HACA's Heritage: A Free-Radical Pathway to Phenanthrene in Circumstellar Envelopes of Asymptotic Giant Branch Stars
- Univ. of Hawaii, Honolulu, HI (United States). Dept. of Chemistry
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division
- Florida Intl Univ., Miami, FL (United States). Dept. of Chemistry and Biochemistry
- Samara National Research Univ. (Russian Federation). Dept. of Physics
The hydrogen-abstraction/acetylene-addition (HACA) mechanism has been central for the last decades in attempting to rationalize the formation of polycyclic aromatic hydrocarbons (PAHs) as detected in carbonaceous meteorites such as in Murchison. Nevertheless, the basic reaction mechanisms leading to the formation of even the simplest tricyclic PAHs like anthracene and phenanthrene are still elusive. Here, by exploring the previously unknown chemistry of the ortho-biphenylyl radical with acetylene, we deliver compelling evidence on the efficient synthesis of phenanthrene in carbon-rich circumstellar environments. However, the lack of formation of the anthracene isomer implies that HACA alone cannot be responsible for the formation of PAHs in extreme environments. Considering the overall picture, alternative pathways such as vinylacetylene-mediated reactions are required to play a crucial role in the synthesis of complex PAHs in circumstellar envelopes of dying carbon-rich stars.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of Hawaii at Manoa, Honolulu, HI (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division; Government of the Russian Federation
- Grant/Contract Number:
- AC02-05CH11231; FG02‐03ER15411; FG02‐04ER15570; 14.Y26.31.0020; FG02-03ER15411; FG02-04ER15570
- OSTI ID:
- 1464146
- Alternate ID(s):
- OSTI ID: 1376753; OSTI ID: 1602963
- Journal Information:
- Angewandte Chemie (International Edition), Vol. 56, Issue 16; Related Information: © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim; ISSN 1433-7851
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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