjugated hydrocarbons via resonantly stabilized free‐radical intermediates defy conventional wisdom that PAH growth is predominantly a high‐temperature phenomenon and thus may represent an overlooked path to PAHs as complex as coronene and corannulene in cold regions of the interstellar medium like in the Taurus Molecular Cloud.